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Hindawi Publishing CorporationJournal of ChemistryVolume 2013 Article ID 314790 12 pageshttpdxdoiorg1011552013314790

Research ArticleOptimization of Preparation of Activated Carbon fromRicinus communis Leaves byMicrowave-Assisted Zinc ChlorideChemical Activation Competitive Adsorption of Ni2+ Ions fromAqueous Solution

MMakeswari and T Santhi

Department of Chemistry Karpagam University Tamil Nadu Coimbatore 641021 India

Correspondence should be addressed to T Santhi ssnilasriyahoocoin

Received 29 June 2012 Accepted 11 August 2012

Academic Editor Alvin A Holder

Copyright copy 2013 M Makeswari and T Santhiis 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

e preparation of activated carbon (AC) from Ricinus communis leaves was investigated in this paper Orthogonal array expe-rimental designmethod was used to optimize the preparation of AC usingmicrowave assisted zinc chloride Optimized parameterswere radiation power of 100W radiation time of 8min concentration of zinc chloride of 30 by volume and impregnation timeof 24 h respectively e surface characteristics of the AC prepared under optimized conditions were examined by pHZPC SEM-EDAX XRD and FTIR Competitive adsorption of Ni2+ ions on Ricinus communis leaves by microwave assisted zinc chloridechemical activation (ZLRC) present in binary and ternary mixture was compared with the single metal solution e effects ofthe presence of one metal ion on the adsorption of the other metal ion were investigated e experimental results indicated thatthe uptake capacity of one metal ion was reduced by the presence of the other metal ion e extent of adsorption capacity ofthe binary and ternary metal ions tested on ZLRC was low (48ndash69) as compared to single metal ions Comparisons with thebiosorption of Ni2+ ions by the biomass of ZLRC in the binary (4898ndash6841-simNi-Cu and 6976ndash6629-simNi-Cr) and ternarysolution (6732ndash5707-simNindashCu and Cr) could lead to the conclusion that biosorption of Ni2+ ions was reduced by the inuenceof Cu2+ and Cr3+ ions e euilibrium data of the adsorption was well tted to the Langmuir isotherm e adsorption processfollows the pseudo-second-order kinetic model

1 Introduction

e pollution of water resources due to the indiscriminatedisposal of heavymetals has been causingworldwide concernfor the last few decades It is well known that some metalscan have toxic or harmful effects on many forms of lifeAmong the most toxic metals are chromium (Cr) copper(Cu) lead (Pb) zinc (Zn) and mercury (Hg) which is one ofthe 11 hazardous priority substances in the list of pollutantscontained in the Water Framework Directive (Directive200060EC) [1] Many industries discharge heavy metalssuch as lead cadmium copper nickel and zinc in their wastewaters [2] Among these metals Ni is known to be essential toplants humans and animals but they can also have adverse

effects if their availability in water exceeds certain thresholdvalues erefore the removal of such heavy metals fromwaste streams before discharge to public water sources is ofprimary concern

Some workers indicated that precipitation is a suitablemethod for metal removal from wastewaters containinghigh concentrations of heavy metals [3] In some cases ionexchange and activated carbon adsorption have been used[4 5] Electrochemical treatment membrane process andbiological methods are also used However these meth-ods become noneconomical when dealing with very smallconcentrations of metals due to the need to use expensivemonitoring systems Adsorption is considered to be one ofthe most economical and effective methods for removal of

2 Journal of Chemistry

metals from wastewaters Activated carbon was widely usedin the removal of dyes and metals from industrial wastewaters which had relatively high sorption capacity for a widevariety of dyes and metals

Activated carbons (AC) are an amorphous form of car-bon characterized by high internal porosity and conse-quently high adsorptivity It has wide applications likeremoval of organic inorganic pollutants from drinking waterand as catalyst support [6] Adsorption capacity of activatedcarbon strongly depends on its porosity and surface areaTextural property of AC depends on method of preparationand startingmaterial [7] Generally twomethods are used forthe preparation of AC via physical and chemical activationDuring physical activation the raw material is carbonizedrst at high temperature and then it is activated by CO2 orsteam under pressure to increase porosity and surface area ofAC In chemical activation both carbonization and activationtakes place simultaneously in which raw material is rstimpregnated with activating chemical and then carbonizedat desired temperature that varies according to activatingchemical used [6] Chemical activation is held in presence ofdehydrating reagents such as KOH K2CO3 NaOH ZnCl2and H3PO4 which inuence pyrolytic decomposition andinhibit tar formation e carbon yield obtained is higherand the temperature used in chemical activation is lowerthan that of physical activation Behaviors of the reagentsduring chemical activation show different effects on the nalproduct ZnCl2 is widely used as activating reagent since itresulted in high surface areas and high yield [8 9] In the useof ZnCl2 the activated carbons had large surface areas andmore micropore structure [10 11]

AC with high surface area and porosity can be preparedfrom many lignocellulosic materials such as coal coconutshell [7 12] wood agricultural waste saw dust cashew nutshell and jackfruit feel waste Researcherrsquos interest is growingin the use of other low cost and abundantly available lingo-cellulosic material as a precursor for the preparation of AC[10ndash14] Adsorption capacity of prepared activated carbonsespecially for metal ion depends on a number of acidicpolar oxygen functional groups present on its surface Forpreparing activated carbon conventional heating method isusually adopted in which the energy is produced by electricalfurnace Recently microwave heating technology has beenapplied to fabricate activated carbon due to its rapid heatingand uniformity [15]

e application of microwave (MW) heating technologyfor regenerating industrial waste activated carbon has beeninvestigated with very promising results [15 16] e maindifference between MW devices and conventional heatingsystems is the way of heat generated In the MW device themicrowaves supply energy directly to the carbon bed Energytransfer is not by conduction or convection as in conventionalheating but microwave energy is readily transformed heatinto inside the particles by dipole rotation and ionic conduc-tion [15ndash17]

e aim of the present work was to optimize the ZLRCpreparation conditions using orthogonal array experimentaldesign method investigate the ability of a nickel sorbentprepared from Ricinus communis leaves and study the effect

T 1 Design factors and levels

Independent variables Symbol Range and levels1 2 3 4

Radiation power (W) A 100 200 400 600Radiation time (min) B 4 6 8 10Concentration of ZnCl2 (vol) C 30 40 50 60Impregnation time (h) D 16 20 24 28

of several parameters (pH contact time initial metal con-centration pHZPC and foreign ions effect) on the adsorptionefficiency of nickel from aqueous solution

2 Experimental Section

21 Materials e Ricinus communis leaves were obtainedfrom an agricultural form in Tirupur district (Tamil Nadu)It was air-dried and powdered in a grinder and then itwas used for further experimental studies Samples of zincchloride (ZnCl2) hydrochloric acid (HCl) sodiumhydroxide(NaOH) and nickel sulphate hexa hydrate (NiSOsdot6H2O)were obtained from Aluva Edayar (specrum reagents andchemicals pvt Ltd) All other chemicals used in this studywere analytical grade and purchased from Aluva Edayar(spectrum reagents and chemicals pvt Ltd)

22 Preparation of Stock Solution Nickel stock standardsolution (1000mgL) was prepared from a readymade nickelsulphate hexa hydrate (NiSO4sdot6H2O) standard Workingnickel solutionswere prepared just before used by appropriatedilutions of stock solution

23 Preparation of ZLRC e Ricinus communis leaves wereobtained from the agricultural form inTirupur district (TamilNadu) It was air-dried and powdered in a grinder DriedRicinus communiswith themass of 6 gweremixedwith 30mLof ZnCl2 to vary concentrations in the range of 30ndash60by volume e slurry was kept at room temperature forvarious time spans in the range of 16ndash28 h to ensure theaccess of the ZnCl2 to the Ricinus communis leaves Aermixing the slurry was placed in a MW heating apparatus(MW71E SAMSUNG) Aer a certain microwave heatingpower andmicrowave radiation time the carbonized sampleswere washed with 05M HCl hot water and cold distilledwater until the pH of the washing solution reached 6-7ltered and nally dried at 150∘C

24 Optimization of ZLRC Preparation Conditions In orderto optimize the preparation conditions of the ZLRC Taguchiexperimental design method was used [18] An L16 orthogo-nal array with four operational parameters each in four levelswas used to evaluate the corresponding optimal valuesesevariables and their values are summarized in Table 1 ecomplete design matrix of the experiments and the obtainedresults are shown in Table 2 Iodine is considered as probemolecules for assessing the adsorption capacity of adsorbentsfor solutes of molecular sizes less than 10Aring Iodine number

Journal of Chemistry 3

T 2 Experimental design matrix and results

Runs Variables Responses (Y)A B C D Yield (Y1 ) Iodine number (Y2 mgg)

1 1 1 1 1 4943 735502 2 1 1 1 5551 898973 3 1 1 1 5640 980704 4 1 1 1 4169 940405 1 1 1 1 3564 1389306 1 2 1 1 4864 1307607 1 3 1 1 4857 1552978 1 4 1 1 4785 1320769 1 1 1 1 4579 8984010 1 1 2 1 4695 10621011 1 1 3 1 4990 11441012 1 1 4 1 4313 10621013 1 1 1 1 4943 7355014 1 1 1 2 5252 9806715 1 1 1 3 5834 12258716 1 1 1 4 5618 114410

was normally listed as specication parameter for ZLRCerefore the responses were yield (Y1 ) and the iodinenumber (Y2 mgg) was obtained at 25 plusmn 1∘C on the basis ofthe standard Test method e yield of the carbon sampleswas estimated according to

119884119884 1198841198721198721198721198720times 100 (1)

where119872119872 is the weight of ZLRC and1198721198720 is the weight of air-dried Ricinus communis leaves

25 Characterization of ZLRC e surface physical mor-phology of ZLRCwas identied by using SEM technique (Jeoljsm-6390) A Fourier transform infrared spectroscopy (SHI-MADZU IR Affinity-1) with KBr pellet was used to studythe surface functional groups of the ZLRC with a scanningrange of 4000ndash400 cmminus1 e crystalline structure of ZLRCwas evaluated by XRD analysis e point of zero surfacecharge characteristic of ZLRC was (pHZPC) determined byusing the solid addition method [19]

26 Batch Equilibrium Studies To study the effect of param-eters such as adsorbent dose metal ion concentration andsolution pH for the removal of adsorbate on ZLRC batchexperiments were performed Stock solutions of nickel wereprepared by dissolving NiSO4sdot6H2O in deionized water andfurther diluted to the 50ndash200mgL concentrations for theexperiments pH was adjusted by adding 01M HCl or 01MNaOH into the solutions with known initial nickel ion con-centrations Batch adsorption experiments were conductedin asset of 250mL stoppered asks containing 02 g of ZLRCand 50mL of metal solutions with different concentrations(50 100 150 and 200mgL) at pH 7e asks were agitatedusing a mechanical orbital shaker and maintained at roomtemperature for 2 h until the equilibrium was reached e

suspensions were ltered and metal concentrations in thesupernatant solutions were measured using a UV-vis spec-trophotometer at 232 nm e amount of uptake of Ni2+ions by ZLRC in the equilibrium (119902119902119890119890) was calculated by thefollowing mass-balance relationship

119902119902119890119890 119884100764910076491198621198620 minus 11986211986211989011989010076651007665119882119882times 119881119881 (2)

where 119862119862119900119900 and 119862119862119890119890 (mgL) are the liquid phase concentrationsof metal at initial and equilibrium respectively V (L) is thevolume of the solution and 119882119882 (g) is the mass of adsor-bent used We used different models Langmuir FreundlichTemkin and Dubinin-Radushkevich to investigate the equi-librium behavior of Ni2+ ion adsorption on the preparedZLRC samples

27 Batch Kinetic Studies e kinetic experiments were per-formed using a procedure similar to the equilibrium studiesSamples containing adsorption studies were conducted in250mL shaking asks at a solution pH of 7 e adsorbentdose of 02 g was thoroughly mixed with 50mL of nickelsolution (100mgL) and the suspensionswere shaken at roomtemperature at required time intervals ltered for the clearsolutions and analyzed for residual nickel ion concentrationin the solutions In order to determine the best kinetic modelwhich ts the adsorption experimental data the pseudo-rst-order pseudo-second-order Elovich and intraparticlediffusion models were examined

3 Results and Discussion

31 Optimization of ZLRC Preparation

311 Effect of Independent Variables on ZLRC PreparationAccording to the L16 array designed by Taguchi method 16


different ZLRC samples were prepared e iodine numberand yield of each samplewere determined and shown in Table2 e effect of operational parameters on responses of theprepared ZLRC samples is shown in Figure 1

Effect of microwave radiation power (parameter A) onadsorption capacity and the yield of ZLRC were evaluatedunder the concentration of ZnCl2 (XZn) of 30mL andmicrowave radiation time of 4min Figure 1 shows that theyield of ZLRC samples was increased with the increasingof microwave power level from 100 to 400W and thendecreased with the increasing of the level of 600W erewere similar tendency of the iodine number on ZLRC epossible reason was that the higher energy was offered to thesamples with increasing the power level the more active sitesand pores on the samples When microwave power reacheda certain level overfull energy could make a small quantityof carbon burnt and the structure of pores was destroyedSimilar results have been obtained by other researchers [920]

Effects of microwave radiation time (parameter B) onthe yield and iodine number of ZLRC were evaluated underthe conditions of XZn of 30mL and microwave power of100W (Figure 1) It revealed that the yield of ZLRC wasincreased with increasing the radiation time up to 8minand then decreased when the time was increased to 10minere were same tendency of the iodine number of ZLRCSimilar trendswere also foundby Li et al when they preparedthe activated carbon from tobacco stems using microwaveradiation [21] e activation degree was much more depen-dent on the microwave radiation timeWith the prolongationof microwave radiation time much more active sites andpores were formed on the surface of samples erefore theadsorption capacity of ZLRC would be increased with theprolongation of microwave radiation time However whenmicrowave radiation time reached a certain value the poresof carbon would be burnt off by microwave heating whichwould lower the iodine number the amount of nickel uptakeand the yield of ZLRC

Under the microwave power of 100W radiation time of8min the effects of the impregnation ratio (parameter C) ofZnCl2 on the yield and iodine number of ZLRC were studied(Figure 1) With the increasing XZn from 30mL to 90mL theyield the iodine number and the amount of MG adsorptionof ZLRC were all increased While XZn was further increasedto 120mL these two parameters were all decreased Withincrease in impregnation ratio the initial effect of ZnCl2is to inhibit the release of volatile matter which results inhigher yield and iodine number of ZLRC Subsequentlywith the further increase in impregnation ratio the zincchloride assumed a dehydration agent role during activationIt inhibits the formation of tars and any other liquids thatcould clog up the pores of the sample the movement of thevolatiles through the pore passages would not be hinderedthe volatiles will be subsequently released from the carbonsurface during activation erefore the yield and iodinenumber of carbon were all decreased Similar trends werealso reported by Lua and Yang [22] Guo and Lua [23] intheir studies on the preparation of activated carbon frompistachio-nut shell and oil-palm shells respectively

0

200

400

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1200

1400

1600

1800

0

10

20

30

40

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70

Levels of parameters

Yield

Iodine number

A1

A2

A3

A4

B1

B2

B3

B4

C1

C2

C3

C4

D1

D2

D3

D4

F 1 e effect of operational parameters on responses of theprepared ZLRC samples ((A) radiation power (B) radiation time(C) concentration of ZnCl2 and (D) impregnation time)

e results presented in Figure 1 also shows that impreg-nation time (parameter D) had little inuence on the yieldand iodine number e action of ZnCl2 on the lignocellu-losicmaterial could be expressed as the followingmechanism

During impregnation stage the base attacked the cellularstructure of Ricinus communis leaves forming cleavage to thelinkages between the lignin and cellulose It was followed byrecombination reactions where larger structural units andstrong cross linked solids were formed is base workedprincipally in early stage during impregnation and mightextended to have a slight effect in the carbonization stage [24]

312 Optimized Conditions In the production of AC rel-atively high product yield and adsorption capacity wereexpected erefore more attention should be paid toimprove the carbon yield and enhance its adsorption capacityfor economical viability However it was difficult to optimizeboth these responses under the same condition for the dif-ferent interest in different region From the discussions men-tioned above the microwave radiation power microwaveradiation time impregnation ratio and the impregnationtime of ZnCl2 had signicant effects on the yield and theadsorption capacity of the activated carbon from Ricinuscommunis leaves with ZnCl2 activation by microwave radi-ation erefore the optimum conditions were obtainedas following the microwave power of 100W microwaveradiation time of 8min XZn of 30mL and impregnationtime of 24 h e iodine number and the yield of activatedcarbon prepared under optimum conditions were 5818and 179793 (mgg) respectively e ZLRC was used in thecharacterization analysis and adsorption experiments whichwere prepared under optimum conditions

32 Characterization of ZLRC

321 Zero Surface Charges e Characteristic Analysis ofZLRC e zero surface charge characteristic of ZLRC wasdetermined by using the solid addition method [19] eexperiment was conducted in a series of 250mL glass stop-pered asks Each ask was lled with 50mL of different


initial pHNaNO3 solutions and 02 g of ZLRCe pH valuesof the NaNO3 solutions were adjusted between 2 to 10 byadding either 01M HNO3 or 01M NaOHe suspensionswere then sealed and shaken for 2 h at 150 rpme nal pHvalues of the supernatant liquid were noted e differencebetween the initial pH (pH119894119894) and nal pH (pH119891119891) values (pH =pH119894119894 minus pH119891119891) was plotted against the values of pH119894119894 e pointof intersection of the resulting curve with abscissa at whichpH is 0 gave the pHZPC

e pHZPC of an adsorbent is a very important character-istic that determines the pH at which the adsorbent surfacehas net electrical neutrality Figure 2 shows the plot betweenΔpH that is (pH119894119894 minus pH119891119891) and pH119894119894 for pHZPC measuremente point of zero charge for ZLRC is found to be 604 isresult indicated that the pHZPC of ZLRC depended on theraw material and the activated agency e zero point charge(pHZPC = 604 for ZLRC) is below the solution pH (pH = 7)and hence the negative charge density on the surface of ZLRCincreased which favours the adsorption of Ni2+ ions [25]

322 Functional Group Analysis of ZLRC e aim of usingFTIR analysis is to determine the existence of functionalgroups and identication of characteristic peaks is based onthe studies reported in the literature e FTIR spectrum ofZLRC was shown in Figure 3

e FTIR spectrum of ZLRC showed that the mostpredominant peaks in the spectrumoriginate fromOHvibra-tions CH2 and CH3 asymmetric and symmetric stretchingvibrations e intense bent at about 292794 cmminus1 for theprecursor was attributed to the asymmetric and symmetricvibration modes of methyl and methylene group [26] epeak around 1651 cmminus1 can be assigned to symmetric andasymmetric stretching vibrations of the C=C groupe bandobserved at 1396 cmminus1 is associated to oxygen functionalitiessuch as highly conjugated CndashO stretching e peaks at(1155ndash1033 cmminus1) region related to ligninerefore it is pos-sible that cellulose hemicelluloses and lignin having manyOH groups in their structure make up most of the absorbinglayer e peak present at 821 cmminus1 indicates the presence ofaromatic heterocyclic molecules

323 XRD Analysis of ZLRC Adsorption reaction may leadto changes in molecular and crystalline structure of theadsorbent and hence an understanding of the molecularand crystalline structures of the adsorbent and the result-ing changes thereof would provide valuable informationregarding adsorption reactionHence XRDpatterns of ZLRCbefore adsorption of Ni2+ ions have been studied

As a representative case the XRD patterns of ZLRC beforeadsorption of Ni2+ ions are shown in Figure 4 e resultsindicated that the diffraction proles of ZLRC exhibitedbroad peaks and the absence of a sharp peak revealed apredominantly amorphous structure the broad peak seemsto be appear at around 2120579120579 = 26∘ which was similar to the peakof crystalline carbonaceous structure such as graphite Fromthe XRD analysis for the adsorbent (ZLRC) we concludedthat the activation was completed for the preparation ofZLRC as activated carbon

0

1

2

3

4

0 2 4 6 8 10 12

pHZPC-ZLRC

minus1minus2minus3

F 2 Zero point charges of ZLRC

38

80

78

38

59

56

38

49

92

38

22

91

37

34

19

34

00

5

29

29

87

23

85

95

23

12

65

23

12

34

21

10

12

20

89

31

22

05

99

82

03

68

3

16

39

49

15

29

55 1

44

08

31

41

76

81

37

52

5

13

23

17

12

44

09

11

53

43

10

33

85

81

58

9

57

67

2

51

11

44

78

35

45

32

74

37

84

4000 3500 3000 2500 2000 1750 1500 1250 1000 750 500

ZLRC-B (1cm)

30

375

45

525

60

F 3 FTIR spectra of ZLRC

33 Adsorption of Nickel Ion

331 e Effect of pH e experiments carried out at dif-ferent pH shows that there was a change in the percentremoval of nickel ion over the entire pH range of 2 to 10shown in Figure 5 pH is one of the most important param-eters controlling the adsorption process e effect of pHof the solution on the adsorption desorption and recyclingability of nickel ion on ZLRC was determined e result isshown in Figure 5 e pH of the solution was controlledby the addition of 01M HCl or 01M NaOH e uptakeof nickel ion in aqueous solution was greatly affected bythe variation of pH value as shown in Figure 5 When thepH was lower than 3 the uptake went up sharply with theincrease of pHemaximumnickel ion uptakewas obtainedat 7 pH At the initial metal ion concentration of 100mgLremoval efficiency was 903 at a solution pH of 20 forZLRC but it increased when solution pH increases from 2to 7 At pH 7 the removal efficiency was 7081 for ZLRC(pHZPC = 604 for ZLRC) However when the pH of thesolution was increased from 7 to 10 the uptake of nickelions was decreased It appears that a change in pH of thesolution results in the formation of different ionic speciesand different carbon surface charge At pH values lower than5 the nickel ions can enter into the pore structure this maybe due to its small size


ZLRC-B

0

1000

2000

20 30 40 50 60 70

F 4 XRD analysis for ZLRC

0

10

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70

80

2 3 4 5 6 7 8 9 10

Rem

ova

l of

nic

kel

io

n (

)

Initial pH

Effect of pH

Adsorption of nickel ()

Desorption of nickel ()

Recycling adsorption of nickel ()

F 5 Effect of pH on the adsorption desorption and recyclingadsorption of Ni2+ ion [Ni] = 1000mgL contact time = 2 hadsorbent dose = 02 g50mL

Desorption studies help to elucidate the nature of adsorp-tion and recycling of the spent adsorbent and the nickel ionIf the adsorbed nickel ion can be desorbed using neutral pHwater then the attachment of the nickel ion of the adsorbentis by weak bonds To study the effect of solution pH onnickel ion desorption 50mL of distilled water at different pHvalues (2ndash10) was agitatedwith 02 g of ZLRC in amechanicalorbital shaker at room temperaturee effect of pHon nickelion desorption were studied by varying the pH from 20to 90 e pH was adjusted with 01M NaOH and 01MHCl solutions We could get maximum removal of 4344of adsorbed nickel ion for 7 pH water onto ZLRC aer 2 hof contact time between the loaded matrix and the desorbingagents

Recycling ability of ZLRC was found to be maximum atpH 7 From the result it is evident that optimum pH of 7 isrequired for appreciable removal of nickel ions and hence thispH is employed as an optimum pH for further studies

332 e Effect of Contact Time e effect of time on thesorption of Ni2+ ions byRicinus communis leaves was studiedFigure 6 indicates that the removal efficiency increased with

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10 20 30 40 50 60 70 80 90 100

Ad

sorp

tio

n o

f n

ick

el i

on

(

)

Time (min)

Effect of contact time

F 6 Effect of contact time on the adsorption of Ni2+ ions(100mgL of nickel pH 7 and 02 g50mL of ZLRC)

0102030405060708090

100

200 400 600 800 1000

Ad

sorp

tio

n o

f n

ick

el i

on

(

)

Adsorbent dose (mgL)

Effect of adsorbent dose

F 7 Effect of adsorbent dose on the removal of Ni2+ ions ontoZLRC (Ni2+ concentration 100mgL contact time 2 h solution pH7)

an increase in contact time before equilibrium is reachedis may be due to the attainment of equilibrium conditionat 100min of contact time for ZLRC which is xed as theoptimum contact time At the initial stage the rate of removalof Ni2+ ions was higher due to the availability of more thanrequired number of active sites on the surface of carbons andbecame slower at the later stages of contact time due to thedecreased or lesser number of active sites

333e Effect of Adsorbent Dosage e inuence of adsor-bent dose on nickel ion removed at a xed initial nickelconcentration of 2mgL and pH 7 is shown in Figure 7 Itwas noticed that percentage removal of Ni2+ ion increasedwith an increase in adsorbent dose from 02 to 1 gLis wasattributed to increased carbon surface and availability ofmoreadsorption sites From the result it is evident that optimumdosage of 02 g50mL is required for appreciable removal ofNi2+ ions and hence this amount is employed as a dose forfurther studies

334 e Effect of Initial Nickel Ion Concentration eexperimental results of adsorption of Ni2+ ions on theactivated carbon at various concentrations (10 20 30 and40mgL) are shown in Figure 8 It reveals that the percentageof adsorption decreased with the increase in initial nickel


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25 50 75 100 125 150 175 200

Ad

sorp

tio

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on

(

)

Effect of metal ion concentration

Concentration of Ni2+ ion (ppm)

F 8 Effect of Initial concentration of Ni2+ ions on ZLRC(Adsorbent dose 02 g50mL contact time 2 h solution pH 7)

ion concentration It means that the adsorption is highlydependent on initial concentration of nickel ion at is whyat lower concentration the ratio of the initial number ofnickel ion to the variable surface area is low and subsequentlythe fractional adsorption becomes independent of initialconcentration

e nuene o te ons o ina an enaMetal Solutions Effects of the presence of Cu2+ andCr3+ ionson the adsorption of Ni2+ ions were investigated by varyingthe concentrations of Cu2+ and Cr3+ ions from 10mgL to40mgL A comparison of the adsorption percentage of Ni2+

ions at equilibrium between the solutions with Ni2+ ionspresent as the single and with the presence of increasingconcentration of Cu2+ and Cr3+ ions was given in Figure 9

As shown in Figure 9 the results indicated that the equi-librium uptake of Ni2+ ions decreased with increasing con-centration of Cu2+ and Cr3+ ions from 10 to 40mgL In thesingle ion situation the maximum uptake obtained at initialconcentration of Ni2+ ions 100mgL pH 7 was found tobe 7081 while the uptake obtained in the binary (Ni-Cuand Ni-Cr) metal solutions at the same initial concentrationof Ni2+ ions was found to be 7041 6718 6391 and5898when the initial concentration of Cu2+ ion was 10 2030 and 40mgL respectively Cr3+ ion in the binary solutionslightly affect Ni2+ ion uptake on the ZLRC as much as Cu2+

ions (Figure 9) e maximum Ni2+ uptake obtained at thesame conditions was found to be 6976 6802 6739 and6629 when the concentration of Cr3+ ions was 10 20 30and 40mgL respectively

As shown in Figure 9 the adsorption capacity ofZLRC for the ternary system with initial concentrationsNi2+ 100mgL Cu2+ 10ndash40mgL and Cr3+ 10ndash40mgLremained lower than that for the single metal ions and couldbe ascribed to the overlapping of biosorption sites of respec-tive metal ions e effect on the adsorption of other ions internary system of Ni2+ ion was found to be 6732 64166123 and 5707 when the concentration of Cu2+ andCr3+ ions was 10 20 30 and 40mgL

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(

)

Concentration of metal solution (mgL)

Ni = 100 mgL Cu =Ni = 100 mgL Cr =Ni = 100 mgL Cu and Cr =

10 20 30 and 40 mgL

10 20 30 and 40 mgL10 20 30 and 40 mgL

F 9 Effect of other ions on the adsorption of Ni2+ ions(Adsorbent dose 02 g50mL contact time 2 h solution pH 7)

A xed quantity of nickel ion onto ZLRC could onlyoffer a nite number of surface binding sites some of whichwould be expected to be saturated by the competing metalsolutions e decrease in sorption capacity of the sameactivated carbon in target metal solution than that of singlemetal may be ascribed to the less availability of binding sitesIn case of binary and ternary metal solution the binding siteis competitively divided among the various metal ions

It is generally complicated to nd a common rule toidentify howmetal properties affect the competitive sorptionAmong various factors that affect the sorption preferences ofa sorbent binding of metal ions on material largely dependson physicochemical properties of metals

e HSAB (hard and so acids and bases) theory wasdeveloped by Pearson [27] and extended to activated carbonsadsorption by Alfarra et al [28] Once acids and bases havebeen classied as hard or so a simple rule of the HSABprinciple can be given hard acids prefer to bond to hardbases and so acids prefer to bond to so bases Generallythe CndashO or C=O bonds are more polar and less polarizablehence harder than theCndashCorC=Cbonds In this concept theoxygen surface groups of ZLRC are the hard sites that x hardmetal ions According to this theory Ni2+ Cu2+ and Cr3+cations are borderline acids [27] Changing the experimentalconditions metal ions with a borderline hardness can bebiosorbed by the hard sites of ZLRC e cationic exchangebetween the oxygenated surface groups (hard base) of ZLRCand borderline acids gives ionic bonds which are moreeasily dissociated But the competitive process cannot beexplained exactly by the hardness of cations because othereffective factors and hardness values of Ni2+ Cu2+ and Cr3+borderline acids are close to each other

It has been reported that in general the greater theatomic weight electronegativity electrode potential andionic size the greater will be the affinity for sorption [29]Electronegativities and ionic radius of the elements are givenin Table 3 It is clear that electronegativity is dominant factorfor biosorption


34 Adsorption Isotherms Langmuir Freundlich Temkinand Dubinin-Radushkevich isotherm models are frequentlyused for estimating the quantication of the adsorptivecapacity of ZLRC

Langmuir [30] proposed a theory to describe the adsorp-tion of gas molecules onto metal surfaces e Langmuiradsorption isotherm has been successfully applied to manyreal sorption processes Langmuir isotherm [31] assumesmonolayer adsorption onto a surface containing a nitenumber of adsorption sites It also assumes uniform energiesof adsorption onto the surface without transmigration ofadsorbate in the plane of the surface [32] erefore theLangmuir isotherm model was chosen for estimation of themaximum adsorption capacity corresponding to completemonolayer coverage on the adsorbent surface e Langmuirnonlinear equation is commonly expressed as follows

119902119902119890119890 =1198761198761198981198981198701198701198711198711198621198621198901198901 + 119870119870119871119871119862119862119890119890

(3)

In (3) 119862119862119890119890 and 119902119902119890119890 are dened as before in (2) 119876119876119898119898 is aconstant and reects a complete monolayer (mgg) and119870119870119871119871 isadsorption equilibrium constant (Lmg) that is related to theapparent energy of sorption e Langmuir isotherm (3) canbe linearized into the following form [33 34]

119862119862119890119890119902119902119890119890=1119870119870119871119871119876119876119898119898+1119876119876119898119898times 119862119862119890119890 (4)

A plot of 119862119862119890119890119902119902119890119890 versus 119862119862119890119890 should indicate a straight line ofslope 1119876119876119898119898 and an intercept of 1119870119870119871119871119876119876119898119898e results obtainedfrom the Langmuir for the removal of Ni2+ ions onto ZLRCare shown in Table 4 e correlation coefficients reported inTable 4 showed strong positive evidence on the adsorption ofNi2+ ions onto ZLRC following the Langmuir isotherm eapplicability of the linear form of Langmuir model to ZLRCwas proved by the high correlation coefficients 1198771198772 = 0999is suggests that the Langmuir isotherm provides a goodmodel of the sorption system e maximum monolayercapacity 119876119876119898119898 obtained from the Langmuir is 250mgg

e Freundlich isotherm is an empirical equation assum-ing that the adsorption process takes place on a heteroge-neous surface through a multilayer adsorption mechanismand adsorption capacity is related to the concentration ofmetal at equilibrium [35] e Freundlich equation is givenas

119902119902119890119890 = 1198701198701198911198911198621198621119899119899119890119890 (5)

where 119902119902119890119890 is the amount of adsorbate adsorbed at equilibrium(mgg) 119862119862119890119890 is the equilibrium concentration of the adsorbate(mgL) 119870119870119891119891 is the Freundlich adsorption constant relatedto adsorption capacity of the adsorbent ((mgg) (Lmg)1119899119899)and 1119899119899 is the adsorption intensity A linear form of theFreundlich equation is generally expressed (5) as follows

ln 119902119902119890119890 = ln119870119870119891119891 +1119899119899ln119862119862119890119890 (6)

e values of 119870119870119891119891 and 1119899119899 were calculated from the interceptand slope of the plot of log 119902119902119890119890 versus log 119862119862119890119890 e applicability

T 3 Electronegativities and ionic radius of Ni2+ Cu2+ and Cr3+ions

Ion Ionic radius (pm) Electronegativity (Pauling scale)Ni2+ 83 175Cu2+ 73 190Cr3+ 755 166

of the Freundlich adsorption isotherm was also analyzedusing the same set of experimental data by plotting log 119902119902119890119890 ver-sus log119862119862119890119890edata obtained from linear Freundlich isothermplot for the adsorption of nickel onto ZLRC was showed inTable 4 e correlation coefficient (09280) showed that theFreundlich model is comparable to the Langmuir modele1119899119899 is lower than 10 indicating that Ni2+ ion is favorablyadsorbed by ZLRC

Temkin and Pyzhev considered the effects of some indi-rect sorbateadsorbate interactions on adsorption isothermsand suggested that because of these interactions the heatof adsorption of all molecules in the layer would decreaselinearly with coverage [36] e Temkin isotherm has beenused in the following form

119902119902119890119890 =119877119877119877119877119887119887ln 1007649100764911987011987011987711987711986211986211989011989010076651007665 (7)

where 119870119870119877119877 is the equilibrium binding constant (Lg) 119887119887 isrelated to heat of adsorption (Jmol) 119877119877 is the universal gasconstant (8314 Jmol K) and 119877119877 is the absolute temperature(K)

Equation (7) can be written as the following form

119902119902119890119890 = 1198611198611 ln 1007649100764911987011987011987711987711986211986211989011989010076651007665 (8)

e Temkin adsorption isotherm parameters are calculatedand the values are summarized in Table 4 e adsorptiondata were analyzed according to the linear of the Temkinisotherm Examination of the data shows that the Temkinisotherm tted well the Ni2+ ion adsorption data for ZLRCe heat of Ni2+ ion adsorption onto ZLRC was found to be54811KJmol e correlation coefficient 1198771198772 obtained fromTemkinmodel was comparable to that obtained for Langmuirand Freundlich equations which explains the applicability ofTemkin model to the adsorption of Ni2+ ions onto ZLRC

e Dubinin-Radushkevich (D-R) equation can beexpressed [37] as

119902119902119890119890 = 119902119902119898119898119890119890minus1198701198701205761205762 (9)

where 120576120576 (Polanyi potential) is equal to 119877119877119877119877 ln1198771 + 1119862119862119890119890) 119902119902119890119890is the amount of nickel adsorbed per unit activated carbon(molg) 119902119902119898119898 is the theoretical monolayer saturation capacity(molg) 119862119862119890119890 is the equilibrium concentration of the metalsolution (molL)119870119870119870 is the constant of the adsorption energy(mol2kJ2) 119877119877 the gas constant (kJmol K) and 119877119877 is thetemperature (K) e linear form of the D-R isotherm is

ln 119902119902119890119890 = ln 119902119902119898119898 minus 1198701198701205761205762 (10)


T 4 Adsorption isotherm parameters for adsorption of Ni2+ ions onto ZLRC

Isotherm model Parameters119876119876119898119898 (mggminus1) 250

Langmuir 119887119887 (Lmg minus1) 008511198771198772 099901119899119899 03777

Freundlich 119870119870119891119891 (mggminus1) 4111471198771198772 09280120572120572 (Lgminus1) 00611

Temkin 120573120573 (mgLminus1) 45960119887119887 548111198771198772 09790

119876119876119898119898 (mggminus1) 177237

Dubinin-Radushkevich 119870119870 (times10minus5 mol2kJminus2) 10000119864119864 (kJmolminus1) 007091198771198772 08310

119870119870119870 is related to mean adsorption energy (119864119864 kJmol) as [38]

119864119864 1198641100352410035242119870119870 (11)

e constant obtained from D-R isotherms are shown inTable 4 e mean adsorption energy (119864119864) gives informationabout chemical and physical adsorption [39] e value of119864119864 was found to be 00709KJmol which indicats that thephysicosorption process plays the signicant role in theadsorption of Ni2+ ions onto ZLRC

e equilibrium isotherms was studied by varying theinitial concentration of Ni2+ ions under the conditionsof pH 70 contact time 2 h and activated carbon dose02 gmL Adsorption isotherm models adopted in this workand their parameters are presented in Table 4 e ttingresults that is isotherm parameters and the coefficient ofdetermination 1198771198772 values were shown in Table 4 Accordingto a linear regression method the Freundlich Temkin andDubinin-Radushkevich isotherms were poorly suitable to theadsorption of ZLRC in comparison to Langmuir isotherme validity of the Langmuir model suggested that the metaluptakewas due tomonolayer coverage of solute particles ontothe surface of the activated carbon and adsorption of eachmolecule has equal activation energy

35 Adsorption Kinetics Pseudo-rst-order pseudo-second-order Elovich and intraparticle diffusion models were usedto test the experimental data and thus explain the adsorptionkinetic process e procedure of adsorption kinetic wasidentied to adsorption equilibrium were withdrawn at timeintervals and the concentrations of Ni2+ ions were similarlymeasured

e pseudo-rst-order equation of Lagergren is generallyexpressed as follows [40 41]

119889119889119889119889119905119905119889119889119905119905119864 1198961198961 10076491007649119889119889119890119890 minus 11988911988911990511990510076651007665 (12)

Aer integration and applying boundary conditions 119905119905 119864 119905 to119905119905 119864 119905119905 and 119889119889119905119905 119864 119905 to 119889119889119905119905 119864 119889119889119905119905 the integrated form of the aboveequation becomes

119889119889119905119905 119864 119889119889119890119890 100765010076501 minus 119890119890minus 119870119870111990511990510076661007666 (13)

However (13) is transformed into its linear form for use inthe kinetic analyses of data

ln 10076491007649119889119889119890119890 minus 11988911988911990511990510076651007665 119864 ln 119889119889119890119890 minus 1198961198961119905119905119905 (14)

where 119889119889119890119890 (mgg) and 119889119889119905119905 (mgg) are the amount of adsorbedadsorbate at equilibrium and at time 119905119905 respectively and 1198961198961(1min) is the rate constant of pseudo rst-order adsorptione straight line plots of log (119889119889119890119890 minus 119889119889119905119905) against 119905119905 of (14) weremade at room temperature e parameters were summa-rized in Table 5 From the linear correlation coefficients (1198771198772)it is seen that Lagergren equation does not represent a goodt with the experimental data

If the rate of adsorption has a second-order mechanismthe pseudo-second-order chemisorption kinetic rate equa-tion is expressed as

11990511990511988911988911990511990511986411198961198961198891198892119890119890+1119889119889119890119890119905119905119905 (15)

where 119889119889119890119890 and 119889119889119905119905 are the sorption capacities at equilibriumand at time 119905119905 respectively (mgg) and 119896119896 is the rate constantof pseudo-second-order sorption (gmgmin) Where ℎ canbe regarded as the initial sorption rate as 119889119889119905119905119905119905 tents to zerohence

ℎ 119864 1198961198961198891198892119890119890 (16)

Equation (16) can be written as

119905119905119889119889 1199051199051198641ℎ+1119889119889119890119890times 119905119905 (17)

Equation (17) does not have the disadvantage of the prob-lem with assigning an effective 119889119889119890119890 If pseudo-second-order


T 5 Comparison of the correlation coefficients of kinetic parameters for the adsorption of Ni2+ ions onto ZLRC

Models Parameters1198961198961 (minminus1) 00253

Pseudo-rst-order model 119902119902119890119890 (mgg) 1811301198771198772 0821

1198961198962 (gmgmin) 00207

Pseudo-second-order model 119902119902119890119890 (mgg) 2500ℎ 518001198771198772 09020

119896119896dif (mg(gsdotmin12)) 1711Intra-particle diffusion model 119862119862 52520

1198771198772 0960119860119860119864119864 (mg (gmin)) 00217

Elovich model 119887119887 (gmg) 407681198771198772 08750

kinetics is applicable the plot of 119905119905119905119902119902119905119905 against 119905119905 of (16) shouldgive a linear relationship Values of 119902119902119890119890 119896119896 and ℎ can bedetermined from the slope and intercept of the plots of1119905119902119902119905119905 versus 119905119905 e linear plots of 119905119905119905119902119902119905119905 versus 119905119905 show goodagreement between experimental and calculated 119902119902119890119890 valuese linear correlation coefficient for the second-order kineticmodel was obtained to be 09020 which led to believethat the Pseudo-second order kinetic model provided goodcorrelation for the adsorption of Ni2+ ions onto ZLRC

e adsorption ofNi2+ ions onto ZLRCmay be controlledby via external im diffusion at earlier stages and later bythe particle diffusione possibility of intraparticle diffusionresistance was identied by using the following intraparticlediffusion model as [42]

119902119902119905119905 = 119870119870dif11990511990511199052 + 119862119862119862 (18)

where 119870119870dif is the intraparticle diffusion rate constant (mg(gsdotmin11199052)) 119862119862 is the intercept e values of 119902119902119905119905 were found tobe correlated linearly with values of 11990511990511199052 and the rate constant119870119870dif directly evaluated from the slope of regression line (Table5)e values of119862119862 provide information about the thickness ofthe boundary layer e constant 119862119862 was found to be 52520e 1198771198772 values given in Table 5 are close to unity indicatingthe application of this model is may conrm that therate-limiting step is the intraparticle diffusion process elinearity of the plots demonstrated that intraparticle diffusionplayed a signicant role in the uptake of the adsorbate byadsorbent s still there is no signicant indication about itHo [43] has shown that if the intraparticle diffusion is the solerate-limiting step it is essential for the 119902119902119905119905 versus 119905119905

11199052 plotsto pass through the origin which is not the case it may beconcluded that surface adsorption and intraparticle diffusionwere concurrently operating during the Ni2+ ions and ZLRCinteractions

e Elovich equation is another rate equation based onthe adsorption capacity generally expressed as follows

119889119889119902119902119905119905119889119889119905119905= 119861119861119864119864exp

minus(119860119860119864119864119902119902119905119905)119862 (19)

where 119861119861119864119864 is the initial adsorption rate constant (mg (gmin))and 119860119860119864119864 is the desorption constant (gmg) during any experi-ment

It is simplied by assuming 119860119860119864119864119861119861119864119864119905119905 119905 119905119905 and by applyingthe boundary conditions 119902119902119905119905 = 0 at 119905119905 = 0 and 119902119902119905119905 = 119905119905 at 119905119905 = 119905119905(19) becomes

119902119902119905119905 =11198601198601198641198641007649100764911986111986111986411986411986011986011986411986410076651007665 +

1119860119860119864119864ln 119905119905119905 (20)

If Ni2+ ion adsorption by ZLRC ts the Elovich model aplot of 119902119902119905119905 versus ln (119905119905) should yield a linear relationship witha slope of (1119905119860119860119864119864) and an intercept of (1119905119860119860119864119864) ln (119860119860119864119864119861119861119864119864)usthe constants can be obtained from the slope and the interceptof the straight linee calculated parameters were presentedin Table 5

4 Conclusion

It had indicated that ZnCl2 was a suitable activating agent forthe preparation of ZLRC by microwave radiation Taguchimethod was used to optimize the preparation conditionsof ZLRC Radiation time and concentration of ZnCl2 weresignicant factors for ZLRC yield Concentration of ZnCl2was the greatest impact factor on iodine number of ZLRCe optimum conditions were radiation power of 100Wradiation time of 8min concentration of ZnCl2 of 30 byvolume and the impregnation time of 24 h e yield andiodine number of ZLRC were 5818 and 179793mggLangmuir isotherm better ts the experimental equilibriumdata of nickel adsorption on the prepared ZLRC e inu-ence of binary and ternary mixture of heavy metal solutiononto the surface of ZLRC was found to be competitive wherethe percentage adsorption ofmetals with those of singlemetalions e maximum nickel adsorption capacity on ZLRCis 250mgg e data indicate that the adsorption kinet-ics follows the pseudo-second-order rate with intraparticlediffusion as one of the rate determining steps e present


study concludes that the ZLRC could be employed as low-cost adsorbent as alternative to commercial activated carbonfor the removal of metals from water and waste water

References

[1] F Rozada M Otero A Moraacuten and A I Garciacutea ldquoAdsorptionof heavy metals onto sewage sludge-derived materialsrdquo Biore-source Technology vol 99 no 14 pp 6332ndash6338 2008

[2] K K Krishnani XMeng C Christodoulatos andVM BodduldquoBiosorption mechanism of nine different heavy metals ontobiomatrix from rice huskrdquo Journal of Hazardous Materials vol153 no 3 pp 1222ndash1234 2008

[3] D Feng C Aldrich and H Tan ldquoTreatment of acid mine waterby use of heavy metal precipitation and ion exchangerdquoMineralsEngineering vol 13 no 6 pp 623ndash642 2000

[4] C P Huang and D W Blankenship ldquoe removal of mercury(II) from dilute aqueous solution by activated carbonrdquo WaterResearch vol 18 no 1 pp 37ndash46 1984

[5] S Babel and T A Kurniawan ldquoLow-cost adsorbents for heavymetals uptake from contaminated water a reviewrdquo Journal ofHazardous Materials vol 97 no 1ndash3 pp 219ndash243 2003

[6] J Hayashi A Kazehaya K Muroyama and A P WatkinsonldquoPreparation of activated carbon from lignin by chemicalactivationrdquo Carbon vol 38 no 13 pp 1873ndash1878 2000

[7] A T Mohd Din B H Hameed and A L Ahmad ldquoBatchadsorption of phenol onto physiochemical-activated coconutshellrdquo Journal of Hazardous Materials vol 161 no 2-3 pp1522ndash1529 2009

[8] C Almansa M Molina-Sabio and F Rodriacuteguez-ReinosoldquoAdsorption of methane into ZnCl2-activated carbon deriveddiscsrdquoMicroporous and Mesoporous Materials vol 76 no 1ndash3pp 185ndash191 2004

[9] W Li L B Zhang J H Peng N Li and X Y Zhu ldquoPreparationof high surface area activated carbons from tobacco stems withK2CO3 activation using microwave radiationrdquo Industrial Cropsand Products vol 27 no 3 pp 341ndash347 2008

[10] P TWilliams andA R Reed ldquoDevelopment of activated carbonpore structure via physical and chemical activation of biomassbre wasterdquo Biomass and Bioenergy vol 30 no 2 pp 144ndash1522006

[11] M Molina-Sabio and F Rodriacuteguez-Reinoso ldquoRole of chemicalactivation in the development of carbon porosityrdquo Colloids andSurfaces A vol 241 no 1ndash3 pp 15ndash25 2004

[12] M C Basso E G Cerrella and A L Cukierman ldquoActivatedcarbons developed from a rapidly renewable biosource forremoval of cadmium(II) andnickel(II) ions fromdilute aqueoussolutionsrdquo Industrial and Engineering Chemistry Research vol41 no 2 pp 180ndash189 2002

[13] J Guo and A C Lua ldquoCharacterization of adsorbent preparedfrom oil-palm shell by CO2 activation for removal of gaseouspollutantsrdquoMaterials Letters vol 55 no 5 pp 334ndash339 2002

[14] T Budinova E Ekinci F Yardim et al ldquoCharacterization andapplication of activated carbon produced by H3PO4 and watervapor activationrdquo Fuel Processing Technology vol 87 no 10 pp899ndash905 2006

[15] C O Ania J B Parra J A Meneacutendez and J J Pis ldquoEffect ofmicrowave and conventional regeneration on the microporousand mesoporous network and on the adsorptive capacity ofactivated carbonsrdquoMicroporous and Mesoporous Materials vol85 no 1-2 pp 7ndash15 2005

[16] J M V Nabais P J M Carrott M M L R Carrott andJ A Meneacutendez ldquoPreparation and modication of activatedcarbon bres by microwave heatingrdquo Carbon vol 42 no 7 pp1315ndash1320 2004

[17] D A Jones T P Lelyveld S D Mavrodis S W Kingman andN J Miles ldquoMicrowave heating applications in environmentalengineeringmdashA reviewrdquo Resources Conservation and Recyclingvol 34 no 2 pp 75ndash90 2002

[18] H Deng G Zhang X Xu G Tao and J Dai ldquoOptimization ofpreparation of activated carbon from cotton stalk bymicrowaveassisted phosphoric acid-chemical activationrdquo Journal of Haz-ardous Materials vol 182 no 1ndash3 pp 217ndash224 2010

[19] A Kumar B Prasad and I M Mishra ldquoAdsorptive removalof acrylonitrile by commercial grade activated carbon kineticsequilibrium and thermodynamicsrdquo Journal of Hazardous Mate-rials vol 152 no 2 pp 589ndash600 2008

[20] H Deng L Yang G Tao and J Dai ldquoPreparation and charac-terization of activated carbon from cotton stalk by microwaveassisted chemical activation-Application in methylene blueadsorption from aqueous solutionrdquo Journal of Hazardous Mate-rials vol 166 no 2-3 pp 1514ndash1521 2009

[21] W Li L-B Zhang J H Peng N Li and X Y Zhu ldquoPreparationof high surface area activated carbons from tobacco stems withK2CO3 activation using microwave radiationrdquo Industrial Cropsand Products vol 27 no 3 pp 341ndash347 2008

[22] A C Lua and T Yang ldquoCharacteristics of activated carbonprepared from pistachio-nut shell by zinc chloride activationunder nitrogen and vacuum conditionsrdquo Journal of Colloid andInterface Science vol 290 no 2 pp 505ndash513 2005

[23] J Guo and A C Lua ldquoTextural characterization of activatedcarbons prepared from oil-palm stones pre-treated with variousimpregnating agentsrdquo Journal of Porous Materials vol 7 no 4pp 491ndash497 2000

[24] A N A El-Hendawy A J Alexander R J Andrews and GForrest ldquoEffects of activation schemes on porous surface andthermal properties of activated carbons prepared from cottonstalksrdquo Journal of Analytical and Applied Pyrolysis vol 82 no2 pp 272ndash278 2008

[25] P JanošH Buchtovaacute andMRyacuteznarovaacute ldquoSorption of dyes fromaqueous solutions onto y ashrdquoWater Research vol 37 no 20pp 4938ndash4944 2003

[26] K Nakanishi Infrared Absorption Spectroscopy-PracticalHolden-Day San Francisco CA 1962

[27] R G Pearson ldquoHard and so acids and basesrdquo Journal of theAmericanChemical Society vol 85 no 22 pp 3533ndash3539 1963

[28] A Alfarra E Frackowiak and F Beacuteguin ldquoeHSAB concept asa means to interpret the adsorption of metal ions onto activatedcarbonsrdquo Applied Surface Science vol 228 no 1ndash4 pp 84ndash922004

[29] Y Sag B Akeael and T Kutsal ldquoTernary biosorption equilibriaof Cr(VI) Cu(II) and Cd(II) on Rhizopus arrihzusrdquo SeparationScience and Technology vol 37 pp 279ndash309 2002

[30] I Langmuir ldquoe adsorption of gases on plane surfaces ofglassmica and platinumrdquoe Journal of the AmericanChemicalSociety vol 40 no 9 pp 1361ndash1403 1918

[31] I Langmuir ldquoe constitution and fundamental properties ofsolids and liquids Part I Solidsrdquo e Journal of the AmericanChemical Society vol 38 no 2 pp 2221ndash2295 1916

[32] MDoğanMAlkan andYOnganer ldquoAdsorption ofmethyleneblue from aqueous solution onto perliterdquo Water Air and SoilPollution vol 120 no 3-4 pp 229ndash248 2000


[33] D G Kinniburgh ldquoGeneral purpose adsorption isothermsrdquoEnvironmental Science and Technology vol 20 no 9 pp895ndash904 1986

[34] E Longhinotti F Pozza L Furlan et al ldquoAdsorption of anionicdyes on the biopolymer chitinrdquo Journal of the BrazilianChemicalSociety vol 9 no 5 pp 435ndash440 1998

[35] H M F Freundlich ldquoOver the adsorption in solutionrdquo Journalof Physical Chemistry vol 57 pp 385ndash470 1906

[36] M J emkin and Pyzhev ldquoRecentmodications to LangmuirisothermsrdquoActa Physiochimica URSS vol 1 pp 217ndash222 1940

[37] B Acemioğlu ldquoAdsorption of Congo red from aqueous solutiononto calcium-rich y ashrdquo Journal of Colloid and InterfaceScience vol 274 no 2 pp 371ndash379 2004

[38] HOBSON JP ldquoPhysical adsorption isotherms extending fromultrahigh vacuum to vapor pressurerdquo Journal of Physical Chem-istry vol 73 no 8 pp 2720ndash2727 1969

[39] W Riemam and H Walton Ion Exchange in Analytical Chem-istry vol 38 of International Series of Monographs in AnalyticalChemistry Pergamon Press Oxford UK 1970

[40] G Crini H N Peindy F Gimbert and C Robert ldquoRemoval ofCI Basic Green 4 (Malachite Green) from aqueous solutionsby adsorption using cyclodextrin-based adsorbent kinetic andequilibrium studiesrdquo Separation and Purication Technologyvol 53 no 1 pp 97ndash110 2007

[41] M Oumlzacar and I A Şengil ldquoA kinetic study of metal complexdye sorption onto pine sawdustrdquo Process Biochemistry vol 40no 2 pp 565ndash572 2005

[42] W J Weber and J C Morris ldquoKinetics of adsorption on carbonfrom aqueous solutionrdquo Journal of the Sanitary EngineeringDivision vol 89 pp 31ndash59 1963

[43] Y S Ho ldquoRemoval of copper ions from aqueous solution by treefernrdquoWater Research vol 37 no 10 pp 2323ndash2330 2003

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metals from wastewaters Activated carbon was widely usedin the removal of dyes and metals from industrial wastewaters which had relatively high sorption capacity for a widevariety of dyes and metals

Activated carbons (AC) are an amorphous form of car-bon characterized by high internal porosity and conse-quently high adsorptivity It has wide applications likeremoval of organic inorganic pollutants from drinking waterand as catalyst support [6] Adsorption capacity of activatedcarbon strongly depends on its porosity and surface areaTextural property of AC depends on method of preparationand startingmaterial [7] Generally twomethods are used forthe preparation of AC via physical and chemical activationDuring physical activation the raw material is carbonizedrst at high temperature and then it is activated by CO2 orsteam under pressure to increase porosity and surface area ofAC In chemical activation both carbonization and activationtakes place simultaneously in which raw material is rstimpregnated with activating chemical and then carbonizedat desired temperature that varies according to activatingchemical used [6] Chemical activation is held in presence ofdehydrating reagents such as KOH K2CO3 NaOH ZnCl2and H3PO4 which inuence pyrolytic decomposition andinhibit tar formation e carbon yield obtained is higherand the temperature used in chemical activation is lowerthan that of physical activation Behaviors of the reagentsduring chemical activation show different effects on the nalproduct ZnCl2 is widely used as activating reagent since itresulted in high surface areas and high yield [8 9] In the useof ZnCl2 the activated carbons had large surface areas andmore micropore structure [10 11]

AC with high surface area and porosity can be preparedfrom many lignocellulosic materials such as coal coconutshell [7 12] wood agricultural waste saw dust cashew nutshell and jackfruit feel waste Researcherrsquos interest is growingin the use of other low cost and abundantly available lingo-cellulosic material as a precursor for the preparation of AC[10ndash14] Adsorption capacity of prepared activated carbonsespecially for metal ion depends on a number of acidicpolar oxygen functional groups present on its surface Forpreparing activated carbon conventional heating method isusually adopted in which the energy is produced by electricalfurnace Recently microwave heating technology has beenapplied to fabricate activated carbon due to its rapid heatingand uniformity [15]

e application of microwave (MW) heating technologyfor regenerating industrial waste activated carbon has beeninvestigated with very promising results [15 16] e maindifference between MW devices and conventional heatingsystems is the way of heat generated In the MW device themicrowaves supply energy directly to the carbon bed Energytransfer is not by conduction or convection as in conventionalheating but microwave energy is readily transformed heatinto inside the particles by dipole rotation and ionic conduc-tion [15ndash17]

e aim of the present work was to optimize the ZLRCpreparation conditions using orthogonal array experimentaldesign method investigate the ability of a nickel sorbentprepared from Ricinus communis leaves and study the effect

T 1 Design factors and levels

Independent variables Symbol Range and levels1 2 3 4

Radiation power (W) A 100 200 400 600Radiation time (min) B 4 6 8 10Concentration of ZnCl2 (vol) C 30 40 50 60Impregnation time (h) D 16 20 24 28

of several parameters (pH contact time initial metal con-centration pHZPC and foreign ions effect) on the adsorptionefficiency of nickel from aqueous solution

2 Experimental Section

21 Materials e Ricinus communis leaves were obtainedfrom an agricultural form in Tirupur district (Tamil Nadu)It was air-dried and powdered in a grinder and then itwas used for further experimental studies Samples of zincchloride (ZnCl2) hydrochloric acid (HCl) sodiumhydroxide(NaOH) and nickel sulphate hexa hydrate (NiSOsdot6H2O)were obtained from Aluva Edayar (specrum reagents andchemicals pvt Ltd) All other chemicals used in this studywere analytical grade and purchased from Aluva Edayar(spectrum reagents and chemicals pvt Ltd)

22 Preparation of Stock Solution Nickel stock standardsolution (1000mgL) was prepared from a readymade nickelsulphate hexa hydrate (NiSO4sdot6H2O) standard Workingnickel solutionswere prepared just before used by appropriatedilutions of stock solution

23 Preparation of ZLRC e Ricinus communis leaves wereobtained from the agricultural form inTirupur district (TamilNadu) It was air-dried and powdered in a grinder DriedRicinus communiswith themass of 6 gweremixedwith 30mLof ZnCl2 to vary concentrations in the range of 30ndash60by volume e slurry was kept at room temperature forvarious time spans in the range of 16ndash28 h to ensure theaccess of the ZnCl2 to the Ricinus communis leaves Aermixing the slurry was placed in a MW heating apparatus(MW71E SAMSUNG) Aer a certain microwave heatingpower andmicrowave radiation time the carbonized sampleswere washed with 05M HCl hot water and cold distilledwater until the pH of the washing solution reached 6-7ltered and nally dried at 150∘C

24 Optimization of ZLRC Preparation Conditions In orderto optimize the preparation conditions of the ZLRC Taguchiexperimental design method was used [18] An L16 orthogo-nal array with four operational parameters each in four levelswas used to evaluate the corresponding optimal valuesesevariables and their values are summarized in Table 1 ecomplete design matrix of the experiments and the obtainedresults are shown in Table 2 Iodine is considered as probemolecules for assessing the adsorption capacity of adsorbentsfor solutes of molecular sizes less than 10Aring Iodine number




1 1 1 1 1 4943 735502 2 1 1 1 5551 898973 3 1 1 1 5640 980704 4 1 1 1 4169 940405 1 1 1 1 3564 1389306 1 2 1 1 4864 1307607 1 3 1 1 4857 1552978 1 4 1 1 4785 1320769 1 1 1 1 4579 8984010 1 1 2 1 4695 10621011 1 1 3 1 4990 11441012 1 1 4 1 4313 10621013 1 1 1 1 4943 7355014 1 1 1 2 5252 9806715 1 1 1 3 5834 12258716 1 1 1 4 5618 114410


119884119884 1198841198721198721198721198720times 100 (1)





119902119902119890119890 119884100764910076491198621198620 minus 11986211986211989011989010076651007665119882119882times 119881119881 (2)











0

200

400

600

800

1000

1200

1400

1600

1800

0

10

20

30

40

50

60

70


Yield

Iodine number

A1

A2

A3

A4

B1

B2

B3

B4

C1

C2

C3

C4

D1

D2

D3

D4














0

1

2

3

4

0 2 4 6 8 10 12

pHZPC-ZLRC

minus1minus2minus3


38

80

78

38

59

56

38

49

92

38

22

91

37

34

19

34

00

5

29

29

87

23

85

95

23

12

65

23

12

34

21

10

12

20

89

31

22

05

99

82

03

68

3

16

39

49

15

29

55 1

44

08

31

41

76

81

37

52

5

13

23

17

12

44

09

11

53

43

10

33

85

81

58

9

57

67

2

51

11

44

78

35

45

32

74

37

84

4000 3500 3000 2500 2000 1750 1500 1250 1000 750 500

ZLRC-B (1cm)

30

375

45

525

60





ZLRC-B

0

1000

2000

20 30 40 50 60 70


0

10

20

30

40

50

60

70

80

2 3 4 5 6 7 8 9 10

Rem

ova

l of

nic

kel

io

n (

)

Initial pH

Effect of pH








0

10

20

30

40

50

60

70

80

10 20 30 40 50 60 70 80 90 100

Ad

sorp

tio

n o

f n

ick

el i

on

(

)

Time (min)



0102030405060708090

100

200 400 600 800 1000

Ad

sorp

tio

n o

f n

ick

el i

on

(

)








0

10

20

30

40

50

60

70

80

90

100

25 50 75 100 125 150 175 200

Ad

sorp

tio

n o

f n

ick

el i

on

(

)










0

10

20

30

40

50

60

70

80

0 10 20 30 40 50

Ad

sorp

tio

n o

f n

ick

el i

on

(

)



10 20 30 and 40 mgL

10 20 30 and 40 mgL10 20 30 and 40 mgL









119902119902119890119890 =1198761198761198981198981198701198701198711198711198621198621198901198901 + 119870119870119871119871119862119862119890119890

(3)


119862119862119890119890119902119902119890119890=1119870119870119871119871119876119876119898119898+1119876119876119898119898times 119862119862119890119890 (4)



119902119902119890119890 = 1198701198701198911198911198621198621119899119899119890119890 (5)


ln 119902119902119890119890 = ln119870119870119891119891 +1119899119899ln119862119862119890119890 (6)






119902119902119890119890 =119877119877119877119877119887119887ln 1007649100764911987011987011987711987711986211986211989011989010076651007665 (7)



119902119902119890119890 = 1198611198611 ln 1007649100764911987011987011987711987711986211986211989011989010076651007665 (8)



119902119902119890119890 = 119902119902119898119898119890119890minus1198701198701205761205762 (9)


ln 119902119902119890119890 = ln 119902119902119898119898 minus 1198701198701205761205762 (10)






Temkin 120573120573 (mgLminus1) 45960119887119887 548111198771198772 09790

119876119876119898119898 (mggminus1) 177237



119864119864 1198641100352410035242119870119870 (11)





119889119889119889119889119905119905119889119889119905119905119864 1198961198961 10076491007649119889119889119890119890 minus 11988911988911990511990510076651007665 (12)


119889119889119905119905 119864 119889119889119890119890 100765010076501 minus 119890119890minus 119870119870111990511990510076661007666 (13)


ln 10076491007649119889119889119890119890 minus 11988911988911990511990510076651007665 119864 ln 119889119889119890119890 minus 1198961198961119905119905119905 (14)



11990511990511988911988911990511990511986411198961198961198891198892119890119890+1119889119889119890119890119905119905119905 (15)


ℎ 119864 1198961198961198891198892119890119890 (16)


119905119905119889119889 1199051199051198641ℎ+1119889119889119890119890times 119905119905 (17)






1198961198962 (gmgmin) 00207



1198771198772 0960119860119860119864119864 (mg (gmin)) 00217




119902119902119905119905 = 119870119870dif11990511990511199052 + 119862119862119862 (18)




119889119889119902119902119905119905119889119889119905119905= 119861119861119864119864exp

minus(119860119860119864119864119902119902119905119905)119862 (19)



119902119902119905119905 =11198601198601198641198641007649100764911986111986111986411986411986011986011986411986410076651007665 +

1119860119860119864119864ln 119905119905119905 (20)


4 Conclusion




References






















































Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of




1 1 1 1 1 4943 735502 2 1 1 1 5551 898973 3 1 1 1 5640 980704 4 1 1 1 4169 940405 1 1 1 1 3564 1389306 1 2 1 1 4864 1307607 1 3 1 1 4857 1552978 1 4 1 1 4785 1320769 1 1 1 1 4579 8984010 1 1 2 1 4695 10621011 1 1 3 1 4990 11441012 1 1 4 1 4313 10621013 1 1 1 1 4943 7355014 1 1 1 2 5252 9806715 1 1 1 3 5834 12258716 1 1 1 4 5618 114410


119884119884 1198841198721198721198721198720times 100 (1)





119902119902119890119890 119884100764910076491198621198620 minus 11986211986211989011989010076651007665119882119882times 119881119881 (2)











0

200

400

600

800

1000

1200

1400

1600

1800

0

10

20

30

40

50

60

70


Yield

Iodine number

A1

A2

A3

A4

B1

B2

B3

B4

C1

C2

C3

C4

D1

D2

D3

D4














0

1

2

3

4

0 2 4 6 8 10 12

pHZPC-ZLRC

minus1minus2minus3


38

80

78

38

59

56

38

49

92

38

22

91

37

34

19

34

00

5

29

29

87

23

85

95

23

12

65

23

12

34

21

10

12

20

89

31

22

05

99

82

03

68

3

16

39

49

15

29

55 1

44

08

31

41

76

81

37

52

5

13

23

17

12

44

09

11

53

43

10

33

85

81

58

9

57

67

2

51

11

44

78

35

45

32

74

37

84

4000 3500 3000 2500 2000 1750 1500 1250 1000 750 500

ZLRC-B (1cm)

30

375

45

525

60





ZLRC-B

0

1000

2000

20 30 40 50 60 70


0

10

20

30

40

50

60

70

80

2 3 4 5 6 7 8 9 10

Rem

ova

l of

nic

kel

io

n (

)

Initial pH

Effect of pH








0

10

20

30

40

50

60

70

80

10 20 30 40 50 60 70 80 90 100

Ad

sorp

tio

n o

f n

ick

el i

on

(

)

Time (min)



0102030405060708090

100

200 400 600 800 1000

Ad

sorp

tio

n o

f n

ick

el i

on

(

)








0

10

20

30

40

50

60

70

80

90

100

25 50 75 100 125 150 175 200

Ad

sorp

tio

n o

f n

ick

el i

on

(

)










0

10

20

30

40

50

60

70

80

0 10 20 30 40 50

Ad

sorp

tio

n o

f n

ick

el i

on

(

)



10 20 30 and 40 mgL

10 20 30 and 40 mgL10 20 30 and 40 mgL









119902119902119890119890 =1198761198761198981198981198701198701198711198711198621198621198901198901 + 119870119870119871119871119862119862119890119890

(3)


119862119862119890119890119902119902119890119890=1119870119870119871119871119876119876119898119898+1119876119876119898119898times 119862119862119890119890 (4)



119902119902119890119890 = 1198701198701198911198911198621198621119899119899119890119890 (5)


ln 119902119902119890119890 = ln119870119870119891119891 +1119899119899ln119862119862119890119890 (6)






119902119902119890119890 =119877119877119877119877119887119887ln 1007649100764911987011987011987711987711986211986211989011989010076651007665 (7)



119902119902119890119890 = 1198611198611 ln 1007649100764911987011987011987711987711986211986211989011989010076651007665 (8)



119902119902119890119890 = 119902119902119898119898119890119890minus1198701198701205761205762 (9)


ln 119902119902119890119890 = ln 119902119902119898119898 minus 1198701198701205761205762 (10)






Temkin 120573120573 (mgLminus1) 45960119887119887 548111198771198772 09790

119876119876119898119898 (mggminus1) 177237



119864119864 1198641100352410035242119870119870 (11)





119889119889119889119889119905119905119889119889119905119905119864 1198961198961 10076491007649119889119889119890119890 minus 11988911988911990511990510076651007665 (12)


119889119889119905119905 119864 119889119889119890119890 100765010076501 minus 119890119890minus 119870119870111990511990510076661007666 (13)


ln 10076491007649119889119889119890119890 minus 11988911988911990511990510076651007665 119864 ln 119889119889119890119890 minus 1198961198961119905119905119905 (14)



11990511990511988911988911990511990511986411198961198961198891198892119890119890+1119889119889119890119890119905119905119905 (15)


ℎ 119864 1198961198961198891198892119890119890 (16)


119905119905119889119889 1199051199051198641ℎ+1119889119889119890119890times 119905119905 (17)






1198961198962 (gmgmin) 00207



1198771198772 0960119860119860119864119864 (mg (gmin)) 00217




119902119902119905119905 = 119870119870dif11990511990511199052 + 119862119862119862 (18)




119889119889119902119902119905119905119889119889119905119905= 119861119861119864119864exp

minus(119860119860119864119864119902119902119905119905)119862 (19)



119902119902119905119905 =11198601198601198641198641007649100764911986111986111986411986411986011986011986411986410076651007665 +

1119860119860119864119864ln 119905119905119905 (20)


4 Conclusion




References






















































Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of






0

200

400

600

800

1000

1200

1400

1600

1800

0

10

20

30

40

50

60

70


Yield

Iodine number

A1

A2

A3

A4

B1

B2

B3

B4

C1

C2

C3

C4

D1

D2

D3

D4














0

1

2

3

4

0 2 4 6 8 10 12

pHZPC-ZLRC

minus1minus2minus3


38

80

78

38

59

56

38

49

92

38

22

91

37

34

19

34

00

5

29

29

87

23

85

95

23

12

65

23

12

34

21

10

12

20

89

31

22

05

99

82

03

68

3

16

39

49

15

29

55 1

44

08

31

41

76

81

37

52

5

13

23

17

12

44

09

11

53

43

10

33

85

81

58

9

57

67

2

51

11

44

78

35

45

32

74

37

84

4000 3500 3000 2500 2000 1750 1500 1250 1000 750 500

ZLRC-B (1cm)

30

375

45

525

60





ZLRC-B

0

1000

2000

20 30 40 50 60 70


0

10

20

30

40

50

60

70

80

2 3 4 5 6 7 8 9 10

Rem

ova

l of

nic

kel

io

n (

)

Initial pH

Effect of pH








0

10

20

30

40

50

60

70

80

10 20 30 40 50 60 70 80 90 100

Ad

sorp

tio

n o

f n

ick

el i

on

(

)

Time (min)



0102030405060708090

100

200 400 600 800 1000

Ad

sorp

tio

n o

f n

ick

el i

on

(

)








0

10

20

30

40

50

60

70

80

90

100

25 50 75 100 125 150 175 200

Ad

sorp

tio

n o

f n

ick

el i

on

(

)










0

10

20

30

40

50

60

70

80

0 10 20 30 40 50

Ad

sorp

tio

n o

f n

ick

el i

on

(

)



10 20 30 and 40 mgL

10 20 30 and 40 mgL10 20 30 and 40 mgL









119902119902119890119890 =1198761198761198981198981198701198701198711198711198621198621198901198901 + 119870119870119871119871119862119862119890119890

(3)


119862119862119890119890119902119902119890119890=1119870119870119871119871119876119876119898119898+1119876119876119898119898times 119862119862119890119890 (4)



119902119902119890119890 = 1198701198701198911198911198621198621119899119899119890119890 (5)


ln 119902119902119890119890 = ln119870119870119891119891 +1119899119899ln119862119862119890119890 (6)






119902119902119890119890 =119877119877119877119877119887119887ln 1007649100764911987011987011987711987711986211986211989011989010076651007665 (7)



119902119902119890119890 = 1198611198611 ln 1007649100764911987011987011987711987711986211986211989011989010076651007665 (8)



119902119902119890119890 = 119902119902119898119898119890119890minus1198701198701205761205762 (9)


ln 119902119902119890119890 = ln 119902119902119898119898 minus 1198701198701205761205762 (10)






Temkin 120573120573 (mgLminus1) 45960119887119887 548111198771198772 09790

119876119876119898119898 (mggminus1) 177237



119864119864 1198641100352410035242119870119870 (11)





119889119889119889119889119905119905119889119889119905119905119864 1198961198961 10076491007649119889119889119890119890 minus 11988911988911990511990510076651007665 (12)


119889119889119905119905 119864 119889119889119890119890 100765010076501 minus 119890119890minus 119870119870111990511990510076661007666 (13)


ln 10076491007649119889119889119890119890 minus 11988911988911990511990510076651007665 119864 ln 119889119889119890119890 minus 1198961198961119905119905119905 (14)



11990511990511988911988911990511990511986411198961198961198891198892119890119890+1119889119889119890119890119905119905119905 (15)


ℎ 119864 1198961198961198891198892119890119890 (16)


119905119905119889119889 1199051199051198641ℎ+1119889119889119890119890times 119905119905 (17)






1198961198962 (gmgmin) 00207



1198771198772 0960119860119860119864119864 (mg (gmin)) 00217




119902119902119905119905 = 119870119870dif11990511990511199052 + 119862119862119862 (18)




119889119889119902119902119905119905119889119889119905119905= 119861119861119864119864exp

minus(119860119860119864119864119902119902119905119905)119862 (19)



119902119902119905119905 =11198601198601198641198641007649100764911986111986111986411986411986011986011986411986410076651007665 +

1119860119860119864119864ln 119905119905119905 (20)


4 Conclusion




References






















































Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of








0

1

2

3

4

0 2 4 6 8 10 12

pHZPC-ZLRC

minus1minus2minus3


38

80

78

38

59

56

38

49

92

38

22

91

37

34

19

34

00

5

29

29

87

23

85

95

23

12

65

23

12

34

21

10

12

20

89

31

22

05

99

82

03

68

3

16

39

49

15

29

55 1

44

08

31

41

76

81

37

52

5

13

23

17

12

44

09

11

53

43

10

33

85

81

58

9

57

67

2

51

11

44

78

35

45

32

74

37

84

4000 3500 3000 2500 2000 1750 1500 1250 1000 750 500

ZLRC-B (1cm)

30

375

45

525

60





ZLRC-B

0

1000

2000

20 30 40 50 60 70


0

10

20

30

40

50

60

70

80

2 3 4 5 6 7 8 9 10

Rem

ova

l of

nic

kel

io

n (

)

Initial pH

Effect of pH








0

10

20

30

40

50

60

70

80

10 20 30 40 50 60 70 80 90 100

Ad

sorp

tio

n o

f n

ick

el i

on

(

)

Time (min)



0102030405060708090

100

200 400 600 800 1000

Ad

sorp

tio

n o

f n

ick

el i

on

(

)








0

10

20

30

40

50

60

70

80

90

100

25 50 75 100 125 150 175 200

Ad

sorp

tio

n o

f n

ick

el i

on

(

)










0

10

20

30

40

50

60

70

80

0 10 20 30 40 50

Ad

sorp

tio

n o

f n

ick

el i

on

(

)



10 20 30 and 40 mgL

10 20 30 and 40 mgL10 20 30 and 40 mgL









119902119902119890119890 =1198761198761198981198981198701198701198711198711198621198621198901198901 + 119870119870119871119871119862119862119890119890

(3)


119862119862119890119890119902119902119890119890=1119870119870119871119871119876119876119898119898+1119876119876119898119898times 119862119862119890119890 (4)



119902119902119890119890 = 1198701198701198911198911198621198621119899119899119890119890 (5)


ln 119902119902119890119890 = ln119870119870119891119891 +1119899119899ln119862119862119890119890 (6)






119902119902119890119890 =119877119877119877119877119887119887ln 1007649100764911987011987011987711987711986211986211989011989010076651007665 (7)



119902119902119890119890 = 1198611198611 ln 1007649100764911987011987011987711987711986211986211989011989010076651007665 (8)



119902119902119890119890 = 119902119902119898119898119890119890minus1198701198701205761205762 (9)


ln 119902119902119890119890 = ln 119902119902119898119898 minus 1198701198701205761205762 (10)






Temkin 120573120573 (mgLminus1) 45960119887119887 548111198771198772 09790

119876119876119898119898 (mggminus1) 177237



119864119864 1198641100352410035242119870119870 (11)





119889119889119889119889119905119905119889119889119905119905119864 1198961198961 10076491007649119889119889119890119890 minus 11988911988911990511990510076651007665 (12)


119889119889119905119905 119864 119889119889119890119890 100765010076501 minus 119890119890minus 119870119870111990511990510076661007666 (13)


ln 10076491007649119889119889119890119890 minus 11988911988911990511990510076651007665 119864 ln 119889119889119890119890 minus 1198961198961119905119905119905 (14)



11990511990511988911988911990511990511986411198961198961198891198892119890119890+1119889119889119890119890119905119905119905 (15)


ℎ 119864 1198961198961198891198892119890119890 (16)


119905119905119889119889 1199051199051198641ℎ+1119889119889119890119890times 119905119905 (17)






1198961198962 (gmgmin) 00207



1198771198772 0960119860119860119864119864 (mg (gmin)) 00217




119902119902119905119905 = 119870119870dif11990511990511199052 + 119862119862119862 (18)




119889119889119902119902119905119905119889119889119905119905= 119861119861119864119864exp

minus(119860119860119864119864119902119902119905119905)119862 (19)



119902119902119905119905 =11198601198601198641198641007649100764911986111986111986411986411986011986011986411986410076651007665 +

1119860119860119864119864ln 119905119905119905 (20)


4 Conclusion




References






















































Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of


ZLRC-B

0

1000

2000

20 30 40 50 60 70


0

10

20

30

40

50

60

70

80

2 3 4 5 6 7 8 9 10

Rem

ova

l of

nic

kel

io

n (

)

Initial pH

Effect of pH








0

10

20

30

40

50

60

70

80

10 20 30 40 50 60 70 80 90 100

Ad

sorp

tio

n o

f n

ick

el i

on

(

)

Time (min)



0102030405060708090

100

200 400 600 800 1000

Ad

sorp

tio

n o

f n

ick

el i

on

(

)








0

10

20

30

40

50

60

70

80

90

100

25 50 75 100 125 150 175 200

Ad

sorp

tio

n o

f n

ick

el i

on

(

)










0

10

20

30

40

50

60

70

80

0 10 20 30 40 50

Ad

sorp

tio

n o

f n

ick

el i

on

(

)



10 20 30 and 40 mgL

10 20 30 and 40 mgL10 20 30 and 40 mgL









119902119902119890119890 =1198761198761198981198981198701198701198711198711198621198621198901198901 + 119870119870119871119871119862119862119890119890

(3)


119862119862119890119890119902119902119890119890=1119870119870119871119871119876119876119898119898+1119876119876119898119898times 119862119862119890119890 (4)



119902119902119890119890 = 1198701198701198911198911198621198621119899119899119890119890 (5)


ln 119902119902119890119890 = ln119870119870119891119891 +1119899119899ln119862119862119890119890 (6)






119902119902119890119890 =119877119877119877119877119887119887ln 1007649100764911987011987011987711987711986211986211989011989010076651007665 (7)



119902119902119890119890 = 1198611198611 ln 1007649100764911987011987011987711987711986211986211989011989010076651007665 (8)



119902119902119890119890 = 119902119902119898119898119890119890minus1198701198701205761205762 (9)


ln 119902119902119890119890 = ln 119902119902119898119898 minus 1198701198701205761205762 (10)






Temkin 120573120573 (mgLminus1) 45960119887119887 548111198771198772 09790

119876119876119898119898 (mggminus1) 177237



119864119864 1198641100352410035242119870119870 (11)





119889119889119889119889119905119905119889119889119905119905119864 1198961198961 10076491007649119889119889119890119890 minus 11988911988911990511990510076651007665 (12)


119889119889119905119905 119864 119889119889119890119890 100765010076501 minus 119890119890minus 119870119870111990511990510076661007666 (13)


ln 10076491007649119889119889119890119890 minus 11988911988911990511990510076651007665 119864 ln 119889119889119890119890 minus 1198961198961119905119905119905 (14)



11990511990511988911988911990511990511986411198961198961198891198892119890119890+1119889119889119890119890119905119905119905 (15)


ℎ 119864 1198961198961198891198892119890119890 (16)


119905119905119889119889 1199051199051198641ℎ+1119889119889119890119890times 119905119905 (17)






1198961198962 (gmgmin) 00207



1198771198772 0960119860119860119864119864 (mg (gmin)) 00217




119902119902119905119905 = 119870119870dif11990511990511199052 + 119862119862119862 (18)




119889119889119902119902119905119905119889119889119905119905= 119861119861119864119864exp

minus(119860119860119864119864119902119902119905119905)119862 (19)



119902119902119905119905 =11198601198601198641198641007649100764911986111986111986411986411986011986011986411986410076651007665 +

1119860119860119864119864ln 119905119905119905 (20)


4 Conclusion




References






















































Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of


0

10

20

30

40

50

60

70

80

90

100

25 50 75 100 125 150 175 200

Ad

sorp

tio

n o

f n

ick

el i

on

(

)










0

10

20

30

40

50

60

70

80

0 10 20 30 40 50

Ad

sorp

tio

n o

f n

ick

el i

on

(

)



10 20 30 and 40 mgL

10 20 30 and 40 mgL10 20 30 and 40 mgL









119902119902119890119890 =1198761198761198981198981198701198701198711198711198621198621198901198901 + 119870119870119871119871119862119862119890119890

(3)


119862119862119890119890119902119902119890119890=1119870119870119871119871119876119876119898119898+1119876119876119898119898times 119862119862119890119890 (4)



119902119902119890119890 = 1198701198701198911198911198621198621119899119899119890119890 (5)


ln 119902119902119890119890 = ln119870119870119891119891 +1119899119899ln119862119862119890119890 (6)






119902119902119890119890 =119877119877119877119877119887119887ln 1007649100764911987011987011987711987711986211986211989011989010076651007665 (7)



119902119902119890119890 = 1198611198611 ln 1007649100764911987011987011987711987711986211986211989011989010076651007665 (8)



119902119902119890119890 = 119902119902119898119898119890119890minus1198701198701205761205762 (9)


ln 119902119902119890119890 = ln 119902119902119898119898 minus 1198701198701205761205762 (10)






Temkin 120573120573 (mgLminus1) 45960119887119887 548111198771198772 09790

119876119876119898119898 (mggminus1) 177237



119864119864 1198641100352410035242119870119870 (11)





119889119889119889119889119905119905119889119889119905119905119864 1198961198961 10076491007649119889119889119890119890 minus 11988911988911990511990510076651007665 (12)


119889119889119905119905 119864 119889119889119890119890 100765010076501 minus 119890119890minus 119870119870111990511990510076661007666 (13)


ln 10076491007649119889119889119890119890 minus 11988911988911990511990510076651007665 119864 ln 119889119889119890119890 minus 1198961198961119905119905119905 (14)



11990511990511988911988911990511990511986411198961198961198891198892119890119890+1119889119889119890119890119905119905119905 (15)


ℎ 119864 1198961198961198891198892119890119890 (16)


119905119905119889119889 1199051199051198641ℎ+1119889119889119890119890times 119905119905 (17)






1198961198962 (gmgmin) 00207



1198771198772 0960119860119860119864119864 (mg (gmin)) 00217




119902119902119905119905 = 119870119870dif11990511990511199052 + 119862119862119862 (18)




119889119889119902119902119905119905119889119889119905119905= 119861119861119864119864exp

minus(119860119860119864119864119902119902119905119905)119862 (19)



119902119902119905119905 =11198601198601198641198641007649100764911986111986111986411986411986011986011986411986410076651007665 +

1119860119860119864119864ln 119905119905119905 (20)


4 Conclusion




References






















































Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of




119902119902119890119890 =1198761198761198981198981198701198701198711198711198621198621198901198901 + 119870119870119871119871119862119862119890119890

(3)


119862119862119890119890119902119902119890119890=1119870119870119871119871119876119876119898119898+1119876119876119898119898times 119862119862119890119890 (4)



119902119902119890119890 = 1198701198701198911198911198621198621119899119899119890119890 (5)


ln 119902119902119890119890 = ln119870119870119891119891 +1119899119899ln119862119862119890119890 (6)






119902119902119890119890 =119877119877119877119877119887119887ln 1007649100764911987011987011987711987711986211986211989011989010076651007665 (7)



119902119902119890119890 = 1198611198611 ln 1007649100764911987011987011987711987711986211986211989011989010076651007665 (8)



119902119902119890119890 = 119902119902119898119898119890119890minus1198701198701205761205762 (9)


ln 119902119902119890119890 = ln 119902119902119898119898 minus 1198701198701205761205762 (10)






Temkin 120573120573 (mgLminus1) 45960119887119887 548111198771198772 09790

119876119876119898119898 (mggminus1) 177237



119864119864 1198641100352410035242119870119870 (11)





119889119889119889119889119905119905119889119889119905119905119864 1198961198961 10076491007649119889119889119890119890 minus 11988911988911990511990510076651007665 (12)


119889119889119905119905 119864 119889119889119890119890 100765010076501 minus 119890119890minus 119870119870111990511990510076661007666 (13)


ln 10076491007649119889119889119890119890 minus 11988911988911990511990510076651007665 119864 ln 119889119889119890119890 minus 1198961198961119905119905119905 (14)



11990511990511988911988911990511990511986411198961198961198891198892119890119890+1119889119889119890119890119905119905119905 (15)


ℎ 119864 1198961198961198891198892119890119890 (16)


119905119905119889119889 1199051199051198641ℎ+1119889119889119890119890times 119905119905 (17)






1198961198962 (gmgmin) 00207



1198771198772 0960119860119860119864119864 (mg (gmin)) 00217




119902119902119905119905 = 119870119870dif11990511990511199052 + 119862119862119862 (18)




119889119889119902119902119905119905119889119889119905119905= 119861119861119864119864exp

minus(119860119860119864119864119902119902119905119905)119862 (19)



119902119902119905119905 =11198601198601198641198641007649100764911986111986111986411986411986011986011986411986410076651007665 +

1119860119860119864119864ln 119905119905119905 (20)


4 Conclusion




References






















































Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of






Temkin 120573120573 (mgLminus1) 45960119887119887 548111198771198772 09790

119876119876119898119898 (mggminus1) 177237



119864119864 1198641100352410035242119870119870 (11)





119889119889119889119889119905119905119889119889119905119905119864 1198961198961 10076491007649119889119889119890119890 minus 11988911988911990511990510076651007665 (12)


119889119889119905119905 119864 119889119889119890119890 100765010076501 minus 119890119890minus 119870119870111990511990510076661007666 (13)


ln 10076491007649119889119889119890119890 minus 11988911988911990511990510076651007665 119864 ln 119889119889119890119890 minus 1198961198961119905119905119905 (14)



11990511990511988911988911990511990511986411198961198961198891198892119890119890+1119889119889119890119890119905119905119905 (15)


ℎ 119864 1198961198961198891198892119890119890 (16)


119905119905119889119889 1199051199051198641ℎ+1119889119889119890119890times 119905119905 (17)






1198961198962 (gmgmin) 00207



1198771198772 0960119860119860119864119864 (mg (gmin)) 00217




119902119902119905119905 = 119870119870dif11990511990511199052 + 119862119862119862 (18)




119889119889119902119902119905119905119889119889119905119905= 119861119861119864119864exp

minus(119860119860119864119864119902119902119905119905)119862 (19)



119902119902119905119905 =11198601198601198641198641007649100764911986111986111986411986411986011986011986411986410076651007665 +

1119860119860119864119864ln 119905119905119905 (20)


4 Conclusion




References






















































Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of





1198961198962 (gmgmin) 00207



1198771198772 0960119860119860119864119864 (mg (gmin)) 00217




119902119902119905119905 = 119870119870dif11990511990511199052 + 119862119862119862 (18)




119889119889119902119902119905119905119889119889119905119905= 119861119861119864119864exp

minus(119860119860119864119864119902119902119905119905)119862 (19)



119902119902119905119905 =11198601198601198641198641007649100764911986111986111986411986411986011986011986411986410076651007665 +

1119860119860119864119864ln 119905119905119905 (20)


4 Conclusion




References






















































Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of



References






















































Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of






















Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of










Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of

Documents

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