Magnetic hierarchical flower-like Fe(3)O(4)@ZIF-67/CuNiMn-LDH catalyst with enhanced redox cycle for Fenton-like degradation of Congo red: optimization and mechanism

ABSTRACT: A novel flower-like CuNiMn-LDH was synthesized and modified, to obtain a promising Fenton-like catalyst, Fe(3)O(4)@ZIF-67/CuNiMn-LDH, with a remarkable degradation of Congo red (CR) utilizing H(2)O(2) oxidant. The structural and morphological characteristics of Fe(3)O(4)@ZIF-67/CuNiMn-LDH were analyzed via FTIR, XRD, XPS, SEM-EDX, and SEM spectroscopy. In addition, the magnetic property and the surface’s charge were defined via VSM and ZP analysis, respectively. Fenton-like experiments were implemented to investigate the aptness conditions for the Fenton-like degradation of CR; pH medium, catalyst dosage, H(2)O(2) concentration, temperature, and the initial concentration of CR. The catalyst exhibited supreme degradation performance for CR to reach 90.9% within 30 min at pH 5 and 25 °C. Moreover, the Fe(3)O(4)@ZIF-67/CuNiMn-LDH/H(2)O(2) system revealed considerable activity when tested for different dyes since the degradation efficiencies of CV, MG, MB, MR, MO, and CR were 65.86, 70.76, 72.56, 75.54, 85.99, and 90.9%, respectively. Furthermore, the kinetic study elucidated that the CR degradation by the Fe(3)O(4)@ZIF-67/CuNiMn-LDH/H(2)O(2) system obeyed pseudo-first-order kinetic model. More importantly, the concrete results deduced the synergistic effect between the catalyst components, producing a continuous redox cycle consisting of five active metal species. Eventually, the quenching test and the mechanism study proposed the predominance of the radical mechanism pathway on the Fenton-like degradation of CR by the Fe(3)O(4)@ZIF-67/CuNiMn-LDH/H(2)O(2) system. GRAPHICAL ABSTRACT: [Image: see text] SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1007/s11356-023-27430-2.