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1、ClayMinerals,(2012)47,429–440Kineticandequilibriumstudiesoffluoridesorptionontosurfactant-modifiedsmectites1,21S.GAMOUDI*,N.FRINI-SRASRAANDE.SRASRA1LaboratoiredePhysico-chimiedesMate′riauxMine′rauxetleursApplications,CentreNationaldesRecherchesen2SciencesdesMate′riaux,Tech
2、nopoledeBorjCe′dria,Tunisie,andDe′partementdeChimie,Faculte′desSciencesdeTunis,Universite′ElManarTunisie(Received1April2012;revised16June2012;Editor:JohnAdams)ABSTRACT:Theuseoforganoclaysasadsorbentsintheremediationofpollutedwaterhasbeenthesubjectofmanyrecentstudies.Inthep
3、resentwork,aTunisiansmectitemodifiedwithtwocationicsurfactantswasusedasanadsorbenttoexaminetheadsorptionkinetics,isothermsandthermodynamicparametersoffluorideionsfromaqueoussolution.VariouspHvalues,initialconcentrationsandtemperatureshavebeentested.Twosimplifiedkineticmode
4、ls,first-orderandpseudo-second-order,wereusedtopredicttheadsorptionrateconstants.Itwasfoundthattheadsorptionkineticsoffluorideontomodifiedsmectitesatdifferentoperatingconditionscanbestbedescribedbythepseudo-second-ordermodel.Adsorptionisothermsandequilibriumadsorptioncapac
5、itiesweredeterminedbythefittingoftheexperimentaldatatowellknownisothermmodelsincludingthoseofLangmuirandFreundlich.TheresultsshowedthattheLangmuirmodelappearstofittheadsorptionbetterthantheFreundlichadsorptionmodelfortheadsorptionoffluorideionsontomodifiedsmectites.Theequi
6、libriumconstantswereusedtocalculatethermodynamicparameters,suchasthechangeoffreeenergy,enthalpyandentropy.Resultsofthisstudydemonstratedtheeffectivenessandfeasibilityoforganoclaysfortheremovaloffluorideionsfromaqueoussolution.KEYWORDS:organoclays,fluorideions,sorption,Lang
7、muirmodel,Freundlichmodel,Tunisia.ThepresenceoffluorideindrinkingwatercanbeFluoridepollutionofwatercouldoccurduetobeneficialorharmfuldependingonitsconcentra-bothnaturalreasonsandhumanactivities.Sincetion.Infact,anappropriatevaluebetween0.5andthiselementispresentinseveralmi
8、nerals,itcould11.0mg.lisseentopreventdentalcavities.beleachedoutbyrainwater,therebycausi
