Fe/Cu Bimetallic Nanoparticles Highly Dispersed in MOF-Derived N-Doped Porous Carbon as Stable Heterogeneous Fenton Catalysts for Enrofloxacin Degradation

Metal–organic frameworks (MOFs) were used as precursors to prepare iron-based heterogeneous Fenton catalysts Fe@C, FeCu@C, and FeCu@N–C via pyrolysis. The catalytic activities were evaluated by measuring the decomposition rate of hydrogen peroxide (H₂O₂). The morphology, structure, and physical properties of the catalysts were analyzed through X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), and nitrogen adsorption. The results showed that at 60 min, the decomposition rates of H₂O₂ by FeCu@C and FeCu@N–C were 95.4% and 92.5%, respectively, which were 18.5% and 15.6% higher than that by Fe@C, respectively. It was speculated that the iron and copper species present in the bimetallic nanoparticles were available active sites for the Fenton reaction. The synergistic effects between them can promote the activation and decomposition of H₂O₂. In addition, the nitrogen-doped catalysts FeCu@N–C had better pH applicability, better reusability, and lower iron leaching than FeCu@C. Nitrogen-doped carbon contributed to the enhanced catalytic performance. This can be attributed to the well dispersibility of Fe and Cu species on the N-doped carbon matrix. The FeCu@N–C was applied to the treatment of enrofloxacin (ENR) antibiotic wastewater. The results indicated that a 90% degradation rate can be achieved in 60 min under the initial concentration of ENR 20 mg/L, catalyst dosage 20 mg/L, H₂O₂ concentration 1.5 mM, the initial solution pH 3.60, 25 ℃. The rapid degradation of ENR was more relevant to the surface-bound ٠OH rather than free ٠OH and the heterogeneous Fenton reaction played the dominant role. This work provides a potential heterogeneous Fenton catalyst for antibiotics wastewater treatment.