Magnetic biochar coupled with bismuth tungstate for multiple antibiotic removal from contaminated water: Characteristics, performance, and competitive adsorption synergistic photocatalysis mechanism

In this study, a magnetic biochar-based bismuth tungstate composite photocatalyst was synthesized to investigate the competitive adsorption behaviors of multiple antibiotics, specifically ciprofloxacin (CIP) and tetracycline (TC), as target pollutants in aqueous environments. We aimed to elucidate the mechanism of adsorption-photocatalysis synergy for the removal of multiple antibiotics in water. Our results demonstrated that the composite catalyst exhibited remarkable degradation efficiencies of 92.41% for CIP and 95.34% for TC within the multi-solute system. Additionally, we found that the composite photocatalyst showed preferential adsorption selectivity toward CIP in this multi-solute system. The adsorption process followed a monolayer chemisorption mechanism on the catalyst surface, primarily driven by π–π interactions and surface complexation with functional groups. The photocatalytic reaction relied on the generation of·OH,·O2−, and h+ as the primary active species for degrading TC and CIP. Moreover, we observed that incorporating magnetic properties into the composite enhanced its recovery rate. We hope that these results provide new insights into the removal of various antibiotics from water.