Direct photolysis of estrogens in aqueous solutions

Direct photolysis of two estrogens 17β-estradiol (E2) and estrone (E1) in aqueous solutions radiated by UV-light and UV–Vis-light was studied preliminarily. The results suggest that the photolysis of E2 in aqueous solutions occurs under irradiation with UV disinfection lamp (λ=254 nm, 30 W), while E1 can also undergo photolysis under irradiation with a high-pressure mercury lamp (λ 365 nm, 125 W). The photolysis reactions of E2 and E1 at the concentration of 3.0–20 mg l−1 in aqueous solutions were all in accordance with pseudo-first-order law. The photolysis rate of estrogens in aqueous solutions reached the lowest value at pH approximately 5.0, while the highest at pH 8.0 over the range of 2.0–8.0. The higher the initial concentration of the two estrogens, the lower the rate of photolysis.