Investigation of Metal Porphyrin-Based Porous Organic Polymers for Catalytic Peroxymonosulfate Activation in the Degradation of Organic Pollutants

In this study, metal-porphyrin porous organic polymers (M-P/POP, where M = Fe, Co, or Cu) were synthesized and successfully applied as catalysts for PMS activation to degrade organic pollutants. The catalytic activity was attributed to the selective generation of high-valence metal oxo species (HVMOs: Fe(IV)=O, Co(IV)=O, and Cu(III)=O), which served as the primary reactive species in a non-radical electron transfer pathway. Mechanistic investigations, including quenching experiments, electron paramagnetic resonance (EPR) spectroscopy, and isotope labeling, confirmed that conventional radicals (•OH, SO4•−, and O2•−) contributed negligibly to pollutant degradation, further validating the predominance of the HVMO oxidation mechanism. The Fe-P/POP and Co-P/POP catalysts demonstrated superior catalytic performance compared to Cu-P/POP, achieving higher degradation efficiencies across a range of organic pollutants. Theoretical calculations revealed a strong correlation between pollutant ionization potential (IP) and degradation rate constants (K_obs), supporting the hypothesis that oxidation proceeded via electron transfer from the pollutant’s HOMO to the catalyst’s LUMO. Additionally, the M-P/POP/PMS system exhibited excellent stability, recyclability, and negligible metal leaching, confirming its feasibility for long-term applications. Overall, this study advances the understanding of PMS activation mechanisms and highlights the potential of M-P/POP catalysts for practical wastewater treatment. The combination of high efficiency, selective degradation pathways, and environmental sustainability makes M-P/POP a promising candidate for the removal of persistent organic pollutants in contaminated water sources.