Co-removal of norfloxacin and Cr(VI) by Co/N-doped carbon activating peroxymonosulfate: 1O2 oxidation coupled with interfacial electron transfer

The coexistence of antibiotics and hexavalent chromium (Cr(VI)) in aquatic environments complicates remediation due to their incompatible transformation pathways. Herein, a Co/N-doped carbon catalyst (CoNC) was prepared to activate peroxymonosulfate (PMS) for co-removal of norfloxacin (NOR) and Cr(VI), achieving 91.69% NOR degradation (k obs  = 0.3135 min −1 ) within 60 min and near-complete Cr(VI) reduction (k obs  = 0.5098 min −1 ) within 20 min. Mechanistic analysis revealed that NOR degradation was mainly governed by singlet oxygen ( 1 O 2 ) and electron transfer mediated non-radical pathways, while Cr(VI) reduction was facilitated through interfacial electron transfer. Electrons released during NOR oxidation enhanced Cr(VI) reduction and promoted the Co(II)/Co(III) cycle, maintaining PMS activation and 1 O 2 generation. Co–N coordination sites promoted 1 O 2 formation, and the N-doped carbon matrix mediates interfacial electron transfer. This work highlights the potential of CoNC/PMS system for efficient treatment of wastewater co-contaminated with antibiotics and Cr(VI), providing insights into coupled oxidative-reductive mechanisms.