Visible Light Catalytic Degradation of Methyl Orange in Aqueous Solution by Bi4TaO8X (X=Cl, Br, I).

Bi-based oxyhalide Bi4TaO8X (X=Cl, Br, I) photocatalysts have been prepared by the combined method of liquid phase and solid state reactions and characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and Ultraviolet-visible diffuse reflectance spectroscopy (UV-vis DRS). Using the azo dye wastewater simulated by aqueous methyl orange (MO) solutions, photocatalytic activity of these catalysts was studied under ultraviolet light, visual light, and solar irradiation. All of the samples had high photocatalytic activity. After 2 h of ultraviolet radiation, the degradation efficiency of methyl orange by Bi4TaO8X (X=Cl, Br, I) was as high as 100%. Under visible-light and solar irradiation, the photocatalytic activity decreased in the order Bi4TaO8I>Bi4TaO8Br>Bi4TaO8Cl. More than 90% degradation efficiency was observed for Bi4TaO8I after 12 h of solar irradiation. Furthermore, the photocatalytic degradation kinetics of methyl orange have been investigated under different types of light irradiation. [ABSTRACT FROM AUTHOR]