Highly Efficient Decomposition of BPA by Single-Atom-Fe Activated Peroxydisulfate: the Dominant Role of High-Valent Iron-Oxo Species

Persulfate-based advanced oxidation processes (PS-AOPs) represent a green and sustainable approach for degrading environmental contaminants like bisphenol A (BPA). However, the practical application of conventional heterogeneous iron-based catalysts in PS-AOPs is often hindered by their low atom-utilization efficiency, complex active sites, and suboptimal catalytic performance. To address these limitations, this study reports the successful synthesis of a single-atom iron catalyst anchored on 3D N-doped porous carbon (SAC-Fe) for efficient activation of peroxydisulfate (PDS) to degrade BPA. The SAC-Fe catalyst demonstrated superior performance, achieving 100% BPA degradation with an impressive turnover frequency of 13.62 L·min–1·g–1. The system demonstrated good robustness, maintaining high performance across a broad pH window (3–9) and in the presence of common inorganic anions and complex water matrices. Mechanistic investigations including scavenging tests, probe experiments, and electron paramagnetic resonance (EPR) spectroscopy revealed that the catalytic degradation of BPA by SAC-Fe/PDS follows a synergistic nonradical pathway. In this pathway, PDS first reacts with atomically dispersed Fe–NX active sites on SAC-Fe to generate a surface-bound, high-valent iron-oxo intermediates, which is followed by the degradation of BPA by this active species. Additionally, the NC support in SAC-Fe also participates in PDS activation, promoting BPA degradation synergistically following the electron transfer process. Further investigation indicated this pathway also possesses superior selectivity toward representative emerging contaminants containing electron-donating groups.