Optimization preparation of composite membranes as proton exchange membrane for gaseous acetone fed microbial fuel cells

Abstract

To synthesize a proton exchange membrane (PEM) with both low oxygen diffusivity and high proton conductivity (PC) for applications in microbial fuel cells (MFC), we produce composite membranes using different polyvinyl alcohol (PVA) and conductive carbon black (CCB) ratios. The CCB and PVA preparation ratios are used as the independent variables and oxygen diffusivity and PC as the response variables to calculate the optimal PEM by response surface methodology. The correlation coefficients of the experimental and predicted values for oxygen diffusivity and PC are all greater than 0.99. The optimum concentration of PVA and CCB is 10.04 % and 0.82 m3 g−1, respectively, with 62.9 % desirability. The oxygen diffusivity and PC of the modified PEM are better than those of the unmodified PEM. In particular, PC is increased by 20-fold. Applying the modified PEM to a biotrickling filter-MFC (BTF-MFC) improves removal efficiency of gaseous acetone to >97 %. To enhance BTF-MFC performance, we design a mode where the exhaust gas flowed from cathode to anode. We find that this mode not only provides the cathode with sufficient oxygen to facilitate reduction but also reduces the oxygen content in the anode tank.