PPO-based ion exchange membranes with distinct functional groups for bioelectrochemical systems: A comparative study of sulfonated and quaternized types in MFC and MEC modes

Abstract

Ion exchange membranes (IEMs) play a crucial role in the performance and viability of bioelectrochemical systems (BESs), including microbial fuel cells (MFCs) and microbial electrolysis cells (MECs). In this study, we synthesized sulfonated and quaternized poly(phenylene oxide) (SPPO and QPPO) membranes and compared them with commercial membranes (Nafion 211, Nafion 424, and ASVN) in terms of physicochemical and electrochemical properties, gas permeability, and BES performance. Comprehensive membrane characterization was followed by dual-mode operation in lab-scale MFC and MEC systems. QPPO demonstrated excellent mechanical stability, low electrical resistance, and high ionic transport, resulting in strong power generation and hydrogen production efficiencies. To determine the most suitable membrane for BES application, three multicriteria evaluation methods-weighted scoring, TOPSIS, and Z-score normalization-were employed. All methods consistently ranked QPPO and Nafion 211 as the most competitive IEMs, with QPPO offering a high cost-effectiveness.