Photocatalytic degradation of malachite green by waste derived bio-char impregnated Bi₅O₇Br/Fe₃O₄ magnetic composite

We report the fabrication of a novel waste-derived biochar-impregnated Bi₅O₇Br/Fe₃O₄ (WBF) magnetic composite for photocatalytic removal of malachite green pollutant. The newly prepared catalyst was applied for the removal of malachite green dye under visible light irradiation. It was found that the composite degrades 99.39% MG dye within 20 min of the experiment as compared to Bi₅O₇Br, Fe₃O_4, and biochar with 83.19%, 75.09%, and 55.47% in the 50-min experiment. The findings demonstrated that a photocatalytic integrated composite quickly transfers charges across surfaces and effectively separates electron-hole pairs, considerably increasing charge carrier separation and photocatalytic activity. Further, the kinetics show that the rate constant for WBF composite is 7.1 times higher than that observed for Bi₅O₇Br. Scavenging experiments reveal the huge role of.OH and •O₂⁻ radicals in malachite green degradation. Additionally, the magnetic nature of the catalyst ensures the easy separation of the catalyst during photocatlytic experiments and reduces the chance of secondary pollution. The results showed that integrating Bi₅O₇Br and biochar with Fe₃O₄ to create photocatalytic composites is a very efficient strategy to boost photocatalytic activity for environmental waste water treatment.