Characterization of uncharged and sulfonated porous poly(vinylidene fluoride) membranes and their performance in microbial fuel cells

Uncharged porous PVDF and sulfonated porous PVDF membranes were prepared as alternative materials to Nafion membrane for application in a microbial fuel cell (MFC). Performances of Nafion, uncharged porous PVDF and sulfonated porous PVDF membranes in an air-cathode MFC were evaluated. Both uncharged and sulfonated porous PVDF membranes performed better than the Nafion membrane during MFC operation. The observed properties of low membrane electrical resistance, high ion exchange capacity, moderate oxygen permeability, and high ion selectivity also indicated that the sulfonated PVDF membrane is the most appropriate membrane for MFC applications. The uncharged porous PVDF membrane exhibited the lowest oxygen permeability resulting in a higher performance than the Nafion membrane. The impedance of the MFC systems was measured and analyzed with an equivalent circuit which accounts for the electrolyte (as media for microorganisms), both electrodes, and a membrane as components. It was found that the high performance of the sulfonated porous PVDF membrane is due to the low impedance of all components in the MFC. The sulfonated porous PVDF membrane, prepared for low resistance proton transport, is successfully applied to the MFC in this study.