Temperature-tuned Co-ZIF-67@Fe-MIL(101) derived catalysts for advanced peroxymonosulfate activation in enrofloxacin removal from water.

Binary MOF@MOF structure offers enhanced porosity, active site density, and structural stability in term of using mono MOFs. In this study, a novel bimetallic composite based on binary MOFs structure, Co-ZIF-67@Fe-MIL(101), was synthesized and subsequently subjected to thermal treatment at 500 °C, resulting in a carbonized catalyst (ZF@ML-500) enriched with mixed metal oxides. This thermally derived composite retained the hierarchical structure of the parent MOF@MOF and exhibited strong ferromagnetic properties and high surface reactivity. The catalyst demonstrated excellent efficiency in activating peroxymonosulfate (PMS) for the degradation of enrofloxacin achieving over 99.2 % removal within 30 min at an optimal dose of 50 mg L-1. ZF@ML-500 also showed excellent tolerance to inorganic anions (HCO3-, CO32-) and minimal metal leaching Fe and Co with superior reusability over 8 cycles. Mechanistic analysis confirmed the generation of reactive oxygen species (•OH, SO4•-, O2•-) and involvement of high-valent metal-oxo species (Fe(IV)-O, Co(IV)-O). Density functional theory (DFT) and LC-MS were employed to identify degradation pathways and ENR attack sites. This work demonstrates that thermally treated binary MOF-derived catalysts offer a promising, robust, and environmentally friendly approach for antibiotic degradation in wastewater treatment.