Potential Anionic Sorbent Use of Iron Oxides from Abandoned Mine Drainage Discharges

Abstract

Abstract. This study examines the potential to reuse mine-drainage derived iron oxides as anionic sorbents for sustainable water treatment purposes. Pure iron oxides have been established as effective sorptive media or coatings for water treatment processes; yet, iron oxides from mine drainages remain to be an abundant but unproven source of this raw material. Iron oxides from both passive mine drainage treatment systems as well as environmental discharges of mine water and their associated iron deposits were examined. Based on prior physical characterization, three samples were selected (according to their specific surface area) to evaluate their anionic sorptive capacities pertaining to naturally occurring concentrations of orthophosphate (1.13 ± 0.03 mg/L) in surface waters, and arsenate (117.79 ± 4.08 µg As/L ) in drinking waters. The mine drainage derived iron oxides' performances were compared against a commercial grade iron oxide product, Bayoxide E33 P at static pH values of 6.00, 7.00, 8.00, and 9.00 ± 0.10 standard pH units via laboratory scale sorption batch experiments. As a result of these experiments it was observed that the mine drainage derived iron oxides were more effective at contaminant removal than the commercial product. Promising contaminant removal efficiencies of up to 95% (arsenate) and 99% (orthophosphate) were documented at specific pH values for the mine drainage derived iron oxides, while adhering to virtually all US EPA primary and secondary drinking water standards; thus suggesting that it may be feasible to beneficially reuse mine drainage derived iron oxide in water treatment technologies.

Iron and Trace Metal Retention in Net Alkaline Co2-Rich Mine Waters via Aerobic Processes

“…In addition, the trace metal sorptive capabilities of Fe solids are long well-documented (e.g., Benjamin and Leckie 1981, Dzombak and Morel 1990, Kairies et al 2005, Zeng et al 2008, Neely 2010). Neely and Nairn (2011) describe iron oxides as prime candidates for mixed media filtration applications because of their large specific surface area and high affinity to form surface complexes with dissolved cations and anions (dependent upon the pH point of zero charge).…”