Photocatalytic degradation of rhodamine B, reactive orange, and bisphenol A under visible light irradiation over AgX/ZnO (X=Cl, Br, I) prepared from green approach

Abstract

Silver halide/zinc oxide (AgX/ZnO, X = Cl, Br, I) powders were prepared by a two-step method. A solution of Zn2+ ions was mixed with water extract of wood ash to generate a ZnO precursor which was transformed to ZnO by calcination at 900 °C. The AgX deposited on the surface of ZnO was achieved by a reaction between Ag+ and halide (X−) ions. The photocatalytic activities of AgX/ZnO were evaluated through the degradation of the pollutant models: rhodamine B (RhB), reactive orange (RO), and bisphenol A (BPA) under visible light irradiation. AgX could increase the visible light absorption ability of AgX/ZnO and this improved the photocatalytic activities of the AgX/ZnO composites. The AgCl/ZnO showed higher photocatalytic activity than AgBr/ZnO and AgI/ZnO. Mass spectrometry confirmed that the RhB, RO, and BPA were degraded into smaller molecules over AgX/ZnO. In the case of photocatalysis of BPA with AgBr/ZnO, the degraded product showed a higher molecular mass that could probably be assigned to the [M-2H + Br]− ion.