Efficient removal of trace-level bisphenols in drinking water using the Mn(VII)/CaSO₃ process

Bisphenols are a class of emerging pollutants frequently detected in drinking water with concentrations ranging from ng/L to μg/L. However, previous studies have typically investigated their degradation at much higher levels (mg/L), limiting the relevance of those findings to the actual scenarios. Given the persistent challenge of effectively removing bisphenols at environmentally relevant concentrations, the development of efficient treatment methods is critical. In this study, we investigated the performance and mechanism of removing 18 trace-level bisphenols from drinking water via a calcium sulfite (CaSO₃)-coupling permanganate (Mn(VII)/CaSO₃) process. Trace-level bisphenols (1.0 μg/L) could be effectively removed by the Mn(VII)/CaSO₃ process at environmentally relevant pH ranges (6.0–8.5). Quantitative structure-activity relationship analysis demonstrated that the degradation rates of bisphenols in this process were strongly positively correlated with their average polarizability. Reactive manganese species were identified to play a dominant role in the degradation of bisphenols. The potential risks of bisphenols could be effectively reduced after degradation by the Mn(VII)/CaSO₃ system. Moreover, the removal of trace-level bisphenols was resistant to interference from the water matrix and efficient in real water samples. Overall, the findings of this study highlight the Mn(VII)/CaSO₃ system as a promising pre-oxidation process for controlling trace-level bisphenols in drinking water.