Transforming goethite into high-valent iron active centers on montmorillonite‑carbon paired minerals for singlet‑oxygen-dominated peroxydisulfate water oxidation

Phthalate esters (PAEs), widely used as plasticizers, persist as recalcitrant organic pollutants with severe ecological implications. In this study, a dual-step pyrolysis strategy was employed to engineer a Fe-N-RHC@p-MMt composite photocatalyst enriched with high-valent Fe sites, nitrogen dopants, and oxygen vacancies. The tailored hybrid achieved a remarkable 92 ± 1.4% degradation of dimethyl phthalate (DMP) with a pseudo-first-order rate constant of 0.64 min −1 in a peroxydisulfate (PDS)-mediated oxidation system under near-visible light irradiation. Structural and spectroscopic analyses revealed graphitized carbon frameworks with superior conductivity, efficient charge migration, and abundant Fe(IV) = O species formation. Mechanistic analysis reveals that Fe₄N centers regulate interfacial electron transfer, stabilize high-valent Fe(IV) = O species, and drive selective non-radical PDS activation dominated by singlet oxygen ( 1 O₂). Moreover, the generated intermediates exhibited significantly reduced toxicity, mutagenicity, and bioaccumulation risks (although intermediates P1, P3, and P6 showed elevated toxicity), validating the process's environmental compatibility. These results highlight Fe-N-RHC@p-MMt as a safe and efficient catalyst for sustainable remediation of PAE-contaminated water.