Visible-light-driven impressive activation of persulfate by Bi5O7Br-modified ZnO for photodegradation of tetracycline: Facile synthesis, kinetic and mechanism study

Abstract

In this work, a novel ZnO/Bi5O7Br photocatalyst was successfully prepared by the facile co-precipitate synthesis approach and used for photo-degradation of tetracycline hydrochloride (TC) under visible light. Various techniques (XRD, EDX, FTIR, FESEM, TEM, DRS, PL, EIS, BET) were used for the characterization of materials. The ZnO/Bi5O7Br (20 %) photocatalyst showed a remarkable photocatalytic capability to remove the TC among prepared binary nanocomposites. The influence of initial pH and catalyst dosage on TC photodegradation was assessed. The effect of prepared photocatalyst on persulfate (PS) activation in photocatalytic performance was also investigated, which the kinetic studies represent the ZnO/Bi5O7Br (20 %) + PS degradation rate is 17 and 6.43-folds as large as ZnO and ZnO/Bi5O7Br (20 %), respectively. The increased degradation efficiency of the ZnO/Bi5O7Br (20 %) + PS system can be attributed to the significant light absorption in the visible region, low recombination resulting from the constitution type II-heterojunction between ZnO and Bi5O7Br, and also sulfate radical’s production by PS. Therefore, using the ZnO/Bi5O7Br (20 %) + PS system, 98 % degradation of tetracycline was achieved in 60 min. Eventually, the mechanism of photocatalytic degradation based on band structure and active species was proposed.