Removal of copper from aqueous solution by electrodeposition in cathode chamber of microbial fuel cell

Based on energetic analysis, a novel approach for copper electrodeposition via cathodic reduction in microbial fuel cells (MFCs) was proposed for the removal of copper and recovery of copper solids as metal copper and/or Cu2O in a cathode with simultaneous electricity generation with organic matter. This was examined by using dual-chamber MFCs (chamber volume, 1 L) with different concentrations of CuSO4 solution (50.3 ± 5.8, 183.3 ± 0.4, 482.4 ± 9.6, 1007.9 ± 52.0 and 6412.5 ± 26.7 mg Cu2+/L) as catholyte at pH 4.7, and different resistors (0, 15, 390 and 1000 Ω) as external load. With glucose as a substrate and anaerobic sludge as an inoculum, the maximum power density generated was 339 mW/m3 at an initial 6412.5 ± 26.7 mg Cu2+/L concentration. High Cu2+ removal efficiency (>99%) and final Cu2+ concentration below the USA EPA maximum contaminant level (MCL) for drinking water (1.3 mg/L) was observed at an initial 196.2 ± 0.4 mg Cu2+/L concentration with an external resistor of 15 Ω, or without an external resistor. X-ray diffraction analysis confirmed that Cu2+ was reduced to cuprous oxide (Cu2O) and metal copper (Cu) on the cathodes. Non-reduced brochantite precipitates were observed as major copper precipitates in the MFC with a high initial Cu2+ concentration (0.1 M) but not in the others. The sustainability of high Cu2+ removal (>96%) by MFC was further examined by fed-batch mode for eight cycles.