Improving sulfamethoxazole degradation and power generation in bio-electro-Fenton systems using a bimetallic-insect exuviae melanin composite cathode

Abstract

The bio-electro-Fenton (BEF) process, powered by microbial fuel cells, can oxidize refractory organic pollutants. However, the poor electrochemical performance of BEF limits its H₂O₂ in-situ generation capability. This study addresses these limitations by improving the BEF system's power generation and degradation capabilities by introducing a modified cathode incorporating a Fe–Cu bimetallic and melanin (Me) composite. The BEF system equipped with the Fe–Cu–Me composite cathode achieves a 99.75 % removal efficiency of 10 mg/L of sulfamethoxazole (SMX) in 5 h and demonstrates the highest cumulative H₂O₂ generation (201.63 mg/L), which is 5.38 times higher than that of the unmodified carbon fiber system. The biotoxicity of the water treated by the Fe–Cu–Me cathode system shows a light inhibition percentage of only approximately 1 %, indicating an excellent degradation ability. Applying the Fe–Cu–Me composite alters the microbial composition in the anode tank and promotes the growth of electrochemically active and pollutant-degrading bacteria. Integrating Fe–Cu bimetallic and Me in the composite cathode significantly improves the electrochemical performance and pollutant degradation efficiency of the BEF system, providing a highly efficient approach for electrochemical treatment.