This study investigates the performance of halogen-doped δ-MnO 2 (F⁻, Cl⁻, Br⁻) for direct degradation of bisphenol A (BPA) under acidic conditions. Characterization techniques, including XPS and XRD, confirmed that halogen doping significantly increased the surface Mn(III) content, identified as the primary active species responsible for BPA oxidation. Among the doped MnO 2 , F-δ-MnO 2 exhibited superior activity, achieving >99% BPA removal within 30 minutes, attributed to its highest Mn(III) concentration (32.97%). Mechanistic studies, employing pyrophosphate complexation, ABTS oxidation assays, and quenching experiments, revealed that surface-bound Mn(III) drives the reaction, while dissolved Mn(III) and reactive oxygen species play negligible roles. The degradation pathway involved single-electron transfer from BPA to Mn(III), yielding less toxic intermediates, as confirmed by toxicity assessments. The doped MnO 2 demonstrated excellent stability, with F-δ-MnO 2 maintaining >90% efficiency over four cycles, and strong anti-interference capability against common water matrix components (e.g., Cl⁻, humic acid). This work highlights halogen doping as an effective strategy to enhance the oxidative capacity of δ-MnO 2 via Mn(III) enrichment, offering insights for designing efficient, oxidant-free water treatment technologies.
Deng et al. (2026) studied this question.