Chlorination of bisphenols in water: Understanding the kinetics and formation mechanism of 2-butene-1,4-dial and analogues

While it is widely accepted that 2-butene-1,4-dial (BDA) is a toxic metabolite with genotoxic and carcinogenic properties, little is known about BDA and its analogues (BDAs) formation during water disinfection. In this study, the effects of different chlorination conditions on the formation of BDAs from bisphenol and its analogues (BPs analogues) were evaluated. A transformation pathway for the formation of BDAs upon chlorination of BPs analogues is proposed. The time profile of the transformation of BPs analogues into BDAs reveals that the generation of dichlorohydroquinone, dichloro-hydroxybenzenesulfonic acid and 2,4,6-trichlorophenol, are significantly associated with the formation of BDAs in the disinfected water. Owing to the different bridging groups contributing to the electrophilicity of BPs analogues in varying degrees, the stronger the electrophilicity of BPs analogues the more BDAs are formed. In addition, the type of BDAs produced is also affected. Four types of BDAs were detected in this study, one of which was newly identified. This study confirms that BPs analogues are an important source of BDAs and provides more insights into the formation of BDAs during chlorination. Greater attention should be given to the formation of BDAs in chlorinated water and their potential threat to humans and the ecosystem.