Enhanced photocatalytic degradation of sulfamethoxazole by visible-light-sensitive TiO2 with low Cu addition

Abstract

Abstract In this study, the one-pot microwave-assisted impregnation method was developed to prepare the visible-light-sensitive Cu–TiO 2 at low mass ratios of 0.006–0.063 wt% for the enhanced photocatalytic degradation of sulfamethoxazole (SMX) under visible light irradiation. The electron probe microanalysis and X-ray absorbance near-edge spectroscopic results indicated that the distribution of copper ions was even on TiO 2 nanoparticles and the dominant species of copper element was CuO. The photodegradation efficiency and rate of SMX by Cu–TiO 2 increased positively upon increasing Cu loading from 0.006 to 0.045 wt% Cu and then decreased when further increasing the Cu mass loading to 0.063 wt%. The pseudo-first-order rate constants for SMX photodegradation by Cu–TiO 2 were in the range 0.0103–0.0506 min −1 , which were 1.9–13.1 times higher than that of pure Degussa P25 TiO 2 . The photodegradation efficiency and rate of SMX can be maintained in the pH range of 5–9, and the release of Cu ions in the solution was only few μg/L, which indicates the stability of Cu–TiO 2 during the photocatalytic reaction in aqueous solutions. In addition, the Cu–TiO 2 could be recycled for at least 4 cycles and maintained the highly stable photoactivity toward SMX degradation under visible light irradiation. Results obtained in this study clearly demonstrate that low mass loading of Cu(II) onto TiO 2 can effectively shorten the route of electron transfer and can serve as the efficient visible-light-driven photocatalysts for photodegradation of SMX and other pharmaceutical products.