Simulated sunlight-driven activation of Ferrate(VI) with BiOBr for accelerated oxidation of bisphenol S (BPS)

Bisphenol S (BPS), a prevalent substitute for Bisphenol A, is a concerning endocrine-disrupting chemical frequently detected in the environment. This study constructs a novel synergistic system coupling BiOBr photocatalyst with Ferrate(VI) [Fe(VI)] under simulated sunlight (Xe lamp) for rapid BPS degradation. The system achieved 93.9 % removal of 10 μM BPS within 5 min at pH 8.0, with an apparent second-order rate constant of 459.10 M^-1 s^-1, approximately 80 times higher than that of the Fe(VI)-single/Dark system. Mechanistic investigation by electron spin resonance and quenching experiments identified singlet oxygen (¹O₂) as the primary reactive species responsible for the enhancement. Acting synergistically, BiOBr promoted Fe(VI) decomposition to boost ¹O₂ generation while facilitating electron transfer from BPS to oxidants, as verified by electrochemical and spectroscopic analyses. Eight transformation products were identified, unveiling degradation pathways involving hydroxylation, polymerization, carboxylation, and bond cleavage. The system exhibited excellent environmental compatibility, showing strong anti-interference ability against common water constituents, high degradation efficiency in real river water, and outstanding catalyst reusability with minimal bismuth leaching (0.062 mg/L). Moreover, toxicity assessment indicated an overall detoxification effect. This work provides a practical and sustainable strategy for water purification using the synergistic BiOBr-Fe(VI) system.