Selenium and cobalt co-doped carbon catalyst to activate peroxymonosulfate for efficient tetracycline hydrochloride degradation: Primary role of non-radicals

• A selenium-doped carbon composite material (CoSe@C) was synthesized from metal-organic framework. • The CoSe@C can effectively active PMS to degrade tetracycline hydrochloride (TC). • The selenium doping enhanced graphitization and electron transfer capacity for PMS activation. • High-valent cobalt and electron transfer were the main non-radical pathways for TC degradation. Peroxymonosulfate (PMS)-based advanced oxidation process has been proved to be an effective method for antibiotic treatment, however, the activation of PMS should be improved for practical applications. A selenium-cobalt co-doped carbon composite material (CoSe@C) was successfully synthesized through pyrolyzing of ZIF-67 with selenium powder. The CoSe@C was used to degrade tetracycline hydrochloride (TC). Under optimized conditions of 0.05 g/L CoSe@C, 0.1 g/L PMS and pH = 4.8 at 25 °C, 89.1% TC removal was achieved within 60 min. Characterization confirmed that cobalt provides abundant active sites, while selenium doping enhances graphitization and electron transfer capacity. The non-radical pathway played the primary role, with high valent cobalt and electron transfer contributing the mainly TC degradation in CoSe@C/PMS system. Two possible degradation pathways were proposed in CoSe@C/PMS system, and the most intermediates have lower toxicity than initial TC. The catalyst also exhibited good reusability. This work demonstrates the potential of MOF-derived Se-doped catalysts in advanced oxidation processes for antibiotic-contaminated wastewater treatment.