Synergistic antibiotic degradation by polydopamine/BiOBr-modified photocathode in self-powered...

This study developed a self-powered photo-bio-electrochemical system (PBES) featuring a polydopamine/BiOBr (PDA/BiOBr) modified photocathode for sulfonamide (SA) antibiotic removal. The system achieved 96.5 ± 1.1 % SA removal at a rate of 21.2 ± 0.1 g/m³·d while simultaneously generating a current density of 119.2 ± 10.4 mA/m²,significantly outperforming the efficiencies of both unmodified and PBES-BiOBr systems (2.0 ± 0.4 % and 64.5 ± 6.1 %). Mechanistic studies revealed that PDA facilitated electron transfer from the bioanode to the photocathode, where they reduced O₂ to form ·O₂^-. Photogenerated holes in the valence band of BiOBr oxidized surface-adsorbed H₂O or OH^-, producing ·OH under visible light. These radicals preferentially attacked high electron-density sites in SA, cleaning CS and CN bonds. Ecotoxicity assessment revealed that the degradation intermediates were fivefold less toxic than the parent SA compound. The PBES demonstrates great potential as a sustainable and effective strategy for antibiotic wastewater treatment.