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NiO-NiFe<sub>2</sub>O<sub>4</sub>-rGO Magnetic Nanomaterials for Activated Peroxymonosulfate Degradation of Rhodamine B

Xu, Xiaochen, Li, Yanfang, Zhang, Guoquan, Yang, Fenglin, He, Ping
Water 2019 v.11 no.2
X-ray diffraction, X-ray photoelectron spectroscopy, ambient temperature, catalysts, catalytic activity, ecosystem services, electron paramagnetic resonance spectroscopy, energy-dispersive X-ray analysis, free radicals, magnetism, nanoparticles, nickel, pollutants, rhodamines, scanning electron microscopy, transmission electron microscopes, transmission electron microscopy
Magnetic spinel ferrites that act as heterogeneous catalysts and generate powerful radicals from peroxymono-sulfate (PMS) for the degradation of organic pollutants have received much attention in recent years due to the characteristic of environmental benefits. In this study, NiO-NiFe<inf>2</inf>O<inf>4</inf>-rGO magnetic nanomaterials were synthesized using a calcinated Ni-Fe-LDH-rGO precursor. The morphology, structure, and chemical constitution were characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), X-ray energy dispersive spectroscopy (EDS), transmission electron microscope (TEM), N<inf>2</inf> adsorption-desorption isotherms, X-ray photoelectron spectroscopy (XPS), and vibrating sample magnetometer (VSM). The catalytic performance of NiO-NiFe<inf>2</inf>O<inf>4</inf>-rGO nanoparticles was thoroughly evaluated for peroxymonosulfate (PMS) activation and its removal of rhodamine B (RhB) from water. The influence of different process parameters on the RhB degradation efficiency was examined. Further, the catalytic stability was evaluated. Under optimized conditions, the NiO-NiFe<inf>2</inf>O<inf>4</inf>-rGO/PMS system was very efficient; RhB fully degraded after 40 min at room temperature. Quenching experiments and electronic paramagnetic resonance (EPR) results suggested that SO<inf>4</inf>&minus;&middot; and OH&middot; were the main active species in the degradation process. Moreover, NiO-NiFe<inf>2</inf>O<inf>4</inf>-rGO catalyst was stable without any apparent activity loss after three cycling runs.