Textile waste upcycling into air-cathode for microbial fuel cell with energy recovery

The development of sustainable and cost-effective cathode catalysts remains a major challenge in microbial fuel cells (MFCs). This study investigated the use of textile-derived char-obtained from pyrolyzed linen, denim, and sweater waste-as an alternative cathodic material in single-chamber air-cathode MFCs. Pyrolysis also recovered significant amounts of energy-rich gas and oil, at least 4.1 MJ/kg_textile, demonstrating the potential for sustainable energy recovery. The physicochemical properties and electrochemical behavior of the chars were characterized to evaluate their suitability as cathode catalysts. Among the tested materials, sweater-derived char exhibited the highest nitrogen content of 12.0 % and a surface area of 43.6 m²/g, which could enhance oxygen reduction reaction (ORR) activity. MFCs with textile-based cathodes achieved significantly higher current and power densities than the carbon black control, and COD removal efficiencies exceeded 80 % for all but linen, which showed reduced performance due to excessive hydrophilicity. Coulombic efficiencies were also higher than the control, suggesting improved electron recovery, and protein quantification confirmed reduced biofouling on textile-derived cathodes. These results indicate that the combination of nitrogen-rich composition, moderate hydrophilicity, and adequate surface area in textile-derived chars enhances ORR kinetics and resists biofouling. While this study demonstrates the feasibility of repurposing textile waste into high-performing, eco-friendly MFC cathodes, it is constrained by lab-scale, short-term operation, limited surface area of the chars, and the absence of CO₂ integration. Future work should assess long-term stability with real wastewater, optimize pyrolysis and activation processes to enhance ORR activity, and incorporate CO₂ capture to improve performance and scalability.