Efficient Adsorption\nand Degradation of Tetracycline\nHydrochloride Using Metal–Organic Framework-Derived Cobalt-Based\nCatalysts and Mechanism Insight

High-performance Co-based catalysts were derived by pyrolysis\nusing\nsynthesized MOFs as self-sacrificial templates. Various catalytic\nsystems were constructed by peroxymonosulfate (PMS) to degrade tetracycline\nhydrochloride (TC). Adsorption–degradation efficiencies, cycle\nperformance, dynamics, and the adsorption catalytic mechanism of various\ncatalytic systems for TC were studied. The effects of different synthetic\nsolvents, pyrolysis temperatures, and single/bimetallic element compositions\non degradation efficiency were innovatively compared. The optimal\ncatalyst and PMS dosage for the experiment were determined to be 10\nmg and 0.1 mL, respectively. The results indicated that all catalytic\nsystems could efficiently degrade TC and have a high acid–base\nresistance. The catalyst activity was significantly influenced by\nthe pyrolysis temperature. The optimum pyrolysis temperatures for\nZn@Co-N-C-<i>T</i>, CH<sub>3</sub>OH@Co-N-C-<i>T</i>, and H<sub>2</sub>O@Co-N-C-<i>T</i> were 1000, 900 and\n900 °C, respectively. More abundant pore structures and active\nsites were generated in Zn@Co-N-C-1000, exhibiting an excellent TC\ndegradation efficiency and adsorption capacity, achieving 94.73% and\n167.564 mg/g, respectively. Meanwhile, the total organic carbon (TOC)\nof TC (50 mL, 50 mg/L) achieved a removal rate (TOC/TOC<sub>0</sub>) of 50.28%. Zn@Co-N-C-1000/PMS maintained over 83.27% TC degradation\nafter five cycles. The adsorption mechanism of the catalyst for TC\nwas investigated through the analysis of adsorption kinetics and isotherm\nmodels. The quenching test and EPR results indicated that TC was primarily\ndegraded through the nonradical pathway. The efficient degradation\nof TC is attributed to the rapid electron transfer processes occurring\nat the two-phase interface and the redox cycling of Co<sup>0</sup>/Co<sup>2+</sup>/Co<sup>3+</sup>. Finally, LC–MS was used\nto analyze the intermediate products of TC degradation in the Zn@Co-N-C-1000/PMS\nsystem, and two degradation pathways were proposed.