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.

Mine Drainage Residual Additions to Lake Sediments Alter Phosphorus and Trace Metal Distributions

“…First, increasing pH over time (pH 9.3-10.0 between day 40 and day 138) exceeded the point of zero charge (PZC) of natural iron oxyhydroxides, typically between 5 and 8 (Schwertmann and Fechter 1982). Neely (2010) found a PZC of 7.24 ± 0.42 for MRPTS MDRs. Available binding sites for phosphate were decreased due to the negatively charged solid surface and competition with hydroxyl ions (Jin et al 2006;Peng et al 2007;Wei et al 2008).…”