Simultaneous enhancement of copper removal and power production using a sediment microbial fuel cell with oxygen separation membranes

This study used polyvinyl alcohol (PVA) as the proton exchange membrane (PEM) of sediment microbial fuel cells (SMFCs) to assess the oxygen diffusion and proton transfer performance of two types of PEMs, i.e. PVA elastomer (PVA-E) and PVA hydrogel (PVA-H). The oxygen diffusion coefficient of the PVA-E (0.42 × 10−4 cm 2/s) was 36.7% of that of the PVA-H. By reducing the amount of oxygen diffused from the cathode to the anode, a favorable water absorption rate (74.7%), 2.10–3.55 times of those obtained in previous studies, was achieved, enabling the rate of proton transfer by the PVA-E to reach 200.7 μM H+/s/m. The Cu2+ removal efficiency of the SMFCs with oxygen separation membranes was 1.21 times that of the SMFCs without oxygen separation membranes. With high external resistance, the SMFCs generated low currents under high voltage output, which was conducive to Cu2+ migration. This explains the voltage output peak (168.0 mV) under an external resistance of 1000 Ω. Furthermore, under the same external resistance, the Cu2+ removal (55.1%) was 1.14–1.38 times that of the corresponding rates achieved under external resistances of 20 and 510 Ω, respectively. X-ray diffraction revealed that electrocoagulation constituted the main mechanism of Cu2+ removal from sediment with SMFCs. Integrating PVA-E and SMFC can facilitate the fabrication of a device with high power output and potential for use in removing Cu2+ from sediment. [Display omitted] •PVA-E is favorable proton transfer and can reduce cathode–anode oxygen diffusion.•PVA-E increases the voltage output and RE of organic compounds by SMFCs.•The higher the external resistance, the higher the RE of Cu2+ by SMFCs.•Cu(OH)2 is formed at the cathode by electrocoagulation.