Photochemical reactions between bromophenols and hydroxyl radical generated in aqueous solution: A laser flash photolysis study

Bromophenols (BPs) have been reported as precursor compounds to form some more toxic pollutants such as hydroxylated polybrominated diphenyl ethers (OH-PBDEs), polybrominated dibenzo-p-dioxin/ dibenzofurans (PBDD/Fs), but only limited data about environmental fate of BPs is available to assess their ecological risks. In this study, the photochemical reactions of eight BPs and hydroxyl radical ((OH)-O-center dot) generated from NaNO2 were investigated using laser flash photolysis (LFP) in aqueous solution. Two transient intermediates, OH adducts and bromophenoxyl radicals, were identified after irradiation, and the possible reaction pathways were proposed. Both numbers and positions of bromine atoms significantly affected their formation by different mechanisms. Lifetimes of all eight bromophenoxyl radicals were also determined to be longer than 100 mu s. More OH adducts were generated at lower pH values and higher Fe (III) concentrations, while the relative amounts of bromophenoxyl radicals were bigger at higher pH values and Fe (III) concentrations. In addition, fulvic acid (FA) showed promoting effects for the formation of the two transient species in low concentration, while inhibitive effects in high concentration. These results will provide vital insights into the photochemical process of BPs in natural water environments. (C) 2016 Elsevier B.V. All rights reserved.