Use of novel permeable membrane and air cathodes in acetate microbial fuel cells

Abstract

In the existing microbial fuel cells (MFCs), the use of platinized electrodes and Nafion ® as proton exchange membrane (PEM) leads to high costs leading to a burden for wastewater treatment. In the present study, two different novel electrode materials are reported which can replace conventional platinized electrodes and can be used as very efficient oxygen reducing cathodes. Further, a novel membrane which can be used as an ion permeable membrane (Zirfon ®) can replace Nafion ® as the membrane of choice in MFCs. The above mentioned gas porous electrodes were first tested in an electrochemical half cell configuration for their ability to reduce oxygen and later in a full MFC set up. It was observed that these non-platinized air electrodes perform very well in the presence of acetate under MFC conditions (pH 7, room temperature) for oxygen reduction. Current densities of −0.43 mA cm −2 for a non-platinized graphite electrode and −0.6 mA cm −2 for a non-platinized activated charcoal electrode at −200 mV vs. Ag/AgCl of applied potential were obtained. The proposed ion permeable membrane, Zirfon ® was tested for its oxygen mass transfer coefficient, K 0 which was compared with Nafion ®. The K 0 for Zirfon ® was calculated as 1.9 × 10 −3 cm s −1.