Fenton-Like Reaction-Driven Intrinsic Electron Transfer in Metal–Organic Complex Molecular Reactors for Photocatalytic Uranium Removal

The leaching and nonrecoverability of metal ions have persistently constrained the practical application of Fenton-like processes. To address this limitation, this study synthesized Schiff base-based metal-organic complexes (MOC-M) for efficient U(VI) removal via a Fenton-like reaction-driven strategy. This strategy synergistically coupled metal valence cycling and ligand stability. Under 30 min of visible light irradiation, the Fe-based complex (MOC-Fe) achieved efficient U(VI) removal. The corresponding rate constant was 0.098, which was approximately 1.66 and 4.26 times higher than those of MOC-Cu and MOC-Co complexes, respectively, demonstrating MOC-Fe's superior catalytic efficiency. Furthermore, MOC-Fe exhibits 93% activity after four cycles in real uranium mine wastewater and displays resistance to ionic interference (efficiencies greater than 95% under 5 mM Na₂CO₃), thus demonstrating its potential for use in engineering applications. We attribute this efficient uranium removal to metal valence cycling (Fe²⁺/Fe³⁺) and ligand-to-metal charge transfer, synergistically driving •O₂^- generation. The resulting •O₂^- radicals produce substantial H₂O₂, which coordinates with UO₂²⁺ to form insoluble (UO₂)O₂·2H₂O via peroxo-complexation. This study provides valuable insights for advancing Fenton-like technologies and radioactive environmental remediation.