LAUSR

Abstract The sustained massive use of bromophenols in industrial products leads to their especially pernicious in aquatic environments. This study explored the oxidation kinetics of 2,4-bromophenol (2,4-DBP) and formation potential of bromate (BrO3−) and brominated polymeric products of concern during water treatment by UV/persulfate (PDS) and UV/hydrogen peroxide (H2O2). 2,4-DBP exhibited appreciable reactivity toward sulfate radical (SO4− ) and hydroxyl radical (HO ). The second-order rate constants of SO4− and/or HO with 2,4-DBP at pH 9 were higher than those at pH 5 and 7. It is mainly due to the deprotonation of the hydroxyl group in 2,4-DBP when pH > pKa (pKa = 7.79). The chloride ions (Cl−) significantly inhibited 2,4-DBP degradation in UV/PDS process, which showed little inhibition in the UV/H2O2 process. Carbonate/bicarbonate (CO32−/HCO3−) and natural organic matters (NOM) significantly retarded 2,4-DBP degradation in both processes. BrO3− formation in UV/PDS process in the presence of 2,4-DBP (as organic carbon model compound) exhibited biphasic kinetics, i.e., BrO3− was undetectable in the lag phase and rapid generated in the secondary rapid phase. However, BrO3− was not detected throughout UV/H2O2 process. According to the analysis by electrospray ionization-triple quadruple mass spectrometry, tentative oxidation pathway was proposed. The results showed that brominated polymeric products in the reaction of 2,4-DBP with SO4− and/or HO were readily produced by electrophilic addition and coupling reactions. Given the enhanced toxicological effects of these BrO3− and brominated polymeric products compared with the bromophenols precursors, it is important to better understand their reactivities and fates when UV/PDS or UV/H2O2 is applied for the oxidative treatment of bromophenols-containing waters.