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Studies on Photocatalytic Oxidation of Industrial

Waste Water

BY

Mr.Nileshkumar J. Thanvi

(M-Tech. Chemical Second Year)

Guide/Supervisor

Prof.S.V.Khedkar C.O.E.T. Akola.

Department of Chemical Engineering

College of Engineering & Tech., Babhulgaon, Akola (M.S).

S.G.B.A.University, Amravati.

A Synopsis submitted for the partial fulfillment of Master of Technology

Degree Course in Chemical Engineering.

Session: 2011-2012


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1INTRODUCTION

A large number of organic substances are nowdays introduced into the water system

from various sources such as industrial effluents, agricultural runoff and chemicalspills. Their

toxicity, stability to natural decomposition and persistence in theenvironment has been the

cause of much concern to societies and regulation authoritiesaround the world. [1]

Dyes[4], phenols [3], pesticides, fertilizers, detergents, and other chemical products

are disposed of directly into the environment, without being treated, controlled or

uncontrolled and without an effective treatment strategy [1]. Steps should be taken for

recycling wastewater of the various industries, as water has now become a key symbol of

protest around the world and is seen as the most serious social and political issue of this

generation.

The appearance of compounds that are difficult to degrade by conventional chemical

or biological methods (toxic, mutagenic, carcinogenic pollutants) in natural waters recently

created a pressing need for the development of efficient water-treatment processes. The

search for a solution to this problem has involved extensiveexaminations in the field of

advanced oxidation processes (AOPs). In chemicaloxidation processes, reaction mechanisms

change structure, and chemical properties of the organic substances. Molecules break in

smaller fragments; higher percent ofoxygen appears in these molecules in form of alcohols,

carboxylic acids etc. oxidationof organic compounds with oxidation such as ozone or OH.

Radicals usually yieldsmore oxidized ones which are in most cases more easily biodegradable

than the former ones. This is the general idea that yields to the combination of a chemical

oxidation processes. Oxidation with ozone or hydrogen peroxide has been found to be an

important alternative to chlorination, because the oxidation does not result in toxicchlorinated

organic compound .Advanced OxidationTechnologies (AOTs),including Advanced Oxidation

Process (AOPs)[2].

1.1AIM AND OBJECTIVE

AIM

To study the effect of light on the pollutants present in water. To study the effect of light in combination with catalyst like TiO2. To study and design a suitable UV assisted treatment process for industrial

wastewater.


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OBJECTIVES

To investigate and removal of organic pollutant from wastewater. To degrade textile effluent ORdecolorization of a Reactive Dye. To reduce the harmful effect of textile effluent. To study the effect of time irradiation of UV light towards degradationactivities To study the effect of catalyst concentration towards the photocatalyticdegradation. To remove or to degrade harmful chemical present in wastewater.

1.2 SCOPE OF STUDY

The work in this project will be focused on the potential utilization of UV radiation

and catalyst which produces OH radicals with water.Photocatalysis are the combination of

using a catalyst and UV or visible light for the treatment of wastewaters pollutants[6]. When

illuminating a photocatalyst using UV or visible light, various organic compounds (e.g.,

aromatic, organochloride and organ phosphorous compounds) can be oxidized and

mineralized at the photocatalyst surface or oxidized in solution ambient and atmospheric

conditions.Photocatalysis is one of the most important advanced oxidation technologies. It is

used for oxidative treatment of wastewater containing various organic and inorganic

compounds. Various physical, chemical and biological pre-treatment and post-treatment

techniques have been developed over the last two decades to remove color from dye

contaminated wastewaters in order to cost effectively meet environmental regulatory

requirements. Chemical and biological treatments have been conventionally followed till now

but these treatment methods have their own disadvantages. The aerobic treatment process is

associated with production and disposal of large amounts of biological sludge, while

wastewater treated by anaerobic treatment method does not bring down the pollution

parameters to the satisfactory level and activated charcoal adsorption and air strippingmethods simply transfer the pollutants from one medium to another. They either transfer it to

the atmosphere, which causes air pollution, or to a solid which is often disposed of in landfills

or must be treated in an energy-intensive regeneration process. Merely transferring toxic

materials from one medium to another is not a long term solution to the problem of hazardous

waste loading on the environment[1] These methods rely on the formation of highly reactive

chemical species that degrade more number of recalcitrant molecules into biodegradable

compounds and are called advanced oxidation processes (AOPs)


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2. LITERATURE REVIEW

Industrial development is pervasively connected with the disposal of number of

toxicpollutants that are harmful to the environment & the human and are also not easily

degraded in nature. Wastewater generated from industries which degrades local streams with

bacteriaand other pollutants, threatening human health, landmass fertility, and our

environment. In order to meet international standards treatment of industrial water containing

pollutants is mandatory. The removal of organic pollution from water supplies has

traditionally been effected by adsorption with activated carbon. For this reason attention is

being given to alternative photocatalytic oxidation processes for water treatment, frequently

referred to as advanced oxidation processes. The object of destructive oxidation processes is

to mineralize organic contaminants, i.e., convert them to carbon dioxide, water and the

oxidised inorganic anions of any heteroatoms present. These processes frequently include the

addition of oxidizing agents such as hydrogen peroxide,TiO2 ,ZnO etc in the presence of a

UV light. Hydroxyl radicals are known to be involved in most of these processes.[12]

2.1.1ADVANCED OXIDATION PROCESSES:

In 1987, Glaze defined AOPs as near ambient temperature andpressure water

treatment processes which involve the generation of hydroxyl radicals in sufficient quantity

to effect water purification. The hydroxyl radical (OH) is a powerful, non-selective

chemical oxidant (Table 1), which acts very rapidly with most organic compounds.The

reaction rate constants of molecular ozone with different organic compounds.These reaction

rate constants vary in quite a wide range from 0.01 to 104

M1

s1

. Once generated, the

hydroxyl radicals aggressively attack virtually all organic compounds. Depending upon the

nature of the organic species, two types of initial attack are possible: the hydroxyl radical can

abstract a hydrogen atom from water, as with alkanes or alcohols, or it can add itself to the

contaminant, as in the case of olefins or aromatic compounds.[5]

Methods Available for generating OH radicals:-[5]

Several methods are available for generating OH radicals. These include both non-

photochemical and photochemical methods:

1. Ozonation at elevated pH (>8.5)

2. Ozone + hydrogen peroxide (O3/H2O2)

3. Ozone + catalyst (O3/CAT)4. Fenton system (H2O2/Fe2+)


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5. O3/UV

6. H2O2/UV

7. O3/H2O2/UV

8. Photo-Fenton/Fenton-like systems

9. Photo catalytic oxidation (UV/TiO2)

10. Sonophotocataytic oxidation

Table 1.Relative oxidation power of some oxidizing species [5]

Sr.No Oxidizing Species Relative oxidation Power

1. Chlorine 1.00

2. Hypochlorous acid 1.10

3. Permaganate 1.24

4. Hydrogen Peroxide 1.31

5. Ozone 1.52

6. Atomic oxygen 1.78

7. Titanium Dioxide 2.35

8. Hydroxyl radical 2.05

A common reaction is the abstraction of hydrogen atom to initiate a radical chain

oxidation: [5]RH +

OH H2O +

R(1)

2OH H2O2 (2)

R + H2O2 ROH +

OH(3)

R + O2 ROO(4)

ROO+ RH ROOH + R(5)

2.1.2 PHOTOCATALYSIS [4]

Photocatalysis is defined as the acceleration of a photoreaction in the presence of a

catalyst, while photolysis is defined as a chemical reaction in which a chemical compound is

broken down by photons. In catalyzed photolysis, light is absorbed by an adsorbed

substrate.Photocatalysis on semiconducting oxides relies on the absorption of photons with

energy equal to or greater than the band gap of the oxide, so that electrons are promoted from

the valence band to the conduction band:

Semiconductor +hv h++e

-


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2.1.3 PHOTOCATALYTIC TREATMENT OF PRIORITY POLLUTANTS

T.E. Agustina and H.M. Ang (2005) gave a synergistic effect of photocatalysis and

ozonation for the treatment of wastewater that contain recalcitrant organic compounds, such

as organohalogens,organic pesticides, surfactants, and colouring matters, wastewater

engineers are now required to develop advanced treatment processes. A promising way to

perform the mineralization of this type of substance is the application of an advanced

oxidation process (AOPs). [7]

The photocatalytic degradation and oxidation to carbon dioxide of aqueous phenol

solutions have been studied (R.W. Matthews and S.R. McEvoy (1992)) using natural sunlight

in geometries simulating shallow ponds. The photo catalyst was titanium dioxide freely

suspended in the solution or immobilized on sand or silica gel. Photo degradation rates wereapproximately three times faster with the free suspension than with the immobilized catalyst

under the same conditions, and were dependent on the time of the year and the time of the

day. The seasonal variation correlated roughly with seasonal solar irradiance tabulations for

the UV component of the spectrum. [8]

Advanced oxidation processes (AOPs) are used for the treatment of wastewaters

containing non-easily removable organic compounds (Marc Pera-Titus et al. (2003)).

Chlorophenols (CPs) are a group of special interest due to their high toxicity and low

biodegradability. Data concerning the degradation of CPs by means of AOPs reported during

the period 19952002 are evaluated in this work. Among the AOPs, the following

techniques are studied: processes based on hydrogen peroxide (H2O2+UV, Fenton, photo-

Fenton and Fenton-like processes), photolysis, photocatalysis and processes based on ozone

(O3, O3+UV and O3+catalyst). Half-life times and kinetic constants for CP degradation are

reviewed and the different mechanistic degradation pathways are taken into account. [12]

The photochemical oxidationof phenol and chlorophenol aqueous solutions in a batch

recycle photochemical reactor using ultraviolet irradiation, hydrogen peroxide and TiO2 (as

photocatalyst) was studied. The study showed that the combined treatment process was the

most effective process under acidic conditions and showed a higher rate of degradation of

phenol and chlorophenol at a very short radiation time. The reaction was found to follow the

first order kinetics and was influenced by the pH, the input concentration of H2O2 and the

dosing amount of the TiO2 photocatalyst. The results indicate maximum 74.6% and 79.8%

degradation of phenol and chlorophenol respectively within 90 minutes of radiation time.[11]


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A comparative study of the treatment of raw and biotreated (upflow anaerobic

sludgeblanket, UASB) textile dye bath effluent using advanced oxidation processes (AOPs) is

presented. The AOPs applied on raw and biotreated textile dye bath effluent, after

characterization in terms of COD, colour, BOD and pH, were ozone, UV, UV/H 2O2 and

photo-Fenton. The decolorization of raw dye bath effluent was 58% in the case of ozonation.

However it was 98% in the case of biotreated dye bath effluent when exposed to UV/H2O2.

It is, therefore, suggested that a combination of biotreatment and AOPs be adopted to

decolorize dye bath effluent in order to make the process more viable and effective.

Biodegradability was also improved by applying AOPs after biotreatment of dye bath

effluent.[13]

A process ofpesticide removal from industrial waste water using Fentons reaction

has been analyzed. Most of the pesticide were completely degraded at H2O2 concentration of2.5 gm/dm

3; however, only at 5g/dm

3were all examined pesticide completely removed and

the result repeatable. Organo-chlorine pesticides were removed with efficiency of more than

90%.[14]

3. MATERIALS AND METHODS:-

3.1 MATERIALS:-

INDUSTRIALWASTEWATER(textile , pharmaceutical,fertilizer,etc) andSynthetic Waste water of (phenol, Dyes, oxalic acid, humic acid,etc)

CATALYST(H2O2, ZnO of Merck Chemical) UVLIGHT(8volt, 11 inch, ofOsramCompany) and its assembly. pH METER

pH of the solution was monitored by, pH Meter

AIR SPARGERAir is continuously supplied during experiments in UV reactor order to oxidize the

organic matter.

Analysis of sample will be done by UV Spectrophoto Meter.3.2 Method

Experimental Procedure

As shown in below figure UV reactor consist of UV lamp, UV lamp chock, and UV

lamp glass Sleeve, electrical Connection, Effluent holding glass cylinder. Glass cylinder


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which holds effluent is rapped with aluminumfoil, which acts as reflector for UV rays to

transmit it back.UV lamp is placed in glass sleeve as shown in figure.A known quantity of

effluent is taken in glass cylinder and hydrogen peroxide is added which act as catalyst.

The mixture is irradiated with UV light for known period of time. The degradation of

pollutants is than measured with the help of UV spectrophotometer.

Tentative Experimental set-up of PhotocatalyticReactor:-

EFFECT AND PRECAUTION:-

Effect of UV light

Exposure of UV lightis harmful to the skin and eyes. Excessive UV light exposure cause painful sunburn, accelerate wrinkling and increase

the risk of skin cancer.

UV light causes eye inflammation, cataracts, and retinal damage.Precaution while handling UV light

A person handling UV light must cover his body fully. Eye must be cover with UV light barring goggles. Hand must be covered with gloves. Face must be covered with cloth mask. Body parts which are bare must be applied with sunscreenlotion.

PROBABLE OBSERVATIONS:-

Colour change

Turbidity

UV Tube

Glass Sleeve

For UV Tube

GlassCylinder

UV lamp electric

supply

UV lamp chock


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OBSERVATION TABLE:-

Sr.No Sample Catalyst Initial

concentration

Final

concentration

Light

Power

(W)

Contact

Time

(min)

PROBABLE RESULTS AND DISCUSSIONS

The photocatalytic degradation of waste water sampleunder UV irradiation employing

H2O2.Photocatalysis by H2O2involves under UV light excitation the generation of e- and h+

in the conduction and valence band, respectively. These species undergo charge transfer

reactions across the interface with oxygen, water and organic pollutants. The reaction of h+

with -OH or H2O leads to the generation of reactive. OH radicals having, which are powerful

oxidants attacking the recalcitrant organic compounds of interest. [1,11]

PROBABLE CONCLUSIONS

Photocatalysis is a promising technique, for the photodegradation of various

hazardouschemicals that are present in industrial wastewater and it mineralize the organic

contaminants, into final end product. Photocatalysis is eco-friendly way to reduce

thepollutants load of wastewater.[12]The advanced chemical oxidation processes used

successfully in the removal of organic pollutants from its aqueous solution which is helpful to

determine the optimum conditions for their removal from industrial wastewater containing

organic pollutants with high removal efficiency.While at neutral and basic pH there was a

major contribution of the free radical pathway and the addition of hydrogen peroxide can

promote or inhibit the reaction of free radical. Method can be used as a preliminary step prior

to a biological wastewater treatment. The biodegradability of the treated waste increased with

increasing in hydrogen peroxide this revealed that destruction of organic pollutants.

[2]Photocatalysis offers some significant advantages over competing technologies such as

adsorption on activated carbon in those areas where photocatalysis can

compete.Photocatalysis could become even more viable by increasing the intensity of the

source used to activate the catalyst.[9]


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REFERENCES

1. S.Kaur,2007, Light induced oxidative degradation studies of organic dyes and thereintermediates, school of chemistry and biochemistry Thapar university Patiala.

2. I.G.Rashed,M.A.Hanna,H.F.El-Gamal, Overview on chemical oxidation technologyin wastewater treatment ,Ninth international water technology conferences,IWTC9

2005, sharm El-Sheikh Egypt.pg.no.115-132

3. S.P.Devipriya,S.Yesodharan , May 2010 Photocatalytic degradation of phenol inwater using TiO2and ZnO , Journal of environmental biology page no.247-249.

4. F.H.Hussain, Chapter 12 photchemical treatment of textile industries wastewater,chemistry dep. College of science, Babylon university IRAQ.

5. R.Munter, 2001, Advanced oxidation process-current status and prospects,proc.EstonianAcad.Sci.chem., page no.59-80.

6. Metcalf And Eddy, Inc Wastewater Engineering Treatment And Reuse , FourthEdition.PageNo.95, 1298 to1329,1196 to 1202

7. Kobal L., 2007, Advanced technologies for colour removal and technological waterreuse of textile effluent,University Ofnova goria graduate school.

8.

E.S.Elmolla,M.Chaudhry, Antibiotics wastewater treatment , International seminaron civil and infrastructure engineering 11-12 june 2008 University

TeknologyMara,ShahAlam ,page no.1-7.

9. Watler.A.Zeltner, Shedding Light on photocatlysis,American Society of heating,refrigerating Air-Condationing Engineers. Page No 523-534.

10.M.Fiter,A.Canut,G.Badal,A.Pasual, oct29-30 2007 Advanced oxidation process forthe organic matter removal of agro-food brine wastewater, IOA conference and

exhibition Valencia,Spain, Page No 1-6.

11.Abhilasha Dixit, A.K.Mungray and MousumiChakraborty, 2010, PhotochemicalOxidation of Phenol and Chlorophenol by UV/H2O2/TiO2 Process : A Kinetic Study,

International Journal of Chemical Engineering and Applications, Vol. 1, No. 3,

12.SumitRana, JUNE-2009, The photocatalytic degradation of priority pollutants,Department of biotechnology & environmental sciences,Thapar university Patiala-

147004 (Punjab)

13.Muhammad*, A. Shafeeq, M. A. Butt, Z. H. Rizvi, M. A. Chughtai and S.Rehman,2008, Decolorization and removal of cod and bod from raw and biotreated


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textile dye bath effluent through advanced oxidation processes (AOPS), Institute of

Chemical Engineering & Technology, University of the Punjab, Brazilian Journal of

Chemical Engineering, Vol. 25, No. 03, page No. 453459

14.K.barbusinki, K.Filipek, 2001, Use of Fentons Reagent for Removal of Pesticidefrom Industrial Wastewater, Institute of Water and Wastewater Engineering, Silesian

University of Technology, Poland; Polish Journal of Environmental Studies

Vol.10,No.4,Page No.207-212

Student Signature Guide Signature

(Mr.NileshKumar Thanvi) (Prof.S.V.Khedkar)

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