Enhanced Electricity Generation from Electrochemical Oxidation of FeII in an Air–Cathode Fuel Cell Amended with Chelating Anions

Abstract

The air–cathode fuel cell approach is promising for ferrous (FeII) ion removal from acid mine drainage because iron and electricity are simultaneously recovered in the treating process. Here we show that electricity generation from FeII can be enhanced by amending chelating anions to facilitate FeII oxidation at the anode of the fuel cell. A series of FeII-fed fuel cells were operated with various chelating anions, including carboxylate, phosphate, and borate ligands. The average power densities of these fuel cells varied over a wide range from 0.08 ± 0.5 to 107.85 ± 1.50 mW m–2. Citrate-amended fuel cells operated at pH 8–9 and carbonate-amended fuel cells operated at pH 6–8 exhibited greater charge-recovery efficiencies than others, which ranged from 93.5% to 96.1%. The redox potential of an anodic solution and redox activity of FeII were two important factors affecting the electrooxidation of FeII in fuel cells.