Photodegradation behaviors of 17β-estradiol in different water matrixes

17 beta-Estradiol (E2), a typical endocrine disrupting compound, is frequently detected in aquatic environments, and this has caused serious concerns about its potential risks. In this study, the photodegradation behaviors of E2 in ultrapure water and different water matrixes such as those containing HCO3-, NO3-, NO2-, and humic acid (HA) were investigated under simulated irradiation using a 300-W xenon lamp. The results showed that E2 photodegradation in all cases followed pseudo-first-order kinetics. In ultrapure water, the photodegradation rate constant and half-life of E2 were 0.1304h(-1) and 5.32 h, respectively. The contributions of direct photolysis, hydroxyl radicals ((OH)-O-center dot), and singlet oxygen free radicals (102) to E2 removal were 72%, 21.2%, and 6.8%, respectively. The effects of different concentrations of HCO3-, NO3-, NO2-, and HA on the photodegradation behavior of E2 were clearly different. In the presence of HCO3- (0.16-2.46 mM), the E2 removal rate decreased from 0.1236 to 0.1144h(-1) as the HCO3- concentration increased. Quenching experiments revealed that the contribution of (OH)-O-center dot decreased gradually from 21.2% to 10.9% in the presence of HCO3-. In contrast, in the presence of NO3- (0-1.29mM), NO2- (0-1.29 mM), and HA (0-24mg/L), the E2 removal rates increased significantly as their concentrations increased, and quenching experiments revealed that the contribution of (OH)-O-center dot increased to 24.8%, 29.1%, and 62.4%, respectively. It can be concluded that hydroxyl radicals were predominantly responsible for the indirect photodegradation of E2. (C) 2017 Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.