Acceleration of the Fenton-Like Reaction by Carboxylated UiO-66(Zr)-Loaded Fe3O4: A Synergistic Catalytic Approach for Carboxylate-Bridged Curation to Enhance Degradation Efficiency

In Fenton-like reactions, the catalysts generally have an inherent drawback: Their active centers are prone to being lost from the catalyst supports, leading to a continuous decline in catalytic efficiency and causing secondary pollution. To address this issue, two catalysts, including Fe 3 O 4 @UiO-66(Zr) and Fe 3 O 4 @UiO-66(Zr)-COOH, were prepared in this study by confining Fe 3 O 4 active centers within the pores of UiO-66(Zr) and grafting -COOH groups to enhance metal coordination interactions. The Fe 3 O 4 @UiO-66(Zr)-COOH achieved 99% removal efficiency of carbamazepine within 5 min under the conditions of pH = 3.0, 40 mM H 2 O 2 , 20 mg·L −1 carbamazepine, and 2 g·L −1 catalyst. This efficiency far exceeded that of Fe 3 O 4 @UiO-66(Zr) (61.5%) and was 3.96 times higher than that of the Fenton-like system. The rapid degradation of CBZ was realized through stabilized active centers and enhanced metal coordination. In this work, the iron-based material was found to enhance the coordination between Fe and Zr. As confirmed by quenching experiments, electron spin resonance, electrochemical tests, and density functional theory calculations, ·OH and 1 O 2 were identified as the dominant active species. The -COOH, acting as electron bridges, enhanced electrical conductivity and reduced electron transfer barriers, thereby facilitating faster charge transfer processes. In addition, it was demonstrated by six cycles of experiments that Fe 3 O 4 @UiO-66(Zr)-COOH possessed excellent stability. It was also shown by the characterization of the catalyst after the cycles that both the performance and morphology of the composite material could be maintained unchanged.