Synergistic antibiotic degradation by polydopamine/BiOBr-modified photocathode in self-powered photo-bio-electrochemical system

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/m 3 ·d while simultaneously generating a current density of 119.2 ± 10.4 mA/m 2 ,   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 O 2 to form ·O 2 − . Photogenerated holes in the valence band of BiOBr oxidized surface-adsorbed H 2 O or OH − , producing ·OH under visible light. These radicals preferentially attacked high electron-density sites in SA, cleaning C S and C N 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.