Electricity generation from ammonia in landfill leachate by an alkaline membrane fuel cell based on precious-metal-free electrodes

Ammonia contaminated wastewater poses a great hazard to the safety and quality of water resources. Use of ammonia fuel cells to remove ammonia from wastewater is a promising strategy, which not only eliminates ammonia but also generates electricity as a bonus. For ammonia fuel cells, the key challenge is to identify stable and highly active precious-metal-free catalysts to be used as electrodes. In this study, a composite material α-MnO2/C was prepared through a simple reaction of potassium permanganate with carbon black in a concentrated H2SO4 solution. An alkaline membrane fuel cell was prepared using the as-synthesized α-MnO2/C as the cathode, previously reported NiCu/C as the anode, and an alkaline membrane as the electrolyte. The electrochemical activities of the MnO2/C cathode and the performance of this fuel cell utilizing ammonia as the fuel were investigated. Finally, leachate from a local landfill site was tested in the fuel cell. Without the addition of alkali, the ammonia concentration in landfill leachate was reduced from 2711 to 95 ppm. Over the operational period of approximately 6 h, 96.5% of the ammonia in the leachate was removed by the fuel cell. These results demonstrate that the ammonia present within wastewater can efficiently be removed by a fuel cell employing non-precious metal electrodes at room temperature, while simultaneously generating electricity as a bonus. This provides an exciting new technology for the treatment of ammonia-rich wastewater.