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1、ChemicalEngineeringJournal129(2007)173180Defluoridationofdrinkingwaterusingchitin,chitosanandlanthanum-modifiedchitosanSanjayP.Kamblea,SnehaJagtapa,NitinK.Labhsetwara,DilipThakarea,SamuelGodfreyb,SukumarDevottaa,SadhanaS.Rayalua,∗aEnvironmentalMaterialsUnit,NationalEnvironmentalEngineeringResea
2、rchInstitute,NehruMarg,Nagpur400020,IndiabUNICEF,Bhopal,IndiaReceived16August2006;receivedinrevisedform16October2006;accepted20October2006AbstractChitin,anaturallyoccurringabundantbiopolymer,anditsdeacetylatedproductchitosanhasbeenwidelyusedformetaladsorptionfromwaterandwastewaters,buttheappl
3、icationofthesematerialsasanadsorbenttoremovefluoridefromdrinkingwaterhasseldombeenexplored.Inthisworktheapplicabilityofchitin,chitosanand20%-lanthanumincorporatedchitosan(20%La-chitosan)asadsorbentsfortheremovalofexcessfluoridefromdrinkingwaterwasstudied.Theeffectsofvariousphysico-chemicalparam
4、eterssuchaspH,adsorbentdose,initialfluorideconcentrationandthepresenceofinterferingionsonadsorptionoffluoridewerestudied.ItwasobservedthattheuptakeoffluoridewasmaximumatoriginalpH(pH6.7).TheequilibriumadsorptiondatawerefittedreasonablywellforFreundlichisothermmodel.Thepresenceofchloride,sulfate,c
5、arbonateandbicarbonateionsindrinkingwatergreatlyaffecttheuptakeoffluorideindicatingthattheseanionscompetewithsorptionoffluorideon20%La-chitosan.Therateofadsorptionwasrapidandmaximumfluorideuptakewasattainedwithin20min.Themechanismofadsorptionoffluorideonlanthanum-modifiedchitosanisalsoexplained.Th
6、ecomparisonofuptakeoffluorideindistilledwaterandfieldwatershowsrelativelyhigheruptakeoffluorideindistilledwater.ThiscouldbeduetothecompetingeffectofotheranionspresentandhigherpHofthefieldwater.©2006PublishedbyElsevierB.V.Keywords:Defluoridation;Chitinandmodifiedchitosan;EffectsofpHandanions;Freundl
7、ichisothermmodel;Kineticmodeling1.Introductionwaterhasalreadybecomeaveryseriousissueinmanycountries[1,4].Traditionaltreatmentmethodssuchaschemicalprecipi-Thepresenceoffluorideioninpotablewaterhasadversetationasmetalhydroxide,electrodeposition,
