Degradation of Tetrabromobisphenol S by thermo-activated Persulphate Oxidation: reaction Kinetics, transformation Mechanisms, and brominated By-products.

Brominated flame retardants (BFRs) are a group of contaminants of emerging environmental concern. In this study, systematic exploration was carried out to investigate the degradation of tetrabromobisphenol S (TBBPS), a typical emerging BFRs, by thermally activated persulfate (PDS) oxidation. The removal of 5.0 μM TBBPS was 100% after 60 min oxidation treatment under 60°C. Increasing the temperature or initial PDS concentration facilitated the degradation efficiency of TBBPS. The quenching test indicated that TBBPS degradation occurred via the attack of both sulphate radicals and hydroxyl radicals. Natural organic matter (NOM) decreased the removal rate, however, complete disappearance of TBBPS could still be obtained. Six intermediate products were formed during reactions between TBBPS and radicals. Transformation pathways including debromination, β-Scission, and cross-coupling were proposed. Brominated disinfection by-products (DBPs) formed during the degradation of TBBPS were also investigated, such as bromoform and dibromoacetic acid. The presence of NOM reduced the formation rates of brominated DBPs. Results reveal that although thermo-activated PDS is a promising method for TBBPS-contaminated water, it can lead to potential brominated DBPs risks, which should be paid more attention to when SO-based oxidation technology is applied.