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 approximately 5nm, while KMnO4/Fe(II) treatments yielded rod-like nanomaterials with diameters of 10-50nm 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 34.7mgAs/gdry resin and were generally higher for the M treated media in comparison to the permanganate treated media. The separation factors for perchlorate over chloride (alpha(Cl-)(ClO4-)) for the HIX media were lower than its untreated counterparts. The HIX prepared via the M treatment, had higher alpha(Cl-)(ClO4-) than the HIX obtained by the KMnO(4)/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.
Hristovski
Kiril
K
Environmental Technology Laboratory, Arizona State University, 6075 S. WMS Campus Loop W, Mesa, AZ 85212, United States. kiril.hristovski@asu.edu
Westerhoff
Paul
P
Möller
Teresia
T
Sylvester
Paul
P
Condit
Wendy
W
Mash
Heath
H
D000327:Adsorption; D001149:Arsenates / Q000302:isolation & purification*; D005290:Ferric Compounds / Q000737:chemistry*; D007475:Ion Exchange Resins; D053768:Metal Nanoparticles; D008855:Microscopy, Electron, Scanning; D010472:Perchlorates / Q000302:isolation & purification*
D001149:Arsenates; D005290:Ferric Compounds; D007475:Ion Exchange Resins; D010472:Perchlorates; C000499:ferric oxide; C025657:arsenic acid; C494474:perchlorate