The Feasibility of Using Palm Oil Fuel Ash (POFA) as a Potential Proton Exchange Membrane for Microbial Fuel Cell Application in Comparison With Montmorillonite (MMT) Membrane

The incorporation of waste-derived materials in membrane technology is gaining interest due to their low cost, favorable physical properties, and potential to improve membrane stability. These materials are also attractive for their renewability, low production energy, and environmental benefits. Therefore, this study investigates the use of palm oil fuel ash (POFA) as a proton exchange membrane (PEM) for microbial fuel cell (MFC) application, comparing with montmorillonite (MMT) membrane along with its antifouling properties. POFA and MMT membranes were prepared via a phase inversion method and were sintered at 1150°C. These membranes were hydrothermally coated with sodium dodecyl sulfate (SDS), producing POFA-SDS and MMT-SDS membranes. The POFA membranes exhibited higher conductivity (0.0926 mS/cm) and ion exchange capacity (0.913 meq/g) than the MMT (0.0079 mS/cm; 0.674 meq/g), while the MMT had a higher surface charge (−42.3 mV) than POFA (−17.6 mV). The MMT exhibited superhydrophilicity, while the POFA was moderately hydrophilic. With the attachment of SDS, the hydrophilicity of the POFA increased. Antifouling tests showed cell concentration reductions of 53.85% (POFA-SDS) and 66.27% (MMT-SDS), which were over two-fold higher than the pristine membranes. SEM-EDX revealed that the POFA-SDS had biofilm agglomeration with fewer attached microbes, suggesting better long-term antifouling potential. In MFC tests using municipal sewage as a feed, the pristine POFA and MMT showed low current densities (3.72 and 3.88 mA/m², respectively). SDS coating increased current density to 26.17 mA/m² for the POFA-SDS and 21.19 mA/m² for the MMT-SDS, with power densities of 12.31 and 10.59 mW/m², respectively. Despite their relatively low baseline performance, the POFA demonstrated promising potential as sustainable proton exchange membrane (PEM) materials.