BiOBr/MgFe2O4 composite as a novel catalyst for the sonocatalytic removal of tetracycline in aqueous environment

Abstract

A series of BiOBr/MgFe2O4 composites were synthesized and characterized. Tetracycline (TET) was used as a model antibiotic to verify the sonocatalytic activities of these BiOBr/MgFe2O4 composites. When the mass ratio of BiOBr to MgFe2O4 in the BiOBr/MgFe2O4 composites was 20%, the BiOBr/MgFe2O4 composite (BM-20) showed the best catalytic performance to the sonocatalytic removal of TET. Under the optimum conditions, such as the addition of catalyst 2.0 g/L, pH 7 and ultrasonic power 500 W, the initial concentration of TET 10 mg/L, the sonocatalytic removal rate of TET reached 91.10±2.36% in 30 min using BM-20 as a sonocatalyst, which was significantly better than that of MgFe2O4 (52.3±2.23%). The generated hydroxyl free radicals (•OH), holes (h+) and superoxide anion radical (•O2−) played major roles in the sonocatalytic removal process. The improved sonocatalytic performance of BM-20 was due to the S-scheme heterojunction formed between BiOBr and MgFe2O4, which could separate electron-hole (e−-h+) pairs effectively. Besides, BM-20 had great stability and reusability. To conclude, the fabrication of heterojunction was an effective method to improve the sonocatalytic performance of catalyst. The BiOBr/MgFe2O4 composites could be satisfactory utilized as a catalyst in the sonocatalytic elimination of organic contaminant.