Simultaneous removal of perchlorate and arsenate by ion-exchange media modified with nanostructured iron (hydr)oxide

Hybrid ion-exchange (HIX) media for simultaneous removal of arsenate and perchlorate were prepared by impregnation of non-crystalline iron (hydr)oxide nanoparticles onto strong base ion-exchange (IX) resins using two different chemical treatment techniques. In situ precipitation of Fe(III) (M treatment) resulted in the formation of sphere-like clusters of nanomaterials with diameters of similar to 5 mn, while KMnO4/Fe(II) treatments yielded rod-like nanomaterials with diameters of 10-50 mn inside the pores of the media. The iron content of most HIX media was >10% of dry weight. The HIX media prepared via the M treatment method consistently exhibited greater arsenate adsorption capacity. The fitted Freundlich adsorption intensity parameters (q = K x C-E(1/n)) for arsenate (1/n < 0.6) indicated favorable adsorption trends. The K values ranged between 2.5 and 34.7 mgAs/g dry resin and were generally higher for the M treated media in comparison to the permanganate treated media. The separation factors for perchlorate over chloride for the HIX media were lower than its untreated counterparts. The HIX prepared via the M treatment, had higher alpha(ClO4-)(Cl-) than the HIX obtained by the KMnO4/Fe(II) treatments suggesting that permanganate may adversely impact the ion-exchange base media. Short bed adsorber (SBA) tests demonstrated that the mass transport kinetics for both ions are adequately rapid to permit simultaneous removal using HIX media in a fixed bed reactor. (c) 2007 Elsevier B.V. All rights reserved.