Degradation kinetics and mechanism of bis(2-chloroethyl) ether by electromagnetic induction electrodeless lamp activated persulfate

摘要

Bis(2-chloroethyl) ether (BCEE) has become one of the most frequently detected chlorinated ether contaminants in the US and Europe, and is classified as a B2 carcinogen. In this study, the degradation rate of BCEE by mercury lamps, xenon lamp and electromagnetic induction electrodeless lamp (EIEL) activated persulfate were compared, and EIEL activated persulfate was confirmed to have higher degradation capability and lower energy consumption. In this sense, the degradation kinetics and mechanism in EIEL system were further investigated. The degradation reaction followed pseudo first-order, and the removal rate of BCEE exceeded 95% in 60 min when the initial pH, the concentration of BCEE and Na2S2O8 were 3, 4 mg L-1 and 15 mM, respectively. Presence of inorganic anions and humic acids would reduce the degradation rate constant. In accordance with the results of electron paramagnetic resonance and quenching experiments, SO4-center dot was dominant in the acidic regime and OH center dot was dominant in the alkaline regime. Meanwhile, OH center dot had higher degradation rate with BCEE when initial pH was 7. Seven degradation products were identified and the reaction pathways included OH center dot substitution and free radical coupling. Although the total organic carbon was eliminated slowly during the degradation of BCEE, the predicted toxicity of most degradation products to Fathead minnow, Daphnia magna and oral rat were lower than BCEE. (C) 2020 Elsevier Ltd. All rights reserved.