Degradation of tetrabromobisphenol A by ferrate(VI)-CaSO3 process: Kinetics, products, and impacts on following disinfection by-products formation

Abstract

Tetrabromobisphenol A (TBBPA) is one of the most widely applied brominated flame retardants and has been widely detected in water environment, which might pose risks of brominated disinfection by-products formation in water treatment system. Ferrate(VI)-CaSO3 (Fe(VI)-CaSO3) system could effectively degrade TBBPA at pH 7.0–9.0 but the decomposition rate of TBBPA dropped with increasing pH. The presence of 0.5 mg C/L humic acid (HA) had negligible impact on TBBPA removal, but the removal of TBBPA decreased to ~87% and 80% at pH 7.0 and 8.0, respectively, in the presence of 5.0 mg C/L HA. The transformation products of TBBPA detected in Fe(VI)-CaSO3 process revealed that TBBPA degradation mainly proceeded via electron abstraction, debromination, and ring-opening pathways and Br− was released. In the presence of TBBPA, Fe(VI)-CaSO3 pre-oxidation decreased the generation of all determined DBPs during chlorination at pH 8.0 but it lessened the generation of some DBPs and slightly increased the formation of the other DBPs at pH 7.0. The toxic risk analysis showed that Fe(VI)-CaSO3 pre-oxidation of TBBPA could reduce the toxic risk of DBPs in both synthetic water and natural water at pH 8.0, indicating that Fe(VI)-CaSO3 process has the potential to be applied in practical water treatment.