Mn redox-mediated extracellular electron transfer enhances tetracycline degradation and power generation in microbial fuel cells

Microbial fuel cells (MFCs) face challenges in treating tetracycline (TC) wastewater, including low anode electron transfer efficiency, long pollutant degradation cycles, and limited degradation capacity, which limit their practical applications. In order to solve the above problems, this study developed a unique graded sea urchin type MnO 2 -PANI/CF composite anode material, aiming to simultaneously improve the power generation performance and tetracycline degradation efficiency of MFC. This anode significantly enhances electron transfer efficiency between the anode and microorganisms through an extracellular electron transfer mechanism mediated by Mn redox reactions. The results showed that the MnO 2 -PANI/CF anode significantly improved the performance of MFC, with a maximum power density of 4.702 W/m 3 , which is three times that of the bare CF anode (1.541 W/m 3 ). When treating high concentration tetracycline wastewater (50 mg/L), the TC degradation rate reached 94.64 %. The system maintained a high power output of 4.418 W/m 3 under continuous operation, demonstrating a good synergistic enhancement effect of power generation and degradation. The superiority of this composite anode lies in its low charge transfer resistance, high specific surface area, superhydrophilicity, and excellent biocompatibility. Microbial community analysis further showed that MnO 2 -PANI/CF anode promoted the enrichment of bacterial phyla (such as Bacillota and Actinobacteriota), enhancing the synergistic effect between microbial metabolism and anodic electrochemical processes. This contributes to the mutual promotion between pollutant degradation and electrical energy output. This study provides an effective strategy for designing high-performance MFC anodes for simultaneous power generation and antibiotic wastewater treatment.