Petal-like hierarchical Co3O4/N-doped porous carbon derived from Co-MOF for enhanced peroxymonosulfate activation to remove tetracycline hydrochloride

Developing hierarchical and efficient catalysts with multiple active sites to activate peroxymonosulfate (PMS) for the degradation of persistent organic contaminants is crucial, whereas it's still a challenge. Herein, a novel petal-like N-doped porous carbon embedded with ultrafine cobalt oxide nanoparticles (NPs) (named as Co3O4/NC) was unprecedentedly fabricated via the pyrolysis of N-enriched Co-MOF (named as Co-TA), where the unique hierarchical structure, rich active sites and large specific area were contributed to improve the excellent catalytic activity toward tetracycline hydrochloride (TCH). As expected, the removal efficiency of TCH in Co3O4/NC/peroxymonosulfate system was 96.4 % within 30 min, extraordinary superior to direct air-calcining nano-Co3O4, commercial Co3O4 and Co-TA, in which the kinetic constant was 10.4 times higher than pure Co-TA. Besides, above 97 % removal efficiency TCH was maintained over a wide pH range of 5-9, and 71 % of total organic carbon (TOC) could be eliminated. The TCH degradation was mainly characterized by the coexistence of multiple active substances using EPR analysis, where SO4 center dot- and O-1(2) were the dominant contributors. The degradation pathways of TCH were also clarified based on theoretical calculation and HPLC-TOF-MS2 data. This work can extend the application of metal-organic frameworks (MOFs)-derived nanocatalysts in the environment field, and may offer a promising metal oxide heterogeneous catalyst for the rapid elimination of persistent organic pollutants by sulfate radical-based advanced oxidation processes (SR-AOPs).