부산대학교 도서관

Bi-based oxyhalide [Bi.sub.4]Ta[O.sub.8]X (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 [Bi.sub.4]Ta[O.sub.8]X (X=Cl, Br, I) was as high as 100%. Under visible-light and solar irradiation, the photocatalytic activity decreased in the order [Bi.sub.4]Ta[O.sub.8]I>[Bi.sub.4]Ta[O.sub.8]Br>[Bi.sub.4]Ta[O.sub.8]Cl. More than 90% degradation efficiency was observed for [Bi.sub.4]Ta[O.sub.8]I after 12 h of solar irradiation. Furthermore, the photocatalytic degradation kinetics of methyl orange have been investigated under different types of light irradiation.