Carbon-based single atom catalyst engineered to mediate non-radical pathway for antibiotics degradation under multiple complex water matrices by peroxymonosulfate activation

Efficient degradation of antibiotics in complex water matrices remains a significant challenge. In this study, a carbon-based single atom catalyst (C-SAC) was engineered to mediate a non-radical pathway in peroxymonosulfate (PMS) activation system. The C-SAC/PMS system has successfully addressed the limitations that radicals were susceptible to water matrices. The experimental results proved that FeN4 in the form of single Fe atom was the active site. C-SAC with FeN4 sites demonstrated excellent catalytic performance, removing antibiotics completely within 15 min. Quenching experiments, electron paramagnetic resonance (EPR), and probe experiments proved that the C-SAC/PMS system was dominated by a non-radical pathway, with singlet oxygen (1O2) as the major reactive species. The C-SAC/PMS system maintained excellent performance under multiple complex water matrices, showing high efficiency in both groundwater and surface water over a wide pH range of 2 to 9. In addition, C-SAC retained desired catalytic performance after five cycles, demonstrating its outstanding stability. This study provides valuable insights into the rational design of catalysts for antibiotics degradation in complex water matrices.