Preparation and characterization of a copper phosphotungstate/titanium dioxide (Cu-H3PW12O40/TiO2) composite and the photocatalytic oxidation of high-concentration ammonia nitrogen.

Currently, the majority of wastewater with a high concentration of ammonia nitrogen (NH4+/NH3) 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-H3PW12O40/TiO2) 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 NH4+/NH3 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 TiO2. 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-H3PW12O40 was 40%, and the aeration rate was 1.5 L·min-1, the removal rate of NH4+/NH3 by the composite photocatalyst could reach >80%. Very little NO2- and NO3- were produced, and N2 was the main product.