Visible-light activation of peroxydisulfate by magnetic BiOBr/MnFe2O4 nanocomposite toward degradation of tetracycline

A facile solvothermal method was employed to prepare magnetic BiOBr/MnFe2O4 (BM) nanocomposite, which was characterized in detail and used to activate peroxydisulfate (PDS) for tetracycline (TC) degradation under visible light illumination. Coupling BiOBr with MnFe2O4 not only solves the separation problem of BiOBr but also improves its photocatalytic activity for PDS activation. After exposure to visible light for 90 min, the removal efficiency of TC (20 mg L−1) from water by BM-10/PDS system was 76.5%, which was higher than that of BiOBr/PDS system. The influence of some key process parameters (reaction temperature, catalyst dose, solution pH and inorganic anions) on TC degradation in BM-10/PDS system was investigated. The mechanism for PDS activation and TC degradation in BM-10/PDS/visible light system were proposed, and the SO4·−, ·OH, h+ and O2·− all participated in TC degradation. TC removal from the different real water matrices by BM-10/PDS/visible light oxidation system was also studied.