Benchmarking anion vs. cation exchange membranes in microbial fuel cells: A comparative study of PTFE and Nafion 117

This study investigates the comparative performance of two types of ion-exchange membranes, polytetrafluoroethylene (PTFE) as an anion exchange membrane (AEM) and Nafion 117 as a cation exchange membrane (CEM), in microbial fuel cells(MFCs). The evaluation focuses on key operational parameters, including power generation, chemical oxygen demand (COD) removal efficiency, and coulombic efficiency (CE). In CEM-based MFCs, protons (H⁺) migrate from the anode to the cathode, whereas in AEM-based systems, hydroxide ions (OH^-) move from the cathode to the anode. This ion transfer helps maintain pH balance, which is essential for microbial metabolism and catalytic activity. Experimental results demonstrated that the CEM-MFC achieved a power density of 181.5 mW/m² and a COD removal rate of 67 %, while the AEM-MFC produced 272.3 mW/m² and achieved 75 % COD removal. Furthermore, the CE improved from 24.4 % in CEM-MFC to 29 % in AEM-MFC. These results indicate that AEM-MFCs can generate approximately 50 % more power and exhibit enhanced CE, making them more promising candidates for sustainable energy production and wastewater treatment. The superior performance of AEM-MFC is attributed to more favorable microbial activity, better cathodic oxygen reduction reaction (ORR) conditions, and extended pH equilibrium. Additionally, the efficient transfer of OH^- ions in AEMs prevents acidification in the anode compartment and supports stable microbial growth. These findings underscore the potential of anion exchange membranes as viable and sustainable alternatives in the design of high-performance MFCs for simultaneous environmental remediation and bioenergy production. This study is a pioneering work that investigates the long-term performance of cost-effective PTFE anion exchange membranes in microbial fuel cells operating with real wastewater (POME), providing crucial insights into pH regulation and microbial stability compared to the benchmark Nafion 117.