Characterization of polyester cloth as an alternative separator to nafion membrane in microbial fuel cells for bioelectricity generation using swine wastewater

Abstract

Polyester cloth (PC) was selected as a prospective inexpensive substitute separator material for microbial fuel cells (MFCs). PC was compared with a traditional Nafion proton exchange membrane (PEM) as an MFC separator by analyzing its physical and electrochemical properties. A single layer of PC showed higher mass transfer (e.g., for O2/H+/ions) than the Nafion PEM; in the case of oxygen mass transfer coefficient (ko), a rate of 50.0 × 10-5 cm·s-1 was observed compared with a rate of 20.8 × 10-5 cm/s in the Nafion PEM. Increased numbers of PC layers were found to reduce the oxygen mass transfer coefficient. In addition, the diffusion coefficient of oxygen (DO) for PC (2.0-3.3 × 10-6 cm2/s) was lower than that of the Nafion PEM (3.8 × 10-6 cm2/s). The PC was found to have a low ohmic resistance (0.29-0.38 Ω) in the MFC, which was similar to that of Nafion PEM (0.31 Ω); this resulted in comparable maximum power density and maximum current density in MFCs with PC and those with Nafion PEMs. Moreover, a higher average current generation was observed in MFCs with PC (104.3 ± 15.3 A/m3) compared with MFCs with Nafion PEM (100.4 ± 17.7 A/m3), as well as showing insignificant degradation of the PC surface, during 177 days of use in swine wastewater. These results suggest that PC separators could serve as a low-cost alternative to Nafion PEMs for construction of cost-effective MFCs.