Magnetic-seeding-of-non-magnetic-adsorbent-powders

Magneticseedingofnon-magneticadsorbentpowdersbycoagulationusingferricchlorideandmagnetiteC.C.BorghiandM.FabbriABSTRACTAmagneticmodificationofconventionaladsorbentpowderstoremovethemrapidlyfromwaterisinvestigated.Inthispaperwestudythepossibilityofusinganon-magneticadsorbentpowdermixedwithmagnetiteandacoagulantsuchasferricchlorideaddedaftertheadsorptiontocreatemagneticflocsthatcanbemagneticallyseparated(magneticseeding).AnaturalzeoliteandNa-activatedzeolitemixedwithmagnetiteandferricchloridearetested.Thecombinationofsedimentation(withcoagulant)followedbymagneticfiltrationisfromsixto30timesfasterthanonlysedimentation(withcoagulant)inattainingthesamefinalturbidity.Also,amagneticactivatedcarbon(MAC)powderwithandwithouttheadditionofferricchlorideistested.Theprocessconditionsthatleadtoaresidualturbiditylessthan10%after5–10minofmagneticseparationaredefinedforallthepowders.ThetestsonMn(II)adsorptiononNa-activatedzeolite–magnetitemixturesshowthattheadsorptionimprovementduetoactivationisnotaffectedbytheadditionofthecoagulant.Moreover,adsorptionofthetestedcationicsurfactantsonMACisupto30%higherbyaddingferricchloride.NegligibleconcentrationsofFe(III)arefoundinalltreatedsamples.Thistechniquecanpotentiallybeappliedtoanynon-magneticadsorbentpowderand/ortoanyexistingcoagulation/flocculationtreatment.C.C.Borghi(correspondingauthor)M.FabbriDepartmentofElectric,ElectronicandInformationEngineering‘GuglielmoMarconi’(DEI),UniversityofBologna,VialeRisorgimento2,40136Bologna,ItalyE-mail:chiara.borghi2@unibo.itKeywords|adsorbentpowders,coagulation,magneticseeding,magneticseparation,watertreatmentINTRODUCTIONThemagneticseparationofpollutantsfromwaterisnotanewprocess(Svoboda;Nishijima&Takeda;Tangetal.).Amagneticfilterexploitsthemagneticforceactingonamagnetizableparticleinanexternallyappliedfluxdensityfieldwithaspatialgradient(Abbasov;Marianietal.).InMarianietal.(),Borghietal.(,)andBorghi&Fabbri()acontinuous-flowmagneticsystemusingsteelwoolorsteelspheresasthe