Comparative study of the activation of peroxymonosulfate and persulfate by ferrocene for bisphenol A degradation

Persulfate-based advanced oxidation processes (PS-AOPs) exhibit enhanced oxidant stability and radical persistence compared to traditional H 2 O 2 -AOPs. This study comparatively evaluates redox-active ferrocene (Fc/Fc + ) for activating peroxymonosulfate (PMS) and peroxydisulfate (PDS) toward bisphenol A (BPA) degradation. The Fc/PMS system demonstrates superior BPA removal efficiency and kinetics relative to Fc/PDS, mechanistically attributed to the lower activation barrier for asymmetric PMS (accepting 0.91 e − from Fc) versus symmetric PDS (accepting 0.88 e − from Fc), as quantified by density functional theory (DFT) with Bader charge analysis. Sulfate (SO 4 •− ) and hydroxyl (• OH) radicals were identified as the dominant reactive species in both systems. Crucially, O 2 -mediated Fc-to-Fc + oxidation promotes electrostatic migration of anionic persulfates to the catalyst surface, enhancing activation efficiency. Both systems sustain contaminant removal through Fc + reduction by persulfates, demonstrating regenerative catalytic behavior. For practical application, future work should prioritize catalyst design strategies to accelerate Fc + recycling kinetics and enhance system resilience under oxygen-limited conditions.