A novel Co-N-doped carbon catalyst to activate peroxymonosulfate for efficient removal of sulfamethazine: Role of singlet oxygen and high-valent cobalt-oxo species

In this study, a coral-like Co-N-doped carbon (Co@NC) was prepared through a simple one-pot synthesis method. The catalyst effectively activated peroxymonosulfate (PMS) for sulfamethazine (SMZ) degradation via non-radical pathways, achieving a 100 % removal efficiency of SMZ within 20 min. The Co@NC/PMS system maintained excellent removal capability for SMZ under a broad range of pH (3.0–9.0) and pollutant concentrations (10 mg/L-50 mg/L). Mechanistic studies suggested that the synergistic interaction between Co-Nx sites and graphitic carbon facilitated the generation of singlet oxygen (1O2) and high valent cobalt-oxo species (Co(IV) = O), which played dominant roles in the degradation of SMZ. Investigating the effects of different concentrations of anions and humic acid on SMZ degradation, the Co@NC/PMS system demonstrated resistance to interference from common water constituents. Upon examining the degradation capability of the Co@NC/PMS system against different pollutants, the system exhibited selective oxidation towards organic pollutants containing electron-donating moieties, such as hydroxyl and amide groups. This study synthesized a novel Co-N-doped carbon as a highly efficient activator for PMS and conducted an in-depth investigation into the mechanism of SMZ degradation dominated by non-radical pathways.