Preparation and characterization of a copper phosphotungstate/titanium dioxide (Cu-H_3PW_(12)O_(40)/TiO_2) composite and the photocatalytic oxidation of high-concentration ammonia nitrogen

摘要

Currently, the majority of wastewater with a high concentration of ammonia nitrogen (NH_4~+/NH_3) is treated using biological methods, which have poor biodegradability and low removal efficiency. In this paper, a composite photocatalyst of copper phosphotungstate/titanium dioxide (Cu-H_3PW_(12)O_(40)/TiO_2) was prepared by sol-gel hydrothermal synthesis, and the composite catalyst was characterized by X-ray diffraction (XRD), UV-vis-diffuse reflectance spectroscopy (UV-VIS-DRS), Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS) 、 scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS). The photocatalytic oxidation of a high-concentration NH_4~+/NH_3 solution was carried out under ultraviolet (UV) light to explore the effects of different influencing factors on the photocatalytic effect and to optimize the reaction conditions. The prepared composite catalyst exhibited higher photocatalytic activity than that of TiO_2. When the initial concentration of the solution was 300 mg·L~(-1), the initial pH was 11, the catalyst concentration was 1.5 g·L~(-1), the loading level of Cu-H_3PW_(12)O_(40) was 40%, and the aeration rate was 1.5 L·min~(-1), the removal rate of NH_4~+/NH_3 by the composite photocatalyst could reach ＞80%. Very little NO_2~- and NO_3~- were produced, and N_2 was the main product.