Characteristics of the single chamber fuel cell with iron anode and air-cathode for electricity generation and electrocoagulation

Abstract

Acid mine drainage (AMD) from coal and mineral mining operations causes environmental pollution that affects many countries having historic or current mining industries. In addition to the acid contribution to surface waters, AMD may cause metals such as arsenic, cadmium, copper, silver, and zinc to leach from mine wastes. For treatment of that problem, we used a single chamber fuel cell with an iron anode and an air cathode, was a new and innovative concept for electrocoagulation. This research investigated the main reactions, which dominantly contributed to the production of electricity and iron hydroxides in solution. An initial pH 5 in solution of 0.06 M NaHCO3, 0.05 M NaCl was the optimal condition for producing maximum power density of 1997 mW/m2 after 24 h. Increases of bicarbonate and solution-ionic strength induced a corresponding decrease in anode potential and an increase of cathode potential, which resulted in an increase in cell potential and power density. The increase of NaHCO3 concentration to 0.1 M and solution-ionic strength to 0.56 M induced an increase of the maximum power densities to 2436 mW/m2 and 4343 mW/m2, respectively. Initial pHs of 7.5 and 8.5 in solution of 0.06 M NaHCO3, 0.05 M NaCl were used to synthesize magnetic iron hydroxides with magnetite and maghemite. These results suggest that this fuel cell technology can be used not only for electrocoagulation with removal of contaminants but also for producing useful products, such as electricity and magnetic iron hydroxides. Advances in wastewater air-metal fuel cell will enable more efficient power generation and systems suitable for scale-up.