Review Article Recent Developments in Environmental ... · Some of these organic pollutants eventually contaminate groundwater and surface waters; however, groundwater contamination

Review ArticleRecent Developments in Environmental PhotocatalyticDegradation of Organic Pollutants The Case of TitaniumDioxide NanoparticlesmdashA Review

Mphilisi M Mahlambi1 Catherine J Ngila1 and Bhekie B Mamba2

1Department of Applied Chemistry University of Johannesburg PO Box 17011 Doornfontein 2028 South Africa2Nanotechnology and Water Sustainable Unit College of Science Engineering and Technology University of South AfricaFlorida Campus Johannesburg 17025 South Africa

Correspondence should be addressed to Mphilisi M Mahlambi mmahlambiyahoocouk

Received 29 April 2015 Revised 29 July 2015 Accepted 5 August 2015

Academic Editor Xin Zhang

Copyright copy 2015 Mphilisi M Mahlambi et al This is an open access article distributed under the Creative Commons AttributionLicense which permits unrestricted use distribution and reproduction in any medium provided the original work is properlycited

The presence of both organic and inorganic pollutants in water due to industrial agricultural and domestic activities has led to theglobal need for the development of new improved and advanced but effective technologies to effectively address the challenges ofwater quality It is therefore necessary to develop a technology which would completely remove contaminants from contaminatedwaters TiO

2(titania) nanocatalysts have a proven potential to treat ldquodifficult-to-removerdquo contaminants and thus are expected to

play an important role in the remediation of environmental and pollution challenges Titania nanoparticles are intended to beboth supplementary and complementary to the present water-treatment technologies through the destruction or transformationof hazardous chemical wastes to innocuous end-products that is CO

2and H

2O This paper therefore explores and summarizes

recent efforts in the area of titania nanoparticle synthesis modifications and application of titania nanoparticles for water treatmentpurposes

1 Introduction

The South African National Water Act (Act number 36 of1998) specifically states that water resources must remain fitfor use on a sustainable basis and that their quality must beconstantly monitored [1] Therefore the availability of watershould be based not only on the quantity but also on the qual-ity of the available water [2] However due to agriculturalindustrial and domestic activities the quality of river wateror groundwater continues to deteriorate due to pollution byhazardous materials [3 4] Water pollution is defined as thedirect or indirect introduction of substances into the waterbodies These pollutants may be harmful to human healthor the quality of aquatic ecosystems thus affecting the use ofamenities and other legitimate uses of water [1]

The sources of water pollution are categorised as eithera point source or nonpoint source (diffuse sources) Pointsource water pollution occurs when the polluting substance

is emitted directly into the water system for example a pipethat spews sewage directly into a river while nonpoint source(NPS) pollution refers to diffuse contamination which occurswhen pollutants enter a water system through runoff forexample when fertiliser is washed into a river by surfacerunoffs Water pollutants can be classified as physical (odourcolour solids or temperature) biological (pathogens) orchemical (organic or inorganic compounds) [1 2 5ndash9]Organic pollutants are of more concern than the other typesbecause of their carcinogenic andmutagenic effects even afterexposure to minute concentrations [10 11]

11 Organic Pollutants Organic contaminants have becomeof more concern due to the inability of conventionalwater-treatment technologies to completely decompose thesecontaminants in aqueous media [12 13] The ubiquitousappearance of organic contaminants in sewage effluentsgroundwater drinking water and sludge poses a significant

Hindawi Publishing CorporationJournal of NanomaterialsVolume 2015 Article ID 790173 29 pageshttpdxdoiorg1011552015790173

2 Journal of Nanomaterials

threat to humans and aquatic organisms [14] Volatile organiccompounds (VOCs) are known to be toxic and carcinogenicand have been implicated in the depletion of the stratosphericozone layer while also contributing to global warming [1015] These pollutants have been reported as being mutagenicand hence are responsible for the emergence of antibioticresistance bacteria and genes [16]

Some organic pollutants are referred to as persistentorganic pollutants (POPs) because when they enter theenvironment they do not readily break down and mayremain there for very long periods of time for examplepolychlorinated biphenyls (PCBs) and may enter the foodchains and accumulate to levels detrimental to organisms thatare high up in the food chain [17] Also organic pollutantsare a serious threat because they can be transported fromthe source of contamination through air as vapour or asdust particles by water currents or sediments and releasedin a new environment [17] Some of these organic pollutantseventually contaminate groundwater and surface watershowever groundwater contamination is likely to be theprimary source of human contact with these toxic chemicals[18] Generally exposure to organic contaminants could bethrough breathing through ingestion through drinking orby skin contact

12 Natural Organic Matter Natural organic matter (NOM)is an agglomeration of organic compounds that naturallyoccur when animal and plant material break down [19ndash21]NOM consists of a wide range of compounds with diversechemical properties (due to geographic origin and age ofthe decomposing organism) and occurs in all natural watersources [20 22 23] NOM components are a heterogeneousmixture of complex organic materials which consists of bothhydrophilic and hydrophobic components The hydrophiliccomponents are microbial by-products and contain a higherproportion of aliphatic carbon and nitrogenous compoundswith relatively high charge density such as amino acidsand proteins as well as polysaccharides [22 24 25] Humicsubstances (HS) constitute the more hydrophobic fractionof NOM and exhibit relatively high specific ultravioletabsorbance (SUVA) values due to the presence of a relativelylarge proportion of aromatic carbon phenolic structures andconjugated double bonds [5 19 21 22 24 25]

Due to the complexity of NOM no single tool can give itsdefinitive structural or functional information Nondestruc-tive spectroscopic techniques appear to be the most usefulanalytical techniques for NOM characterisation [20] Treat-ment options for the removal of NOM include coagulationthe use of magnetic ion-exchange resins activated carbonmembrane filtration and advanced oxidation processes [22]Characterisation of the structure and reactivity of NOM isvital because its presence creates problems in the quality ofdrinking water as well as in water-treatment processes [2026] The presence of NOM results in an increased coagulantand disinfectant dosage resulting in increased sludge It alsoincreases biological growth in water-distribution networksand may also result in increased levels of heavy metal com-plexes and adsorbed organic pollutants [22] Furthermorethe presence of NOM causes membrane fouling as well as

aesthetic and malodour problems in water The organic acidsthat result from the oxidation of NOM have the capabilityto corrode turbines and engineering systems and this affectstransportation of contaminants [19 22 27 28] Thus under-standing the impact of NOM in water-treatment processes isvital for human health and water-treatment plants as well asindustrial processes where pure water is a prerequisite

13 Disinfection By-Products In the water-treatment pro-cesses NOM may have adverse effects since it may reactwith disinfectants (eg chlorine or chloramines) resultingin the formation of disinfection by-products (DBPs) manyof which are either carcinogenic or mutagenic [5 25 2629] For example haloacetic acids (HAAs) are a componentof DBPs that are considered harmful to human healthThese have been found to result in impaired reproductiveand developmental retardation when tested on laboratoryanimals [24 30ndash33] Also trihalomethanes (THMs) havebeen classified as possible carcinogens to humans [30 32 3435] Nitrosamines are another group of DBPs formed dueto the reaction of NOM with disinfectants that have beenreported to be a threat to human life due to its carcinogenicity[32 36ndash38]

14 Industrial Effluents Industrial development is directlyrelated to the release of various toxic pollutants into the envi-ronment especially to aqueous streams and these pollutantsare harmful and hazardous to the environment [12 39ndash41]Prevention of industrial pollution is currently a major focusof environmentalists and therefore treatment of industrialeffluents before disposal into the ecosystem is imperativeto protect human life and environmental quality [3 4042] Thus a constant effort to protect water resources isbeing made by various government and nongovernmentalorganisations (eg US EPA WHO and DWAF) through theintroduction of increasingly strict legislation covering pollu-tant release into the environment with particular emphasison liquid industrial effluents [5 40 43 44] There are majortypes of industries in the industrial complex for examplepulp and paper mills food pharmaceutical electroplatingtextile photographic mining and agriculture to mentionjust a few which do not generate uniform waste streamsindustrial effluents are complex mixtures of chemical andbiological compositions that have various environmentalimpacts depending on the source of the toxicant [45 46]

141 Textile Industry Effluents Textile-processing industriesform the economic backbone of most developing countriesEffluents from textile industries are characterised by a varietyof chemicals generated from the dyeing bleaching andwashing processes [47 48] Wastewaters discharged fromtextile industries are a serious environmental threat due totheir characteristic high colour fluctuating pH malodourhigh biological oxygen demand (BOD) and chemical oxygendemand (COD) acids and alkalis as well as various heavymetals that breach environmental standards [48ndash50] Dyesare soluble in water and even a small amount of dye is highlyvisible and reduces the transparency of water bodies [49 51]

Journal of Nanomaterials 3

Table 1 Molecular structure and chemical properties of Rhodamine B [6 52ndash54]

Molecular structure Chemical properties

Rhodamine B

H3CH2C

CH2CH3

COOH

CH2CH3

CH2CH3

NClminusON+

ClassChemical formulaMolecular weight

UV absorption maximum

TriphenylmethaneC28H31ClN2O3

47902 gsdotmolminus1553 nm

Also dyes can bemutagens and carcinogens [49 50] and thusthey need to be removed from industrial effluents

It is estimated that about 1 to 20 of the total worldproduction of dyes is lost to the environment during syn-thesis and dyeing processes These textile effluents are anenvironmental burden as they contain a large amount ofazoic anthraquinonic and heteropolyaromatic dyes [6 50]The discharge of these highly pigmented synthetic dyes tothe ecosystem causes aesthetic pollution eutrophication andperturbations in aquatic life as they hinder light penetrationresulting in decreased photosynthesis [48 49 51] Thereforetextile wastewaters need to be treated to acceptable levels tomeet the national discharge standard before being dischargedto the environmental ecosystem

142 Rhodamine B Rhodamine B (Rh B) is a type oftriphenylmethane dyes Triphenylmethane (TPM) dyes areextensively used in textile printing food photographic andcosmetic industries [52] TPM dyes can persist for long peri-ods in the aquatic environment because they are resistant tochemical and biological (bacterial) attacks Rh B is a commondye in the TPM family which contains four (4) N-ethylgroups at either side of the xanthene rings (Table 1) It hasachieved its prominent use due to its good stability as a lasermaterial and is one of the major sources of pollution in thetextile and photographic industry effluent streams [53] Alsoalthough Rhodamine B is a highly phosphorescent (fluores-cent) dye its toxicity is not dependent on the synergic effectof visible light [52 54] As a dye in the TPM family (ie azoicanthraquinonic and heteropolyaromatic dyes) the presenceof Rh B in the ecosystem causes aesthetic pollution eutroph-ication and perturbations in aquatic life [6 50 52 53]

143 Other Industrial Effluents Other sources of industrialpollution are from surface treatment (mechanical and chem-ical surface-finishing processes) thermal power stationsand agricultural activities to name but a few Effluentsoriginating from surface-treatment processes contain bothorganic and metal pollution from the washing and rinsingof process baths [43] Fly ash is the by-product of combus-tion in thermal power plants using coal and lignite and ismainly used as landfills [39] However studies to charac-terise leachate originating from these landfills have indicated

that leachates contain hazardous pollutants like arsenidesPCBs and sulfanilamides [14 16 55 56] Commonly usedpesticides from agricultural activities (either domestic orlarge commercial scale) have high recalcitrant organic groupsand hence are extremely difficult to break down throughnormal degradation [2 38 42 57] Also the use of nitrogen-containing fertilisers causes acidification and eutrophicationof ecosystems due to leaching [44 58 59] These nitrogen-containing pollutants from agricultural activities are usuallyintermediates to the formation of refractory organic pollu-tants [44]

2 Refractory Organic Pollutants

Degradation of refractory organic pollutants is a challengebecause these pollutants cannot be degraded using thecurrent water-treatment technologies They are resistant toaerobic microbial degradation in conventional biologicaltreatment processes and the natural environment [44 60 61]High-molecular-weight organics are the typical refractorypollutantsThe presence of refractory pollutants in industrialwastewaters causes problems in the water-treatment system[46] These pollutants cause biomass poisoning and die-offin conventional biological water-treatment systems Othertechniques such as flocculation precipitation or reverseosmosis require posttreatment to dispose of the pollutantswhile the use of chemical techniques either fails to adequatelyremove these organic pollutants or results in the formation ofDBPs [28 33 36 44 62]

Current water-treatment technologies are designed todeal with either organic or inorganic pollutants in an aqueousmedium but not both In addition due to the diversityand varying chemical properties of organic pollutants thesetechnologies fail to remove pollutants to the required lev-els Furthermore the presence of NOM in water-treatmentprocesses may have adverse effects since it may react withdisinfectants (eg chlorine or chloramines) and result in theformation of DBPsTherefore the development of techniquesthat can remove both contaminants simultaneously withoutthe production of DBPs would be ideal Nanocatalysts haveshown the ability to cost-effectively mineralise recalcitrantorganic pollutants and reduce metal ions in aqueous mediaproducing innocuous products that is H

2O and CO

2 and


zero-valent metals respectivelyThe approaches that we haveundertaken in our laboratories in an attempt to address theseproblems are also described in this review

3 Advanced Oxidation Processes (AOPs)

Due to the aforementioned limitations of the conventionalwater-treatment methods there is an ongoing research inter-est to develop more efficient and environmentally friendlysystems for the treatment of recalcitrant organic pollutantsAdvanced oxidation processes (AOPs) have demonstratedthe capability to develop such a green system AOPs providean effective remediation for the treatment of water since theyhave the ability to completely degrade a variety of organicpollutants oxidise heavy metals and destroy microbialsubstances Advanced oxidation processes exploit the highreactivity of hydroxyl radicals as the oxidation driving forceresulting in the formation of benign by-products (ie H

2O

and CO2) hence they are environmentally friendly [41 63ndash

67]

31 Supercritical Water Oxidation Supercritical water oxida-tion (SCWO) is a technique that has been proven to destroyhighly persistent organic pollutants without the productionof harmful products SCWO reactions are carried out abovethe critical point of water (374∘C and 221MPa) and at thispoint the volume of water is three times higher than at roomtemperature with a density of 0322 gsdotmLminus1 and a dielec-tric constant of 53 [68ndash71] A homogeneous single phaseresults when oxygen and organic compounds are dissolvedin supercritical water [69 71 72] SCWO has been studied inthe degradation of nitrogenated compounds (eg pyridineaniline nitrobenzene and ammonia) phenolic compoundsand radioactive wastes [70]

SCWO is regarded as an environmentally friendly pro-cess because not only does it produce CO

2and H

2O during

oxidation but also none of the NO119909and SO

119909compounds

are produced due to the relatively mild operating conditions(340∘C to 400∘C and 2229MPa to 2533MPa) [69 71] How-ever during the degradation of halogenated hydrocarbonsthe SCWOprocess is subject to corrosion problems due to theformation of acidic conditions aswell as fouling problems dueto the utilisation of neutralising processes and these are themajor obstacles that have led to the noncommercialisation ofSCWO [71 73]

32 Wet Oxidation Wet oxidation also referred to as wet airoxidation (WAO) is used to oxidise organic and inorganicsubstances in either suspension or solution forms in thepresence of an oxidant (water or air) at elevated temperatureand pressure [44 61 74] WAO technology has a highpotential for the treatment of effluents containing a highcontent of organic matter andor hazardous materials forwhich biological treatment is not feasible [44] In WAOtechnology the organic pollutants are either partially oxidisedinto biodegradable intermediate products with lowmolecularweights or completely mineralised to water carbon diox-ide and innocuous end-products at temperatures rangingbetween 125∘Cand 320∘Cand at pressures of between 05MPa

and 200MPa in the aqueous phase [44 59] The mechanismofwet oxidation seems to take place bymeans of a free radicalHowever WAO is only effective for aliphatic and aromaticcompounds that do not have halogenated groups Moreoverinvestment andoperation costs ofWAOplants are not feasibledue to excessive temperatures and pressures while treatmentof effluents containing refractory organic pollutants wouldfurther escalate the operating costs [75 76]

33 Electrochemical Oxidation Electrochemical oxidationprocesses employ an electrochemical cell to generate oxidis-ing species which are used to destroy organic pollutants atambient temperatures [60 77ndash79] The mechanism of elec-trochemical oxidation involves three stages which are elec-trocoagulation electroflotation and electrooxidation [79]

RH minuseminus

997888997888997888rarr RH+

RH+ minusH+

997888997888997888rarr R∙

R∙ + R∙ 997888rarr R minus R

(1)

Electrochemically organic pollutants can be oxidised eitherdirectly or indirectly In direct anodic oxidation the pollu-tants are adsorbed on the anode before being destroyed bythe oxidising species (mediator ions) produced at the anodewhile indirect electrochemical oxidation makes use of strongoxidising agents and the pollutants are oxidised in the bulksolution [77ndash79] Although electrochemical oxidation pro-cesses offer an environmentally friendly prospect the processis economically not viable due to high energy consumptionFurthermore fouling of the electrodes has been observed dueto either the deposition of oligomers formed during phenoloxidation or radical combination as an effect of pH [60 80]

34 Photolysis In photolysis a chemical compound absorbsradiation energy is elevated to a state of higher energy andan excited state and produces radicals that carry out thephotochemical reactions The source of radiation is eithersolar energy or low and medium-pressure mercury lamps[27 33 81 82] In photolysis the hydroxyl compounds aregenerated by water splitting

H2O ℎ]997888rarr H∙ +OH∙ (2)

These radicals then react with the organic pollutant splittingit to smaller and more bioavailable compounds [27] How-ever photolysis is a poor source of radicals and the radicalsproduced are not efficient enough to fully degrade refractorypollutants due to slow reaction kinetics observed in photoly-sis [8] To accelerate these photochemical processes metallicsalts called semiconductors which act as catalysts to speed upthe photochemical processes need to be added giving rise tothe so-called advanced oxidation processes [8 83ndash85]

4 Semiconductor Photocatalysis

41 Introduction Interest in semiconductor photocatalysishas recently risen exponentially because of the potential and


Table 2 Band gap energies of some semiconductor photocatalysts[8 52 89]

PhotocatalystBand gapenergy(eV)


Si 11 SiC 30WSe2 12 TiO

2rutile 302

120572-Fe2O3 22 Fe

2O3 31

CdS 24 TiO2anatase 32

NaBiO3 262 ZnO 32

V2O5 27 SrTiO

3 34B2WO6 278 SnO

2 35WO3 28 ZnS 37

opportunities it offers in a variety of fields These includetreatment of environmental pollution biotissue generationand biosensors medicine (destruction of cancer and viruses)and pharmaceutical industries [7 18 86ndash90] The majoradvantages of semiconductor photocatalysis are that it offersa good substitute for the energy-intensive treatment methodsand has the capacity to use renewable and pollution-free solarenergy Also unlike the conventional treatment methodswhich not only transfer pollutants from one medium toanother but also transform those to more refractory pollu-tants semiconductor photocatalysis converts contaminantsto innocuous products such as CO

2and H

2O Furthermore

the reaction conditions are mild and the reaction time ismodest and can be applied to aqueous gaseous and solid-phase treatments with the possibility of being both sup-plementary and complementary to the present technologies[8 18 52 83 87 88] Semiconductor photocatalysts thereforehave the advantage of not only minimising running costs butalso generating the desired product in the most efficient andeffective way

42 Properties of Semiconductor Photocatalysts The definingproperty of a good semiconductor photocatalyst material isthat the core element making up the material can reversiblychange its valence state to accommodate a hole withoutdecomposing the semiconductor (eg Ti3+ rarr Ti4+ in non-stoichiometric TiO

2) [8 18 91] The photogenerated holes

should be highly oxidizing to produce hydroxyl radicals(∙OH) and the photogenerated electrons should be reducingenough to produce superoxides from the oxygen [92] Alsothe element should have more than one stable valence in thesemiconductor so that it is not decomposed (photocorrosion)by the formation of holes (eg Zn2+ in ZnO and Cd2+ in CdSare photocorroded by the formation of holes) [8 18 93ndash95]Furthermore the semiconductor must have a suitable bandgap which is highly stable to chemical corrosion nontoxicand generally of low cost [8 18 92 93 96 97] The band gapenergies of some semiconductor photocatalysts are shown inTable 2

43 Mechanism of Photocatalysis Semiconductor photocata-lysts do not have a continuum of electronic states like metals

but they have a void region that extends from the top ofthe highest occupied molecular orbital (HOMO) that is thevalence band (VB) to the bottom of the lowest unoccupiedmolecular orbital (LUMO) which is also referred to as theconduction band (CB)This void region is called the band gap(119864119892) [8 18 98ndash100] When the semiconductor is illuminated

with light it absorbs a photon (ℎ]) andwhen the energy of thephoton is equal to or exceeds the band gap energy an electron(ecbminus) is promoted from the VB to the CB leaving a hole

(hvb+) in the VB (Figure 1) [2 18 99ndash101] The electron-hole

pair then migrates to the surface of the photocatalyst whereit can recombine and dissipate the energy as heat get trappedin metastable surface states or react with electron donorsor acceptors adsorbed on the surface of the semiconductor[18] Generally the hole oxidises water to form hydroxylradicals and initiates a chain reaction that then proceeds tooxidise organics while the electron can be donated to anelectron acceptor for exampleO

2 leading to the formation of

superoxides or a metal ion that is reduced to its lower valencestate and deposited on the catalyst surface [8 18 98 102 103]

The mechanism for semiconductor photocatalysis (of aM(IV) lattice metal eg TiO

2) can be summarised in the

following reaction steps [8 18]

(i) Excitation of photon greater than band gap resultingin the formation of electrons (ecb

minus) and holes (hvb+)

that is charge-carrier generation

TiO2+ ℎ] 997888rarr hvb

++ ecbminus (3)

(ii) Charge-carrier trapping

hvb++ TiIVOH 997888rarr TiIVOH∙

+ (4)

ecbminus+ TiIVOH 997888rarr TiIIIOH (5)

(iii) Charge-carrier recombination producing thermalenergy

hvb++ TiIIIOH 997888rarr TiIVOH + heat (6)

ecbminus+ TiIVOH∙

+

997888rarr TiIVOH + heat (7)

(iv) Interfacial charge transfer

TiIVOH∙+

+ Red 997888rarr TiIVOH + Red∙+ (8)

ecbminus+Ox 997888rarr TiIVOH +Ox∙minus (9)

where Red is an electron donor (reductant) and Ox isan electron acceptor (oxidant)

(v) Reduction of metal ions by ecbminus if present

119899ecbminus+M119899+ 997888rarr M0 (10)

This fundamental phenomenon observed in semiconductorphotocatalysts to oxidise (degrade) organic compounds andreduce metal ions is a promising technique in the treatmentof refractory organic pollutants and heavy metals present inwastewater treatment plants


VB

CB

Band

gap

Degraded products

Degraded products

Hole

ElectronReduction

Oxidation

h M2+ M+

O2 O2∙minus

Red+∙

M2+ M3+

OHminus ∙OH

Oxid+∙

M2+M3+

+ +

minus minus

Figure 1 Mechanism for semiconductor photocatalysis [18]

5 Nanophotocatalysts in Water Treatment

Due to industrial and geographical reasons there is alwaysa difference in the quality of water across the world Itis therefore acceptable that there is no possibility of onesolution that can solve all the problems of water contami-nation Thus in the design for water-treatment technologiesnanotechnology will always play a key role The intrigue ofnanotechnology is the ability to control the manipulationof nanoscale (approximately 1 nm to 100 nm) structuredmaterials and integrate them into large material componentssystems and architecture that have novel properties andfunctions [2 86 113 114] The merits of using semiconductorphotocatalysts in their nanorange far outweigh their use intheir bulk form [115] For example in the case of adsorptionwhere surface sites of the adsorbent are utilised diffusion isusually hindered due to the lack of a porous structure in thebulk materials This is because the surface-to-volume ratioincreases drastically with the decrease of the adsorbent frombulk to nanodimensions [2 7 11 87 113]

Also new physical and chemical properties emerge whenthe size of a material is reduced to the nanoscale levelThe surface energy per nanoparticle increases significantlyin the nanorange This increase in surface energy directlyresults in an increase in contaminant removal even at lowconcentrations The use of nanocatalysts also results inless waste generation especially in posttreatment since lessquantity of nanomaterial will be required compared to itsbulk form Furthermore with the use of nanomaterials novelreactions can be accomplished at nanoscale due to an increasein the number of surface atoms which is not possible withits analogous bulk material for example the degradationof pesticides by nanoparticles which cannot be done by themetals in their bulk form [2 7 93 94 113]

6 Titanium DioxideTiO2TitaniaPhotocatalysts

61 Introduction Among the nanophotocatalysts used in thetreatment of environmental wastewater titanium dioxidealso known as titania or TiO

2 has been extensively studied

[88 116ndash119] Since the discovery of the phenomenon ofphotocatalytic splitting of water on a TiO

2electrode under

UV light enormous efforts devoted to titania research haveled to promising applications in the fields of photovoltaicsphotocatalysis photoelectrochromics ceramics and sensors[120ndash126] As the most promising semiconductor photocat-alyst TiO

2-based materials are therefore expected to play

a major role to curb serious environmental and pollutionchallenges and ease the energy crisis through the use ofrenewable solar energy [93 127ndash134]

62 Synthetic Methods for TiO2 Nanoparticles There are anumber of available techniques for the synthesis of titaniananoparticles and these include sol-gel sol hydrothermalsolvothermal and chemical vapour deposition to name justa few [88 135 136] These synthetic methods are highlightedin the following subsections The method used plays a signif-icant role in the shape size and photochemical properties ofTiO2

621 Sol-Gel Method The sol-gel method is the most com-monly used technique for the synthesis of TiO

2nanoparticles

[137ndash140] In a typical sol-gel process a colloidal suspension(a sol) is formed from the hydrolysis of the precursors usuallyinorganic metal salts or metal inorganic salts such as metalalkoxides [16 88] For titania synthesis the sol-gel processusually proceeds via an acid-catalysed hydrolysis of titanium(IV) alkoxides followed by condensation [88 138]The sol-gelprocess has found more extensive use in the synthesis of tita-nia because the reaction takes place at low temperatures doesnot use complicated equipment results in the formation ofhighly homogeneous and pure products and allows for mod-ification to produce specific desired products [138 141ndash143]

Also the sol-gel method results in the synthesis of highsurface-area nanomaterials It also allows for easy control ofshape size and distribution as well as the easy introductionof foreign materials into the catalyst lattice and at lowtemperatures [135 141 144ndash147] Moreover nanomaterialsprepared by this method have a well-crystalline phase anda small crystalline size which benefit thermal stability andphotocatalytic activity Hence in this study the sol-gel


process was used for the synthesis of TiO2nanoparticles as

well as the introduction of metal ions into the crystal latticeof the TiO

2nanoparticles

622 Sol Method This method is also referred to as thenonhydrolytic sol-gel process and usually involves the reac-tion of titanium chloride with oxygen donating materials forexample metal alkoxides or organic ethers [88 148ndash152]Thereaction between TindashCl and TindashOR leads to the formationof TindashOndashTi bridges The alkoxide groups are formed insitu by the reaction of titanium chloride with alcohols orethers The length of the alkyl substituent of the alcoholsaffects the reaction speed (the longer the chain the fasterthe reaction) but not the average particle size Howeverthe variation of the halogen (eg TiF

4and TiI

4) affects the

average particle size [88 153] Also the shape and size ofthe titania nanoparticles can be controlled by the additionof a surfactant For example TiCl

3was added to a solution

of trioctylphosphine oxide (TOPO) and lauric acid and thereaction conditions controlled to produce either diamond-shaped bullet-shaped nanocrystals or a mixture of branchedand unbranched TiO

2nanorods [88 153ndash155]

623 Hydrothermal Method Hydrothermal synthesis ofnanoparticles takes place under controlled temperatureandor pressure in an autoclave [88 127] The reaction takesplace in an aqueous medium The hydrothermal process iseffective for selective crystallisation of anatase titania fromthe amorphous phase However the presence of the Clminus ion(from the precursor TiCl

3) results in the formation of a mix-

ture of anatase and the brookite phases Thermal treatmentof the amorphous phase below 300∘C results in a mixtureof the anatase and the brookite phases due to a solid-stateepitaxial growth mechanism At temperatures above 300∘Cthe formation of only the anatase phase is achieved becausethe dissolutionprecipitationmechanismdominates [88 127]

The hydrothermal process is thought to be environ-mentally friendly since the reactions are carried out in aclosed system and the contents can be recovered and reusedafter cooling down to room temperature [53] Moreoverproper and careful control of the hydrothermal processingconditions allows for the control over the physical propertiesof titania such as crystallite size and form surface areacontamination morphology and phase uniform distributionand high-dispersion and stronger interfacial adsorptionproperties [53 88 127]

624 Solvothermal Method The solvothermal method isalmost identical to the hydrothermal method except thatit uses nonaqueous solvents [88 156 157] However in thesolvothermal method the temperature can be elevated muchhigher than in the hydrothermal method and a variety oforganic solvents with high boiling points can be used Withthe solvothermal method there is a better control of thesize shape and the crystallinity of the TiO

2nanoparticle

distributions than hydrothermal methods [158] Thus thesolvothermalmethod has been found to be a versatilemethodfor the synthesis of a variety of nanoparticles with controlled

particle size narrow size distribution and dispersity [159ndash162] Also the versatility of this method is seen in that it canbe employed to synthesise TiO

2nanoparticles and nanorods

with or without the aid of surfactants

625 Chemical Vapour Deposition (CVD)Method Chemicalvapour deposition (CVD) is a process in which materials ina vapour state are condensed to form a solid-phase material[88 163] This process alters the mechanical electricalthermal optical corrosion resistance and wear-resistanceproperties of various substrates [163] CVD has been used toform free-standing bodies films and fibres and to infiltratefabric to form composite materials and recently in thefabrication of various nanomaterials [164 165] Chemicalvapour deposition of titanium dioxide is usually carriedout through the reaction of titanium tetrachloride (TiCl

4)

with oxygen or through the thermal reaction of a titaniumalkoxide such as Ti(OPri)

4 which already displays the Tindash

O4tetrahedral motif of the titanium dioxide lattice in its

chemical structure [165ndash167]CVD processes usually take place within a vacuum

chamber If no chemical reaction occurs within the reactionchamber the process is called physical vapour deposition(PVD) In CVDprocesses the gaseous precursor compoundschemically react on a heated substrate surface and thedeposition reaction is driven by thermal energyThe reactionsusually happen in an inert atmosphere in the presence ofa gas for example N

2 Ar or He [163ndash165 167] Moreover

the reaction conditions in a CVD process can be tunedto determine the phase size and morphology of the TiO

2

nanostructures

63 Properties of TiO2 Nanoparticles Titanium dioxide hasgained prominence for use as an environmental remediationcatalyst to completely mineralise organic and inorganic con-taminants because of its outstanding characteristics Theseinclude high thermal stability high photocatalytic activityhigh resistance to chemical and photocorrosion nontoxicityand dielectric properties as well as being inexpensive [168ndash172]Thephotocatalytic activity of TiO

2depends on its crystal

phase crystallinity particle size lattice impurities densityof surface hydroxyl groups and the surface area Titaniahas three (3) phases namely anatase (tetragonal) rutile(tetragonal) and brookite (orthorhombic) and the anatasephase of titania is the most photoreactive of the phases[121 172ndash174] Of the three phases the anatase phase hasthe smallest particle sizes (lt50 nm) high concentrations ofsurface hydroxyl (OH) groups and a high surface area hencethe high photocatalytic activity [169]

However the band gap of anatase TiO2is 32 eV and can

only be activated under UV light irradiation with wavelengthof 387 nm [117 175ndash177] This high-energy band gap rulesout the use of solar energy as the photoactivity source TheUV source requires large quantities of electrical energy whichwould result in high costs in practical applications [52]Moreover titania is characterised by low quantum yields (ielow electron transfer rate) resulting in high electron-holepair recombination which results in the termination of thephotocatalytic reactions [41 104 168 178ndash180] As a result a


number of reformative initiatives have been investigated as ameans of overcoming these drawbacks

64 TiO2 Modifications The main aim for titania modifica-tions is to reduce the band gap of titania thus shifting itsoptical response to the visible-light region and to reducethe rate of electron-hole pair recombination to increase itsphotoreactivity [105 132 180] TiO

2modifications result in

the ldquodecreaserdquo of the band gap by means of introducing adonor level on the valence band (Figure 2) The paramountcondition for titaniamodification is to ensure that the anatasephase is maintained The most common techniques used forTiO2modifications include anion doping dye sensitizers

the use of binary oxides and metal-ion doping These arediscussed in the following subsections

641 Metal-Ion Doping Doping of titanium dioxide nano-particles with transition and noble metal ions for the degra-dation of organic pollutants is the most studied phenomenonand has been found to enhance both the photoresponse andphotoresponse and photocatalytic activity of TiO

2nanopar-

ticles under visible-light irradiation [47 96 105 142 181ndash191]The electronic states of titania can be decomposed into threeparts 120575 bonding of O p and Ti 119890

119892orbitals or states that are

located in the lower region120587 bonding ofO p120587and Ti 119890

119892states

in the middle energy region and O p120587states in the higher

energy region (Figure 3) The bottom of the lower CB has theTi d119909119910

orbital and contributes to the metal-metal interactionsdue to 120575 bonding of the Ti t

2119892ndashTi t2119892

states The top of thelower CB consists of the Ti t

2119892states that are antibonding

with the O p120587states The upper CB is characterised by the

120575 antibonding orbitals between the O p120575and Ti 119890

119892states

[88]During metal-ion doping the energy due to the metal-

ion dopant either lies at the top of the valence band orproduces midgap states When the atomic number of thedopants is increased the localised level shifts to lower energythus significantly contributing to the formation of the valenceband with the O p and Ti 3d electrons This results in theband gap narrowing due to the introduction of electron statesinto the band gap of TiO

2resulting in the formation of a new

lowest unoccupiedmolecular orbital (LUMO) [88] Basicallymetal ions provide a ldquocushionrdquo on the valence band (the donorlevel) which results in the ldquodecreaserdquo in the band gap

Metal doping should be differentiated from metal ionscodissolved in a photodegraded solution and noble metalsdeposited on the semiconductor surface [88 105] Metal ions(dopants) are therefore incorporated into the TiO

2lattice

resulting in a ldquodecreaserdquo between the valence band and theconduction band hence altering the band gap energy therebyshifting the absorption band to the visible-light region[47] Metal-ion dopants are nanoscale metal semiconductorcontacts that act as electron scavengers hence resulting inincreased photocatalysis [192 193]

It is worth noting that although the introduction ofmetal-ion dopants on the titania lattice drastically shifts the absorp-tion edge to the visible-light region it can also result inreduced photocatalytic activities Metal doping can increase

the rate of electron-hole pair recombination and the pho-tocatalyst can also cause thermal instability [57 176] It istherefore imperative to avoid this by taking into considerationthe adequate amount of the dopant (metal) when preparingdoped titania [105 194] This is because when the dopantlevel passes the optimal limit which usually lies at a very lowdopant concentration the metal ions act as recombinationcentres resulting in reduced photoactivity The presenceof adequate amounts of metal doping (optimal limit) alsoensures that the metal particles only act as electron trapshence aiding electron-hole separation [105 195]

642 Anion Doping Anion doping of titania has increasedrecently and has been reported to shift the absorption edgetowards the visible-light region and increase the photocat-alytic activity [16 102 119 176 196ndash199]The narrowing of theband gap is as a result of the mixing of either the p or the 2pstates of the halogen (X) with the 2p states of the oxygen (O)atom in the valence band of the TiO

2nanoparticles [88 196

197] However the mixing of the p states of the halogen andthe 2p states of the O atom has the most positive effect onthe band gap narrowing as it induces some states which act asshallow donors on the valence band [88]The anion thereforetraps holes resulting in less recombination of the electron-hole pair and displaces the surface OH groups increasing therate of electron scavenging by O

2resulting in the formation

of an increased yield of superoxide radicals [103] Anionstherefore undergo innersphere ligand substitution reactionswith surface hydroxyl groups

643 Dye Sensitizers Organic dyes have been widely em-ployed as sensitizers for titanium dioxide nanomaterial toimprove its optical properties as they are light absorbingchromophores [6 84 88 125 193 200] Organic dyes areusually transition-metal complexes with low-lying excitedstates for example polypyridine phthalocyanine and met-alloporphyrin complexes The metal centres for the dyesinclude Ru(II) Zn(II) Mg(II) Fe(II) and Al(III) whilethe ligands include nitrogen heterocycles with delocalised120587 or aromatic ring systems The conduction band usuallyacts as a mediator for transferring the electrons from theexcited sensitizer to the substrate on the titania surface [84125 187]

These organic dyes act as both sensitizers and substratesand are normally linked to the TiO

2nanoparticle surfaces

via functional groups The various interactions between thedyes and the TiO

2nanoparticle substrates include covalent

attachment by directly linking groups of interest or via link-ing agents electrostatic interactions via ion-exchange ion-pairing or donor-acceptor interactions hydrogen bondingvan der Waals forces or hydroxyl groups [84 88 95] Mostdyes of interest link via direct covalent bonding with thefunctional groups that are on the TiO

2surface Carboxylic

and phosphonic acid derivatives react with the hydroxylgroups to form esters while amide linkages are obtained viathe reaction of amine derivatives on TiO

2[88 95] However

dye sensitizers are not stable and are usually prone tothermal instabilities which result in increased recombinationcentres Furthermore they are susceptible to damage from


Visible light UV light

Donor level

Nar

row

ban

d ga

p

Wid

e ban

d ga

p

Degraded products

Degraded products

(LUMO)

Pollutant(HOMO)

VB

CBReduction

Oxidation

h M2+

++

M+

O2 O2∙minus

M2+ M3+

OHminus

M2+M3+

∙OH

Pollutantlowast

eminus

minusminus

Pollutant+∙

Pollutant+∙

TiO2120582 ge 380nm

Figure 2 Band gap (effect of doping) and photocatalysis mechanism of TiO2[18 104 105]

GAP

VB

Lower CB

Upper CB

O p120587

Ti eg states

O p120587 states

O p120575 states

Ti-O120575lowast

Ti-O120587lowast

M-M120587lowast

M-M120575lowast

M-M120587

M-M120575

Ti-O120587

Ti-O120575

Ti t2g states

Figure 3 Bonding diagram of TiO2[18]

reactive oxygen species (ROS) which destroy the catalyst[92 176]

644 Binary Oxides Binary metal oxides like TiO2SiO2

TiO2ZrO2 TiO

2WO3 TiO

2Fe2O3 TiO

2SnO2 TiO

2

Ln2O3 andTiO

2RuO2systems have been applied in the pho-

tocatalytic degradation of environmental pollutants undervisible light [3 95 118 124 140 201ndash207] The photoactivityof these binary oxides was found to be enhanced becausethe metal oxides increased the acidity of the titania surfaceThe surface acidity takes the form of surface hydroxyls andaccepts holes generated by illumination of the catalyst andoxidises the adsorbed molecules [118 204] Basically since

the coupling oxide is activated under visible light it isbelieved that the metal oxide will absorb visible light and thephotocatalytic activity of the titanium dioxide will be used tomineralise organic pollutants The metal oxides also enhancethe separation properties of titania suspended particles fromsolution and thus decrease the effect of beam splitting byagglomerated particles [118] Moreover the metal oxides actas supports of the catalysts [10] However some of the metaloxides are thermodynamically unstable for example RuO

2

TiO2 thus resulting in electron-hole pair recombination and

significantly decreasing the photocatalytic activity [95]Other techniques that have been used to shift the absorp-

tion edge of titania towards the visible-light region and


reduce the rate of electron-hole pair recombination includecarbon nanotube-titania composites metal-anion codopingmounting TiO

2on activated carbon exfoliated graphite and

polymeric substrates for example chitosan [116 130 208ndash213] For the purposes of this research metal-ion-doped tita-nia will be synthesised and investigated for its photocatalyticproperties under visible-light irradiation

65 TiO2 Applications

651 Industrial Applications The existing and potentialapplications of titaniumdioxide nanomaterials include tooth-paste paint UV protection photovoltaics photocatalysissensing electrochromics and photochromics The photo-catalytic properties of TiO

2have found application as well

as potential application in the manufacture of self-cleaningsurfaces air cleaning devices and self-sterilising devices[88 92 194 214 215] Photochromic and electrochromiccompounds (with a redox potential above the conductionband edge of titania) exhibit different colours in differentoxidation states and TiO

2acts as an electron conductor

between the conduction band and the photoelectrochromicmaterial Electrochromic devices like electrochromic win-dows displays contact lenses catheters and spectacles withTiO2as the electron conductors have been synthesised and

commercialised [131 216ndash218] Also biomedically TiO2has

shown much potential in cancer therapy (endoscopic-likeinstruments) due to its antitumor activity [92]

652 Environmental Applications The photocatalytic prop-erties of TiO

2make it an important semiconductor in appli-

cations in environmental remediation Titanium dioxide hasshown tremendous ability not only as a sensor for chemicalbiological and various gases (H

2 NO119909 CO etc) even at

low concentrations but also to photocatalytically degradeand self-clean the contaminated environment [88 200 219ndash222] Moreover the degradation of organic pollutants andreduction of metals to their zero oxidation states have beenearmarked as one of the peak applications of TiO

2for the

treatment of river water groundwater the drainage waterfrom fish-feeding tanks and industrial wastewater [57 65 9192 117 223 224] Furthermore photodegradation of organicpollutants by titanium dioxide results in the formation ofinnocuous products and therefore eliminates the problemsassociated with the recalcitrant DBPs [18 83 174 175 225]Although titania has the ability to completely degrade organicrefractory pollutants and to be cousedwith the existingwater-treatment technologies its large-scale industrial applicationin drinking-water treatment is still considered to be milesaway

66 Problems Associated with TiO2 Applications The use ofTiO2in suspension form is efficient due to its large surface

area but there are fourmajor technical challenges that restrictits large-scale application and its use in water-treatmenttechnologies Firstly it has a relatively wide band gap (sim32 eVwhich falls in the UV range of the solar spectrum) andtherefore it is unable to harness visible light thus ruling outsunlight as the energy source of its photoactivation [9 16

211 226ndash229] Secondly it has low quantum efficiency dueto the low rate of electron transfer to oxygen resulting ina high recombination of the photogenerated electron-holepairs [226 227 230] Thirdly when used in a suspensiontitaniumdioxide aggregates rapidly due to its small size (4 nmto 30 nm) and its aggregates may cause scattering of thelight beam resulting in loss of catalytic efficiency [66 211231] And lastly the application of powdered TiO

2catalysts

requires posttreatment separation to recover the catalyst fromwater This is normally difficult is energy consuming andis economically not viable for use in water-treatment plants[12 66 156 211 230] Therefore new research initiatives needto be explored to counter these challenges

One of the major challenges facing scientists and govern-ment bodies is the development of materials using ldquocleanrdquoenergy applications the so-called Green Science to relievethe environmental burden due to pollution TiO

2has the

potential to be that green material and hence so muchresearch has been ongoing to try and harness its potentialapplications To achieve this doping metals into the TiO

2

lattice is an effective strategy to reduce the band gap and shiftthe absorption edge towards the visible-light range [57 84105 107 191 227 232 233]However the amount of themetal-ion dopant when preparing doped titania is important Thisis because when the dopant level passes the optimal limit(sim04) the metal ions then act as recombination centresresulting in reduced photoactivity [105 194]

Also TiO2nanoparticles can be supported on catalyst

supports This would help improve the photocatalytic activ-ity and potential application of the titania nanoparticlesFurthermore to avoid the aggregation and posttreatmentchallenges TiO

2can also be assembled onto different sub-

strates and fabricated into different types of titania thin films[150 211 214 234ndash237] The advantage of using thin films isthat they are known to be chemically stable and possess ahigh dielectric constant a high refractive index and excellenttransmittance therefore they have the ability to retain thephotocatalytic activity of the assembled catalysts [236]

7 Catalyst Supports

71 Introduction A support material is very important incatalysis because it determines the catalytic activity of acatalyst [238 239] Catalyst supports are porous and havehigh surface areas [44 240 241] The electronic interactionsbetween the support and the catalyst bring about slightlyacidic conditions which increases the rate of electron transferthus reducing the rate of electron-hole combination Alsosupports result in an increased adsorption ability and stabilityof the catalyst and hence increase the rate of oxidationof organic pollutants [44 76 242 243] Moreover catalystsupport materials do not only shift the band edge towards thevisible-light energy region but also have the ability to dispersethe supported catalysts thus preventing them from agglom-erating and also helping to improve catalyst separation fromposttreatment wastes [130 238 243ndash247] These conditionsare therefore important since they enhance the photocatalyticactivity and the application of the supported TiO

2catalysts

The common types of supports used for catalysts include


alumina (120574-Al2O3) supports carbon supports and carbon-

covered alumina (CCA) supports

711 Alumina Supports 120574-Alumina as a catalyst supporthas a high surface area good mechanical properties andnumerous pores as well as the ability to disperse the activemetal phase [238 239 247 248] However its exclusive useas a support has been found to have some disadvantagesFor example its acidity results in low catalytic activity ofthe supported catalysts Furthermore its reactive surfacesform unwanted metal oxides upon calcination The reactivesurfaces of alumina react with the promoter ions resultingin the formation of oxides which lower the catalytic activityof the catalysts [238 247ndash249] The strong interactions ofthe alumina support with the metal atoms are thereforeundesirable since it is detrimental to the catalyst activity

712 Carbon Supports Carbon has also been used to supportcatalysts Carbon supports have mild interactions with thesupported metals and have a neutral surface good thermalconductivity and high surface area with controlled porevolume Carbon is also resistant to nitrogen poisoning andcontains variable surface functional groups [246 248ndash251]However it also has some undesirable properties that limit itsuse as a catalyst support It has poor mechanical propertiesand a low surface area Moreover it is also microporousand has poor adsorption properties and hence catalysts maybe deposited on the micropores thus making their photo-catalytic effect trivial [238 246 248ndash251] These propertiestherefore make the sole use of carbon as a support materialinapplicable

72 Carbon-Covered Alumina (CCA) Supports As describedbefore the sole use of either carbon or alumina as supportmaterials has some shortcomings A support system thatexploits the merits of both carbon and alumina can providean ideal support system This is because it overcomes theirshortcomings while improving their advantages In thissystem the alumina is coated with a thin layer of carbon priorto catalyst impregnation which results in a support materialthat possesses both the textural and mechanical propertiesof alumina and the favourable surface properties of carbon[238 250 252ndash255] The properties of this carbon-coveredalumina (CCA) support include reduction of the aluminaacidity (sim by 90) due to the presence of carbon increasedelectron-charge transfer and reduced metal-support interac-tions resulting in increased catalytic activity and increasedmechanical strength and increased surface area [238 239247 252ndash254 256 257] CCA supports are therefore superiorcatalyst supports due to the integration of the properties ofboth the carbon and alumina

73 Synthesis of CCA Supports Themost common approachto the synthesis of CCA supports is based on the ldquopyrolyzabil-ityrdquo of organic compounds such as cyclohexene acetyleneor ethane on the surface of alumina at elevated temperatures(600∘C to 700∘C) in the flow of nitrogen that is chemicalvapour deposition (CVD) of organic compounds [247 249254 258ndash260] However it has been found that the materials

synthesised by this method have some drawbacks For exam-ple their textural properties are dependent on the amountof carbon deposited and the type of the hydrocarbon usedhence the carbon coating is nonuniform [254] Furthermoreincreasing the degree of surface coverage of the alumina bycarbon through CVD results in the aggregation of carbon onthe alumina surface and this decreases the apparent surfacearea and pore volume which are key to catalytic activity ofthe supported catalysts

Another method used to synthesise CCA involves theimpregnation of alumina with sucrose solutions [198 238250 253 257] In this method the sucrose-impregnatedalumina is dried in an oven and the pyrolysis of the sucrosetakes place in an inert atmosphere at elevated temperatures(600∘C to 700∘C) to produce CCA supports The CCAsupports produced by the impregnation of sucrose have auniform carbon layer hence this is regarded as a bettermethod than CVD of organic compounds Lately Sharandaet al have synthesised CCA supports using an adsorption-equilibriummethod [254 261] In thismethod highly reactivecompounds like acetylacetone and isocyanates form surfacecomplexes with the OH groups of the alumina via the C=Oand N=C=O bond openings respectively Upon pyrolysisa carbon coating is expected to form on the surface ofthe alumina The equilibrium adsorption method has theadvantage of forming better CCA supports since the interac-tion between the C and alumina is a chemical process andnot a physical or mechanical one like in the case of CVDand sucrose impregnation Hence for the purposes of thisstudy the adsorption-equilibrium method was adopted forthe synthesis of CCA supports

74 Applications of CCA Supports CCA supports have foundutilisation as supports for hydrotreating catalysts in theFischer-Tropsch conversion of heavy crude oil into lightfractions [252 258] Also CCA supports have a high surfacearea and high adsorption affinity for both organic andinorganic compounds (Al

2O3is a polar adsorbent and C is

a nonpolar adsorbent) These properties have been exploitedand CCA supports have been used as packing material forhigh-performance chromatography [249 260 261] RecentlyJana and Ganesan [255] have synthesised CCA in the formof foams and increased its surface area and also enhancedits adsorptive properties Due to their high catalytic activityand stability CCA supports have been used to support Rucatalysts in the synthesis of NH

3[262] Ag nanoparticles have

been used in CCA supports and used to remove bacteria indrinking water [239] Since not much work has been done onthe environmental application of CCA-supported catalyststhis research therefore seeks for the first time to supportanatase TiO

2nanoparticles on CCA supports and apply them

in the degradation of organic pollutants

8 CCA-Supported TiO2 Nanoparticles

Titania nanoparticles have been recently attached on CCAsupports and used for the photocatalytic degradation of Rho-damine B under visible-light irradiation [263] Metal-dopedtitania has also been supported on these CCA supports Ag


CoNi and Pdwere used as themetal dopants [106]TheCCAsupports were synthesised from glucose and an impregnationmethod was used to attach the nanoparticles on the supportsAccording to the results obtained attaching the titaniananoparticles on the CCA supports greatly enhanced theirphotocatalytic activity Both these CCATiO

2and CCAm-

TiO2nanoparticles had a large surface area due to the porous

nature of the CCA supports and they were highly activeunder visible-light irradiation and exhibited less electron-hole combination due to the presence of C (which acts aselectron traps) on the supports Also the band gap of theCCA-supported titania nanoparticles was highly reducedThe decrease in the band gap of the CCA-supported catalystswas found to be much higher than the decrease of 014 eVwhich is usually observed for carbon doped titania The SEMimages (Figure 4) revealed that the carbon formed a layer ontop of the alumina and that the nanoparticles were success-fully impregnated on the highly porous CCA supports

Figure 5 showed that the catalysts were successfullyimpregnated onto the CCA supports The authors alsorevealed that the catalysts were evenly distributed on theCCAsupports Uniform distribution is a distinguishing featureof CCA supports due to their high adsorption and porousnature The CCA-supported catalysts were found not to havelost their crystallinity whichwould have inversely affected thephotocatalytic activity of the catalysts

9 Thin Films

As mentioned earlier the tendency of titanium dioxidenanoparticles to aggregate and scatter incident light as wellas the need for posttreatment recovery has made its large-scale application economically impractical [91 211 264]Thishad led to the exploration of a number of techniques to tryand immobilise TiO

2nanoparticles on solid supports not

only to solve posttreatment problems but also to facilitate therenewable use of the catalyst [66] Also TiO

2thin films retain

the photocatalytic properties of its powder form TIO2thin

films can still be applicable in gas sensors electrodes for solarcells electrochromic applications as gate oxides of metal-oxide-semiconductor field transitions laser applications andphotocatalytic degradation of pollutants [150 264ndash267]

Although immobilised titania is less photocatalyticallyactive than suspended titania particles due to reduced surfacearea and less porosity the merits of using immobilised titaniastill far outweigh the disadvantages as it provides new avenuesin the practical utilisation of titania The techniques usedfor synthesis of TiO

2thin films include CVD dip coating

sol-gel spin coating spray pyrolysis sputtering liquid-phasedeposition and layer-by-layer (LbL) self-assembly The sub-strates used include glass single-crystal silicon or polymericsubstrates Some of these thin-film synthesis techniques arediscussed in the following subsections

91 Chemical Vapour Deposition Chemical vapour deposi-tion (CVD) is a versatile method that can be used for thesynthesis of a number of materials To synthesise TiO

2thin

films by CVD either a titanium alkoxide such as titaniumisopropoxide (TTIP) is used which already has the TindashO

4

tetrahedral motif of the TiO2in its chemical structure or

TiCl4is reacted with oxygen to form the TndashO

4tetrahedral

motifThese are thereafter deposited on a substrate at elevatedtemperatures in a vacuum to form the titania thin films [165236 268 269] CVD offers good control of film structure andcomposition excellent uniformity even on highly irregularsubstrates (conformal deposition) and a sufficiently highgrowth rate thus applicable for synthesis of multilayer struc-tures [268 270ndash272] To realise the desired physicochemicalproperties of a material a suitable substrate surface mustbe exposed to a suitable growth environment (temperaturepressure and chemical composition) especially in the gasphase conditions close to the substrate surface [270]

The factors that affect the physicochemical propertiesof the thin films are the choice of precursors carrier gasand their respective flow rates the total pressure in thereactor the substrate temperature the distance between thesubstrate and the nozzle head and the water-vapour contentin the whole reaction chamber [270 273] However CVD isnot a straightforward process and is complicated to controlThe deposition rates uniformity and film properties changewhen one inert gas is replaced by another a different-sizedsubstrate is used a different reactor loading is applied oran identical process is applied in a different reactor setup[270] Moreover the vacuum equipment is expensive anddue to the complicated nature of the reaction kinetics in theCVD reactors CVDprocesses developed in the laboratory aredifficult to scale up to industrial scales [166 235 270]

92 Liquid-Phase Deposition Liquid-phase deposition(LPD) unlike CVD is referred to as a unique soft process inwhich a metal oxide or hydroxide forms thin films throughligand-exchange (hydrolysis) equilibrium deposition at lowtemperatures [232 274] The substrate is immersed in theprecursor solution (soft-solution deposition) and thereafterthe substrate is calcined at high temperatures to obtain crys-talline thin films [232 275] LPD is a cost-effective methodis regarded as environmentally friendly and producessmooth uniform and dense thin films with good adherence[235 275] However the thermal treatment of the thin filmshas been reported to affect the adhesion properties of thenanoparticles on the substrate [235]

93 Dip Coating In dip coating the substrate is slowlyimmersed in a titanium dioxide precursor solution forexample TTIP TiCl

4 or TiCl

3and then slowly pulled out at

a fixed rateThe coated substrate is then immediately dried infurnace before calcination at elevated temperatures (400∘Cto 500∘C) [65 276ndash278] Sometimes a complexing agentand a wetting additive are added to stabilise the solutionand enhance film adherence [279] Dip coating is alsoregarded as a simple cost-effective technique and it producesuniform coatings with controllable film thickness [277 280]However just like in LPD the thermal treatment of the thinfilms affects the adhesion properties of the nanoparticles onthe substrate [235]

94 Spray Pyrolysis Spray pyrolysis (SP) is a simple tech-nique that requires a precursor solution (eg TiCl

3 TiCl

4


(a)

(b) (c)

(d) (e)

Figure 4 SEM images of CCA and CCATiO2nanoparticles [106]

Ti(OEt)4 or TTIP dissolved in water ethanol or other sol-

vents) an atomiser and a heated substrate [156 281] In anSPprocess the solution is atomised into small droplets and thedroplets are transported by a gas to the heated substratewherethey form thin films upon immediate approach or impinge-ment on the substrate (Figure 6) The source of the atomicmist (aerosol which produces large droplets or ultrasonicspraying which produces smaller droplets) determines the

surface morphology of the deposited films [281ndash283] The SPmethod is attractive because it is inexpensive and uses simplefacilities results in rapid film growth large surface-area sub-strate coverage and homogeneity and has the potential formass production [156 283ndash286]

However SP has some drawbacks Poor film quality isobserved due to vapour convection in the hot zone becausethe vapour formed on the heated substrate may hinder the


(a) (b)

(c) (d)

Figure 5 TEM images of the CCA-supported titania nanocatalysts [106]

Gasvalve Air pressure

meter Filter

Controller

Aircompressor

Pump

Precursor

Temperaturecontroller

Substrate

Spraynozzle

Heater

Liquidvalve

Liquid fluxmeter

Controller

Figure 6 Schematic representation of the spray pyrolysis method[107]

source vapour from attaching to the substrate due to thetemperature difference Also as the source liquid vaporiseson the substrate due to thermal decomposition it may

result in the formation of thin films with many cracks dueto precipitate shrinkage [284] Also SP can result in thedeposition of powder on the substrate

95 Sol-Gel Technique The sol-gel technique is the mostwidely used method for the synthesis of TiO

2thin films

The solution precursors are used to make the sol and thesubstrate is immersed in the sol and substrate gelation occursThese substrates are then aged and calcined at elevatedtemperatures to produce the thin films [185 287] The sol-gel method has been widely used in the synthesis of titaniathin films because it is a simple and cost-effective methodthat results in the formation of high porosity low density andlow refractive index high nanoparticle homogeneity tunableparticle size and high substrate coating [185 227 234 288ndash290]The pH of the sol the ageing time amount of surfactanttemplate amount of hydrolysis retardant and calcinationtemperature play an important role in the quality of the thinfilms produced [288] However the sol-gel method has somedrawbacks For example during the ageing of gels and dryingof films the sols produce vapours which cause environmentalpollution [287] Also the thermal treatment of the thin films


NaPSS

NH

NN

PAZO PVS

N

PAPSA PSMDEMA

HN

SPAN

R

R-PHPyV

S

O

PTAA PMPyA PDDA

PAH

NH

PAMPSA

N

HN

NN

HN

PEI

SO3minusNa+

SO2

CO2minus

OHNa+

OSO3minusNa+

HO3S

N+

N+

Iminus

SO3minus

NH2+

OminusNa+

+N

N+Clminus

NH3+Clminus

SO3H

NH2

NH2

NH2

Figure 7 Examples of polyelectrolytes used in LbL thin-film synthesis

affects the adhesion properties of the nanoparticles on thesubstrate [235]

96 Layer-by-Layer (LbL) Self-Assembly

961 Introduction The layer-by-layer (LbL) self-assemblytechnique is a technology that enables the nanoconstructionof multifunctional films on solvent-accessible surfaces It alsoallows for the design of functional surfaces and surface-based nanodevices in a ldquobuild-to-orderrdquo fashion that isthe capacity to build standard or mass-customised prod-ucts upon receipt of spontaneous orders without forecasts[109] Furthermore the LbL technique exceeds simple self-organisation under equilibrium conditions by making itpossible to arrange many different materials at will withnanoscale precision [12 109 291ndash294] The LbL technique

can thus provide solutions for surface modifications andfabrication of thin films that is it permits multifunctionalassemblies of materials since it allows deposition on surfacesof almost any shape and kind [109 295]

962 Fabrication of LbL Thin Films Sequential depositionof polyelectrolytes (polyanions and polycations) on solid sur-faces leads to the build-up of multilayer LbL thin films [108296 297] The LbL self-assembly technique is a physisorp-tion process independent of size and topology of the sub-strate however parameters like solution concentration ionicstrength solvent composition and temperature play animportant role in the multilayer build-up [292 295 298]Examples of polyelectrolytes used for LbL thin-film fabrica-tion are shown in Figure 7


1

23

4

Figure 8 Schematic of the LbL electrolyte spraying depositionprocess [108]

1 2 3 4

(1) Polyanion

(2) Wash

(3) Polycation

(4) WashSubs

trat

e

++++++++++++++

++++++++++++++

minus

minusminusminusminus

minus minus

minusminus

minusminus

minusminus

minusminus

minusminus minusminus

minusminusminusminus minus

minusminusminusminus minus minus minus

minusminusminusminusminus

minus

++++++++++++++

++++

++

+++++ +

+++

+++++ ++

+++

+++

++ +

+++ +

++

++

minus


minus minus

minusminus

minusminus

minusminus

minusminus





minus

Figure 9 Schematic of the LbL electrolyte dipping depositionprocess [109]

To synthesise LbL thin films a substrate is either dippedin or sprayed with oppositely charged polyelectrolytes Alsosolutions can be allowed to flow over the substrate Duringspraying (Figure 8) the electrolyte sprayed on the substrateshould not accumulate on the surface but flow away quicklydriven by gravity and only a thin filmof liquidwhich typicallydries within minutes should initially remain on the surfaceBecause the thickness of the adhering solution is very thinany spray droplet arriving at the surface immediately fuseswith the liquid film and will replace liquid draining off Spraycoating is a fast and convenient application for large surfaceareas Thus this setup provides for mild but permanentagitation as driven by the draining solution [108]

During the dipping method (Figure 9) the substrate isdipped alternately in oppositely charged polyelectrolytesEach dipping step is followed by a rinsing step to removeexcess polyelectrolyte in contact with the surface The wash-ing is important because it avoids the formation of polyelec-trolyte clusters in solution and hence it ensures homogeneityand uniformity of LbL films Also the dipping method formsthicker films than the spraying method [108 109] Thus for

the purposes of this study the dipping deposition process waspreferred

963 Applications of LbL Thin Films There are a num-ber of unprecedented ldquoreagentsrdquo or materials for LbL filmdeposition and these include polymers (linear or branched)colloids (polymeric metallic or oxidic) biomacromolecules(DNAproteins polynucleotides bioaggregates and contactlenses) and nanoparticles (for environmental application)[293 296 297 299] Due to the variety of materials used forLbL thin-film fabrication its application is therefore spreadacross a variety of disciplines which include electric andelectronic devices (rectifiers transistors and switches) filmcoating micropatterning nanobioreactors photocatalysisand drug-delivery systems [300ndash302] Biomedically thin-film coating on medical devices can improve biocompatibil-ity reduce immunological response and enhance targeteddrug delivery [294]The LbL self-assembly technique has alsobeen applied in the synthesis of thin-film microcapsules thatdisintegrate on the target site hence improving drug or DNAdelivery to their active site [298 299 303ndash307] Also LbL thinfilms have been applied to assemble semiconductor catalysts(especially TiO

2) and applied in the degradation of organic

pollutants for environmental remediation [12 293 308] LbLself-assembly of TiO

2on thin films can therefore go a long

way to overcome the problems associated with the practicalapplication of suspended TiO

2nanoparticles

97 Layer-by-Layer TiO2 Thin Films The use of titania inpowder form has the tendency to aggregate and scatterincident light and there are difficulties associated with therecovery of powdered titania after treatment hence its large-scale application is economically not viable TiO

2has been

assembled on substrates using different methods and appliedin catalytic environmental remediation processes Howeversince the other TiO

2thin-film fabricationmethods have some

drawbacks like film cracking poor adhesion to substrate theuse of high temperatures expensive equipment and a highlevel of expertise required the LbL self-assembly providesa better alternative LbL thin films are synthesised at lowtemperature (room temperature) simple equipment is usedthe films require no thermal treatment and strong adhesionbetween nanoparticles electrolyte and substrate is ensureddue to the strong electrostatic interactions [12]

The TiO2nanoparticles assembled by the LbL self-

assembly technique were found to be well separated andhighly accessible for the photocatalytic processes Also theamount of the nanoparticles deposited was easily controllable[12 293]When compared to othermethods like drop-castingand spin-coating the LbL assembled TiO

2show superiority

in terms of film stability and catalyst reusability (thin filmcan be used a number of times with the same efficiency)Also the LbL method has no limit to the number of TiO

2

layers that can be assembled and the higher the number ofthe layers the more the catalytic activity [12] The use of LbLsynthesised thin films therefore overcomes the problemsassociated with the use of powdered TiO

2as well as the

other thin-film assembly techniques and is attractive forpractical application in continuous water-treatment and


(a) (b)

(c) (d)

Figure 10 SEM images of 1 3 5 and 10 bilayers of the m-TiO2nanoparticles thin films [110]

environmental remediation processes However little havebeen reported in recent literature on the assembly and use ofmetal-doped titania by the LbL method

10 Metal-Ion-Doped TiO2 LbL Thin Films

The immobilization ofmetal-ion-doped titania on glass slidesby the LbL method has been reported recently [110] Thisstudy reveals that the metal-ion-doped titanium dioxidenanoparticles were successfully attached on glass slides andthere was an increase in the number of particles and thin-filmthickness with increase in the number of bilayers (Figure 10)PAH and PSS electrolytes were used to immobilise these m-TiO2nanoparticles on the glass slides as thin films The pho-

tocatalytic efficiency of the PAH (PSSmTiO2) thin films was

studied using Rhodamine B under visible-light illuminationThese thin filmswere highly active towards the photocatalyticdegradation of Rhodamine B under visible-light illuminationand did not lose their photocatalytic activity and strengtheven after five cycles This study shows a great stride in theuse of metal-doped titania nanoparticles as it eliminates theproblems associated with aggregation and posttreatment andthus increases the chances for easy use in water treatment

11 Titania Mixed-Matrix Membranes

Recently membrane separation technologies have beenfound to be cheap and fast chemically stable and highlyselective They can also be easily integrated with other water-treatment strategies [309ndash311] Because of these propertiesthey have been found more favourable to be used for water-treatment processes Membrane techniques do not requireaddition of chemical substances and therefore it is easy toincrease their capacity (modular system) The separationprocess is in a continuous mode and therefore applicable inmild environmental conditions [312] Membrane processescan therefore be used in diverse industrial sectors such aspharmaceutical water treatment chemical food processingelectronics (fuel cells) metallurgy and biotechnology [311313ndash317]

Although using polymericmembranes hasmajor benefitsover the conventional water-treatment technologies theirsusceptibility to fouling is a major drawback [309 318]Foulants may be either crystalline particulate thermalcolloidal microbial (biofouling) or organic fouling [309 314318] Polysulfone (PS) has been widely used to synthesisemembranes PS membranes are relatively cheap have a


(a)

(b) (c)

Figure 11 SEM micrographs of the CCATiO2mixed matrix membranes (a) surface morphology (b) cross section and (c) nanoparticles

within the polymer matrix [111 112]

superior film-forming ability strong thermal and chemicalstability and acidic and alkaline resistance and hence havebeenwidely used inmany applications [318 319]Thesemem-branes have goodmechanical and anticompaction propertiesHowever like any other membranes PS membranes havelimitations to be used in water-treatment processes becausethey easily get fouled have a low permeate flux and arehydrophobic in nature [310 311 320] hence the need tomodify their properties

Current research in membrane technology develop-ment is focussed on the improvement of antifouling andhydrophilicity properties while maintaining or improvingtheir throughput characteristics [310 311 319 321]This can beattained by either bulk or surfacemodificationwhich changesthe chemical structure of the membranes Also inorganicnanoparticles can be incorporated through the membranematrix or on the surface [309] Although this phenomenonis still under debate it is widely accepted that the thermo-dynamic state and kinetic properties of the system and howthey vary during processing govern the structure formationpathway of the membrane Also physical parameters likethe temperature the composition of the casting solution thecomposition of the nonsolvent bath and the surroundingatmosphere play a pivotal role in determining the syntheticpathway as well as the final membrane structure [322 323]Incorporating inorganic nanomaterials into polymeric mem-branes has been found to improve the chemical stability thethermal stability the permeation and the mechanical as wellas the antifouling resistance ofmembranes [313 318 321 324]

For such purposes nanoparticles like TiO2 Al2O3 ZrO2 Cu

Ag and SiO2have been utilised in the past [309 311 318 325]

Recently CCA-supported free TiO2(CCATiO

2PSf) and

Pd-doped titania (CCAPd-TiO2PSf) nanoparticles have

been embedded within a polysulfone matrix to synthesisemixed matrix membranes [111 112] In these studies boththe CCATiO

2PSf and the (CCATiO

2PSf) membranes

were found to be highly photoactive for the discolourationof Rhodamine B under visible-light irradiation The CCA-supported nanoparticles were distributed both within andon the surface of the membranes (Figure 11) These studiesrevealed that only aminimal amount of the nanoparticles canbe incorporated within the polymer matrix without compro-mising the mechanical properties Increasing the amount ofthe nanoparticles to about 05 resulted in weakening of themechanical properties of the nanoparticles The presence ofthe nanoparticles also enhanced the permeate flux as well asthe fouling behaviour of the PSf membranes This is thus agreat step that eliminates not only the problems associatedwith posttreatment and aggregation but also fouling of themembranes and thus provides a better alternative in findingmeans to deal with water-treatment problems

12 Conclusion

From the literature discussed the health risks associated withthe presence of pollutants in water due to the failure of con-ventional water-treatment technologies to effectively removeorganic and inorganic pollutants have been highlighted It


has been revealed that TiO2nanoparticles have demonstrated

the ability to completely degrade organic pollutants in anaqueous medium resulting in the formation of innocuousproducts and thus have tremendous potential to be used inwater-treatment processes Reformative processes to shift theabsorption edge of titania to the visible-light region have beendiscussed Supporting the TiO

2on CCA supports has proven

to drastically enhance the dispersion of the nanoparticlesreduce electron-hole pair recombination and increase thesurface area resulting in an increased photocatalytic activityAlso CCA supports were found to play a major role inshifting the absorption edge of titania towards visible-lightirradiation Also the LbL self-assembly of the metal-ion-doped TiO

2on glass substrates overcame the problems

associated with the need for the application of costly post-treatment processes neededwhen using suspended TiO

2The

embedding of the titania nanoparticles within the a polymermatrix has proved to be the recent pivotal advancement inthe application of titania nanoparticles for environmentalremediation processes

Overall this review brings to attention the advancementsof titania nanoparticles in their use for water-treatmentprocesses These advancements thus serve as techniques thatcan be used in conjunction with the present water-treatmenttechnologies to alleviate the problems associated with pol-lutants in drinking water systems Also since titania candegrade organic pollutants while simultaneously oxidisingheavy metal species it serves as a cheap dual process thatcan be further explored to realize the potential of TiO

2in

water-treatment processes Furthermore titania provides acheaper alternative that can be used in conjunction withthe already existing water-treatment technologies especiallymembranes Also the use of titania based systems is a betteralternative for the use since it harnesses the green solar energyand thus reduces the environmental waste due to the use ofchemicals The ability of TiO

2nanoparticles to completely

deal with organic pollutants without producing recalcitrantby-products has thus opened new research avenues to bepursued

Conflict of Interests

The authors declare that there is no conflict of interestsregarding the publication of this paper

Acknowledgment

The authors are grateful to the Department of AppliedChemistry University of Johannesburg South Africa forconstantly supporting our research program on nanomateri-als especially their financial support

References

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[2] T Pradeep and Anshup ldquoNoble metal nanoparticles for waterpurification a critical reviewrdquo Thin Solid Films vol 517 no 24pp 6441ndash6478 2009

[3] M Sun D Li Y Chen et al ldquoSynthesis and photocatalytic activ-ity of calcium antimony oxide hydroxide for the degradation ofdyes in waterrdquo Journal of Physical Chemistry C vol 113 no 31pp 13825ndash13831 2009

[4] X Wang Z Gai B Yu et al ldquoDegradation of carbazole bymicrobial cells immobilized in magnetic gellan gum gel beadsrdquoApplied and Environmental Microbiology vol 73 no 20 pp6421ndash6428 2007

[5] S Hong and M Elimelech ldquoChemical and physical aspectsof natural organic matter (NOM) fouling of nanofiltrationmembranesrdquo Journal of Membrane Science vol 132 no 2 pp159ndash181 1997

[6] T S Natarajan M Thomas K Natarajan H C Bajaj and RJ Tayade ldquoStudy on UV-LEDTiO

2process for degradation of

Rhodamine B dyerdquo Chemical Engineering Journal vol 169 no1ndash3 pp 126ndash134 2011

[7] N Savage and M S Diallo ldquoNanomaterials and water purifi-cation opportunities and challengesrdquo Journal of NanoparticleResearch vol 7 no 4-5 pp 331ndash342 2005

[8] K Kabra R Chaudhary and R L Sawhney ldquoTreatment ofhazardous organic and inorganic compounds through aqueous-phase photocatalysis a reviewrdquo Industrial and EngineeringChemistry Research vol 43 no 24 pp 7683ndash7696 2004

[9] P Romero-Gomez V Rico J P Espinos A R Gonzalez-ElipeR G Palgrave and R G Egdell ldquoNitridation of nanocrystallineTiO2thin films by treatment with ammoniardquo Thin Solid Films

vol 519 no 11 pp 3587ndash3595 2011[10] Z J Bo G Maochu W J Li L Z Min Z Ming and Y Chen

ldquoEffect of metal doping into Ce05Zr05O2on photocatalytic

activity of TiO2Ce045

Zr045

M01OX (M = Y La Mn)rdquo Journal

of Hazardous Materials vol 143 no 1-2 pp 516ndash521 2007[11] I Dror D Baram and B Berkowitz ldquoUse of nanosized catalysts

for transformation of chloro-organic pollutantsrdquoEnvironmentalScience and Technology vol 39 no 5 pp 1283ndash1290 2005

[12] D N Priya J M Modak and A M Raichur ldquoLbL fabricatedpoly(styrene sulfonate)TiO

2multilayer thin films for environ-

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[13] H Choi E Stathatos and D D Dionysiou ldquoPhotocatalyticTiO2films and membranes for the development of efficient

wastewater treatment and reuse systemsrdquoDesalination vol 202no 1mdash3 pp 199ndash206 2007

[14] G V Lowry andKM Johnson ldquoCongener-specific dechlorina-tion of dissolved PCBs by microscale and nanoscale zerovalentiron in a watermethanol solutionrdquo Environmental Science andTechnology vol 38 no 19 pp 5208ndash5216 2004

[15] W Nam J H Park and G Y Han ldquoEnhanced photocatalyticoxidation properties in Pt-TiO

2thin films by groundingrdquo

Korean Journal of Chemical Engineering vol 26 no 2 pp 392ndash397 2009

[16] P Wang T Zhou R Wang and T-T Lim ldquoCarbon-sensitizedand nitrogen-doped TiO

2for photocatalytic degradation of

sulfanilamide under visible-light irradiationrdquo Water Researchvol 45 no 16 pp 5015ndash5026 2011

[17] A Faroon and J Olson Toxilogical Profile for PolychlorinatedBiphenyls (PCBs) Agency for Toxic Substances and DiseaseRegistry US Department of Health and Human Security 2000


[18] M R Hoffmann S T Martin W Choi and D W BahnemannldquoEnvironmental applications of semiconductor photocatalysisrdquoChemical Reviews vol 95 no 1 pp 69ndash96 1995

[19] T I Nkambule R W Krause B B Mamba and J HaarhoffldquoRemoval of natural organic matter from water using ion-exchange resins and cyclodextrin polyurethanesrdquo Physics andChemistry of the Earth vol 34 no 13ndash16 pp 812ndash818 2009

[20] J Chen B Gu E J LeBoeuf H Pan and S Dai ldquoSpectroscopiccharacterization of the structural and functional properties ofnatural organic matter fractionsrdquo Chemosphere vol 48 no 1pp 59ndash68 2002

[21] H C HongM HWong AMazumder and Y Liang ldquoTrophicstate natural organic matter content and disinfection by-product formation potential of six drinking water reservoirs inthe Pearl River Delta Chinardquo Journal of Hydrology vol 359 no1-2 pp 164ndash173 2008

[22] AMatilainen E T Gjessing T Lahtinen L Hed A Bhatnagarand M Sillanpaa ldquoAn overview of the methods used in thecharacterisation of natural organic matter (NOM) in relationto drinking water treatmentrdquo Chemosphere vol 83 no 11 pp1431ndash1442 2011

[23] B Gu J Schmitt Z Chen L Liang and J F McCarthyldquoAdsorption and desorption of natural organic matter on ironoxide mechanisms and modelsrdquo Environmental Science andTechnology vol 28 no 1 pp 38ndash46 1994

[24] V Kanokkantapong T F Marhaba P Pavasant and BPanyapinyophol ldquoCharacterization of haloacetic acid precur-sors in source waterrdquo Journal of Environmental Managementvol 80 no 3 pp 214ndash221 2006

[25] S Mattaraj C Jarusutthirak and R Jiraratananon ldquoA com-bined osmotic pressure and cake filtration model for crossflownanofiltration of natural organic matterrdquo Journal of MembraneScience vol 322 no 2 pp 475ndash483 2008

[26] T I Nkambule R W M Krause J Haarhoff and B BMamba ldquoTreatability and characterization of natural organicmatter (NOM) in South African waters using newly developedmethodsrdquo Physics and Chemistry of the Earth vol 36 no 14-15pp 1159ndash1166 2011

[27] S McDonald A G Bishop P D Prenzler and K RobardsldquoAnalytical chemistry of freshwater humic substancesrdquo Analyt-ica Chimica Acta vol 527 no 2 pp 105ndash124 2004

[28] J Kim Z Cai and M M Benjamin ldquoEffects of adsorbents onmembrane fouling by natural organic matterrdquo Journal of Mem-brane Science vol 310 no 1-2 pp 356ndash364 2008

[29] H Zhang J Qu H Liu and X Zhao ldquoCharacterization ofisolated fractions of dissolved organicmatter from sewage treat-ment plant and the related disinfection by-products formationpotentialrdquo Journal of Hazardous Materials vol 164 no 2-3 pp1433ndash1438 2009

[30] CMM Bougeard EHGoslan B Jefferson and S A ParsonsldquoComparison of the disinfection by-product formation poten-tial of treatedwaters exposed to chlorine andmonochloraminerdquoWater Research vol 44 no 3 pp 729ndash740 2010

[31] A Kanan and T Karanfil ldquoFormation of disinfection by-pro-ducts in indoor swimming pool water the contribution fromfilling water natural organic matter and swimmer body fluidsrdquoWater Research vol 45 no 2 pp 926ndash932 2011

[32] T Bond J Huang M R Templeton and N Graham ldquoOccur-rence and control of nitrogenous disinfection by-products indrinking watermdasha reviewrdquo Water Research vol 45 no 15 pp4341ndash4354 2011

[33] B ChenW Lee P KWesterhoff SW Krasner and P HerckesldquoSolar photolysis kinetics of disinfection byproductsrdquo WaterResearch vol 44 no 11 pp 3401ndash3409 2010

[34] H Zhang J Qu H Liu and D Wei ldquoCharacterization ofdissolved organic matter fractions and its relationship with thedisinfection by-product formationrdquo Journal of EnvironmentalSciences vol 21 no 1 pp 54ndash61 2009

[35] I Kristiana C Joll and A Heitz ldquoPowdered activated carboncoupled with enhanced coagulation for natural organic matterremoval and disinfection by-product control application in awestern Australian water treatment plantrdquo Chemosphere vol83 no 5 pp 661ndash667 2011

[36] R Shen and S A Andrews ldquoDemonstration of 20 pharma-ceuticals and personal care products (PPCPs) as nitrosamineprecursors during chloramine disinfectionrdquo Water Researchvol 45 no 2 pp 944ndash952 2011

[37] S H Mhlongo B B Mamba and R W Krause ldquoMonitoringthe prevalence of nitrosamines in South African waters andtheir removal using cyclodextrin polyurethanesrdquo Physics andChemistry of the Earth Parts ABC vol 34 no 13ndash16 pp 819ndash824 2009

[38] J Nawrocki and P Andrzejewski ldquoNitrosamines and waterrdquoJournal of Hazardous Materials vol 189 no 1-2 pp 1ndash18 2011

[39] V V B Rao and S R M Rao ldquoAdsorption studies on treatmentof textile dyeing industrial effluent by flyashrdquo Chemical Engi-neering Journal vol 116 no 1 pp 77ndash84 2006

[40] S N Husaini J H Zaidi F Malik and M Arif ldquoApplication ofnuclear track membrane for the reduction of pollutants in theindustrial effluentrdquo Radiation Measurements vol 43 no 1 ppS607ndashS611 2008

[41] X-H Ou C-H Wu and S-L Lo ldquoPhotodegradation of 4-chlorophenol by UVphotocatalysts the effect of the interpar-ticle electron transfer processrdquo Reaction Kinetics and CatalysisLetters vol 88 no 1 pp 89ndash95 2006

[42] S M Ali S Z Sabae M Fayez M Monib and N A HegazildquoThe influence of agro-industrial effluents on River Nile pollu-tionrdquo Journal of Advanced Research vol 2 no 1 pp 85ndash95 2011

[43] B Sancey G Trunfio J Charles et al ldquoHeavy metal removalfrom industrial effluents by sorption on cross-linked starchchemical study and impact on water toxicityrdquo Journal of Envi-ronmental Management vol 92 no 3 pp 765ndash772 2011

[44] K-H Kim and S-K Ihm ldquoHeterogeneous catalytic wet airoxidation of refractory organic pollutants in industrial wastew-aters a reviewrdquo Journal of Hazardous Materials vol 186 no 1pp 16ndash34 2011

[45] B Hajem H Hamzaoui and A Mrsquonif ldquoChemical interactionbetween industrial acid effluents and the hydrous mediumrdquoDesalination vol 206 no 1ndash3 pp 154ndash162 2007

[46] L-C Chiang J-E Chang and S-C Tseng ldquoElectrochemicaloxidation pretreatment of refractory organic pollutantsrdquoWaterScience and Technology vol 36 no 2-3 pp 123ndash130 1997

[47] S Ghasemi S Rahimnejad S R Setayesh S Rohani and MR Gholami ldquoTransition metal ions effect on the properties andphotocatalytic activity of nanocrystalline TiO

2prepared in an

ionic liquidrdquo Journal of Hazardous Materials vol 172 no 2-3pp 1573ndash1578 2009

[48] A Kaur S Vats S Rekhi et al ldquoPhysico-chemical analysis ofthe industrial effluents and their impact on the soil microflorardquoProcedia Environmental Sciences vol 2 pp 595ndash599 2010

[49] B Kayan B Gozmen M Demirel and A M Gizir ldquoDegrada-tion of acid red 97 dye in aqueous medium using wet oxidation


and electro-Fenton techniquesrdquo Journal ofHazardousMaterialsvol 177 no 1ndash3 pp 95ndash102 2010

[50] L Lei Q Dai M Zhou and X Zhang ldquoDecolorization ofcationic red X-GRL by wet air oxidation performance opti-mization and degradation mechanismrdquo Physics and Chemistryof the Earth Parts ABC vol 68 no 13ndash16 pp 1135ndash1142 2007

[51] H Y He W X Dong and G H Zhang ldquoPhotodegradation ofaqueous methyl orange on MnTiO

3powder at different initial

pHrdquo Research on Chemical Intermediates vol 36 no 9 pp 995ndash1001 2010

[52] K Yu S Yang H He C Sun C Gu and Y Ju ldquoVisiblelight-driven photocatalytic degradation of rhodamine B overNaBiO

3 Pathways and mechanismrdquo Journal of Physical Chem-

istry A vol 113 no 37 pp 10024ndash10032 2009[53] A Murat A Meltem S Funda K Nadir A Ertugrul and S

Hikmet ldquoA novel approach to the hydrothermal synthesis ofanatase titania nanoparticles and the photocatalytic degrada-tion of rhodamine Brdquo Turkish Journal of Chemistry vol 30 pp333ndash343 2006

[54] N C Respicio and J Heitz ldquoComparative toxicity of rhodamineB and rhodamine 6G to the house fly (Musca domestica L)rdquoBulletin of Environmental Contamination andToxicology vol 27no 2 pp 274ndash281 1981

[55] TMasciangioli andW-X Zhang ldquoEnvironmental technologiesat the nanoscalerdquo Environmental Science and Technology vol 37no 5 pp 102ndash108 2003

[56] S Suarez N Arconada Y Castro et al ldquoPhotocatalytic degra-dation of TCE in dry and wet air conditions with TiO

2porous

thin filmsrdquo Applied Catalysis B Environmental vol 108-109 pp14ndash21 2011

[57] Y Cao H Tan T Shi T Shi T Tang and J Li ldquoPreparationof Ag-doped TiO

2nanoparticles for photocatalytic degradation

of acetamiprid in waterrdquo Journal of Chemical Technology andBiotechnology vol 83 no 4 pp 546ndash552 2008

[58] J Sa and J A Anderson ldquoFTIR study of aqueous nitratereduction over PdTiO

2rdquo Applied Catalysis B Environmental

vol 77 no 3-4 pp 409ndash417 2008[59] C-M Hung ldquoCatalytic wet oxidation of ammonia solution

activity of the nanoscale platinum-palladium-rhodium com-posite oxide catalystrdquo Journal of Hazardous Materials vol 163no 1 pp 180ndash186 2009

[60] ZWu andM Zhou ldquoPartial degradation of phenol by advancedelectrochemical oxidation processrdquo Environmental Science andTechnology vol 35 no 13 pp 2698ndash2703 2001

[61] J Mucha and R Zarzycki ldquoAnalysis of wet oxidation processafter initial thermohydrolysis of excess sewage sludgerdquo WaterResearch vol 42 no 12 pp 3025ndash3032 2008

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[63] M Anpo ldquoUtilization of TiO2photocatalysts in green chem-

istryrdquo Pure and Applied Chemistry vol 72 no 7 pp 1265ndash12702000

[64] J-Y Li W-H Ma P-X Lei and J-C Zhao ldquoDetection of inter-mediates in the TiO

2-assisted photodegradation of Rhodamine

B under visible light irradiationrdquo Journal of EnvironmentalSciences vol 19 no 7 pp 892ndash896 2007

[65] K Sunada Y Kikuchi K Hashimoto and A FujishimaldquoBactericidal and detoxification effects of TiO

2thin film pho-

tocatalystsrdquo Environmental Science and Technology vol 32 no5 pp 726ndash728 1998

[66] A Bhattacharyya S Kawi and M B Ray ldquoPhotocatalyticdegradation of orange II by TiO

2catalysts supported on

adsorbentsrdquo Catalysis Today vol 98 no 3 pp 431ndash439 2004[67] V Mirkhani S Tangestaninejad M Moghadam M H Habibi

and A R Vartooni ldquoPhotodegradation of aromatic amines byAg-TiO

2photocatalystrdquo Journal of the Iranian Chemical Society

vol 6 no 4 pp 800ndash807 2009[68] P E Savage ldquoOrganic chemical reactions in supercritical waterrdquo

Chemical Reviews vol 99 no 2-3 pp 603ndash621 1999[69] H E Barner C Y Huang T Johnson G Jacobs M A Martch

and W R Killilea ldquoSupercritical water oxidation an emergingtechnologyrdquo Journal of Hazardous Materials vol 31 no 1 pp1ndash17 1992

[70] V Marulanda and G Bolanos ldquoSupercritical water oxidationof a heavily PCB-contaminated mineral transformer oil Labo-ratory-scale data and economic assessmentrdquo Journal of Super-critical Fluids vol 54 no 2 pp 258ndash265 2010

[71] S-H Son J-H Lee and C-H Lee ldquoCorrosion phenomenaof alloys by subcritical and supercritical water oxidation of 2-chlorophenolrdquo Journal of Supercritical Fluids vol 44 no 3 pp370ndash378 2008

[72] T Fujii R Hayashi S-I Kawasaki A Suzuki and Y OshimaldquoWater density effects on methanol oxidation in supercriticalwater at high pressure up to 100 MPardquo Journal of SupercriticalFluids vol 58 no 1 pp 142ndash149 2011

[73] P A Marrone and G T Hong ldquoCorrosion control methodsin supercritical water oxidation and gasification processesrdquoJournal of Supercritical Fluids vol 51 no 2 pp 83ndash103 2009

[74] R Hayashi M Onishi M Sugiyama S Koda and Y OshimaldquoKinetic analysis on alcohol concentration and mixture effectin supercritical water oxidation of methanol and ethanol byelementary reaction modelrdquoThe Journal of Supercritical Fluidsvol 40 no 1 pp 74ndash83 2007

[75] F Stuber J Font A Fortuny C Bengoa A Eftaxias and AFabregat ldquoCarbon materials and catalytic wet air oxidation oforganic pollutants in wastewaterrdquoTopics in Catalysis vol 33 no1ndash4 pp 3ndash50 2005

[76] N Li C Descorme andM Besson ldquoCatalytic wet air oxidationof chlorophenols over supported ruthenium catalystsrdquo Journalof Hazardous Materials vol 146 no 3 pp 602ndash609 2007

[77] D Prabhakaran T Kannadasan and C Ahmed Basha ldquoMedi-ated electrochemical oxidation process for destruction ofTOC in a batch recirculation reactorrdquo International Journal ofChemTech Research vol 1 no 4 pp 962ndash969 2009

[78] D Nematollahi and L Mohammadi-Behzad ldquoElectrochemicaloxidation of catechol in the presence of some azacrown ethersand transition metal ions in acetonitrilerdquo International Journalof Electrochemical Science vol 4 no 11 pp 1583ndash1592 2009

[79] L-C Chiang J-E Chang and T-C Wen ldquoIndirect oxida-tion effect in electrochemical oxidation treatment of landfillleachaterdquoWater Research vol 29 no 2 pp 671ndash678 1995

[80] J D Rodgers W Jedral and N J Bunce ldquoElectrochemicaloxidation of chlorinated phenolsrdquo Environmental Science andTechnology vol 33 no 9 pp 1453ndash1457 1999

[81] S Jiao S Zheng D Yin L Wang and L Chen ldquoAqueousphotolysis of tetracycline and toxicity of photolytic products toluminescent bacteriardquo Chemosphere vol 73 no 3 pp 377ndash3822008

[82] L Fang J Huang G Yu and X Li ldquoQuantitative structure-property relationship studies for direct photolysis rate constantsand quantum yields of polybrominated diphenyl ethers in


hexane andmethanolrdquo Ecotoxicology and Environmental Safetyvol 72 no 5 pp 1587ndash1593 2009

[83] B Abramovic D Sojic andV Anderluh ldquoVisible-light-inducedphotocatalytic degradation of herbicide mecoprop in aqueoussuspension of TiO

2rdquo Acta Chimica Slovenica vol 54 no 3 pp

558ndash564 2007[84] E Bae andW Choi ldquoHighly enhanced photoreductive degrada-

tion of perchlorinated compounds on dye-sensitized metalTiO2under visible lightrdquo Environmental Science amp Technology

vol 37 no 1 pp 147ndash152 2003[85] F Zhang J Zhao T Shen H Hidaka E Pelizzetti and N

Serpone ldquoTiO2-assisted photodegradation of dye pollutants

II Adsorption and degradation kinetics of eosin in TiO2

dispersions under visible light irradiationrdquo Applied Catalysis BEnvironmental vol 15 no 1-2 pp 147ndash156 1998

[86] L Zhang and T J Webster ldquoNanotechnology and nanomate-rials promises for improved tissue regenerationrdquo Nano Todayvol 4 no 1 pp 66ndash80 2009

[87] B F G Johnson ldquoNanoparticles in catalysisrdquoTopics in Catalysisvol 24 no 1ndash4 pp 147ndash159 2003

[88] X Chen and S S Mao ldquoTitanium dioxide nanomaterials Syn-thesis properties modifications and applicationsrdquo ChemicalReviews vol 107 no 7 pp 2891ndash2959 2007

[89] Z He C Sun S Yang Y Ding H He and Z Wang ldquoPhoto-catalytic degradation of rhodamine B by Bi

2WO6with electron

accepting agent under microwave irradiation mechanism andpathwayrdquo Journal of Hazardous Materials vol 162 no 2-3 pp1477ndash1486 2009

[90] W Dong and C Zhu ldquoOptical properties of surface-modifiedBi2O3nanoparticlesrdquo Journal of Physics and Chemistry of Solids

vol 64 no 2 pp 265ndash271 2003[91] F Meng F Lu Z Sun and J Lu ldquoA mechanism for enhanced

photocatalytic activity of nano-size silver particle modified tita-nium dioxide thin filmsrdquo Science China Technological Sciencesvol 53 no 11 pp 3027ndash3032 2010

[92] A Fujishima T N Rao and D A Tryk ldquoTitanium dioxidephotocatalysisrdquo Journal of Photochemistry and Photobiology CPhotochemistry Reviews vol 1 no 1 pp 1ndash21 2000

[93] M Ni M K H Leung D Y C Leung and K Sumathy ldquoAreview and recent developments in photocatalytic water-split-ting using TiO

2for hydrogen productionrdquo Renewable and Sus-

tainable Energy Reviews vol 11 no 3 pp 401ndash425 2007[94] W Tang Q Wang X Zeng and X Chen ldquoPhotocatalytic

degradation on Disperse Blue with modified nano-TiO2film

electroderdquo Journal of Solid State Electrochemistry vol 16 no 4pp 1429ndash1445 2012

[95] U Diebold ldquoThe surface science of titanium dioxiderdquo SurfaceScience Reports vol 48 no 5ndash8 pp 53ndash229 2003

[96] A Kudo RNiishiro A Iwase andHKato ldquoEffects of doping ofmetal cations onmorphology activity and visible light responseof photocatalystsrdquo Chemical Physics vol 339 no 1ndash3 pp 104ndash110 2007

[97] A R Malagutti H A J L Mourao J R Garbin and C RibeiroldquoDeposition of TiO

2and AgTiO

2thin films by the polymeric

precursor method and their application in the photodegrada-tion of textile dyesrdquo Applied Catalysis B Environmental vol 90no 1-2 pp 205ndash212 2009

[98] K M Reddy S V Manorama and A R Reddy ldquoBandgap stud-ies on anatase titanium dioxide nanoparticlesrdquoMaterials Chem-istry and Physics vol 78 no 1 pp 239ndash245 2003

[99] R Pode ldquoOn the problemof open circuit voltage inmetal phtha-locyanineC60 organic solar cellsrdquo Advanced Materials Lettersvol 2 pp 3ndash11 2011

[100] R Ferrando J Jellinek and R L Johnston ldquoNanoalloys fromtheory to applications of alloy clusters and nanoparticlesrdquoChemical Reviews vol 108 no 3 pp 845ndash910 2008

[101] L Shivalingappa J Sheng and T Fukami ldquoPhotocatalytic effectin platinum doped titanium dioxide filmsrdquoVacuum vol 48 no5 pp 413ndash416 1997

[102] C Minero G Mariella V Maurino D Vione and E PelizzettildquoPhotocatalytic transformation of organic compounds in thepresence of inorganic ions 2 Competitive reactions of phenoland alcohols on a titanium dioxide-fluoride systemrdquo Langmuirvol 16 no 23 pp 8964ndash8972 2000

[103] C Minero G Mariella V Maurino and E Pelizzetti ldquoPhoto-catalytic transformation of organic compounds in the presenceof inorganic anions 1 Hydroxyl-mediated and direct electron-transfer reactions of phenol on a titanium dioxide-fluoridesystemrdquo Langmuir vol 16 no 6 pp 2632ndash2641 2000

[104] S Wang L Ji B Wu Q Gong Y Zhu and J Liang ldquoInfluenceof surface treatment on preparing nanosized TiO

2supported on

carbon nanotubesrdquo Applied Surface Science vol 255 no 5 pp3263ndash3266 2008

[105] P Bouras E Stathatos and P Lianos ldquoPure versus metal-ion-doped nanocrystalline titania for photocatalysisrdquo AppliedCatalysis B Environmental vol 73 no 1-2 pp 51ndash59 2007

[106] M M Mahlambi A K Mishra S B Mishra R W Krause BB Mamba and A M Raichur ldquoEffect of metal ions (Ag CoNi and Pd) on the visible light degradation of Rhodamine B bycarbon-covered alumina-supported TiO

2in aqueous solutionsrdquo

Industrial and Engineering Chemistry Research vol 52 no 5 pp1783ndash1794 2013

[107] W Weng M Ma P Du et al ldquoSuperhydrophilic Fe dopedtitanium dioxide thin films prepared by a spray pyrolysisdepositionrdquo Surface and Coatings Technology vol 198 no 1ndash3pp 340ndash344 2005

[108] A Izquierdo S S Ono J-C Voegel P Schaaf and G DecherldquoDipping versus spraying exploring the deposition conditionsfor speeding up layer-by-layer assemblyrdquo Langmuir vol 21 no16 pp 7558ndash7567 2005

[109] G Decher ldquoFuzzy nanoassemblies toward layered polymericmulticompositesrdquo Science vol 277 no 5330 pp 1232ndash1237 1997

[110] M M Mahlambi A K Mishra S B Mishra A M RaichurB B Mamba and R W Krause ldquoLayer-by-layer self-assembledmetal-ion- (Ag- Co- Ni- and Pd-) doped TiO

2nanoparticles

synthesis characterisation and visible light degradation ofrhodamine Brdquo Journal of Nanomaterials vol 2012 Article ID302046 12 pages 2012

[111] M M Mahlambi O T Mahlangu G D Vilakati and B BMamba ldquoVisible light photodegradation of rhodamine B dyeby two forms of carbon-covered alumina supported TiO

2poly-

sulfone membranesrdquo Industrial and Engineering ChemistryResearch vol 53 no 14 pp 5709ndash5717 2014

[112] M M Mahlambi G D Vilakati and B B Mamba ldquoSyn-thesis characterization and visible light degradation of rho-damine B dye by carbon-covered alumina supported Pd-TiO2polysulfone membranesrdquo Separation Science and Technol-

ogy vol 49 no 14 pp 2124ndash2134 2014[113] A N Guz and Y Y Rushchitskii ldquoNanomaterials on the mech-

anics of nanomaterialsrdquo International Applied Mechanics vol39 no 11 pp 1271ndash1293 2003


[114] J D Mackenzie and E P Bescher ldquoChemical routes in thesynthesis of nanomaterials using the sol-gel processrdquo Accountsof Chemical Research vol 40 no 9 pp 810ndash818 2007

[115] C E Allmond A T Sellinger K Gogick and J M Fitz-Gerald ldquoPhoto-chemical synthesis and deposition of noblemetal nanoparticlesrdquo Applied Physics A vol 86 no 4 pp 477ndash480 2007

[116] K Ramanathan D Avnir A Modestov and O Lev ldquoSol-gelderived ormosil-exfoliated graphite-TiO

2composite floating

catalyst photodeposition of copperrdquo Chemistry of Materialsvol 9 no 11 pp 2533ndash2540 1997

[117] JWang R Li Z Zhang et al ldquoDegradation of hazardous dyes inwastewater using nanometermixed crystal TiO

2powders under

visible light irradiationrdquoWater Air and Soil Pollution vol 189no 1ndash4 pp 225ndash237 2008

[118] D Beydoun and R Amal ldquoImplications of heat treatmenton the properties of a magnetic iron oxide-titanium dioxidephotocatalystrdquoMaterials Science and Engineering B vol 94 no1 pp 71ndash81 2002

[119] W Ho J C Yu and S Lee ldquoSynthesis of hierarchical nano-porous F-doped TiO

2spheres with visible light photocatalytic

activityrdquo Chemical Communications no 10 pp 1115ndash1117 2006[120] J Yu and J Zhang ldquoA simple template-free approach to TiO

2

hollow spheres with enhanced photocatalytic activityrdquo DaltonTransactions vol 39 no 25 pp 5860ndash5867 2010

[121] H D Jang S-K Kim and S-J Kim ldquoEffect of particle sizeand phase composition of titaniumdioxide nanoparticles on thephotocatalytic propertiesrdquo Journal of Nanoparticle Research vol3 no 2-3 pp 141ndash147 2001

[122] A Pottier C Chaneac E Tronc L Mazerolles and J-P JolivetldquoSynthesis of brookite TiO

2nanoparticles by thermolysis of

TiCl4in strongly acidic aqueous mediardquo Journal of Materials

Chemistry vol 11 no 4 pp 1116ndash1121 2001[123] D-S Seo J-K Lee E-G Lee and H Kim ldquoEffect of aging

agents on the formation of TiO2nanocrystalline powderrdquo

Materials Letters vol 51 no 2 pp 115ndash119 2001[124] M Afuyoni G Nashed and I M Nasser ldquoTiO

2doped with

SnO2and studing its structural and electrical propertiesrdquo

Energy Procedia vol 6 pp 11ndash20 2011[125] S Nakade M Matsuda S Kambe et al ldquoDependence of TiO

2

nanoparticle preparation methods and annealing temperatureon the efficiency of dye-sensitized solar cellsrdquo Journal of PhysicalChemistry B vol 106 no 39 pp 10004ndash10010 2002

[126] M Subramanian S Vijayalakshmi S Venkataraj and RJayavel ldquoEffect of cobalt doping on the structural and opticalproperties of TiO

2films prepared by sol-gel processrdquoThin Solid

Films vol 516 no 12 pp 3776ndash3782 2008[127] J Ovenstone ldquoPreparation of novel titania photocatalysts with

high activityrdquo Journal of Materials Science vol 36 no 6 pp1325ndash1329 2001

[128] Y Zhang A Weidenkaff and A Reller ldquoMesoporous structureand phase transition of nanocrystalline TiO

2rdquoMaterials Letters

vol 54 no 5-6 pp 375ndash381 2002[129] M Behpour S M Ghoreishi and F S Razavi ldquoPhotocatalytic

activity of TiO2Ag nanoparticles on degradation of water

pollutionsrdquo Digest Journal of Nanomaterials and Biostructuresvol 5 no 2 pp 467ndash475 2010

[130] J Arana J M Dona-Rodrıguez E Tello Rendon et al ldquoTiO2

activation by using activated carbon as a support part I Surfacecharacterisation and decantability studyrdquo Applied Catalysis BEnvironmental vol 44 no 2 pp 161ndash172 2003

[131] P C Lansaker J Backholm G A Niklasson and C GGranqvist ldquoTiO

2AuTiO

2multilayer thin films novel metal-

based transparent conductors for electrochromic devicesrdquoThinSolid Films vol 518 no 4 pp 1225ndash1229 2009

[132] M-S Wong S-W Hsu K K Rao and C P Kumar ldquoInfluenceof crystallinity and carbon content on visible light photocatal-ysis of carbon doped titania thin filmsrdquo Journal of MolecularCatalysis A Chemical vol 279 no 1 pp 20ndash26 2008

[133] T Peng D Zhao K Dai W Shi and K Hirao ldquoSynthesis oftitanium dioxide nanoparticles with mesoporous anatase walland high photocatalytic activityrdquo Journal of Physical ChemistryB vol 109 no 11 pp 4947ndash4952 2005

[134] J P Vicente T Gacoin P Barboux J-P Boilot M Rondet andL Gueneau ldquoPhotocatalytic decomposition of fatty stains byTiO2thin filmsrdquo International Journal of Photoenergy vol 5 no

2 pp 95ndash98 2003[135] P Kiri G Hyett and R Binions ldquoSolid state thermochromic

materialsrdquo Advanced Materials Letters vol 1 no 2 pp 86ndash1052010

[136] M I Zaki G A H Mekhemer N E Fouad T C Jagadale andS B Ogale ldquoSurface texture and specific adsorption sites of sol-gel synthesized anatase TiO

2nanoparticlesrdquoMaterials Research

Bulletin vol 45 no 10 pp 1470ndash1475 2010[137] A S Barnard and P Zapol ldquoPredicting the energetics phase

stability and morphology evolution of faceted and sphericalanatase nanocrystalsrdquo Journal of Physical Chemistry B vol 108no 48 pp 18435ndash18440 2004

[138] J Zhu J Zhang F Chen K Iino and M Anpo ldquoHigh acti-vity TiO

2photocatalysts prepared by amodified sol-gelmethod

characterization and their photocatalytic activity for the degra-dation of XRG and X-GLrdquo Topics in Catalysis vol 35 no 3-4pp 261ndash268 2005

[139] J A Navıo G Colon M Macıas C Real and M I LitterldquoIron-doped titania semiconductor powders prepared by a sol-gel method Part I synthesis and characterizationrdquo AppliedCatalysis A General vol 177 no 1 pp 111ndash120 1999

[140] V Panic A Dekanski SMilonjic R Atanasoski and BNikolicldquoThe influence of the aging time of RuO

2and TiO

2sols on

the electrochemical properties and behavior for the chlorineevolution reaction of activated titanium anodes obtained by thesol-gel procedurerdquo Electrochimica Acta vol 46 no 2-3 pp 415ndash421 2000

[141] J Zarzycki ldquoPast and present of sol-gel science and technologyrdquoJournal of Sol-Gel Science and Technology vol 8 no 1ndash3 pp 17ndash22 1997

[142] A Ahmad JThiel and S I Shah ldquoStructural effects of niobiumand silver doping on titanium dioxide nanoparticlesrdquo Journal ofPhysics Conference Series vol 61 no 1 pp 11ndash15 2007

[143] K-R Zhu M-S Zhang J-M Hong and Z Yin ldquoSize effecton phase transition sequence of TiO

2nanocrystalrdquo Materials

Science and Engineering A vol 403 no 1-2 pp 87ndash93 2005[144] T Sugimoto K Okada and H Itoh ldquoSynthesis of uniform

spindle-type titania particles by the gel-sol methodrdquo Journal ofColloid and Interface Science vol 193 no 1 pp 140ndash143 1997

[145] T Sugimoto X Zhou andAMuramatsu ldquoSynthesis of uniformanatase TiO

2nanoparticles by gelndashsol method 1 Solution

chemistry of Ti(OH)(4minus119899)+119899

complexesrdquo Journal of Colloid andInterface Science vol 252 pp 339ndash346 2002


2nanoparticles by gel-solmethod 4 Shape controlrdquo

Journal of Colloid and Interface Science vol 259 no 1 pp 53ndash612003



2nanoparticles by gel-sol method 3 Formation

process and size controlrdquo Journal of Colloid and InterfaceScience vol 259 no 1 pp 43ndash52 2003

[148] W Chen and W Gao ldquoSol-enhanced electroplating of nanos-tructured NindashTiO

2composite coatingsmdashthe effects of sol

concentration on the mechanical and corrosion propertiesrdquoElectrochimica Acta vol 55 no 22 pp 6865ndash6871 2010

[149] Y Lei L D Zhang and J C Fan ldquoFabrication characterizationand Raman study of TiO

2nanowire arrays prepared by anodic

oxidative hydrolysis of TiCl3rdquoChemical Physics Letters vol 338

no 4-6 pp 231ndash236 2001[150] X-S Zhou L-J Li Y-H Lin and C-WNan ldquoCharacterization

and properties of anatase TiO2film prepared via colloidal sol

method under low temperaturerdquo Journal of Electroceramics vol21 no 1ndash4 pp 795ndash797 2008

[151] J Zhu J Ren Y Huo Z Bian and H Li ldquoNanocrystallineFeTiO

2visible photocatalyst with a mesoporous structure

prepared via a nonhydrolytic sol-gel routerdquo Journal of PhysicalChemistry C vol 111 no 51 pp 18965ndash18969 2007

[152] G Guo J K Whitesell and M A Fox ldquoSynthesis of TiO2

photocatalysts in supercritical CO2via a non-hydrolytic routerdquo

Journal of Physical Chemistry B vol 109 no 40 pp 18781ndash187852005

[153] Y-W Jun M F Casula J-H Sim S Y Kim J Cheon and AP Alivisatos ldquoSurfactant-assisted elimination of a high energyfacet as ameans of controlling the shapes of TiO

2nanocrystalsrdquo

Journal of the American Chemical Society vol 125 no 51 pp15981ndash15985 2003

[154] T J Trentler T E Denler J F Bertone A Agrawal and VL Colvin ldquoSynthesis of TiO

2nanocrystals by nonhydrolytic

solution-based reactionsrdquo Journal of the American ChemicalSociety vol 121 no 7 pp 1613ndash1614 1999

[155] B Koo J Park Y Kim S-H Choi Y-E Sung and T HyeonldquoSimultaneous phase- and size-controlled synthesis of TiO

2

nanorods via non-hydrolytic sol-gel reaction of syringe pumpdelivered precursorsrdquo Journal of Physical Chemistry B vol 110no 48 pp 24318ndash24323 2006

[156] A Lopez D Acosta A I Martınez and J Santiago ldquoNanos-tructured low crystallized titaniumdioxide thin filmswith goodphotocatalytic activityrdquo Powder Technology vol 202 no 1ndash3 pp111ndash117 2010

[157] J Liu Y Zhao L Shi et al ldquoSolvothermal synthesis of crystallinephase and shape controlled Sn4+-Doped TiO

2nanocrystals

Effects of reaction solventrdquo ACS Applied Materials and Inter-faces vol 3 no 4 pp 1261ndash1268 2011

[158] J Liao L Shi S Yuan Y Zhao and J Fang ldquoSolvothermal syn-thesis of TiO

2nanocrystal colloids from peroxotitanate com-

plex solution and their photocatalytic activitiesrdquo Journal ofPhysical Chemistry C vol 113 no 43 pp 18778ndash18783 2009

[159] W Q Fang J Z Zhou J Liu et al ldquoHierarchical structures ofsingle-crystalline anatase TiO2 nanosheets dominated by 001facetsrdquo Chemistry vol 17 no 5 pp 1423ndash1427 2011

[160] X Wang J Zhuang Q Peng and Y Li ldquoA general strategy fornanocrystal synthesisrdquo Nature vol 437 no 7055 pp 121ndash1242005

[161] X-L Li Q Peng J-X Yi X Wang and Y Li ldquoNear monodis-perse TiO

2nanoparticles and nanorodsrdquo ChemistrymdashA Euro-

pean Journal vol 12 no 8 pp 2383ndash2391 2006[162] J Xu J-P Ge andY-D Li ldquoSolvothermal synthesis ofmonodis-

perse PbSe nanocrystalsrdquo The Journal of Physical Chemistry Bvol 110 no 6 pp 2497ndash2501 2006

[163] K S Yeung and Y W Lam ldquoA simple chemical vapour deposi-tion method for depositing thin TiO

2filmsrdquo Thin Solid Films

vol 109 no 2 pp 169ndash178 1983[164] H Yoshitake T Sugihara and T Tatsumi ldquoPreparation of

wormhole-like mesoporous TiO2with an extremely large sur-

face area and stabilization of its surface by chemical vapordepositionrdquoChemistry of Materials vol 14 no 3 pp 1023ndash10292002

[165] H Nizard M L Kosinova N I Fainer Y M Rumyantsev BM Ayupov and Y V Shubin ldquoDeposition of titanium dioxidefrom TTIP by plasma enhanced and remote plasma enhancedchemical vapor depositionrdquo Surface and Coatings Technologyvol 202 no 17 pp 4076ndash4085 2008

[166] Y Guo X-W Zhang W-H Weng and G-R Han ldquoStructureand properties of nitrogen-doped titanium dioxide thin filmsgrown by atmospheric pressure chemical vapor depositionrdquoThin Solid Films vol 515 no 18 pp 7117ndash7121 2007

[167] P G Karlsson J H Richter M P Andersson et al ldquoTiO2

chemical vapor deposition on Si(111) in ultrahigh vacuum tran-sition from interfacial phase to crystalline phase in the reactionlimited regimerdquo Surface Science vol 605 no 13-14 pp 1147ndash1156 2011

[168] W-Y Ahn S A Sheeley T Rajh andDMCropek ldquoPhotocata-lytic reduction of 4-nitrophenol with arginine-modified tita-nium dioxide nanoparticlesrdquo Applied Catalysis B Environmen-tal vol 74 no 1-2 pp 103ndash110 2007

[169] B Neppolian H Yamashita Y Okada H Nishijima and MAnpo ldquoPreparation of unique TiO

2nano-particle photocata-

lysts by a multi-gelation method for control of the physico-chemical parameters and reactivityrdquo Catalysis Letters vol 105no 1-2 pp 111ndash117 2005

[170] H Liu W Yang Y Ma et al ldquoSynthesis and characterizationof titania prepared by using a photoassisted sol-gel methodrdquoLangmuir vol 19 no 7 pp 3001ndash3005 2003

[171] Y Bessekhouad D Robert and J V Weber ldquoSynthesis ofphotocatalytic TiO

2nanoparticles optimization of the prepa-

ration conditionsrdquo Journal of Photochemistry and PhotobiologyA Chemistry vol 157 no 1 pp 47ndash53 2003

[172] G Tian H Fu L Jing and C Tian ldquoSynthesis and photocata-lytic activity of stable nanocrystalline TiO

2with high crys-

tallinity and large surface areardquo Journal of Hazardous Materialsvol 161 no 2-3 pp 1122ndash1130 2009

[173] A Daszligler A Feltz J Jung W Ludwig and E KaisersbergerldquoCharacterization of rutile and anatase powders by thermalanalysisrdquo Journal ofThermal Analysis vol 33 no 3 pp 803ndash8091988

[174] W FuH YangM LiM Li N Yang andG Zou ldquoAnatase TiO2

nanolayer coating on cobalt ferrite nanoparticles for magneticphotocatalystrdquo Materials Letters vol 59 no 27 pp 3530ndash35342005

[175] N Chitose S Ueta S Seino and T A Yamamoto ldquoRadiolysisof aqueous phenol solutions with nanoparticles 1 Phenoldegradation and TOC removal in solutions containing TiO

2

induced by UV 120574-ray and electron beamsrdquo Chemosphere vol50 no 8 pp 1007ndash1013 2003

[176] X Li R Xiong and GWei ldquoS-N co-doped TiO2photocatalysts

with visible-light activity prepared by sol-gel methodrdquoCatalysisLetters vol 125 no 1-2 pp 104ndash109 2008

[177] K Mori K Maki S Kawasaki S Yuan and H YamashitaldquoHydrothermal synthesis of TiO

2photocatalysts in the presence

of NH4F and their application for degradation of organic


compoundsrdquo Chemical Engineering Science vol 63 no 20 pp5066ndash5070 2008

[178] M-C Wang H-J Lin C-H Wang and H-C Wu ldquoEffectsof annealing temperature on the photocatalytic activity of N-doped TiO

2thin filmsrdquo Ceramics International vol 38 no 1

pp 195ndash200 2012[179] D-S Bae K-S Han and J H Adair ldquoSynthesis of CuSiO

2

nanosize particles by a reverse micelle and sol-gel processingrdquoJournal ofMaterials Science Letters vol 21 no 1 pp 53ndash54 2002

[180] S-WWei B Peng L-Y Chai Y-C Liu and Z-Y Li ldquoPrepara-tion of doping titania antibacterial powder by ultrasonic spraypyrolysisrdquo Transactions of Nonferrous Metals Society of Chinavol 18 no 5 pp 1145ndash1150 2008

[181] C-C Chan C-C Chang W-C Hsu S-K Wang and J LinldquoPhotocatalytic activities of Pd-loaded mesoporous TiO

2thin

filmsrdquo Chemical Engineering Journal vol 152 no 2-3 pp 492ndash497 2009

[182] M Hamadanian A Reisi-Vanani and A Majedi ldquoSol-gel pre-paration and characterization of CoTiO

2nanoparticles appli-

cation to the degradation of methyl orangerdquo Journal of theIranian Chemical Society vol 7 no 1 pp S52ndashS58 2010

[183] S Klosek and D Raftery ldquoVisible light driven V-doped TiO2

photocatalyst and its photooxidation of ethanolrdquo Journal ofPhysical Chemistry B vol 105 no 14 pp 2815ndash2819 2002

[184] G N Kryukova G A Zenkovets A A Shutilov et al ldquoStruc-tural peculiarities of TiO

2and PtTiO

2catalysts for the pho-

tocatalytic oxidation of aqueous solution of acid orange 7 dyeupon ultraviolet lightrdquo Applied Catalysis B Environmental vol71 no 3-4 pp 169ndash176 2007

[185] RMechiakhN B Sedrine andRChtourou ldquoSol-gel synthesischaracterization and optical properties of mercury-doped TiO

2

thin films deposited on ITO glass substratesrdquo Applied SurfaceScience vol 257 no 21 pp 9103ndash9109 2011

[186] D Jing Y Zhang and L Guo ldquoStudy on the synthesis ofNi doped mesoporous TiO

2and its photocatalytic activity for

hydrogen evolution in aqueous methanol solutionrdquo ChemicalPhysics Letters vol 415 no 1ndash3 pp 74ndash78 2005

[187] J Nair P Nair F Mizukami Y Oosawa and T Okubo ldquoMicro-structure and phase transformation behavior of doped nanos-tructured titaniardquoMaterials Research Bulletin vol 34 no 8 pp1275ndash1290 1999

[188] S S Samal P Jeyaraman and V Vishwakarma ldquoSonochemicalcoating of Ag-TiO

2nanoparticles on textile fabrics for stain

repellency and self-cleaningmdashthe Indian scenario a reviewrdquoJournal of Minerals and Materials Characterization and Engi-neering vol 9 no 6 pp 519ndash525 2010

[189] M Takahashi K Mita H Toyuki and M Kume ldquoPt-TiO2thin

films on glass substrates as efficient photocatalystsrdquo Journal ofMaterials Science vol 24 no 1 pp 243ndash246 1989

[190] A Towata YUwaminoM SandoK Iseda andHTaoda ldquoSyn-thesis of titania photocatalysts dispersed with nickel nanosizedparticlesrdquo Nanostructured Materials vol 10 no 6 pp 1033ndash1042 1998

[191] T Umebayashi T Yamaki H Itoh and K Asai ldquoAnalysis ofelectronic structures of 3d transition metal-doped TiO

2based

on band calculationsrdquo Journal of Physics andChemistry of Solidsvol 63 no 10 pp 1909ndash1920 2002

[192] N Serpone D Lawless J Disdier and J-M Herrmann ldquoSpec-troscopic photoconductivity and photocatalytic studies ofTiO2colloids Naked and with the lattice doped with Cr3+ Fe3+

and V5+ cationsrdquo Langmuir vol 10 no 3 pp 643ndash652 1994

[193] E Stathatos T Petrova and P Lianos ldquoStudy of the efficiency ofvisible-light photocatalytic degradation of basic blue adsorbedon pure and dopedmesoporous titania filmsrdquo Langmuir vol 17no 16 pp 5025ndash5030 2001

[194] M Stir R Nicula and E Burkel ldquoPressure-temperature phasediagrams of pure and Ag-doped nanocrystalline TiO

2photo-

catalystsrdquo Journal of the European Ceramic Society vol 26 no9 pp 1547ndash1553 2006

[195] Y Ao J Xu D Fu and C Yuan ldquoPreparation of Ag-dopedmesoporous titania and its enhanced photocatalytic activityunder UV light irradiationrdquo Journal of Physics and Chemistryof Solids vol 69 no 11 pp 2660ndash2664 2008

[196] C Burda Y Lou X Chen A C S Samia J Stout and J LGole ldquoEnhanced nitrogen doping in TiO

2nanoparticlesrdquoNano

Letters vol 3 no 8 pp 1049ndash1051 2003[197] S S Srinivasan J Wade E K Stefanakos and Y Goswami

ldquoSynergistic effects of sulfation and co-doping on the visiblelight photocatalysis of TiO

2rdquo Journal of Alloys and Compounds

vol 424 no 1-2 pp 322ndash326 2006[198] L LinW Lin Y X Zhu et al ldquoUniform carbon-covered titania

and its photocatalytic propertyrdquo Journal of Molecular CatalysisA Chemical vol 236 no 1-2 pp 46ndash53 2005

[199] Y Ao J Xu D Fu and C Yuan ldquoSynthesis of CNS-tridopedmesoporous titania with enhanced visible light-induced photo-catalytic activityrdquo Microporous and Mesoporous Materials vol122 no 1ndash3 pp 1ndash6 2009

[200] J-A He R Mosurkal L A Samuelson L Li and J KumarldquoDye-sensitized solar cell fabricated by electrostatic layer-by-layer assembly of amphoteric TiO

2nanoparticlesrdquo Langmuir

vol 19 no 6 pp 2169ndash2174 2003[201] M Sorescu and T Xu ldquoThe effect of ball-milling on the thermal

behavior of anatase-doped hematite ceramic systemrdquo Journal ofThermal Analysis and Calorimetry vol 103 no 2 pp 479ndash4842011

[202] A A Ismail I A Ibrahim M S Ahmed R M Mohamed andH El-Shall ldquoSolndashgel synthesis of titaniandashsilica photocatalystfor cyanide photodegradationrdquo Journal of Photochemistry andPhotobiology A Chemistry vol 163 no 3 pp 445ndash451 2004

[203] D Beydoun R Amal G Low and S McEvoy ldquoOccurrenceand prevention of photodissolution at the phase junction ofmagnetite and titanium dioxiderdquo Journal of Molecular CatalysisA Chemical vol 180 no 1-2 pp 193ndash200 2002

[204] J C Yu J Lin and R W M Kwok ldquoEnhanced photocatalyticactivity of Ti1minusxVxO2 solid solution on the degradation of ace-tonerdquo Journal of Photochemistry and Photobiology A Chemistryvol 111 no 1ndash3 pp 199ndash203 1997

[205] D Han Y Li and W Jia ldquoPreparation and characterization ofmolecularly imprinted SiO

2-TiO2and photo-catalysis for 2 4-

dichlorophenolrdquo Advanced Materials Letters vol 1 no 3 pp188ndash192 2010

[206] A Ulgen andW F Hoelderich ldquoConversion of glycerol to acro-lein in the presence of WO

3TiO2catalystsrdquo Applied Catalysis

A General vol 400 no 1-2 pp 34ndash38 2011[207] K T Ranjit H Cohen I Willner S Bossmann and A M

Braun ldquoLanthanide oxide-doped titanium dioxide effectivephotocatalysts for the degradation of organic pollutantsrdquo Jour-nal of Materials Science vol 34 no 21 pp 5273ndash5280 1999

[208] L Chen X Pang G Yu and J Zhang ldquoIn-situ coating ofMWNTs with sol-gel TiO

2nanoparticlesrdquo Advanced Materials

Letters vol 1 no 1 pp 75ndash78 2010


[209] L H Huang C Sun and Y L Liu ldquoPtN-codoped TiO2

nanotubes and its photocatalytic activity under visible lightrdquoApplied Surface Science vol 253 no 17 pp 7029ndash7035 2007

[210] J Matos J Laine and J-M Herrmann ldquoSynergy effect inthe photocatalytic degradation of phenol on a suspendedmixture of titania and activated carbonrdquo Applied Catalysis BEnvironmental vol 18 no 3-4 pp 281ndash291 1998

[211] M A Nawi A H Jawad S Sabar and W S W Ngah ldquoImmo-bilized bilayer TiO

2chitosan system for the removal of phenol

under irradiation by a 45watt compact fluorescent lamprdquoDesa-lination vol 280 no 1ndash3 pp 288ndash296 2011

[212] B Tryba A W Morawski and M A Inagaki ldquoA new routefor preparation of TiO

2-mounted activated carbonrdquo Applied

Catalysis B Environmental vol 46 no 1 pp 203ndash208 2003[213] T Tsumura N Kojitani H Umemura M Toyoda and M

Inagaki ldquoComposites between photoactive anatase-type TiO2

and adsorptive carbonrdquo Applied Surface Science vol 196 no 1ndash4 pp 429ndash436 2002

[214] J Yu X Zhao andQ Zhao ldquoEffect of film thickness on the grainsize and photocatalytic activity of the sol-gel derived nanometerTiO2thin filmsrdquo Journal of Materials Science Letters vol 19 no

12 pp 1015ndash1017 2000[215] W Yuan J Ji J Fu and J Shen ldquoA facile method to con-

struct hybrid multilayered films as a strong and multifunc-tional antibacterial coatingrdquo Journal of Biomedical MaterialsResearchmdashPart B Applied Biomaterials vol 85 no 2 pp 556ndash563 2008

[216] Y Lai H Zhuang K Xie et al ldquoFabrication of uniformAgTiO2

nanotube array structures with enhanced photoelectrochemicalperformancerdquoNew Journal of Chemistry vol 34 no 7 pp 1335ndash1340 2010

[217] S Li I N Germanenko andM S El-Shall ldquoNanoparticles fromthe vapor phase synthesis and characterization of Si GeMoO

3

andWO3nanocrystalsrdquo Journal of Cluster Science vol 10 no 4

pp 533ndash547 1999[218] J Zhao XWang Y Kang X Xu and Y Li ldquoPhotoelectrochem-

ical ativities of W-doped titania nanotube arrays fabricated byanodizationrdquo IEEE Photonics Technology Letters vol 20 no 14pp 1213ndash1215 2008

[219] M Epifani A Helwig J Arbiol et al ldquoTiO2 thin films fromtitanium butoxide synthesis Pt addition structural stabilitymicroelectronic processing and gas-sensing propertiesrdquo Sensorsand Actuators B Chemical vol 130 no 2 pp 599ndash608 2008

[220] Y Li X Yu and Q Yang ldquoFabrication of TiO2nanotube thin

films and their gas sensing propertiesrdquo Journal of Sensors vol2009 Article ID 402174 19 pages 2009

[221] A Serra M ReM Palmisano et al ldquoAssembly of hybrid silverndashtitania thin films for gas sensorsrdquo Sensors and Actuators BChemical vol 145 no 2 pp 794ndash799 2010

[222] M H Yaacob A Z Sadek K Latham K Kalantar-Zadeh andW Wlodarski ldquoOptical H

2sensing performance of anodized

nanoporous TiO2thin filmsrdquoProcedia Chemistry vol 1 pp 951ndash

954 2009[223] D Chen and A K Ray ldquoRemoval of toxic metal ions from

wastewater by semiconductor photocatalysisrdquo Chemical Engi-neering Science vol 56 no 4 pp 1561ndash1570 2001

[224] D G Shchukin E A Ustinovich D V Sviridov andA I KulakldquoTitanium and iron oxide-based magnetic photocatalysts foroxidation of organic compounds and sulfur dioxiderdquo HighEnergy Chemistry vol 38 no 3 pp 167ndash173 2004

[225] D-E Gu B-C Yang andY-DHu ldquoA novelmethod for prepar-ing V-doped titanium dioxide thin film photocatalysts withhigh photocatalytic activity under visible light irradiationrdquoCatalysis Letters vol 118 no 3-4 pp 254ndash259 2007

[226] X Hou X Wu and A Liu ldquoStudies on photocatalytic activityof AgTiO

2filmsrdquo Frontiers of Chemistry in China vol 1 no 4

pp 402ndash407 2006[227] B Zhao and Y-W Chen ldquoAgTiO

2sol prepared by a sol-gel

method and its photocatalytic activityrdquo Journal of Physics andChemistry of Solids vol 72 no 11 pp 1312ndash1318 2011

[228] M C Kao H Z Chen S L Young C Y Kung C C Lin andZ Y Hong ldquoMicrostructure and optical properties of tantalummodified TiO

2thin films prepared by the sol-gel processrdquo

Journal of Superconductivity and Novel Magnetism vol 23 no5 pp 843ndash845 2010

[229] A Bai W Liang G Zheng and J Xue ldquoPreparation andenhanced daylight-induced photo-catalytic activity of transpar-ent C-doped TiO

2thin filmsrdquoThe Journal of Wuhan University

of Technology-Material Science Edition vol 25 pp 738ndash7422010

[230] L Ge M Xu and H Fang ldquoSynthesis and characterizationof the PdInVO

4-TiO2co-doped thin films with visible light

photocatalytic activitiesrdquo Applied Surface Science vol 253 no4 pp 2257ndash2263 2006

[231] J Yu J C Yu B Cheng and X Zhao ldquoPhotocatalytic activityand characterization of the sol-gel derived Pb-doped TiO

2thin

filmsrdquo Journal of Sol-Gel Science and Technology vol 24 no 1pp 39ndash48 2002

[232] N S Begum HM F Ahmed and K R Gunashekar ldquoEffects ofNi doping on photocatalytic activity of TiO

2thin films prepared

by liquid phase deposition techniquerdquo Bulletin of MaterialsScience vol 31 no 5 pp 747ndash751 2008

[233] F Meng X Song and Z Sun ldquoPhotocatalytic activity of TiO2

thin films deposited by RFmagnetron sputteringrdquoVacuum vol83 no 9 pp 1147ndash1151 2009

[234] C Zhang R Chen J Zhou J Cheng and Q Xia ldquoSynthesisof TiO

2films on glass slides by the sol-gel method and their

photocatalytic activityrdquo Rare Metals vol 28 no 4 pp 378ndash3842009

[235] Z He Z Yu H Miao G Tan and Y Liu ldquoPreparation of TiO2

thin film by the LPD method on functionalized organic self-assembledmonolayersrdquo Science in China Series E TechnologicalSciences vol 52 no 1 pp 137ndash140 2009

[236] G A Battiston R Gerbasi M Porchia and A MarigoldquoInfluence of substrate on structural properties of TiO

2thin

films obtained via MOCVDrdquo Thin Solid Films vol 239 no 2pp 186ndash191 1994

[237] F Ren K He Y Ling and J Feng ldquoNovel fabrication of net-like and flake-like Fe doped TiO

2thin filmsrdquo Applied Surface

Science vol 257 no 22 pp 9621ndash9625 2011[238] M Zheng Y Shu J Sun and T Zhang ldquoCarbon-covered

alumina a superior support of noble metal-like catalysts forhydrazine decompositionrdquo Catalysis Letters vol 121 no 1-2 pp90ndash96 2008

[239] V Shashikala V Siva Kumar A H Padmasri et al ldquoAdvan-tages of nano-silver-carbon covered alumina catalyst preparedby electro-chemical method for drinking water purificationrdquoJournal of Molecular Catalysis A Chemical vol 268 no 1-2 pp95ndash100 2007

[240] D R Uhlmann G Teowee and J Boulton ldquoThe future of sol-gel science and technologyrdquo Journal of Sol-Gel Science and Tech-nology vol 8 no 1ndash3 pp 1083ndash1091 1997


[241] J-X Wang L-X Wen Z-H Wang M Wang L Shao and J-F Chen ldquoFacile synthesis of hollow silica nanotubes and theirapplication as supports for immobilization of silver nanoparti-clesrdquo Scripta Materialia vol 51 no 11 pp 1035ndash1039 2004

[242] T I Halkides D I Kondarides and X E Verykios ldquoCatalyticreduction of NO by C

3H6over RhTiO

2catalysts effect of W6+-

cation doping of TiO2on morphological characteristics and

catalytic performancerdquo Applied Catalysis B Environmental vol41 no 4 pp 415ndash426 2003

[243] N L V Carreno I T S Garcia L S S M Carreno et alldquoSynthesis of titaniacarbon nanocomposites by polymeric pre-cursor methodrdquo Journal of Physics and Chemistry of Solids vol69 no 8 pp 1897ndash1904 2008

[244] D Dumitriu A R Bally C Ballif et al ldquoPhotocatalytic degra-dation of phenol by TiO

2thin films prepared by sputteringrdquo

Applied Catalysis B Environmental vol 25 no 2-3 pp 83ndash922000

[245] M Vondrova T Klimczuk V L Miller et al ldquoSupported super-paramagnetic PdCo alloy nanoparticles prepared from a sil-icacyanogel co-gelrdquo Chemistry of Materials vol 17 no 25 pp6216ndash6218 2005

[246] P M Boorman K Chong R A Kydd and J M Lewis ldquoAcomparison of alumina carbon and carbon-covered alumina assupports for Ni-Mo-F additives carbon deposition and modelcompound reaction studiesrdquo Journal of Catalysis vol 128 no 2pp 537ndash550 1991

[247] J P R Vissers F P M Mercx S M A M Bouwens V H J deBeer and R Prins ldquoCarbon-covered alumina as a support forsulfide catalystsrdquo Journal of Catalysis vol 114 no 2 pp 291ndash3021988

[248] P M Boorman and K Chong ldquoPreparation of carbon-coveredalumina using fluorohydrocarbons A new acidic support mate-rialrdquo Applied Catalysis A General vol 95 no 2 pp 197ndash2101993

[249] L Lin W Lin Y X Zhu et al ldquoUniformly carbon-covered alu-mina and its surface characteristicsrdquo Langmuir vol 21 no 11pp 5040ndash5046 2005

[250] M Błachnio P Staszczuk G Grodzicka L Lin and Y X ZhuldquoAdsorption and porosity properties of carbon-covered aluminasurfacesrdquo Journal of Thermal Analysis and Calorimetry vol 88no 2 pp 601ndash606 2007

[251] P M Boorman R A Kydd T S Sorensen K Chong J MLewis and W S Bell ldquoA comparison of alumina carbon andcarbon-covered alumina as supports for NiMoF additives gasoil hydroprocessing studiesrdquo Fuel vol 71 no 1 pp 87ndash93 1992

[252] PM Boorman and K Chong ldquoA comparative gas oil hydropro-cessing study of alumina carbon and carbon-covered aluminasupported nickel-molybdenum catalysts effect of quinolinethiophene and vanadium spikingrdquo Energy amp Fuels vol 6 no3 pp 300ndash307 1992

[253] L Lin W Lin P Wang Y-X Zhu B-Y Zhao and Y-C XieldquoUniform carbon-covered alumina synthesized by pyrolysis ofsucrose120574-Al

2O3rdquo Acta Physico Chimica Sinica vol 20 no 10

pp 1179ndash1181 2004[254] L F Sharanda YV Plyuto I V Babich et al ldquoSynthesis and cha-

racterisation of hybrid carbon-alumina supportrdquo Applied Sur-face Science vol 252 no 24 pp 8549ndash8556 2006

[255] P Jana and V Ganesan ldquoThe production of a carbon-coatedalumina foamrdquo Carbon vol 49 no 10 pp 3292ndash3298 2011

[256] K S R Rao P K Rao S K Masthan L Kaluschnaya and VB Shur ldquoNew type of carbon coated alumina supports for the

preparation of highly ctive ruthenium catalysts for ammoniasynthesisrdquo Applied Catalysis vol 62 no 1 pp L19ndashL22 1990

[257] Y Zhu X Pan and Y Xie ldquoDispersion of sucrose on the surfaceof aluminardquo Acta PhysicomdashChimica Sinica vol 15 no 9 pp830ndash833 1999

[258] S K Maity L Flores J Ancheyta and H Fukuyama ldquoCarbon-modified alumina and alumina-carbon-supported hydrotreat-ing catalystsrdquo Industrial and Engineering Chemistry Researchvol 48 no 3 pp 1190ndash1195 2009

[259] D B Murphy R W Carroll and J E Klonowski ldquoAnalysisof products of high-temperature pyrolysis of various hydrocar-bonsrdquo Carbon vol 35 no 12 pp 1819ndash1823 1997

[260] C Paek A V McCormick and P W Carr ldquoPreparation andevaluation of carbon coated alumina as a high surface areapackingmaterial for high performance liquid chromatographyrdquoJournal of Chromatography A vol 1217 no 42 pp 6475ndash64832010

[261] L F Sharanda Y V Plyuto I V Babich Y A Babich and J AMoulijn ldquoPreparation of carbon-coated alumina by pyrolysis ofadsorbed acetylacetonerdquoMendeleev Communications vol 9 no3 pp 95ndash96 1999

[262] S K Masthan P S S Prasad K S R Rao and P K Rao ldquoHys-teresis during ammonia synthesis over promoted rutheniumcatalysts supported on carbon-covered aluminardquo Journal ofMolecular Catalysis vol 67 no 2 pp L1ndashL5 1991

[263] MMMahlambi A KMishra S B Mishra RW Krause B BMamba and A M Raichur ldquoSynthesis and characterization ofcarbon-covered alumina (CCA) supported TiO

2nanocatalysts

with enhanced visible light photodegradation of Rhodamine BrdquoJournal of Nanoparticle Research vol 14 article 790 2012

[264] J Medina-Valtierra J Garcıa-Servın C Frausto-Reyes and SCalixto ldquoThe photocatalytic application and regeneration ofanatase thin films with embedded commercial TiO

2particles

deposited on glass microrodsrdquo Applied Surface Science vol 252no 10 pp 3600ndash3608 2006

[265] S-Y Lin Y-C Chen C-M Wang and C-C Liu ldquoEffect ofheat treatment on electrochromic properties of TiO

2thin filmsrdquo

Journal of Solid State Electrochemistry vol 12 no 11 pp 1481ndash1486 2008

[266] D J Kim D S Kim S Cho S W Kim S H Lee and J C KimldquoMeasurement of thermal conductivity of TiO

2thin films using

3120596methodrdquo International Journal of Thermophysics vol 25 no1 pp 281ndash289 2004

[267] B R Sankapal M C Lux-Steiner and A Ennaoui ldquoSynthesisand characterization of anatase-TiO

2thin filmsrdquo Applied Sur-

face Science vol 239 no 2 pp 165ndash170 2005[268] C Sarantopoulos A N Gleizes and F Maury ldquoChemical vapor

deposition and characterization of nitrogen doped TiO2thin

films on glass substratesrdquo Thin Solid Films vol 518 no 4 pp1299ndash1303 2009

[269] L Sedlakova M Horakova P Hajkova A Kolouch J Karasekand P Spatenka ldquoPhotocatalytic properties of titanium oxide-based films deposited by PECVDrdquo Journal of SuperhardMateri-als vol 29 no 3 pp 162ndash165 2007

[270] C R Kleijn R Dorsman K J KuijlaarsMOkkerse andH vanSanten ldquoMulti-scale modeling of chemical vapor depositionprocesses for thin film technologyrdquo Journal of Crystal Growthvol 303 no 1 pp 362ndash380 2007

[271] H Y Ha S W Nam T H Lim I-H Oh and S-A HongldquoProperties of the TiO

2membranes prepared by CVD of

titanium tetraisopropoxiderdquo Journal of Membrane Science vol111 no 1 pp 81ndash92 1996


[272] V G Bessergenev I V Khmelinskii R J F Pereira V V KrisukA E Turgambaeva and I K Igumenov ldquoPreparation of TiO

2

films by CVD method and its electrical structural and opticalpropertiesrdquo Vacuum vol 64 no 3-4 pp 275ndash279 2002

[273] K Kamata K Maruyama S Amano and H Fukazawa ldquoRapidformation of TiO

2films by a conventional CVD methodrdquo

Journal of Materials Science Letters vol 9 no 3 pp 316ndash3191990

[274] N S Begum H M Farveez Ahmed and O M Hussain ldquoCha-racterization and photocatalytic activity of boron-doped TiO

2

thin films prepared by liquid phase deposition techniquerdquoBulletin of Materials Science vol 31 no 5 pp 741ndash745 2008

[275] S-Q Sun B Sun W Zhang and D Wang ldquoPreparation andantibacterial activity of Ag-TiO

2composite film by liquid phase

deposition (LPD) methodrdquo Bulletin of Materials Science vol 31no 1 pp 61ndash66 2008

[276] M N Ghazzal N Barthen and N Chaoui ldquoPhotodegradationkinetics of stearic acid on UV-irradiated titania thin film sep-arately followed by optical microscopy and Fourier transforminfrared spectroscopyrdquo Applied Catalysis B Environmental vol103 no 1-2 pp 85ndash90 2011

[277] B J Brasjen A W V Cuijk and A A Darhuber ldquoDip-coatingof chemically patterned surfacesrdquo Chemical Engineering andProcessing vol 50 no 5-6 pp 565ndash568 2011

[278] N Negishi K Takeuchi and T Ibusuki ldquoSurface structure ofthe TiO

2thin film photocatalystrdquo Journal of Materials Science

vol 33 no 24 pp 5789ndash5794 1998[279] R Bayon G San Vicente C Maffiotte and A Morales ldquoChar-

acterization of copper-manganese-oxide thin films deposited bydip-coatingrdquo Solar Energy Materials and Solar Cells vol 92 no10 pp 1211ndash1216 2008

[280] ZWang K Sun S Shen N Zhang J Qiao and P Xu ldquoPrepara-tion of YSZ thin films for intermediate temperature solid oxidefuel cells by dip-coating methodrdquo Journal of Membrane Sciencevol 320 no 1-2 pp 500ndash504 2008

[281] A Nakaruk and C C Sorrell ldquoConceptual model for spraypyrolysis mechanism fabrication and annealing of titania thinfilmsrdquo Journal of Coatings Technology Research vol 7 no 5 pp665ndash676 2010

[282] M Okuya K Nakade and S Kaneko ldquoPorous TiO2thin films

synthesized by a spray pyrolysis deposition (SPD) techniqueand their application to dye-sensitized solar cellsrdquo Solar EnergyMaterials and Solar Cells vol 70 no 4 pp 425ndash435 2002

[283] M Okuya K Shiozaki N Horikawa et al ldquoPorous TiO2thin

films prepared by spray pyrolysis deposition (SPD) techniqueand their application to UV sensorsrdquo Solid State Ionics vol 172no 1ndash4 pp 527ndash531 2004

[284] B-H Kim J-Y Lee Y-H Choa M Higuchi and N MizutanildquoPreparation of TiO

2thin film by liquid sprayed mist CVD

methodrdquo Materials Science and Engineering B vol 107 no 3pp 289ndash294 2004

[285] D R Acosta A I Martinez A A Lopez and C R MaganaldquoTitanium dioxide thin films the effect of the preparationmethod in their photocatalytic propertiesrdquoMicroscopy vol 228pp 183ndash188 2005

[286] L Castaneda A Maldonado and M de la L Olvera ldquoSensingproperties of chemically sprayed TiO2 thin films using Ni Irand Rh as catalystsrdquo Sensors and Actuators B Chemical vol 133no 2 pp 687ndash693 2008

[287] R S Sonawane and M K Dongare ldquoSol-gel synthesis ofAuTiO

2thin films for photocatalytic degradation of phenol in

sunlightrdquo Journal of Molecular Catalysis A Chemical vol 243no 1 pp 68ndash76 2006

[288] L Sun T An S Wan et al ldquoEffect of synthesis conditionson photocatalytic activities of nanoparticulate TiO

2thin filmsrdquo

Separation and Purification Technology vol 68 no 1 pp 83ndash892009

[289] M Vishwas S K Sharma K N Rao SMohan K V A Gowdaand R P S Chakradhar ldquoInfluence of surfactant and anneal-ing temperature on optical properties of sol-gel derived nano-crystalline TiO

2thin filmsrdquo Spectrochimica Acta Part A Molec-

ular and Biomolecular Spectroscopy vol 75 no 3 pp 1073ndash10772010

[290] R Zanoni G Righini A Montenero et al ldquoXPS analysis ofsol-gel processed doped and undoped TiO

2films for sensorsrdquo

Surface and Interface Analysis vol 22 no 1 pp 376ndash379 1994[291] Y Guo W Geng and J Sun ldquoLayer-by-layer deposition of

polyelectrolyte-polyelectrolyte complexes for multilayer filmfabricationrdquo Langmuir vol 25 no 2 pp 1004ndash1010 2009

[292] G Decher J D Hong and J Schmitt ldquoBuildup of ultrathinmultilayer films by a self-assembly process III Consecutivelyalternating adsorption of anionic and cationic polyelectrolyteson charged surfacesrdquo Thin Solid Films vol 210-211 no 2 pp831ndash835 1992

[293] T-H Kim and B-H Sohn ldquoPhotocatalytic thin films contain-ing TiO

2nanoparticles by the layer-by-layer self-assembling

methodrdquo Applied Surface Science vol 201 no 1ndash4 pp 109ndash1142002

[294] H Ai S A Jones and Y M Lvov ldquoBiomedical applica-tions of electrostatic layer-by-layer nano-assembly of polymersenzymes and nanoparticlesrdquo Cell Biochemistry and Biophysicsvol 39 no 1 pp 23ndash43 2003

[295] J B Schlenoff and S T Dubas ldquoMechanism of polyelectrolytemultilayer growth charge overcompensation and distributionrdquoMacromolecules vol 34 no 3 pp 592ndash598 2001

[296] T Sasaki Y Ebina T Tanaka M Harada M Watanabeand G Decher ldquoLayer-by-layer assembly of titania nanosheetpolycation composite filmsrdquo Chemistry of Materials vol 13 no12 pp 4661ndash4667 2001

[297] B Schoeler G Kumaraswamy and F Caruso ldquoInvestigation ofthe influence of polyelectrolyte charge density on the growth ofmultilayer thin films prepared by the layer-by-layer techniquerdquoMacromolecules vol 35 no 3 pp 889ndash897 2002

[298] M M De Villiers D P Otto S J Strydom and Y MLvov ldquoIntroduction to nanocoatings produced by layer-by-layer(LbL) self-assemblyrdquo Advanced Drug Delivery Reviews vol 63no 9 pp 701ndash715 2011

[299] G Decher B Lehr K Lowack Y Lvov and J Schmitt ldquoNewnanocomposite films for biosensors layer-by-layer adsorbedfilms of polyelectrolytes proteins or DNArdquo Biosensors andBioelectronics vol 9 no 9-10 pp 677ndash684 1994

[300] N I Kovtyukhova B RMartin J KNMbindyo T EMalloukM Cabassi and T S Mayer ldquoLayer-by-layer self-assemblystrategy for template synthesis of nanoscale devicesrdquo MaterialsScience and Engineering C vol 19 no 1-2 pp 255ndash262 2002

[301] Y Liu Y Wang and R O Claus ldquoLayer-by-layer ionic self-assembly of Au colloids into multilayer thin-films with bulkmetal conductivityrdquo Chemical Physics Letters vol 298 no 4ndash6pp 315ndash319 1998

[302] K Ariga J P Hill and Q Ji ldquoLayer-by-layer assembly as aversatile bottom-up nanofabrication technique for exploratoryresearch and realistic applicationrdquo Physical Chemistry ChemicalPhysics vol 9 no 19 pp 2319ndash2340 2007


[303] A A Antipov G B Sukhorukov E Donath and H MohwaldldquoSustained release properties of polyelectrolyte multilayer cap-sulesrdquo Journal of Physical Chemistry B vol 105 no 12 pp 2281ndash2284 2001

[304] F Wang J Feng and C Gao ldquoManipulating the properties ofcoacervated polyelectrolyte microcapsules by chemical cross-linkingrdquo Colloid and Polymer Science vol 286 no 8-9 pp 951ndash957 2008

[305] S Anandhakumar and A M Raichur ldquoA facile route to syn-thesize silver nanoparticles in polyelectrolyte capsulesrdquoColloidsand Surfaces B Biointerfaces vol 84 no 2 pp 379ndash383 2011

[306] S Anandhakumar M Debapriya V Nagaraja and A MRaichur ldquoPolyelectrolyte microcapsules for sustained deliveryof water-soluble drugsrdquo Materials Science and Engineering Cvol 31 no 2 pp 342ndash349 2011

[307] S Anandhakumar V Nagaraja and A M Raichur ldquoReversiblepolyelectrolyte capsules as carriers for protein deliveryrdquoColloidsand Surfaces B Biointerfaces vol 78 no 2 pp 266ndash274 2010

[308] N A Kotov I Dekany and J H Fendler ldquoLayer-by-layer self-assembly of polyelectrolyte-semiconductor nanoparticle com-posite filmsrdquo Journal of Physical Chemistry vol 99 no 35 pp13065ndash13069 1995

[309] A Mollahosseini A Rahimpour M Jahamshahi M Peyraviand M Khavarpour ldquoThe effect of silver nanoparticle size onperformance and antibacteriality of polysulfone ultrafiltrationmembranerdquo Desalination vol 306 pp 41ndash50 2012

[310] D Y Koseoglu-Imer B KoseMAltinbas and I Koyuncu ldquoTheproduction of polysulfone (PS) membrane with silver nanopar-ticles (AgNP) physical properties filtration performances andbiofouling resistances of membranesrdquo Journal of MembraneScience vol 428 pp 620ndash628 2013

[311] Z Fan Z Wang N Sun J Wang and S Wang ldquoPerformanceimprovement of polysulfone ultrafiltrationmembrane by blend-ing with polyaniline nanofibersrdquo Journal of Membrane Sciencevol 320 no 1-2 pp 363ndash371 2008

[312] E Saljoughi and S M Mousavi ldquoPreparation and charac-terization of novel polysulfone nanofiltration membranes forremoval of cadmium from contaminated waterrdquo Separation andPurification Technology vol 90 pp 22ndash30 2012

[313] R JWang Y Chen HM Xie G Q Kai Z YWang and J PanldquoPolysaccharide separation mechanism in polysulfone-Fe

3O4

magnetic composite membranesrdquo Chinese Science Bulletin vol56 no 18 pp 1951ndash1956 2011

[314] N A A Hamid A F Ismail T Matsuura et al ldquoMorphologicaland separation performance study of polysulfonetitaniumdioxide (PSFTiO

2) ultrafiltration membranes for humic acid

removalrdquo Desalination vol 273 no 1 pp 85ndash92 2011[315] N Y Abu-Thabit S A Ali and SM J Zaidi ldquoNew highly phos-

phonated polysulfonemembranes for PEM fuel cellsrdquo Journal ofMembrane Science vol 360 no 1-2 pp 26ndash33 2010

[316] S RamaswamyCGopalakrishnanN S KumarA Littleflowerand M Ponnavaikko ldquoFabrication of Ni nanodots templatedby nanoporous polysulfonemembrane structural andmagneticpropertiesrdquo Applied Physics A Materials Science and Processingvol 98 no 3 pp 481ndash485 2010

[317] Y Devrim S Erkan N Bac and I Eroglu ldquoPreparation andcharacterization of sulfonated polysulfonetitanium dioxidecomposite membranes for proton exchange membrane fuelcellsrdquo International Journal of Hydrogen Energy vol 34 no 8pp 3467ndash3475 2009

[318] Y Yang H Zhang P Wang Q Zheng and J Li ldquoThe influenceof nano-sized TiO

2fillers on the morphologies and properties

of PSF UF membranerdquo Journal of Membrane Science vol 288no 1-2 pp 231ndash238 2007

[319] M Padaki A M Isloor A F Ismail and M S AbdullahldquoSynthesis characterization and desalination study of novelPSAB and mPSAB blend membranes with Polysulfone (PSf)rdquoDesalination vol 295 pp 35ndash42 2012

[320] N Ghaemi S S Madaeni A Alizadeh et al ldquoFabricationandmodification of polysulfone nanofiltrationmembrane usingorganic acids morphology characterization and performancein removal of xenobioticsrdquo Separation and Purification Technol-ogy vol 96 pp 214ndash228 2012

[321] S Rajesh S Senthilkumar A Jayalakshmi M T Nirmala AF Ismail and D Mohan ldquoPreparation and performance eval-uation of poly (amide-imide) and TiO

2nanoparticles impreg-

nated polysulfone nanofiltration membranes in the removal ofhumic substancesrdquoColloids and SurfacesA Physicochemical andEngineering Aspects vol 418 pp 92ndash104 2013

[322] M J Eckelman M S Mauter J A Isaacs and M ElimelechldquoNew perspectives on nanomaterial aquatic ecotoxicity pro-duction impacts exceed direct exposure impacts for carbonnanotoubesrdquo Environmental Science and Technology vol 46 no5 pp 2902ndash2910 2012

[323] A Tiraferri N Y Yip W A Phillip J D Schiffman andM Elimelech ldquoRelating performance of thin-film compositeforward osmosis membranes to support layer formation andstructurerdquo Journal of Membrane Science vol 367 no 1-2 pp340ndash352 2011

[324] S Liang Y Kang A Tiraferri E P Giannelis X Huangand M Elimelech ldquoHighly hydrophilic polyvinylidene fluoride(PVDF) ultrafiltration membranes via postfabrication graftingof surface-tailored silica nanoparticlesrdquo ACS Applied Materialsand Interfaces vol 5 no 14 pp 6694ndash6703 2013

[325] M S Mauter Y Wang K C Okemgbo C O Osuji E P Gian-nelis andM Elimelech ldquoAntifouling ultrafiltrationmembranesvia post-fabrication grafting of biocidal nanomaterialsrdquo ACSApplied Materials and Interfaces vol 3 no 8 pp 2861ndash28682011

Submit your manuscripts athttpwwwhindawicom

ScientificaHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

CorrosionInternational Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Polymer ScienceInternational Journal of



CeramicsJournal of


CompositesJournal of

NanoparticlesJournal of



International Journal of

Biomaterials


NanoscienceJournal of

TextilesHindawi Publishing Corporation httpwwwhindawicom Volume 2014

Journal of

NanotechnologyHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Journal of

CrystallographyJournal of


The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014


CoatingsJournal of

Advances in

Materials Science and EngineeringHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Smart Materials Research



MetallurgyJournal of


BioMed Research International

MaterialsJournal of


Nano

materials


Journal ofNanomaterials


threat to humans and aquatic organisms [14] Volatile organiccompounds (VOCs) are known to be toxic and carcinogenicand have been implicated in the depletion of the stratosphericozone layer while also contributing to global warming [1015] These pollutants have been reported as being mutagenicand hence are responsible for the emergence of antibioticresistance bacteria and genes [16]

Some organic pollutants are referred to as persistentorganic pollutants (POPs) because when they enter theenvironment they do not readily break down and mayremain there for very long periods of time for examplepolychlorinated biphenyls (PCBs) and may enter the foodchains and accumulate to levels detrimental to organisms thatare high up in the food chain [17] Also organic pollutantsare a serious threat because they can be transported fromthe source of contamination through air as vapour or asdust particles by water currents or sediments and releasedin a new environment [17] Some of these organic pollutantseventually contaminate groundwater and surface watershowever groundwater contamination is likely to be theprimary source of human contact with these toxic chemicals[18] Generally exposure to organic contaminants could bethrough breathing through ingestion through drinking orby skin contact

12 Natural Organic Matter Natural organic matter (NOM)is an agglomeration of organic compounds that naturallyoccur when animal and plant material break down [19ndash21]NOM consists of a wide range of compounds with diversechemical properties (due to geographic origin and age ofthe decomposing organism) and occurs in all natural watersources [20 22 23] NOM components are a heterogeneousmixture of complex organic materials which consists of bothhydrophilic and hydrophobic components The hydrophiliccomponents are microbial by-products and contain a higherproportion of aliphatic carbon and nitrogenous compoundswith relatively high charge density such as amino acidsand proteins as well as polysaccharides [22 24 25] Humicsubstances (HS) constitute the more hydrophobic fractionof NOM and exhibit relatively high specific ultravioletabsorbance (SUVA) values due to the presence of a relativelylarge proportion of aromatic carbon phenolic structures andconjugated double bonds [5 19 21 22 24 25]

Due to the complexity of NOM no single tool can give itsdefinitive structural or functional information Nondestruc-tive spectroscopic techniques appear to be the most usefulanalytical techniques for NOM characterisation [20] Treat-ment options for the removal of NOM include coagulationthe use of magnetic ion-exchange resins activated carbonmembrane filtration and advanced oxidation processes [22]Characterisation of the structure and reactivity of NOM isvital because its presence creates problems in the quality ofdrinking water as well as in water-treatment processes [2026] The presence of NOM results in an increased coagulantand disinfectant dosage resulting in increased sludge It alsoincreases biological growth in water-distribution networksand may also result in increased levels of heavy metal com-plexes and adsorbed organic pollutants [22] Furthermorethe presence of NOM causes membrane fouling as well as

aesthetic and malodour problems in water The organic acidsthat result from the oxidation of NOM have the capabilityto corrode turbines and engineering systems and this affectstransportation of contaminants [19 22 27 28] Thus under-standing the impact of NOM in water-treatment processes isvital for human health and water-treatment plants as well asindustrial processes where pure water is a prerequisite

13 Disinfection By-Products In the water-treatment pro-cesses NOM may have adverse effects since it may reactwith disinfectants (eg chlorine or chloramines) resultingin the formation of disinfection by-products (DBPs) manyof which are either carcinogenic or mutagenic [5 25 2629] For example haloacetic acids (HAAs) are a componentof DBPs that are considered harmful to human healthThese have been found to result in impaired reproductiveand developmental retardation when tested on laboratoryanimals [24 30ndash33] Also trihalomethanes (THMs) havebeen classified as possible carcinogens to humans [30 32 3435] Nitrosamines are another group of DBPs formed dueto the reaction of NOM with disinfectants that have beenreported to be a threat to human life due to its carcinogenicity[32 36ndash38]

14 Industrial Effluents Industrial development is directlyrelated to the release of various toxic pollutants into the envi-ronment especially to aqueous streams and these pollutantsare harmful and hazardous to the environment [12 39ndash41]Prevention of industrial pollution is currently a major focusof environmentalists and therefore treatment of industrialeffluents before disposal into the ecosystem is imperativeto protect human life and environmental quality [3 4042] Thus a constant effort to protect water resources isbeing made by various government and nongovernmentalorganisations (eg US EPA WHO and DWAF) through theintroduction of increasingly strict legislation covering pollu-tant release into the environment with particular emphasison liquid industrial effluents [5 40 43 44] There are majortypes of industries in the industrial complex for examplepulp and paper mills food pharmaceutical electroplatingtextile photographic mining and agriculture to mentionjust a few which do not generate uniform waste streamsindustrial effluents are complex mixtures of chemical andbiological compositions that have various environmentalimpacts depending on the source of the toxicant [45 46]

141 Textile Industry Effluents Textile-processing industriesform the economic backbone of most developing countriesEffluents from textile industries are characterised by a varietyof chemicals generated from the dyeing bleaching andwashing processes [47 48] Wastewaters discharged fromtextile industries are a serious environmental threat due totheir characteristic high colour fluctuating pH malodourhigh biological oxygen demand (BOD) and chemical oxygendemand (COD) acids and alkalis as well as various heavymetals that breach environmental standards [48ndash50] Dyesare soluble in water and even a small amount of dye is highlyvisible and reduces the transparency of water bodies [49 51]




Rhodamine B

H3CH2C

CH2CH3

COOH

CH2CH3

CH2CH3

NClminusON+













2O and CO

2 and





2O


67]



2and H

2O during


119909compounds





RH minuseminus

997888997888997888rarr RH+

RH+ minusH+

997888997888997888rarr R∙


(1)



H2O ℎ]997888rarr H∙ +OH∙ (2)









2rutile 302

120572-Fe2O3 22 Fe

2O3 31


NaBiO3 262 ZnO 32

V2O5 27 SrTiO

3 34B2WO6 278 SnO

2 35WO3 28 ZnS 37


2and H

2O Furthermore



















++ ecbminus (3)



+ (4)




ecbminus+ TiIVOH∙

+



TiIVOH∙+





119899ecbminus+M119899+ 997888rarr M0 (10)



VB

CB

Band

gap

Degraded products

Degraded products

Hole

ElectronReduction

Oxidation

h M2+ M+

O2 O2∙minus

Red+∙

M2+ M3+

OHminus ∙OH

Oxid+∙

M2+M3+

+ +

minus minus









2electrode under






2nanoparticles






2nanoparticles


4and TiI

4) affects the










2nanoparticle






4)








2

nanostructures













2nanopar-




119892states




2119892ndashTi t2119892





119892states






2lattice















2surface Carboxylic


2[88 95] However




Donor level

Nar

row

ban

d ga

p

Wid

e ban

d ga

p

Degraded products

Degraded products

(LUMO)

Pollutant(HOMO)

VB

CBReduction

Oxidation

h M2+

++

M+

O2 O2∙minus

M2+ M3+

OHminus

M2+M3+

∙OH

Pollutantlowast

eminus

minusminus

Pollutant+∙

Pollutant+∙

TiO2120582 ge 380nm


GAP

VB

Lower CB

Upper CB

O p120587

Ti eg states

O p120587 states

O p120575 states

Ti-O120575lowast

Ti-O120587lowast

M-M120587lowast

M-M120575lowast

M-M120587

M-M120575

Ti-O120587

Ti-O120575

Ti t2g states




TiO2ZrO2 TiO

2WO3 TiO

2Fe2O3 TiO

2SnO2 TiO

2

Ln2O3 andTiO




2





















2for the





2catalysts



2has the


2






7 Catalyst Supports


2catalysts






















2and CCAm-




9 Thin Films




2thin films retain







2thin


4



4tetrahedral





4 or TiCl




3 TiCl

4


(a)

(b) (c)

(d) (e)







(a) (b)

(c) (d)



meter Filter

Controller

Aircompressor

Pump

Precursor


Substrate

Spraynozzle

Heater

Liquidvalve

Liquid fluxmeter

Controller





2thin films



NaPSS

NH

NN

PAZO PVS

N

PAPSA PSMDEMA

HN

SPAN

R

R-PHPyV

S

O

PTAA PMPyA PDDA

PAH

NH

PAMPSA

N

HN

NN

HN

PEI

SO3minusNa+

SO2

CO2minus

OHNa+

OSO3minusNa+

HO3S

N+

N+

Iminus

SO3minus

NH2+

OminusNa+

+N

N+Clminus

NH3+Clminus

SO3H

NH2

NH2

NH2








1

23

4


1 2 3 4

(1) Polyanion

(2) Wash

(3) Polycation

(4) WashSubs

trat

e

++++++++++++++

++++++++++++++

minus


minus minus

minusminus

minusminus

minusminus

minusminus





minus

++++++++++++++

++++

++

+++++ +

+++

+++++ ++

+++

+++

++ +

+++ +

++

++

minus


minus minus

minusminus

minusminus

minusminus

minusminus





minus










2nanoparticles


2has been






2show superiority


2


2as well as the



(a) (b)

(c) (d)











(a)

(b) (c)








2PSf) and




2PSf) membranes


12 Conclusion









2The



2in






Acknowledgment


References















Zr045
















































2prepared in an

















2porous


















2thin film pho-





































2WO6with electron














2and AgTiO










2supported on










2nanoparticles



2poly-









2composite floating



2powders under






2









2doped with



2














2AuTiO

















2and TiO

2sols on



































2nanocrystalsrdquo






2




2nanocrystals





























2with high crys-






2












2




2thin








2and PtTiO




2













2based






2photo-














































3






























2thin













2thin











3H6over RhTiO






























2nanocatalysts



2particles



2thin filmsrdquo



2thin films using














2






2


























2thin filmsrdquo


































3O4



























CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials






Rhodamine B

H3CH2C

CH2CH3

COOH

CH2CH3

CH2CH3

NClminusON+













2O and CO

2 and





2O


67]



2and H

2O during


119909compounds





RH minuseminus

997888997888997888rarr RH+

RH+ minusH+

997888997888997888rarr R∙


(1)



H2O ℎ]997888rarr H∙ +OH∙ (2)









2rutile 302

120572-Fe2O3 22 Fe

2O3 31


NaBiO3 262 ZnO 32

V2O5 27 SrTiO

3 34B2WO6 278 SnO

2 35WO3 28 ZnS 37


2and H

2O Furthermore



















++ ecbminus (3)



+ (4)




ecbminus+ TiIVOH∙

+



TiIVOH∙+





119899ecbminus+M119899+ 997888rarr M0 (10)



VB

CB

Band

gap

Degraded products

Degraded products

Hole

ElectronReduction

Oxidation

h M2+ M+

O2 O2∙minus

Red+∙

M2+ M3+

OHminus ∙OH

Oxid+∙

M2+M3+

+ +

minus minus









2electrode under






2nanoparticles






2nanoparticles


4and TiI

4) affects the










2nanoparticle






4)








2

nanostructures













2nanopar-




119892states




2119892ndashTi t2119892





119892states






2lattice















2surface Carboxylic


2[88 95] However




Donor level

Nar

row

ban

d ga

p

Wid

e ban

d ga

p

Degraded products

Degraded products

(LUMO)

Pollutant(HOMO)

VB

CBReduction

Oxidation

h M2+

++

M+

O2 O2∙minus

M2+ M3+

OHminus

M2+M3+

∙OH

Pollutantlowast

eminus

minusminus

Pollutant+∙

Pollutant+∙

TiO2120582 ge 380nm


GAP

VB

Lower CB

Upper CB

O p120587

Ti eg states

O p120587 states

O p120575 states

Ti-O120575lowast

Ti-O120587lowast

M-M120587lowast

M-M120575lowast

M-M120587

M-M120575

Ti-O120587

Ti-O120575

Ti t2g states




TiO2ZrO2 TiO

2WO3 TiO

2Fe2O3 TiO

2SnO2 TiO

2

Ln2O3 andTiO




2





















2for the





2catalysts



2has the


2






7 Catalyst Supports


2catalysts






















2and CCAm-




9 Thin Films




2thin films retain







2thin


4



4tetrahedral





4 or TiCl




3 TiCl

4


(a)

(b) (c)

(d) (e)







(a) (b)

(c) (d)



meter Filter

Controller

Aircompressor

Pump

Precursor


Substrate

Spraynozzle

Heater

Liquidvalve

Liquid fluxmeter

Controller





2thin films



NaPSS

NH

NN

PAZO PVS

N

PAPSA PSMDEMA

HN

SPAN

R

R-PHPyV

S

O

PTAA PMPyA PDDA

PAH

NH

PAMPSA

N

HN

NN

HN

PEI

SO3minusNa+

SO2

CO2minus

OHNa+

OSO3minusNa+

HO3S

N+

N+

Iminus

SO3minus

NH2+

OminusNa+

+N

N+Clminus

NH3+Clminus

SO3H

NH2

NH2

NH2








1

23

4


1 2 3 4

(1) Polyanion

(2) Wash

(3) Polycation

(4) WashSubs

trat

e

++++++++++++++

++++++++++++++

minus


minus minus

minusminus

minusminus

minusminus

minusminus





minus

++++++++++++++

++++

++

+++++ +

+++

+++++ ++

+++

+++

++ +

+++ +

++

++

minus


minus minus

minusminus

minusminus

minusminus

minusminus





minus










2nanoparticles


2has been






2show superiority


2


2as well as the



(a) (b)

(c) (d)











(a)

(b) (c)








2PSf) and




2PSf) membranes


12 Conclusion









2The



2in






Acknowledgment


References















Zr045
















































2prepared in an

















2porous


















2thin film pho-





































2WO6with electron














2and AgTiO










2supported on










2nanoparticles



2poly-









2composite floating



2powders under






2









2doped with



2














2AuTiO

















2and TiO

2sols on



































2nanocrystalsrdquo






2




2nanocrystals





























2with high crys-






2












2




2thin








2and PtTiO




2













2based






2photo-














































3






























2thin













2thin











3H6over RhTiO






























2nanocatalysts



2particles



2thin filmsrdquo



2thin films using














2






2


























2thin filmsrdquo


































3O4



























CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials







2O


67]



2and H

2O during


119909compounds





RH minuseminus

997888997888997888rarr RH+

RH+ minusH+

997888997888997888rarr R∙


(1)



H2O ℎ]997888rarr H∙ +OH∙ (2)









2rutile 302

120572-Fe2O3 22 Fe

2O3 31


NaBiO3 262 ZnO 32

V2O5 27 SrTiO

3 34B2WO6 278 SnO

2 35WO3 28 ZnS 37


2and H

2O Furthermore



















++ ecbminus (3)



+ (4)




ecbminus+ TiIVOH∙

+



TiIVOH∙+





119899ecbminus+M119899+ 997888rarr M0 (10)



VB

CB

Band

gap

Degraded products

Degraded products

Hole

ElectronReduction

Oxidation

h M2+ M+

O2 O2∙minus

Red+∙

M2+ M3+

OHminus ∙OH

Oxid+∙

M2+M3+

+ +

minus minus









2electrode under






2nanoparticles






2nanoparticles


4and TiI

4) affects the










2nanoparticle






4)








2

nanostructures













2nanopar-




119892states




2119892ndashTi t2119892





119892states






2lattice















2surface Carboxylic


2[88 95] However




Donor level

Nar

row

ban

d ga

p

Wid

e ban

d ga

p

Degraded products

Degraded products

(LUMO)

Pollutant(HOMO)

VB

CBReduction

Oxidation

h M2+

++

M+

O2 O2∙minus

M2+ M3+

OHminus

M2+M3+

∙OH

Pollutantlowast

eminus

minusminus

Pollutant+∙

Pollutant+∙

TiO2120582 ge 380nm


GAP

VB

Lower CB

Upper CB

O p120587

Ti eg states

O p120587 states

O p120575 states

Ti-O120575lowast

Ti-O120587lowast

M-M120587lowast

M-M120575lowast

M-M120587

M-M120575

Ti-O120587

Ti-O120575

Ti t2g states




TiO2ZrO2 TiO

2WO3 TiO

2Fe2O3 TiO

2SnO2 TiO

2

Ln2O3 andTiO




2





















2for the





2catalysts



2has the


2






7 Catalyst Supports


2catalysts






















2and CCAm-




9 Thin Films




2thin films retain







2thin


4



4tetrahedral





4 or TiCl




3 TiCl

4


(a)

(b) (c)

(d) (e)







(a) (b)

(c) (d)



meter Filter

Controller

Aircompressor

Pump

Precursor


Substrate

Spraynozzle

Heater

Liquidvalve

Liquid fluxmeter

Controller





2thin films



NaPSS

NH

NN

PAZO PVS

N

PAPSA PSMDEMA

HN

SPAN

R

R-PHPyV

S

O

PTAA PMPyA PDDA

PAH

NH

PAMPSA

N

HN

NN

HN

PEI

SO3minusNa+

SO2

CO2minus

OHNa+

OSO3minusNa+

HO3S

N+

N+

Iminus

SO3minus

NH2+

OminusNa+

+N

N+Clminus

NH3+Clminus

SO3H

NH2

NH2

NH2








1

23

4


1 2 3 4

(1) Polyanion

(2) Wash

(3) Polycation

(4) WashSubs

trat

e

++++++++++++++

++++++++++++++

minus


minus minus

minusminus

minusminus

minusminus

minusminus





minus

++++++++++++++

++++

++

+++++ +

+++

+++++ ++

+++

+++

++ +

+++ +

++

++

minus


minus minus

minusminus

minusminus

minusminus

minusminus





minus










2nanoparticles


2has been






2show superiority


2


2as well as the



(a) (b)

(c) (d)











(a)

(b) (c)








2PSf) and




2PSf) membranes


12 Conclusion









2The



2in






Acknowledgment


References















Zr045
















































2prepared in an

















2porous


















2thin film pho-





































2WO6with electron














2and AgTiO










2supported on










2nanoparticles



2poly-









2composite floating



2powders under






2









2doped with



2














2AuTiO

















2and TiO

2sols on



































2nanocrystalsrdquo






2




2nanocrystals





























2with high crys-






2












2




2thin








2and PtTiO




2













2based






2photo-














































3






























2thin













2thin











3H6over RhTiO






























2nanocatalysts



2particles



2thin filmsrdquo



2thin films using














2






2


























2thin filmsrdquo


































3O4



























CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials








2rutile 302

120572-Fe2O3 22 Fe

2O3 31


NaBiO3 262 ZnO 32

V2O5 27 SrTiO

3 34B2WO6 278 SnO

2 35WO3 28 ZnS 37


2and H

2O Furthermore



















++ ecbminus (3)



+ (4)




ecbminus+ TiIVOH∙

+



TiIVOH∙+





119899ecbminus+M119899+ 997888rarr M0 (10)



VB

CB

Band

gap

Degraded products

Degraded products

Hole

ElectronReduction

Oxidation

h M2+ M+

O2 O2∙minus

Red+∙

M2+ M3+

OHminus ∙OH

Oxid+∙

M2+M3+

+ +

minus minus









2electrode under






2nanoparticles






2nanoparticles


4and TiI

4) affects the










2nanoparticle






4)








2

nanostructures













2nanopar-




119892states




2119892ndashTi t2119892





119892states






2lattice















2surface Carboxylic


2[88 95] However




Donor level

Nar

row

ban

d ga

p

Wid

e ban

d ga

p

Degraded products

Degraded products

(LUMO)

Pollutant(HOMO)

VB

CBReduction

Oxidation

h M2+

++

M+

O2 O2∙minus

M2+ M3+

OHminus

M2+M3+

∙OH

Pollutantlowast

eminus

minusminus

Pollutant+∙

Pollutant+∙

TiO2120582 ge 380nm


GAP

VB

Lower CB

Upper CB

O p120587

Ti eg states

O p120587 states

O p120575 states

Ti-O120575lowast

Ti-O120587lowast

M-M120587lowast

M-M120575lowast

M-M120587

M-M120575

Ti-O120587

Ti-O120575

Ti t2g states




TiO2ZrO2 TiO

2WO3 TiO

2Fe2O3 TiO

2SnO2 TiO

2

Ln2O3 andTiO




2





















2for the





2catalysts



2has the


2






7 Catalyst Supports


2catalysts






















2and CCAm-




9 Thin Films




2thin films retain







2thin


4



4tetrahedral





4 or TiCl




3 TiCl

4


(a)

(b) (c)

(d) (e)







(a) (b)

(c) (d)



meter Filter

Controller

Aircompressor

Pump

Precursor


Substrate

Spraynozzle

Heater

Liquidvalve

Liquid fluxmeter

Controller





2thin films



NaPSS

NH

NN

PAZO PVS

N

PAPSA PSMDEMA

HN

SPAN

R

R-PHPyV

S

O

PTAA PMPyA PDDA

PAH

NH

PAMPSA

N

HN

NN

HN

PEI

SO3minusNa+

SO2

CO2minus

OHNa+

OSO3minusNa+

HO3S

N+

N+

Iminus

SO3minus

NH2+

OminusNa+

+N

N+Clminus

NH3+Clminus

SO3H

NH2

NH2

NH2








1

23

4


1 2 3 4

(1) Polyanion

(2) Wash

(3) Polycation

(4) WashSubs

trat

e

++++++++++++++

++++++++++++++

minus


minus minus

minusminus

minusminus

minusminus

minusminus





minus

++++++++++++++

++++

++

+++++ +

+++

+++++ ++

+++

+++

++ +

+++ +

++

++

minus


minus minus

minusminus

minusminus

minusminus

minusminus





minus










2nanoparticles


2has been






2show superiority


2


2as well as the



(a) (b)

(c) (d)











(a)

(b) (c)








2PSf) and




2PSf) membranes


12 Conclusion









2The



2in






Acknowledgment


References















Zr045
















































2prepared in an

















2porous


















2thin film pho-





































2WO6with electron














2and AgTiO










2supported on










2nanoparticles



2poly-









2composite floating



2powders under






2









2doped with



2














2AuTiO

















2and TiO

2sols on



































2nanocrystalsrdquo






2




2nanocrystals





























2with high crys-






2












2




2thin








2and PtTiO




2













2based






2photo-














































3






























2thin













2thin











3H6over RhTiO






























2nanocatalysts



2particles



2thin filmsrdquo



2thin films using














2






2


























2thin filmsrdquo


































3O4



























CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials




VB

CB

Band

gap

Degraded products

Degraded products

Hole

ElectronReduction

Oxidation

h M2+ M+

O2 O2∙minus

Red+∙

M2+ M3+

OHminus ∙OH

Oxid+∙

M2+M3+

+ +

minus minus









2electrode under






2nanoparticles






2nanoparticles


4and TiI

4) affects the










2nanoparticle






4)








2

nanostructures













2nanopar-




119892states




2119892ndashTi t2119892





119892states






2lattice















2surface Carboxylic


2[88 95] However




Donor level

Nar

row

ban

d ga

p

Wid

e ban

d ga

p

Degraded products

Degraded products

(LUMO)

Pollutant(HOMO)

VB

CBReduction

Oxidation

h M2+

++

M+

O2 O2∙minus

M2+ M3+

OHminus

M2+M3+

∙OH

Pollutantlowast

eminus

minusminus

Pollutant+∙

Pollutant+∙

TiO2120582 ge 380nm


GAP

VB

Lower CB

Upper CB

O p120587

Ti eg states

O p120587 states

O p120575 states

Ti-O120575lowast

Ti-O120587lowast

M-M120587lowast

M-M120575lowast

M-M120587

M-M120575

Ti-O120587

Ti-O120575

Ti t2g states




TiO2ZrO2 TiO

2WO3 TiO

2Fe2O3 TiO

2SnO2 TiO

2

Ln2O3 andTiO




2





















2for the





2catalysts



2has the


2






7 Catalyst Supports


2catalysts






















2and CCAm-




9 Thin Films




2thin films retain







2thin


4



4tetrahedral





4 or TiCl




3 TiCl

4


(a)

(b) (c)

(d) (e)







(a) (b)

(c) (d)



meter Filter

Controller

Aircompressor

Pump

Precursor


Substrate

Spraynozzle

Heater

Liquidvalve

Liquid fluxmeter

Controller





2thin films



NaPSS

NH

NN

PAZO PVS

N

PAPSA PSMDEMA

HN

SPAN

R

R-PHPyV

S

O

PTAA PMPyA PDDA

PAH

NH

PAMPSA

N

HN

NN

HN

PEI

SO3minusNa+

SO2

CO2minus

OHNa+

OSO3minusNa+

HO3S

N+

N+

Iminus

SO3minus

NH2+

OminusNa+

+N

N+Clminus

NH3+Clminus

SO3H

NH2

NH2

NH2








1

23

4


1 2 3 4

(1) Polyanion

(2) Wash

(3) Polycation

(4) WashSubs

trat

e

++++++++++++++

++++++++++++++

minus


minus minus

minusminus

minusminus

minusminus

minusminus





minus

++++++++++++++

++++

++

+++++ +

+++

+++++ ++

+++

+++

++ +

+++ +

++

++

minus


minus minus

minusminus

minusminus

minusminus

minusminus





minus










2nanoparticles


2has been






2show superiority


2


2as well as the



(a) (b)

(c) (d)











(a)

(b) (c)








2PSf) and




2PSf) membranes


12 Conclusion









2The



2in






Acknowledgment


References















Zr045
















































2prepared in an

















2porous


















2thin film pho-





































2WO6with electron














2and AgTiO










2supported on










2nanoparticles



2poly-









2composite floating



2powders under






2









2doped with



2














2AuTiO

















2and TiO

2sols on



































2nanocrystalsrdquo






2




2nanocrystals





























2with high crys-






2












2




2thin








2and PtTiO




2













2based






2photo-














































3






























2thin













2thin











3H6over RhTiO






























2nanocatalysts



2particles



2thin filmsrdquo



2thin films using














2






2


























2thin filmsrdquo


































3O4



























CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials






2nanoparticles


4and TiI

4) affects the










2nanoparticle






4)








2

nanostructures













2nanopar-




119892states




2119892ndashTi t2119892





119892states






2lattice















2surface Carboxylic


2[88 95] However




Donor level

Nar

row

ban

d ga

p

Wid

e ban

d ga

p

Degraded products

Degraded products

(LUMO)

Pollutant(HOMO)

VB

CBReduction

Oxidation

h M2+

++

M+

O2 O2∙minus

M2+ M3+

OHminus

M2+M3+

∙OH

Pollutantlowast

eminus

minusminus

Pollutant+∙

Pollutant+∙

TiO2120582 ge 380nm


GAP

VB

Lower CB

Upper CB

O p120587

Ti eg states

O p120587 states

O p120575 states

Ti-O120575lowast

Ti-O120587lowast

M-M120587lowast

M-M120575lowast

M-M120587

M-M120575

Ti-O120587

Ti-O120575

Ti t2g states




TiO2ZrO2 TiO

2WO3 TiO

2Fe2O3 TiO

2SnO2 TiO

2

Ln2O3 andTiO




2





















2for the





2catalysts



2has the


2






7 Catalyst Supports


2catalysts






















2and CCAm-




9 Thin Films




2thin films retain







2thin


4



4tetrahedral





4 or TiCl




3 TiCl

4


(a)

(b) (c)

(d) (e)







(a) (b)

(c) (d)



meter Filter

Controller

Aircompressor

Pump

Precursor


Substrate

Spraynozzle

Heater

Liquidvalve

Liquid fluxmeter

Controller





2thin films



NaPSS

NH

NN

PAZO PVS

N

PAPSA PSMDEMA

HN

SPAN

R

R-PHPyV

S

O

PTAA PMPyA PDDA

PAH

NH

PAMPSA

N

HN

NN

HN

PEI

SO3minusNa+

SO2

CO2minus

OHNa+

OSO3minusNa+

HO3S

N+

N+

Iminus

SO3minus

NH2+

OminusNa+

+N

N+Clminus

NH3+Clminus

SO3H

NH2

NH2

NH2








1

23

4


1 2 3 4

(1) Polyanion

(2) Wash

(3) Polycation

(4) WashSubs

trat

e

++++++++++++++

++++++++++++++

minus


minus minus

minusminus

minusminus

minusminus

minusminus





minus

++++++++++++++

++++

++

+++++ +

+++

+++++ ++

+++

+++

++ +

+++ +

++

++

minus


minus minus

minusminus

minusminus

minusminus

minusminus





minus










2nanoparticles


2has been






2show superiority


2


2as well as the



(a) (b)

(c) (d)











(a)

(b) (c)








2PSf) and




2PSf) membranes


12 Conclusion









2The



2in






Acknowledgment


References















Zr045
















































2prepared in an

















2porous


















2thin film pho-





































2WO6with electron














2and AgTiO










2supported on










2nanoparticles



2poly-









2composite floating



2powders under






2









2doped with



2














2AuTiO

















2and TiO

2sols on



































2nanocrystalsrdquo






2




2nanocrystals





























2with high crys-






2












2




2thin








2and PtTiO




2













2based






2photo-














































3






























2thin













2thin











3H6over RhTiO






























2nanocatalysts



2particles



2thin filmsrdquo



2thin films using














2






2


























2thin filmsrdquo


































3O4



























CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials










2nanopar-




119892states




2119892ndashTi t2119892





119892states






2lattice















2surface Carboxylic


2[88 95] However




Donor level

Nar

row

ban

d ga

p

Wid

e ban

d ga

p

Degraded products

Degraded products

(LUMO)

Pollutant(HOMO)

VB

CBReduction

Oxidation

h M2+

++

M+

O2 O2∙minus

M2+ M3+

OHminus

M2+M3+

∙OH

Pollutantlowast

eminus

minusminus

Pollutant+∙

Pollutant+∙

TiO2120582 ge 380nm


GAP

VB

Lower CB

Upper CB

O p120587

Ti eg states

O p120587 states

O p120575 states

Ti-O120575lowast

Ti-O120587lowast

M-M120587lowast

M-M120575lowast

M-M120587

M-M120575

Ti-O120587

Ti-O120575

Ti t2g states




TiO2ZrO2 TiO

2WO3 TiO

2Fe2O3 TiO

2SnO2 TiO

2

Ln2O3 andTiO




2





















2for the





2catalysts



2has the


2






7 Catalyst Supports


2catalysts






















2and CCAm-




9 Thin Films




2thin films retain







2thin


4



4tetrahedral





4 or TiCl




3 TiCl

4


(a)

(b) (c)

(d) (e)







(a) (b)

(c) (d)



meter Filter

Controller

Aircompressor

Pump

Precursor


Substrate

Spraynozzle

Heater

Liquidvalve

Liquid fluxmeter

Controller





2thin films



NaPSS

NH

NN

PAZO PVS

N

PAPSA PSMDEMA

HN

SPAN

R

R-PHPyV

S

O

PTAA PMPyA PDDA

PAH

NH

PAMPSA

N

HN

NN

HN

PEI

SO3minusNa+

SO2

CO2minus

OHNa+

OSO3minusNa+

HO3S

N+

N+

Iminus

SO3minus

NH2+

OminusNa+

+N

N+Clminus

NH3+Clminus

SO3H

NH2

NH2

NH2








1

23

4


1 2 3 4

(1) Polyanion

(2) Wash

(3) Polycation

(4) WashSubs

trat

e

++++++++++++++

++++++++++++++

minus


minus minus

minusminus

minusminus

minusminus

minusminus





minus

++++++++++++++

++++

++

+++++ +

+++

+++++ ++

+++

+++

++ +

+++ +

++

++

minus


minus minus

minusminus

minusminus

minusminus

minusminus





minus










2nanoparticles


2has been






2show superiority


2


2as well as the



(a) (b)

(c) (d)











(a)

(b) (c)








2PSf) and




2PSf) membranes


12 Conclusion









2The



2in






Acknowledgment


References















Zr045
















































2prepared in an

















2porous


















2thin film pho-





































2WO6with electron














2and AgTiO










2supported on










2nanoparticles



2poly-









2composite floating



2powders under






2









2doped with



2














2AuTiO

















2and TiO

2sols on



































2nanocrystalsrdquo






2




2nanocrystals





























2with high crys-






2












2




2thin








2and PtTiO




2













2based






2photo-














































3






























2thin













2thin











3H6over RhTiO






























2nanocatalysts



2particles



2thin filmsrdquo



2thin films using














2






2


























2thin filmsrdquo


































3O4



























CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials





Donor level

Nar

row

ban

d ga

p

Wid

e ban

d ga

p

Degraded products

Degraded products

(LUMO)

Pollutant(HOMO)

VB

CBReduction

Oxidation

h M2+

++

M+

O2 O2∙minus

M2+ M3+

OHminus

M2+M3+

∙OH

Pollutantlowast

eminus

minusminus

Pollutant+∙

Pollutant+∙

TiO2120582 ge 380nm


GAP

VB

Lower CB

Upper CB

O p120587

Ti eg states

O p120587 states

O p120575 states

Ti-O120575lowast

Ti-O120587lowast

M-M120587lowast

M-M120575lowast

M-M120587

M-M120575

Ti-O120587

Ti-O120575

Ti t2g states




TiO2ZrO2 TiO

2WO3 TiO

2Fe2O3 TiO

2SnO2 TiO

2

Ln2O3 andTiO




2





















2for the





2catalysts



2has the


2






7 Catalyst Supports


2catalysts






















2and CCAm-




9 Thin Films




2thin films retain







2thin


4



4tetrahedral





4 or TiCl




3 TiCl

4


(a)

(b) (c)

(d) (e)







(a) (b)

(c) (d)



meter Filter

Controller

Aircompressor

Pump

Precursor


Substrate

Spraynozzle

Heater

Liquidvalve

Liquid fluxmeter

Controller





2thin films



NaPSS

NH

NN

PAZO PVS

N

PAPSA PSMDEMA

HN

SPAN

R

R-PHPyV

S

O

PTAA PMPyA PDDA

PAH

NH

PAMPSA

N

HN

NN

HN

PEI

SO3minusNa+

SO2

CO2minus

OHNa+

OSO3minusNa+

HO3S

N+

N+

Iminus

SO3minus

NH2+

OminusNa+

+N

N+Clminus

NH3+Clminus

SO3H

NH2

NH2

NH2








1

23

4


1 2 3 4

(1) Polyanion

(2) Wash

(3) Polycation

(4) WashSubs

trat

e

++++++++++++++

++++++++++++++

minus


minus minus

minusminus

minusminus

minusminus

minusminus





minus

++++++++++++++

++++

++

+++++ +

+++

+++++ ++

+++

+++

++ +

+++ +

++

++

minus


minus minus

minusminus

minusminus

minusminus

minusminus





minus










2nanoparticles


2has been






2show superiority


2


2as well as the



(a) (b)

(c) (d)











(a)

(b) (c)








2PSf) and




2PSf) membranes


12 Conclusion









2The



2in






Acknowledgment


References















Zr045
















































2prepared in an

















2porous


















2thin film pho-





































2WO6with electron














2and AgTiO










2supported on










2nanoparticles



2poly-









2composite floating



2powders under






2









2doped with



2














2AuTiO

















2and TiO

2sols on



































2nanocrystalsrdquo






2




2nanocrystals





























2with high crys-






2












2




2thin








2and PtTiO




2













2based






2photo-














































3






























2thin













2thin











3H6over RhTiO






























2nanocatalysts



2particles



2thin filmsrdquo



2thin films using














2






2


























2thin filmsrdquo


































3O4



























CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials




















2for the





2catalysts



2has the


2






7 Catalyst Supports


2catalysts






















2and CCAm-




9 Thin Films




2thin films retain







2thin


4



4tetrahedral





4 or TiCl




3 TiCl

4


(a)

(b) (c)

(d) (e)







(a) (b)

(c) (d)



meter Filter

Controller

Aircompressor

Pump

Precursor


Substrate

Spraynozzle

Heater

Liquidvalve

Liquid fluxmeter

Controller





2thin films



NaPSS

NH

NN

PAZO PVS

N

PAPSA PSMDEMA

HN

SPAN

R

R-PHPyV

S

O

PTAA PMPyA PDDA

PAH

NH

PAMPSA

N

HN

NN

HN

PEI

SO3minusNa+

SO2

CO2minus

OHNa+

OSO3minusNa+

HO3S

N+

N+

Iminus

SO3minus

NH2+

OminusNa+

+N

N+Clminus

NH3+Clminus

SO3H

NH2

NH2

NH2








1

23

4


1 2 3 4

(1) Polyanion

(2) Wash

(3) Polycation

(4) WashSubs

trat

e

++++++++++++++

++++++++++++++

minus


minus minus

minusminus

minusminus

minusminus

minusminus





minus

++++++++++++++

++++

++

+++++ +

+++

+++++ ++

+++

+++

++ +

+++ +

++

++

minus


minus minus

minusminus

minusminus

minusminus

minusminus





minus










2nanoparticles


2has been






2show superiority


2


2as well as the



(a) (b)

(c) (d)











(a)

(b) (c)








2PSf) and




2PSf) membranes


12 Conclusion









2The



2in






Acknowledgment


References















Zr045
















































2prepared in an

















2porous


















2thin film pho-





































2WO6with electron














2and AgTiO










2supported on










2nanoparticles



2poly-









2composite floating



2powders under






2









2doped with



2














2AuTiO

















2and TiO

2sols on



































2nanocrystalsrdquo






2




2nanocrystals





























2with high crys-






2












2




2thin








2and PtTiO




2













2based






2photo-














































3






























2thin













2thin











3H6over RhTiO






























2nanocatalysts



2particles



2thin filmsrdquo



2thin films using














2






2


























2thin filmsrdquo


































3O4



























CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials























2and CCAm-




9 Thin Films




2thin films retain







2thin


4



4tetrahedral





4 or TiCl




3 TiCl

4


(a)

(b) (c)

(d) (e)







(a) (b)

(c) (d)



meter Filter

Controller

Aircompressor

Pump

Precursor


Substrate

Spraynozzle

Heater

Liquidvalve

Liquid fluxmeter

Controller





2thin films



NaPSS

NH

NN

PAZO PVS

N

PAPSA PSMDEMA

HN

SPAN

R

R-PHPyV

S

O

PTAA PMPyA PDDA

PAH

NH

PAMPSA

N

HN

NN

HN

PEI

SO3minusNa+

SO2

CO2minus

OHNa+

OSO3minusNa+

HO3S

N+

N+

Iminus

SO3minus

NH2+

OminusNa+

+N

N+Clminus

NH3+Clminus

SO3H

NH2

NH2

NH2








1

23

4


1 2 3 4

(1) Polyanion

(2) Wash

(3) Polycation

(4) WashSubs

trat

e

++++++++++++++

++++++++++++++

minus


minus minus

minusminus

minusminus

minusminus

minusminus





minus

++++++++++++++

++++

++

+++++ +

+++

+++++ ++

+++

+++

++ +

+++ +

++

++

minus


minus minus

minusminus

minusminus

minusminus

minusminus





minus










2nanoparticles


2has been






2show superiority


2


2as well as the



(a) (b)

(c) (d)











(a)

(b) (c)








2PSf) and




2PSf) membranes


12 Conclusion









2The



2in






Acknowledgment


References















Zr045
















































2prepared in an

















2porous


















2thin film pho-





































2WO6with electron














2and AgTiO










2supported on










2nanoparticles



2poly-









2composite floating



2powders under






2









2doped with



2














2AuTiO

















2and TiO

2sols on



































2nanocrystalsrdquo






2




2nanocrystals





























2with high crys-






2












2




2thin








2and PtTiO




2













2based






2photo-














































3






























2thin













2thin











3H6over RhTiO






























2nanocatalysts



2particles



2thin filmsrdquo



2thin films using














2






2


























2thin filmsrdquo


































3O4



























CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials





2and CCAm-




9 Thin Films




2thin films retain







2thin


4



4tetrahedral





4 or TiCl




3 TiCl

4


(a)

(b) (c)

(d) (e)







(a) (b)

(c) (d)



meter Filter

Controller

Aircompressor

Pump

Precursor


Substrate

Spraynozzle

Heater

Liquidvalve

Liquid fluxmeter

Controller





2thin films



NaPSS

NH

NN

PAZO PVS

N

PAPSA PSMDEMA

HN

SPAN

R

R-PHPyV

S

O

PTAA PMPyA PDDA

PAH

NH

PAMPSA

N

HN

NN

HN

PEI

SO3minusNa+

SO2

CO2minus

OHNa+

OSO3minusNa+

HO3S

N+

N+

Iminus

SO3minus

NH2+

OminusNa+

+N

N+Clminus

NH3+Clminus

SO3H

NH2

NH2

NH2








1

23

4


1 2 3 4

(1) Polyanion

(2) Wash

(3) Polycation

(4) WashSubs

trat

e

++++++++++++++

++++++++++++++

minus


minus minus

minusminus

minusminus

minusminus

minusminus





minus

++++++++++++++

++++

++

+++++ +

+++

+++++ ++

+++

+++

++ +

+++ +

++

++

minus


minus minus

minusminus

minusminus

minusminus

minusminus





minus










2nanoparticles


2has been






2show superiority


2


2as well as the



(a) (b)

(c) (d)











(a)

(b) (c)








2PSf) and




2PSf) membranes


12 Conclusion









2The



2in






Acknowledgment


References















Zr045
















































2prepared in an

















2porous


















2thin film pho-





































2WO6with electron














2and AgTiO










2supported on










2nanoparticles



2poly-









2composite floating



2powders under






2









2doped with



2














2AuTiO

















2and TiO

2sols on



































2nanocrystalsrdquo






2




2nanocrystals





























2with high crys-






2












2




2thin








2and PtTiO




2













2based






2photo-














































3






























2thin













2thin











3H6over RhTiO






























2nanocatalysts



2particles



2thin filmsrdquo



2thin films using














2






2


























2thin filmsrdquo


































3O4



























CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials




(a)

(b) (c)

(d) (e)







(a) (b)

(c) (d)



meter Filter

Controller

Aircompressor

Pump

Precursor


Substrate

Spraynozzle

Heater

Liquidvalve

Liquid fluxmeter

Controller





2thin films



NaPSS

NH

NN

PAZO PVS

N

PAPSA PSMDEMA

HN

SPAN

R

R-PHPyV

S

O

PTAA PMPyA PDDA

PAH

NH

PAMPSA

N

HN

NN

HN

PEI

SO3minusNa+

SO2

CO2minus

OHNa+

OSO3minusNa+

HO3S

N+

N+

Iminus

SO3minus

NH2+

OminusNa+

+N

N+Clminus

NH3+Clminus

SO3H

NH2

NH2

NH2








1

23

4


1 2 3 4

(1) Polyanion

(2) Wash

(3) Polycation

(4) WashSubs

trat

e

++++++++++++++

++++++++++++++

minus


minus minus

minusminus

minusminus

minusminus

minusminus





minus

++++++++++++++

++++

++

+++++ +

+++

+++++ ++

+++

+++

++ +

+++ +

++

++

minus


minus minus

minusminus

minusminus

minusminus

minusminus





minus










2nanoparticles


2has been






2show superiority


2


2as well as the



(a) (b)

(c) (d)











(a)

(b) (c)








2PSf) and




2PSf) membranes


12 Conclusion









2The



2in






Acknowledgment


References















Zr045
















































2prepared in an

















2porous


















2thin film pho-





































2WO6with electron














2and AgTiO










2supported on










2nanoparticles



2poly-









2composite floating



2powders under






2









2doped with



2














2AuTiO

















2and TiO

2sols on



































2nanocrystalsrdquo






2




2nanocrystals





























2with high crys-






2












2




2thin








2and PtTiO




2













2based






2photo-














































3






























2thin













2thin











3H6over RhTiO






























2nanocatalysts



2particles



2thin filmsrdquo



2thin films using














2






2


























2thin filmsrdquo


































3O4



























CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials




(a) (b)

(c) (d)



meter Filter

Controller

Aircompressor

Pump

Precursor


Substrate

Spraynozzle

Heater

Liquidvalve

Liquid fluxmeter

Controller





2thin films



NaPSS

NH

NN

PAZO PVS

N

PAPSA PSMDEMA

HN

SPAN

R

R-PHPyV

S

O

PTAA PMPyA PDDA

PAH

NH

PAMPSA

N

HN

NN

HN

PEI

SO3minusNa+

SO2

CO2minus

OHNa+

OSO3minusNa+

HO3S

N+

N+

Iminus

SO3minus

NH2+

OminusNa+

+N

N+Clminus

NH3+Clminus

SO3H

NH2

NH2

NH2








1

23

4


1 2 3 4

(1) Polyanion

(2) Wash

(3) Polycation

(4) WashSubs

trat

e

++++++++++++++

++++++++++++++

minus


minus minus

minusminus

minusminus

minusminus

minusminus





minus

++++++++++++++

++++

++

+++++ +

+++

+++++ ++

+++

+++

++ +

+++ +

++

++

minus


minus minus

minusminus

minusminus

minusminus

minusminus





minus










2nanoparticles


2has been






2show superiority


2


2as well as the



(a) (b)

(c) (d)











(a)

(b) (c)








2PSf) and




2PSf) membranes


12 Conclusion









2The



2in






Acknowledgment


References















Zr045
















































2prepared in an

















2porous


















2thin film pho-





































2WO6with electron














2and AgTiO










2supported on










2nanoparticles



2poly-









2composite floating



2powders under






2









2doped with



2














2AuTiO

















2and TiO

2sols on



































2nanocrystalsrdquo






2




2nanocrystals





























2with high crys-






2












2




2thin








2and PtTiO




2













2based






2photo-














































3






























2thin













2thin











3H6over RhTiO






























2nanocatalysts



2particles



2thin filmsrdquo



2thin films using














2






2


























2thin filmsrdquo


































3O4



























CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials




NaPSS

NH

NN

PAZO PVS

N

PAPSA PSMDEMA

HN

SPAN

R

R-PHPyV

S

O

PTAA PMPyA PDDA

PAH

NH

PAMPSA

N

HN

NN

HN

PEI

SO3minusNa+

SO2

CO2minus

OHNa+

OSO3minusNa+

HO3S

N+

N+

Iminus

SO3minus

NH2+

OminusNa+

+N

N+Clminus

NH3+Clminus

SO3H

NH2

NH2

NH2








1

23

4


1 2 3 4

(1) Polyanion

(2) Wash

(3) Polycation

(4) WashSubs

trat

e

++++++++++++++

++++++++++++++

minus


minus minus

minusminus

minusminus

minusminus

minusminus





minus

++++++++++++++

++++

++

+++++ +

+++

+++++ ++

+++

+++

++ +

+++ +

++

++

minus


minus minus

minusminus

minusminus

minusminus

minusminus





minus










2nanoparticles


2has been






2show superiority


2


2as well as the



(a) (b)

(c) (d)











(a)

(b) (c)








2PSf) and




2PSf) membranes


12 Conclusion









2The



2in






Acknowledgment


References















Zr045
















































2prepared in an

















2porous


















2thin film pho-





































2WO6with electron














2and AgTiO










2supported on










2nanoparticles



2poly-









2composite floating



2powders under






2









2doped with



2














2AuTiO

















2and TiO

2sols on



































2nanocrystalsrdquo






2




2nanocrystals





























2with high crys-






2












2




2thin








2and PtTiO




2













2based






2photo-














































3






























2thin













2thin











3H6over RhTiO






























2nanocatalysts



2particles



2thin filmsrdquo



2thin films using














2






2


























2thin filmsrdquo


































3O4



























CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials




1

23

4


1 2 3 4

(1) Polyanion

(2) Wash

(3) Polycation

(4) WashSubs

trat

e

++++++++++++++

++++++++++++++

minus


minus minus

minusminus

minusminus

minusminus

minusminus





minus

++++++++++++++

++++

++

+++++ +

+++

+++++ ++

+++

+++

++ +

+++ +

++

++

minus


minus minus

minusminus

minusminus

minusminus

minusminus





minus










2nanoparticles


2has been






2show superiority


2


2as well as the



(a) (b)

(c) (d)











(a)

(b) (c)








2PSf) and




2PSf) membranes


12 Conclusion









2The



2in






Acknowledgment


References















Zr045
















































2prepared in an

















2porous


















2thin film pho-





































2WO6with electron














2and AgTiO










2supported on










2nanoparticles



2poly-









2composite floating



2powders under






2









2doped with



2














2AuTiO

















2and TiO

2sols on



































2nanocrystalsrdquo






2




2nanocrystals





























2with high crys-






2












2




2thin








2and PtTiO




2













2based






2photo-














































3






























2thin













2thin











3H6over RhTiO






























2nanocatalysts



2particles



2thin filmsrdquo



2thin films using














2






2


























2thin filmsrdquo


































3O4



























CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials




(a) (b)

(c) (d)











(a)

(b) (c)








2PSf) and




2PSf) membranes


12 Conclusion









2The



2in






Acknowledgment


References















Zr045
















































2prepared in an

















2porous


















2thin film pho-





































2WO6with electron














2and AgTiO










2supported on










2nanoparticles



2poly-









2composite floating



2powders under






2









2doped with



2














2AuTiO

















2and TiO

2sols on



































2nanocrystalsrdquo






2




2nanocrystals





























2with high crys-






2












2




2thin








2and PtTiO




2













2based






2photo-














































3






























2thin













2thin











3H6over RhTiO






























2nanocatalysts



2particles



2thin filmsrdquo



2thin films using














2






2


























2thin filmsrdquo


































3O4



























CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials



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