title: X-ray absorption spectroscopy as a tool investigating arsenic(III) and arsenic(V) sorption by an aluminum-based drinking-water treatment residual.
abstract: Historic applications of arsenical pesticides to agricultural land have resulted in accumulation of residual arsenic (As) in such soils. In situ immobilization represents a cost-effective and least ecological disrupting treatment technology for soil As. Earlier work in our laboratory showed that drinking-water treatment residuals (WTRs), a low-cost, waste by-product of the drinking-water treatment process exhibit a high affinity for As. Wet chemical experiments (sorption kinetics and desorption) were coupled with X-ray absorption spectroscopy measurements to elucidate the bonding strength and type of As(V) and As(III) sorption by an aluminum-based WTR. A fast (1h), followed by a slower sorption stage resulted in As(V) and As(III) sorption capacities of 96% and 77%, respectively. Arsenic desorption with a 5mM oxalate from the WTR was minimal, being always <4%. X-ray absorption spectroscopy data showed inner-sphere complexation between As and surface hydroxyls. Reaction time (up to 48h) had no effect on the initial As oxidation state for sorbed As(V) and As(III). A combination of inner-sphere bonding types occurred between As and Al on the WTR surface because mixed surface geometries and interatomic distances were observed.
authors.affiliation: Cyprus International Institute for the Environment and Public Health in Association with The Harvard School of Public Health, Nicosia 1105, Cyprus. kmakris@cyprusinstitute.org <kmakris@cyprusinstitute.org>
authors.forename: Konstantinos C
authors.initials: KC
authors.lastname: Makris
authors.forename: Dibyendu
authors.initials: D
authors.lastname: Sarkar
authors.forename: Jason G
authors.initials: JG
authors.lastname: Parsons
authors.forename: Rupali
authors.initials: R
authors.lastname: Datta
authors.forename: Jorge L
authors.initials: JL
authors.lastname: Gardea-Torresdey
mesh_terms: D000327:Adsorption; D000535:Aluminum; D001151:Arsenic / Q000032:analysis / Q000302:isolation & purification*; D002627:Chemistry, Physical / Q000379:methods; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D008968:Molecular Conformation; D013499:Surface Properties; D013997:Time Factors; D014865:Waste Disposal, Fluid / Q000379:methods; D014874:Water Pollutants, Chemical / Q000737:chemistry / Q000302:isolation & purification*; D018508:Water Purification / Q000379:methods*; D014881:Water Supply; D056928:X-Ray Absorption Spectroscopy / Q000379:methods*
chemical_list: D014874:Water Pollutants, Chemical; D000535:Aluminum; D001151:Arsenic