XAFS study of starch-stabilized magnetite nanoparticles and surface speciation of arsenate

文档简介Ithasbeenshownthatstarchcaneffectivelystabilizenanoscalemagnetiteparticles,andstarch-stabilizedmagnetitenanoparticles(SMNP)arepromisingforinsituremediationofarsenic-contaminatedsoils.However,amolecularlevelunderstandinghasbeenlacking.Here,wecarriedoutXAFSstudiestobridgethisknowledgegap.FeK-edgeXAFSspectraindicatedthattheFeeOandFeeFecoordinationnumbersofSMNPwerelowerthanthoseforbaremagnetiteparticles,andthesecoordinationnumbersdecreasedwithincreasingstarchconcentration.Thedecreaseintheaveragecoordinationnumberatelevatedstabilizerconcentrationwasattributedtotheincreaseinthesurface-to-volumeratio.ArsenicK-edgeXAFSspectraindicatedthatadsorbedarsenateonSMNPconsistedprimarilyofbinuclearbidentate(BB)complexesandmonodentatemononuclear(MM)complexes.MoreBBcomplexes(energeticallymorefavorable)wereobservedathigherstarchconcentrations,indicatingthatSMNPnotonlyofferedgreateradsorptionsurfacearea,butalsostrongeradsorptionaffinitytowardarsenate.