Activation of peroxymonosulfate by magnetic CuFe2O4@ZIF-67 composite catalyst for the study on the degradation of methylene blue

In this research, a novel magnetically recoverable composite catalyst, CuFe2O4 @ZIF-67, was synthesized. CuFe2O4 @ZIF-67 composite catalyst was applied to degrade methylene blue (MB) in water by activating peroxymonosulfate (PMS). The results showed that the degradation rate of MB (20 mg/L) reached 98.9% in 30 min in the 0.2-CuFe2O4 @ZIF-67 (75 mg/L) + PMS (125 mg/L) system. Both electron paramagnetic resonance (EPR) studies and radical quenching experiments revealed that SO4−•, •OH, 1O2 and •O2− were involved in the degradation of MB. We proposed a catalytic mechanism of PMS activation by CuFe2O4 @ZIF-67. With the synergistic effect of Co3+/Co2+, Fe3+/Fe2+ and Cu2+/Cu+ redox cycles, it can keep its outstanding catalytic activity. Recycling tests showed that the removal rate of MB can still be maintained above 85%, indicating that CuFe2O4 @ZIF-67 has good reusability. In general, owing to its reusability and excellent catalytic activity, the CuFe2O4 @ZIF-67 composite catalyst has a good application prospect in water pollution control.