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Preparation of activated carbon from cattail and its application for dyes removal

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Preparation of activated carbon from cattail and its application for dyes removalof,it,from,and,its,for,dyes

    Preparation of activated carbon from cattail

    and its application for dyes removal

EE

    Availableonlineat,^,\v\?.sciencedirect.com

    ''Directbcience13

    JournalofEnvkonmenmlSciences2010,22(1)91-97

    JoURNALOF

    ENVIRONMENTAL

    SCIENCES

    !墨蔓:!

    CNl12629/X

    Vnv,v-jesc?ac-cn

    Preparationofactivatedcarbonfromcattailanditsapplication

    fordyesremoval

    QianqianShi,JianZhang,ChengluZhang,CongLi,BoZhang,

    WeiweiHu2,

    JingtaoXu,RanZhao

    ,.SchoolofEnvironmentalScienceandEngineering,ShandongUniversity,Jinan250100,China.Email:shuipingdingding@gmail,com

    2.StateKeyJointLaboratoryofEnvironmentalSimulationandPollutionControl,CollegeofEnvironmentalSciences

    andEngineering,PekingUniversity,Beijing100871,China

    Received25February2009;revised14August2009;accepted28August2009 Abstract

    ActivatedcarbonwaspreparedfromcattailbyHPO4activation.Theeffectsinfluencingthesurfaceareaoftheresultingactivated

    carbonfollowedthesequenceofactivatedtemperature>activatedtime>impregnationratio>impregnationtime.Theoptimum

    conditionwasfoundatanimpregnationratioof2.5.animpregnationtimeof9hr,anactivatedtemperatureof50HD.C,andanactivated

    timeof80rainTheBrunauerEmmett

    Tellersurfaceareaandaverageporesizeoftheactivatedcarbonwere1279m/gand5.585 nm,respectively.Aheterogeneousstructureintermsofbothsizeandshapewashighlydevelopedandwidelydistributedonthecarbon

    surface.Somegroupscontainingoxygenandphosphoruswereformed,andthecarboxylgroupwasthemajoroxygencontalmng

    functionalgroup.Anisothermequilibriumstudywascarriedouttoinvestigatetheadsorptioncapacityoftheactivatedcarbon.The

    datafittheLangmuirisothermequation.withmaximummonolayeradsorptioncapacitiesof192.30mg/gforNeutralRedand196.08

    mgforMalachiteGreen.Dyeexhaustedcarboncouldberegeneratedeffectivelybythermaltreatment.Theresultsindicatedthat

    cattail

    derivedactivatedcarbonwasapromisingadsorbentfortheremovalofcationicdyesfromaqueoussolutions,

    Keywords:cattail;activatedcarbon;H3PO4activation;dyesremoval;regeneration DOl:10.1016/S10010742(09)60079-6

    Introduction

    cattailisoneofthemostcommonaquaticplants.and

    itcanbefoundworldwideinwetlands,fens,marginsof

    pondsandlakes.roadsideditches.irrigationcarlals,and

    backwaterareasofriversandstreams(Kimeta1.,2003).

    Itisaveryrecognizableaquaticwetlandplantthatcan

    provideexcellentcoverandnestinghabitatforcertain

    wildlife.Cattailcanutilizesolarenergyeffectivelyand

    growrapidly.Itsrapidgrowthproducesa1argeamountof

    biomass.whichcanbecomeapotentialpollutionresource totheenvironment(HuandYu,2006).Thismotivatesthe investigationofproducingvalueaddedproducts,suchas

    activatedcarbon,fromthisabundantmateria1. Activatedcarbonisawellknownmaterialusedinboth

    gasandliquidphases,includingmedicinaluse,gasstorage, pollutantandodorremoval,gasseparation,andcatalysis fNabaiseta1.,2008).However,commerciallyavailable activatedcarbonsarestillconsideredexpensivematerials formanycountriesduetotheuseofnonrenewableand relativelyexpensivestartingmaterialssuchascoalrMartin eta1..2003).Practicallyanycarbonaceousmateria1.natural orsynthetic.richincarbonandlowinash.istheoretically Correspondingauthor.Email:zhangjian00@sdu.edu.cn

    feasibleforactivatedcarbonproductionfAttiaeta1.,2008). Therefore,inrecentyears,thishaspromptedagrowing interestintheresearchontheproductionofactivated carbonsfromcheaperandrenewableprecursors,which aremainlyindustrialandagriculturalbyproducts.suchas ricehullfGuoandRockstraw,2007),olivecake(Aljundi andJarrah,2008),corncob(Tsengeta1.,2006),apricot stone(Karagozoglueta1.,2007),datestone(Boucheltaet a1.,2008),coconuthusk(Taneta1.,2008),rattansawdust (Hameedeta1.,2008),andbagassebottomashfAwornet a1.2008).However,thereareonlyafewreportsonthe preparationofcattailderivedactivatedcarbon.

    Themanufactureofactivatedcarbonsgenerallyin

    volvestwosteps:pyrolysisandphysicaland/orchemical activation.Comparedwithphysicalactivation.chemical activationhasalowertemperatureandahighercarbon

    productyieldfU~urlueta1..2008).Chemicalactivation consistsofcarbonizationinthepresenceofadehydrating chemicalagent(e.g.,ZnC12,H3PO4,andH2SO4).These chemicalagentsenhancecarbonization,thusresultingin thedevelopmentofadesiredporestructure.Fromboth economicandenvironmentalperspectives.H3PO4isthe prefefredchemicalagentbecauseitisrecoverablefGuo andRockstraw,2006),andtheactivationtemperature QianqianShieta1.Vb1.22

    involvedisrelativelylow(around400-500.C,. Theprincipalobjectiveofthisstudyistopreparean activatedcarbonfromcattailbyH3PO4activationandmea

    sureitsdyeadsorptionproperties.Inordertooptimizethe experimentalprocedure,orthogonalarraydesign(PAD) wasemployed.ThetheoryandmethodologyofPADas achemometricmethodfortheoptimizationofanalytical procedureshasbeendescribedindetailelsewhere(Sobhi eta1.,2008;Yaminieta1.,2008).()ADprocedurewith OA9(3)matrixwasappliedtostudytheeffectofex

    perimentalfactorsonthecarbonsurfacearea.Theresults of0ADexperimentwerethentreatedbyrangeanalysis. Thesampleunderoptimumconditionwasanalyzedfora detailedstudyofitscarboncharacteristics,dyeadsorption, andthermalregeneration.Twocationicdyes.NeutralRed andMalachiteGreen,wereselectedasabsorbatesinthe adsorptionandregenerationexperiments.

    1Materialsandmethods

    1.1Rawmaterial

    Cattailusedinthisstudywasobtainedfromalocal wetlandnearJinan,China.Allreagentswereanalytical

grade.

    1.2Preparationofactivatedcarbon

    Cattai1waswashed.dried,groundinalaboratorymill. andthenimpregnatedwitha40wt.%HaPOdsolutionat acertainratio.Theresultingwetmasswasplacedina mufilefumaceandheatedforseveralminuteswiththe finalactivatedtemperatures.Itwascooleddownafterwards toroomtemperature.Thecarbonizedmaterialproduced waswashedwithdeionizedwateruntilitsfiltratereached neutralpHandthendriedat120.Cfor2hr.

    1.3Orthogonaiexperiment

    oA9(3)matrixwasemployedtostudytheef1ect0ffour

    factorsinfluencingthecarbonsurfacearea:impregnation ratio,impregnationtime,activatedtemperature,andacti- ratedtime.Emphasiswasplacedonthemaineectofthe

    fourfactors;thus,thepossibleinteractionsbetweenthem werenotinthematrix.Thefactorsandlevelsoforthogonal experimentarepresentedinrI1lble1.

    1.4Characterizationofactivatedcarbon

    Thetexturalpropertiesofactivatedcarbonweredeter- minedbyN2adsorption(at-196.C)usingQUADRA

    SORBSIautomatedsurfaceareaandporesizeanalyzer (QuantachromeCorporation,USA).Thesurfacearea Table1Factorsandlevelsoftheorthogonalexperiment mH:amountofphosphoricacid;mc:amountofcattail. andporesizedistributionwereestimatedfollowingtl1e Brunauer-Emmett-Teller(BET)methodandDensityFunc

    tionalTheory(DFr)method,respectively.Thetotal volumeandaverageporesizeweremeasuredusing Quadrawinsoftware.Themicroporevolumeandexternal

    surfaceareawerecalculatedbythet-plotmethod. Thesurfacemorphologyofcarbonwasobservedby scanningelectronmicroscopy(SEM)(HitachiS520,

    Japan).ThesamplewasgoldcoatedpriortoSEMob. servation.Thesurfacechemistrycharacterizationofthe samplewasperformedusingFourierTransfornlInfrared Spectroscopy(FF-IR)andBoehmtitration.Theinfrared spectrumofcarbonwasrecordedatroomtemperatureby anAvatar370spectrometer(NicoletInstrumentCorpora- tion.USA)usingtheKBrdiscmethod.Boehmtitration wasemployedtodeterminetheacidicsurfacegroupsof carbonqualitatively(Boehm,1966).

    1.5Adsorptionexperiments

    Twocationicdyes,NeutralRed(NR,C15H16N4HCl, m=530nm)andMalachiteGreen(MG,C23H25N2C1, =

    618nm),wereusedintheexperiments.Foreach experiment,100mgofactivatedcarbonwasaddedtoa 100mLdyesolution,withaninitialconcentrationranging from80to200mg/L.Afterwards,themixturewasshaken for250minat10,26,and45.C.Theresidualconcentration wasdeterminedbymeasuringitsabsorbanceinaUV- Visiblespectrophotometer(UV-754,Shanghai,China)at themaximumwavelengthofthedye.Theamountofdye adsorbedwascalculatedfromthefollowingmassbalance equation(Eq.(1)):

    qe=

    (CoC1,

    where,CoandClaretheinitialandfinaldyeconcentra- tions,respectively;Visthevolumeofsolution;andmis

themassofcarbon.

    1.6Thermalregenerationofspentactivatedcarbon Intheexperiment,300mgofcarbonwasaddedtoa

    300mLdyesolution(200me/L),andthesuspensionwas mechanicallyshakenfor250minat26.C.Thesolution wasthenfilteredout,andtheamountofdyeadsorbedwas calculated.Thespentactivatedcarbonwasloadedintothe furnace,heatedat300.Cfor30min,andthenallowed tocooldownatroomtemperature.Subsequently,the adsorptionexperimentwascarriedoutagaintoevaluatethe regenerationefficiency(R)ofcarbon,whichwascalculated accordingtothefollowingexpression(Eq.(2)): (2)

    where,MfcandMvcareamountsadsorbedonregenerated andvirgincarbon,respectively.

    No.1

    1200

    800

    Preparationofactivatedcarbonfromcattailanditsapplicationfordyesremoval

    l200

    ImpregnationratioImpregnationtimefhr1Activatedtemperature(?)Activatedtime(min) 2Resultsanddiscussion

    2.1Rangeanalysis

    Fig.1EffectsoffactorsontheBETsurfaceareaofactivatedcarbon Theresultsofdesigningtheorthogonalexperimentare shownin11able2.Undertherangeanalysis.theaverageof BETsurfaceareasforeachfactoratdifferentlevels(Ks, K2,and/(3)andtherangeRaregiveninTable2.

    Theimpregnationratio(A),impregnationtime(B),ac tivatedtemperaturefC),andactivatedtime(D)al1affe:cted

    theBETsurfacearea.AsshowninFig.1themeanvalues (1,and)revealhowtheBETsurfaceareawill

    changewhenthe1evelofthatfactorischangedaswel1.As showninTable2,withdecreasesequenceofR,theorder offactorsinfluencingBETsurfaceareawasC>D>A> B.TheresultsofKwere/(2(A)>K3(A)>KI(A),K2 (B)>(B)>l(B),(C)>(C)>l(C),and (D)>(D)>K1(D).Therefore,thebestcombination wasA2B2C3D,thatjs,theoptimumconditionhadan impregnationratio2.5,impregnationtime9hr,activated temperature500.C.andactivatedtime80min.

    2.2Additionalexperiment

    Theoptimumconditionwasnotincludedintheexperi

    mentalcombinations.Therefore,anadditionalexperiment underthisconditionwascarriedouttoverifythecombi

    nationA2B2C3D1withthelargestBETsurfacearea.The resultoftheBETsurfaceareaintheadditionalexperiment wasl279m/g.whichwaslargerthananyvalueofthe BETsurfaceareaabove.confirmingthattheoptimum conditionwassuitable.Theresultreportedheremayalso becomparedwiththatofcommerciallyavailablecarbons, whichtypicallyhaveasurfaceareaintherange4001500

    m/g(WilliamsandReed.20o31.Theactivatedcarbon obtainedundertheoptimumcondition(namedasAC11

    wasthenusedforcarboncharacteristics,dyeadsorption, andthermalregeneration.

    2.3Surfaceareaandporesizedistribution

    N,adsorptionisconsideredthestandardprocedurefor thecharacterizationoftheporositvtextureofcarbona

ceousadsorbents.Theisoermcanprovideinformation

    ontheporousstructureoftheadsorbentheatofadsorp

    tion.characteristiesofphysicsandchemistr~,andsoon (Onal,2006).Figure2showstheN2adsorptiorgdesorption isotherm(196.C10fAC1,whichisclassifiedasatype

    IVaccordingtoInternationalUnionofPureandApplied Chemistry.1]heisothermindicatesthemicromesoporous

    structureofthecarbon.Theinitialpartoftheisothermfol

    p/p0

    93

    Fig.2Adsorption/desorptionisothermofnitrogenat196.CforACl

    lOWSthesamepathasthecorrespondingtypeIIisotherm, andthusresultingtothemonolayer-multilayeradsorption ONthemesoporewalls(Ryueta1.,1999).

    Theadsorptionmeasurementprovidesauseful"finger- print"ofthemicrostructure.anditisessentialifthecarbon isutilizedasai1adsorbentorcatalystsupport.Theporesize .

    distributionseemstoprovideespeciallyusefulinformation onporoussolids(Seaton

    theporesizedistribution

    andtheBETsurfacearea

    eta1..1989).Figure3shows

    ofAC1.theresultsofwhich

    arepresentedinTable3.Itis

    observedthattheactivatedcarbonpreparedfromcattail hasahighsurfacearea.whichisprimarilyattributedtothe mesoporesandmacroporesasthepercentcontributionof microporesisonlyl3.6%oftheBETsurfacearea.The

totalporevolumewasashighas1.786cm/gforAC

    1.whichcouldbecomparedwithhatofcommercially

    activatedcarbons.thatis.0.60and0.52cm/gforcarbons BPLandPCBproducedbyCalgonCarbonCo.,Pittsburgh, USA.respectively(IoannidouandZabaniotou.2007).The averageporesizeof5.585hillwasalsoobtained.These illustratethenotionthatcattailisasuitableprecursor forthepreparationofmesoactivatedcarbonbyHPC4

    activation

    2.4SEManalysisofmierostructure

    ThemicrostructureofAClisshowninFig.4.The

    scanningelectronmicrographofAClshowedanit-

    regularandheterogeneoussurfacemorphologywitha welldevelopedporousstructure.Poresofdifierentsizes shapescouldbeobserved.Theexternalsurfaceofthe activatedcarbonwasfu11ofcavitiesandquiteirregular. Thedevelopmentoftheporesystemincarbondepends onthestructureofthestartingmaterialandtheactivated g一矗蠢_I.呲?

    一嚣/nu一日qj0?口矗uJ=lo>

    Table3Sre'facea_andporosityofAC1

    

    n

    3

    

    

    >

    Porewidthfllm1

    Fig.3PoresizedistributionofAC1

    process.Thecavitiesresultedfromtheevaporationofthe

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