Mechanism insights into metal-organic framework-derived carbon materials activating periodate for p-chlorophenol removal: The role of S and Fe co-doping

Periodate (PI, IO₄⁻)-based advanced oxidation processes (AOPs) provide an economical and sustainable approach to alleviate water pollution challenges. Developing efficient and stable activators for PI is the focus of current research. Herein, S/Fe-co-doped magnetic porous carbon material (S/Fe-ZIF-950) was prepared by introducing exogenous S atoms using Fe-doped zeolitic imidazolate framework-8 (Fe-ZIF-8) as a precursor, which showed the most superior performance (100 % within 10 min) in activating PI to remove p-chlorophenol (4-CP). Quenching tests, electron spin resonance and electrochemical characterizations revealed that IO₃·, ¹O₂, ·O₂⁻ dominated the 4-CP degradation process with Fe₃C and ZnS as the main active sites. The synergistic effect of S and Fe was the main reason for the enhanced degradation performance of 4-CP in S/Fe-ZIF-950/PI system, among which the reducing S²⁻ could effectively promote the regeneration of Fe(Ⅱ), thus facilitating the continuous generation of active species. Combined with LC-MS results and density functional theory (DFT) calculations, possible degradation routes of 4-CP in the S/Fe-ZIF-950/PI system were presented. Moreover, toxicity assessment showed that the S/Fe-ZIF-950/PI system exhibited low biotoxicity and no toxic iodine by-products were formed. In addition, S/Fe-ZIF-950/PI system demonstrated excellent activity, good stability, outstanding reusability and durability in a variety of complex water environments. This study investigated the activation mechanism of S/Fe-co-doped porous carbon materials on PI, which shed a new light on the catalytic activation of PI by heteroatom-doped Fe-loaded carbon-based materials.