Phototransformation of 2,4,6-tribromophenol in aqueous solution: Kinetics and photolysis products.

In this research, we studied the phototransformation of 2,4,6-tribromophenol (TBP) by UV irradiation in aqueous solution. Effects of typical environmental factors (i.e., pH and the initial concentration of TBP, Fe and NO) were also investigated. Results showed that the transformation process followed pseudo-first-order kinetics. The transformation rate constant of TBP decreased with increasing initial concentration and increased with increasing Fe and NO concentrations as well as increasing pH. Ten photoproducts were tentatively identified after irradiation of TBP, according to HPLC-LTQ-Orbitrap MS and GC/MS analysis. Among them, two dihydroxylated dibromobenzene compounds (di-OH-DBB) were found to be predominant over the reaction time, indicating that hydrodebromination of TBP could be the main phototransformation mechanism. In addition, the identification of eight OH-PBDEs and di-OH-PBBs suggested that photodimerization might also be a reaction pathway for TBP photochemical reactions.