Sustainable Co(III)/Co(II) cycles triggered by Co-Zn bimetallic MOF encapsulating Fe nanoparticles for high-efficiency peracetic acid activation to degrade sulfamethoxazole: Enhanced performance and synergistic mechanism

[Display omitted] •A dual-MOFs assisted strategy is designed to construct Fe3O4@ZIFs for PAA activation.•RO· and 1O2 are predominant in SMX oxidation.•·OH, ·O2–, and high-valent metal contributes to 1O2 generation.•Fe2+/Fe3+ redox cycles promote the reduction of Co3+.•Fe3O4@ZIFs shows superior reusability and stability. Herein, a dual-metal-organic framework (MOF) assisted strategy to construct a core-shell structure magnetic Fe3O4@ZIFs composites was proposed for peracetic acid (PAA) activation. Results showed that the Fe3O4@ZIFs displayed superior activity relative to analogous counterparts, achieving 99.3 % degradation of SMX within 30 min. Both the radical pathways of CH3C(O)OO· and non-radical 1O2 were recognized as the primary mechanisms in SMX oxidation, while the radicals such as ·OH, CH3C(O)O·, and ·O2– along with high-valent metal species (CoIVO2+ and FeIVO2+) demonstrated a limited contribution. During the process, the Co sites on the surface of ZIFs, serving as the primary active sites, activated the PAA through the redox cycle of Co(II)/Co(III) to generate reactive oxygen species (ROS). The encapsulated Fe3O4 nanoparticles were subjected to precise electron transmission, benefiting Co(II) recovery for enhanced Co(II)/Co(III) cycling. Besides, the strong interaction between Zn and Co in outer bimetallic ZIFs effectively mitigated Co leaching, highlighting the synergy effect of the catalytic system with multiple active sites. The Fe3O4@ZIFs composites retained excellent catalytic proficiency after four successive cycles. This study provides a strategy to accelerate Co(II)/Co(III) circulation in heterogeneous systems and highlights the significant potential of MOFs in the construction of high-efficiency Co-based catalysts for PAA activation in environmental remediation.