Chemical oxidation of bis(2-chloroethyl) ether in the Fenton process: Kinetics, pathways and toxicity assessment

Abstract

Bis(2-chloroethyl) ether (BCEE) is a common chemical material and a frequently detected contaminant in groundwater. It has a strong toxicity and some other chemicals such as poly(vinyl chloride-co-isobutyl vinyl ether) contain similar chloroaliphatic ether structure. So the effective degradation method and transformation pathways for BCEE need to be learned. The present study compared the degradation rate of BCEE by Fenton's reagent and other common oxidation methods, and optimized the reaction conditions. Oxidation intermediates and pathways were also proposed and toxicities of the intermediates were investigated. Results showed that Fenton was highly effective to degrade BCEE. pH, Fe2+ and H2O2 concentration all affected the oxidation rate, among which Fe2+ was the most significant variable. A total of twelve chlorinated intermediates were detected. Three main reaction pathways involved cleavage of the ether bond, hydroxyl substitution for hydrogen, and radical coupling. The pathways could be well interpreted and supported by theoretical calculations. The reaction mixture showed a decreasing trend in TOC concentration and toxicity until totally harmless to Vibrio fischeri after 15 min, but it was noteworthy that toxicities of some dimeric intermediates were stronger than BCEE by calculation.