Solar photocatalytic degradation of thidiazuron in Yangtze River water matrix by Ag/AgCl-AC at circumneutral condition.

It is well-known that the degradation of pollutants in real water environment is not only challenging but also has practical value. This paper focuses on the photocatalytic degradation of thidiazuron (TDZ), a popular defoliant, using Ag/AgCl-AC (Ag@AC 2:1); AC stands for activated carbon) in a matrix of Yangtze River water under sunlight irradiation. The prepared composite catalyst exhibits excellent performance in TDZ degradation under near neutral condition, the degradation rate reaches 94% in 200 min under solar irradiation. The common inorganic anions (SO42-, Cl-, and HCO3-) and cations (Ca2+, Cu2+, and Mg2+) show inhibitory effect of different degrees on TDZ degradation. Humic substances such as humic acid and fulvic acid also have an effect on the photocatalytic degradation of TDZ. With the increase of humic acid concentration, there is enhancement of inhibitory effect. As for fulvic acid, its effect is complex due to competitive adsorption and photoinduction action. The degradation products as identified by UHPLC-MS are mainly CO2, SO2, and H2O, indicating that the degradation was thorough. The reusability test of four runs reveals that the performance of the photocatalytic system is stable. The results demonstrate that sunlight can be well utilized for the photocatalytic degradation of TDZ. The study offers a cheap and effective approach for the photocatalytic degradation of organic pollutants in circumneutral water bodies.