Electrochemical degradation of 17-alpha-ethinylestradiol (EE2) and estrogenic activity changes

Abstract

17-alpha-ethinylestradiol (EE(2)) as one of typical representatives of steroid estrogens is detrimental to endocrine systems of animals and humans due to its potential estrogenic activity. The degradation of EE(2) in aquatic solution by electrocatalytic oxidation applying Ti-based SnO(2) (Ti/SnO(2)) electrode as the anode was investigated. A pseudo-first-order kinetics under various initial concentrations of EE(2) was obtained and it was found that the calculated kinetic constant was determined as 0.112 min(-1), 0.053 min(-1), 0.023 min(-1) and 0.019 min(-1), which tended to rise in inverse proportion to EE(2) concentration within selected content of EE(2) as 0.5 mg L(-1), 2.0 mg L(-1), 5 mg L(-1) and 10 mg L(-1). Frozen recombinant yeast was introduced to evaluate estrogenic activities of an aqueous solution of 2.0 mg L(-1) EE(2) and oxidation products. The concentration of EE(2) and EE(2) equivalents (EEEQs) decayed 96.5%, 96.3% respectively in 15 min and 78.5% reduction of TOC in 8 h was observed under current density conditions of 10 mA cm(-2) and 0.2 M Na(2)SO(4) as the electrolyte in the process of electrolysis. On the basis of the results obtained, it indicates that the estrogenic activities of the intermediate products can be negligible.