Efficient degradation of diazinon and adsorption of released phosphate through activating peroxymonosulfate by Zr-doped ZIF-8 encapsulated CoFe2O4 composite

The widespread application of organophosphorus pesticides (OPPs) has caused pollution in many aqueous environments. Sulfate radical-based advanced oxidation processes (SR-AOPs) are effective for degrading refractory organic pollutants. However, only a limited number of studies have been conducted in the field of OPP removal using SR-AOPs. The residue of phosphate generated by the degradation of OPPs is also a problem worth considering. Herein, Zr-doped ZIF-8 encapsulated CoFe2O4 magnetic composite was successfully synthesized (CoFe2O4 @Zr/ZIF-8) to activate peroxymonosulfate (PMS) for the degradation of diazinon (DZ) and adsorb released phosphate. CoFe2O4 @Zr/ZIF-8 demonstrated excellent catalytic performance, with 100% DZ degradation (20 mg/L); most of the phosphates produced during degradation were also adsorbed. The wrapping of ZIF-8 effectively inhibited the leaching of cobalt ions. Different factors affecting DZ removal were investigated. Further study demonstrated that sulfate radicals (SO4•−), hydroxyl radicals (•OH), and singlet oxygen (1O2) are responsible for the degradation of DZ, with SO4•− and 1O2 playing pivotal roles. This study presents a potential strategy for both OPP degradation and phosphate adsorption and provides a new concept for utilizing multifunctional materials in environmental remediation.