AbatchexperimentfordeterminingretardationfactorsofNi2+,Zn2+,Cd2+,andPb2+inunsaturatedzoneofunconsolidatedformationinManXaandChauKhecommunes,BacNinhprovince

Abstract

Thispaperpresentsthe resultsofabatchequilibriumadsorptionexperimentaimedatdeterminingtheretardationfactors(R)offourheavymetalionsNi2+,Zn2+,Cd2+,andPb2+duetotheiradsorptiononsoilparticlesinanunsaturatedzone.Theexperimentswerecarriedoutusingclay-loamsoilsamplescollectedfromManXacommune,YenPhongdistrictandChauKhecommune,TuSoncity,BacNinhprovince,attwodepthsof 0÷15cmand15÷30cmfromthegroundsurface.Theexperimentaladsorptionprocedureisfollowedbytheequilibriumadsorptionmethod.Resultsobtainedshowedthattheadsorptionofthe4ionsonsoilparticlesinthetwostudyareasislinearandfollowedtheFreundlichmodel.Thisallowsonetoestimatetheretardationfactorsofthe4ionsbasedonamodelthatincludestheequilibriumadsorptioncoefficient(Kd),soilbulkdensity(B)andsoilporosity().TheRvaluesofthefourionsinthesoilsofManXaandChauKhevaryfrom2.30÷16.27dependingonthenatureoftheadsorbate.IonPb2+possessesthehighestRvalueforManXasoil.TheadsorptionofPb2+issuggestedtobefollowedbybothphysicalandchemo-adsorptionmechanisms,itparticipatedinanion-exchangeprocesswithprotoniumionofgoethitepresentinthesoil,makingtheRvalueofthespeciestobedifferen