A S-scheme heterojunction of MIL-125(Ti)/BiOBr for remediation of organic and inorganic pollutants coexistent real water: application and mechanism investigation

The remediation of real wastewater consistently garners significant attention; however, the complexity of treating substrates due to the coexistence of organic and inorganic pollutants often renders treatment challenging. In response to this issue, a visible-light-driven photocatalyst, MIL-125(Ti)/BiOBr, was meticulously designed and synthesized. This catalyst was employed to statically treat tetracycline and Cr(VI) individually across three distinct treatment models: adsorption, photocatalysis, and the synergistic combination of adsorption-photocatalysis. Through this exploration, it was determined that the adsorption-photocatalysis synergism emerged as the optimal treatment model. The MIL-125(Ti)/BiOBr system exhibited outstanding tetracycline degradation performance (100% of tetracycline can be removed after 40min and 100% of Cr(VI) can be removed after 45min). Then, MIL-125(Ti)/BiOBr was applied to treat tetracycline and Cr(VI) individually or simultaneously under adsorption-photocatalysis model, to confirm tetracycline and Cr(VI) didn’t interfere each other. At last, to evaluate the practical application of MIL-125(Ti)/BiOBr, it was utilized to treat three real water bodies simultaneously containing tetracycline and Cr(VI) in continuous flowing manner. The results highlight the remarkable capability of MIL-125(Ti)/BiOBr in treating wastewater containing both organic and inorganic pollutants. Mechanistic analysis revealed the establishment of an efficient S-scheme charge-carrier transfer pathway at the interface of MIL-125(Ti) and BiOBr, effectively suppressing charge carrier recombination and thereby enhancing photocatalytic performance. This study offers a novel perspective on the construction of bifunctional photocatalysts, which hold promise in addressing the challenge of intractable wastewater treatment in real-world scenarios.