Study On Benzotriazole Degradation By Ultrasound-Ultraviolet Enhanced Hydrogen Peroxide

Benzotriazole is widely used. It has a relatively high mobility in the aqueous phase and is difficultly biodegradable. According to the highly sensitive photochemical characteristic of benzotriazole, this paper uses ultrasound, hydrogen peroxide and ultraviolet to degrade benzotriazole collaboratively. The degradation of benzotriazole by three advanced oxidation technologies separately ultraviolet radiation, ultrasound-ultraviolet radiation and ultrasound-ultraviolet-hydrogen peroxide was studied, having a preliminary study of the effect of the technical parameters and mechanism of the reaction process. And the reaction kinetics and the synergy effect of ultrasonic-ultraviolet-hydrogen peroxide were analysed.The studies of benzotriazole degradation by ultraviolet radiation showed that lower pH was beneficial for degradation, under the condition of pH3and UV radiation120min, benzotriazole removal rate reached88.11%. But at the reaction time120min, benzotriazole mineralization rate was11.13%, which was very low.The studies of benzotriazole degradation by ultrasound-ultraviolet radiation showed that there was an obvious synergy between ultrasound-ultraviolet, which is closely related to the pH and the reaction time. The benzotriazole removal rate decreases with the increase of pH, ultrasound-UV cofactor S increases with the increase of pH, the synergy factor S of ultrasonic-ultraviolet increases with the increase of pH. At pH9and a reaction time15min, synergy factor S was2.641. Although there was an obvious synergy between ultrasound-ultraviolet, but the mineralization rate was8.72%at the reaction time120min. The degradation removal rate of benzotriazole by ultrasonic-ultraviolet increased by the ultrasonic power and the sound intensity effect on the degradation of benzotriazole. When power increased to250W, benzotriazole removal rate increased to91.18%.The studies of benzotriazole degradation by ultrasound-ultraviolet-hydrogen peroxide indicated that the synergy was obvious, and with the reaction time prolonged, synergy factor S was smaller. When the reaction time was10min, S was1.796which was greater than1, the reaction time was20min, S was1.09, which was equal to1. The hydrogen peroxide can promote the degradation of benzotriazole by ultrasound-ultraviolet, but the effect is not obvious and it was significant for mineralization. Under the experimental conditions of temperature25℃, ultrasonic frequency20kHz, power250W,[CBTri]=23mg/L,[CH2O2]=120mg/L, pH3, the reaction time25min, the benzotriazole removal rate of95.65%; there was a linear relationship between mineralization rate and the reaction time, at the reaction time of120min, the mineralization rate reached91.8%.In addition, the research concluded that the process of benzotriazole degradation by ultrasound-ultraviolet-hydrogen peroxide consistent with first order kinetics. Under the experimental conditions of temperature25℃, ultrasonic frequency20kHz, power250W,[CBTri]=23mg/L, pH3,[CH2O2]=120mg/L, the reaction rate constant k by ultrasound-ultraviolet-hydrogen peroxide was14.643×10-2min-1.