Removal of chloroquine phosphate by ultrafine cobalt nanoparticles in peroxymonosulfate activation

The ultrafine cobalt nanoparticles (CoNPs) are among the best materials for photocatalysis. Co/NC, derived from turnip as a raw material using plant cells as templates and pyrolyzed at 400°C, features highly dispersed 3–5 nm CoNPs embedded in N-doped biochar. The CoNPs with exposed (111)-dominated facets, enable both radical and non-radical peroxymonosulfate (PMS) activation, leading to the highly efficient degradation of 50 mL of chloroquine phosphate (CQP) within 10 minutes under UV-visible light in various water matrices, including river water, reservoir water, and tap water. Density functional theory (DFT) calculations confirmed that the (111)-dominated facets, which serve as the active centers, tend to attack the peroxide bond (O-O) of PMS. Notably, the degradation efficiency of CQP, tetracycline (TC), methyl orange (MO), doxycycline hydrochloride (DH), oxytetracycline (OTC), congo red (CR), and methylene blue (MB) by Co/NC-7/PMS was evaluated in natural water. Additionally, the degradation performance of the above organic pollutant mixture was assessed. Both •OH, ¹ O ₂ , and O ₂ ^•− were confirmed to be the main reactive oxygen species (ROS) participating in the photocatalytic degradation of CQP. The plausible degradation pathways of CQP were also deduced based on the degradation intermediates identified by HPLC-MS analysis.