Enhanced tetracycline degradation efficiency by CoFe2O4 decorated TA-ZIF-8 catalyst via activating peroxymonosulfate under confinement effect

Spinel oxides can be considered effective heterogeneous catalysts in activating peroxymonosulfate (PMS) for wastewater decontamination. However, the intrinsic characteristics of agglomeration and metal ion leaching impede its further application. In this work, to further improve the catalytic efficiency and stability of the catalyst, ZIF-8 was employed as the candidate and further etched by tannic acid (TA) to obtain a core-shell structure with less mass transfer resistance. Following this, CoFe2O4 was anchored on TA-ZIF-8 matrix via a hydrothermal method. Benefiting from the tailored core-shell structure and high activity of CoFe2O4, the as-prepared CoFe2O4 @TA-ZIF-8 catalyst shortened the mass transfer distance of radical to target pollutant, thus realizing high radical utilization efficiency. Accordingly, 98.1% of tetracycline (TC) can be eliminated in 30 min with kinetic constants 3.15 times higher than pristine CoFe2O4. Besides, the TC degradation efficiency can still maintain 84.1% after five consecutive cycles with cobalt leaching lower than 0.306 mg/L, showing favorable stability compared with pristine CoFe2O4. Furthermore, electron paramagnetic resonance (EPR) and quenching experiments exhibited that singlet oxygen and sulfate radicals play dominant roles in TC degradation processes. This work fabricates an efficient CoFe2O4 @TA-ZIF-8 heterogeneous catalyst for degrading refractory TC, which may possess potential applications in wastewater treatment.