Kinetic modeling of liquid-phase adsorption of reactive dyes

PII:S0043-1354(00)00307-9

Wat.Res.Vol.35,No.3,pp.613–618,2001#2001ElsevierScienceLtd.Allrightsreserved

PrintedinGreatBritain

0043-1354/01/$-seefrontmatter

KINETICMODELINGOFLIQUID-PHASEADSORPTIONOF

REACTIVEDYESANDMETALIONSONCHITOSAN

FENG-CHINWU1,RU-LINGTSENG2andRUEY-SHINJUANG3*M

DepartmentofChemicalEngineering,Lien-HoInstituteofTechnology,Miao-Li360,Taiwan;DepartmentofSafety,HealthandEnvironmentalEngineering,Lien-HoInstituteofTechnology,Miao-Li360,Taiwanand3DepartmentofChemicalEngineering,YuanZeUniversity,Chung-Li320,

Taiwan

21

(Firstreceived25February2000;acceptedinrevisedform9June2000)

Abstract}TheratesofadsorptionofthreecommercialreactivedyesandCu(II)fromwaterintheabsenceandpresenceofcomplexingagentsusingchitosanweremeasuredat308C.Threesimpli edkineticmodels,i.e.,pseudo- rst-order,pseudo-second-order,andintraparticledi usion,weretestedtoinvestigatetheadsorptionmechanisms.ItwasshownthattheadsorptionofreactivedyesandCu(II)intheabsenceofcomplexingagentscouldbebestdescribedbytheintraparticledi usionmodel,whereasthatofCu(II)intheabsenceofcomplexingagentssuchasEDTA,citricacid,andtartaricacidbythepseudo-second-orderequation.Kineticparametersofthethreemodelsandthenormalizedstandarddeviationsbetweenthemeasuredandpredictedresultswerealsocalculatedanddiscussed.#2001ElsevierScienceLtd.Allrightsreserved

Keywords}kineticmodeling,liquid-phaseadsorption,chitosan,reactivedyes,metalions,complexingagents

NOMENCLATURE

CtC0DDpk1k2kp;2msqeqtDqrtsoluteconcentrationintheaqueousphaseattimet,g/m3ormol/m3

initialsoluteconcentrationintheaqueousphase,g/m3ormol/m3

di usivityofsoluteintheparticle,m2/saveragediameterofchitosanparticle,mm

rateconstantofpseudo- rst-orderadsorptionde nedinequation(3),1/min

rateconstantofpseudo-second-orderadsorptionde nedinequation(5),kg/gmin

rateparameterofintraparticledi usionmodel,g/kgmin1/2

speci cdosageofdrychitosan,kg/m3

amountofadsorptionatequilibrium,g/kgormol/kg

amountofadsorptionattimet,g/kgormol/kgnormalizedstandarddeviationde nedinequa-tion(9),%

radiusoftheparticle,mtime,min

INTRODUCTION

ChitosanisapartiallyacetylatedglucosaminebiopolymerexistinginthecellwallofsomefungisuchastheMucoralesstrains.However,itmainly

*Authortowhomallcorrespondenceshouldbeaddressed.

Tel.:+886-3-4636800ext555;fax:886-3-4559373;e-mail:cejuang@ce.yzu.edu.tw

613

resultsfromdeacetylationofchitin(Muzzarelli,1983).Chitosanhasmanyusefulfeaturessuchashydrophilicity,biocompatibility,biodegradability,andanti-bacterialproperty.Thisbiopolymerisalsoaknownsorbent,e ectiveinthesorptionoftransitionmetalionsbecausetheamino(–NH2)andhydroxy(–OH)groupsonchitosanchainscanserveascoordinationandelectrostaticinteractionsites,respectively(MonteiroandAiroldi,1999;Guibaletal.,1994;OnsoyenandSkaugrud,1990).Inthisregard,chitosanappearstobemoreeconom-icallyattractivethanactivatedcarbonsforadsorp-tionremovalofcolors,organicandinorganicmattersfromprocess/wastee uentsbecausechitinisthesecondabundantpolymerinnaturenexttocellulose(Baileyetal.,1999;El-Geundi,1997).Incontrasttochitin,adsorptionabilityofmetalsusingchitosanissuperiorduetoitshighercontentofaminofunctionalgroups(YangandZall,1984;Muzzarelli,1983).Inourlaboratory,theexcellentcapabilityofchitosanforadsorptionofreactivedyesandmetalionsfromaqueoussolutions,intheabsenceorpresenceofstrongcomplexingagentssuchasEDTA(ethylenediaminetetraaceticacid),citricandtartaricacids,hasbeenpresented(Juangetal.,1997,1999;Wuetal.,1999;Tsengetal.,1999).Theaimofthispaperistostudythemechanismofsuchadsorptionprocesses.Althoughseveralrigidmodelssuchasthehomogeneoussurfacedi usionmodel,pore

di usion

614Feng-ChinWuetal.

model,andheterogeneousdi usionmodel(alsoknownasporeanddi usionmodel)havebeenextensivelyappliedinbatchreactorstosuccessfullydescribethetransportofmoleculesinsidetheadsorbentparticles(Chatzopoulosetal.,1993;Eichenmulleretal.,1997;Vidicetal.,1994;ZhouandMartin,1995),themathematicalcomplexityofthesemodelsmakethemratherinconvenientforpracticaluse(HoandMcKay,1998;Guibaletal.,1998;Ravenetal.,1998).Here,theconcentration-timepro lesofbatchadsorptionofthreecommercialreactivedyesandCu(II)fromwateronchitosan,andthoseofCu(II)inthepresenceofEDTA,citricandtartaricacids,weremeasured.Threesimpli edkineticmodelssuchaspseudo- rst-andsecond-orderequations,andtheintraparticledi usionmodelwereselected.Thisinformationwillbeusefulforfurtherapplicationsofsystemdesigninthetreatmentofpracticalwastee uents.

MATERIALSANDMETHODS

Adsorbent,reagents,andsolutions

Chitosanproducedfromlobstershellwasteswaso eredas akesfromYing-HuahCo.,Kaohsiung,Taiwan,withoutfurtherpuri cation.Priortouseasadsorbents,theraw akesweregroundandsievedintothreeparticlesizeranges,0.25–0.42,0.42–0.59,and0.59–0.84mm,respectively.Theywererepresentedastheaveragediameterdpof0.335,0.505,and0.715mm.TheBET2surfaceareaswerefoundtobe13.5,13.0,and12.3m/g,respectively,basedonN2adsorptionisothermsusingsorptometer(PorousMaterialsInc.,ModelBET-202A).Thedegreeofdeacetylationofchitosanwasobtainedtobe80mol%followingthemethodofGuibaletal.(1994).Themolarmassofchitosanwasobtainedtobe1.01Â106bytheMark–Houwinkequationfromviscositymeasurementsofsolutionscontainingdi er-entamountsofchitosanin100mol/m3aceticacidand200mol/m3NaCl(RobertsandDomszy,1982).

Thecommercial-gradereactivedyeswerepurchasedfromSumitomoChemicalCo.Ltd.,Japanandusedasreceived.TheywereSumi xSuperScarlet2GF(ReactiveRed222,RR222),Sumi xSuperYellow3RF(ReactiveYellow145,RY145),andSumi xSuperNavyBlueBF(ReactiveBlue222,RB222).Theyallhadmonochlorotriazineandvinylsulfonebifunctionalgroups(Juangetal.,1997).CuSONaOH,EDTA,tartaricandcitricacidsweretheproductsof4,MerckCo.asanalytical-gradereagents.Theaqueoussolutionswerepreparedbydissolvingthesolutesindeionizedwater(MilliporeMilli-Q)withoutpHadjustment.Inthepresenceofcomplexingagents,theaimoftheadditionofNaOHwastoincreasetheaqueoussolu …… 此处隐藏：19371字，全部文档内容请下载后查看。喜欢就下载吧 ……