Activation of peroxymonosulfate by boron nitride loaded with Co mixed oxides and boron vacancy for ultrafast removal of drugs in surface water

The mediation of vacancy in catalysts is crucial for the enhancement of oxidant activation. Here the boron nitride loaded with Co mixed oxides (Co₂O₃-CoO) and boron vacancy (B_v) catalyst (Co/BN-X) was prepared to degrade sulfamethoxazole (SMX) by activating peroxymonosulfate (PMS). Under dark condition, Co/BN-3+PMS system can completely remove SMX in surface water within 15 min, and its removal efficiency constant (0.5154 min⁻¹) was 4.0 and 6.7 times greater than those of Co/BN-2+PMS (0.1284 min⁻¹) and Co/BN-1+PMS (0.0771 min⁻¹), respectively. The system showed excellent performance in different influencing factors and cyclic experiments, and exhibited good practical application potential in secondary effluent. Electron paramagnetic resonance, radical quenching and electrochemical tests certified that singlet oxygen (¹O₂) was the major active species, followed by •O₂^–, and SO₄^•–, further elaborating the activation pathway of PMS in Co/BN-3+PMS system. The density functional theory (DFT) calculations confirmed that CoO and PMS-O₂ sites were the main reaction sites, and the existence of B_v reduced the adsorption energy of Co/BN-3 for PMS. This work reveals the synergistic effect between Co oxide sites and B_v on the catalyst surface and offers a potential modification method to accelerate Fenton-like reaction.