Enhanced PMS activation and NSAID degradation selectivity by hydrophobic microenvironment regulation on Fe³⁺@Cu-MOF

In this study, the activation of peroxymonosulfate (PMS) and selective degradation of nonsteroidal anti-inflammatory drugs were investigated using hydrophobically modified Fe³⁺@Cu-MOF. The Fe³⁺@Cu-MOF-CTAB/PMS system demonstrated high-efficiency, achieving near-complete degradation of diclofenac within 120 min. The degradation rate constants for diclofenac, ibuprofen, and naproxen were 0.0048, 0.00103, and 0.00046 min⁻¹, respectively, positively correlated with their hydrophobicity. Longer hydrophobic surfactant chains in Fe³⁺@Cu-MOFs lead to greater initial adsorption of diclofenac, enhancing degradation efficiency upon the introduction of PMS. The Fe³⁺@Cu-MOF-CTAB/PMS system removes over 80 % of diclofenac in various water matrices, showing optimal efficiency in acidic environments but reduced effectiveness with competing anions. Post-degradation changes in the oxidation states of copper and iron in the MOF structure indicated a synergistic redox mechanism essential for PMS activation. The hydroxylation and C-N bond cleavage in diclofenac were key degradation pathways. This study highlights the potential of hydrophobically modified Fe³⁺@Cu-MOFs in water treatment, providing insights into the interplay between material design, hydrophobic interactions, and catalytic performance.