Ferrate(VI) oxidation of tetrabromobisphenol A in comparison with bisphenol A

Abstract

Ferrate(VI) (Fe(VI)) oxidative removal of various organic micropollutants mainly depends on the reactivity of Fe(VI) to target micropollutants and coexisting constituents present in source water. This study evaluated the potential of Fe(VI) oxidation of the brominated flame retardant tetrabromobisphenol A (TBBPA) by using reaction kinetics, products identification and toxicity evaluation, and investigated the influencing effects of humic acid and clay particles on Fe(VI) removal of TBBPA in comparison with bisphenol A (BPA). The obtained apparent second-order rate constants (kapp) for Fe(VI) reaction with TBBPA ranged from 7.9(±0.3) × 103 M−1 s−1 to 3.3(±0.1) × 101 M−1 s−1 with the half-life (t1/2) ranging from 1.7 s to 419.3 s at pH 7.0-10 for an Fe(VI) concentration of 10 mg L−1. Easier oxidation by Fe(VI) was observed for TBBPA than for BPA. Fe(VI) can destroy and transform the TBBPA molecule through β-scission reaction, yielding the chemical species of low bromine-substituted products. More importantly, the oxidation of TBBPA by Fe(VI) led to the loss of its multiple hormonal activities (androgenic, antiestrogenic and antiandrogenic activities). The organic component humic acid decreased the TBBPA and BPA reactions with Fe(VI), while the inorganic component montmorillonite had no effect on their removal within the tested concentrations. Increasing the Fe(VI) dosage can reduce the effects of soluble organic matter and clay particles present in source waters on the degradation process, leading to the complete removal of target micropollutants.