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Nanophotocatalysts are becoming increasingly popular for removing heavy metals from wastewater, degrading organic pollutants, and producing hydrogen. In this work, MgFe2O4 nanoparticles were prepared by a sol‐gel process to study the photocatalytic degradation of crystal violet (CV), rhodamine blue (RhB), and methylene blue (MB) dyes under sunlight irradiation. The prepared MgFe2O4 nanoparticles were calcined at 500°C and then treated with nonthermal microwave plasma for 60 min. The X‐ray diffraction (XRD) analysis revealed that the crystallinity of plasma‐treated MgFe2O4 nanoparticles increased by showing a different cation distribution compared with plasma‐treated nanoparticles based on the intensity ratios of (220), (400), and (420) diffraction peaks. The intensity ratios of XRD peaks decreased, and the lattice parameter increased after plasma treatment. Crystallite size also increases after plasma treatment. The optical band gap energy of the treated ferrites decreased from 2.21 eV to 2.17, showing increased light absorption in the visible region compared with pristine ferrites. The saturation magnetization of magnetic photocatalysts increased from 40.9 emu/g to 62.16 emu/g after plasma modification. The photocatalytic activity for CV, RhB, and MB degradation increased from 60%, 65%, and 53% to 90%, 91%, and 87% after plasma modification. Plasma treatment enhances dye degradation by promoting the formation of reactive species that can effectively break down the dye molecules. [ABSTRACT FROM AUTHOR]

The influence of microwave (MW) plasma on magnetization and morphology of sol-gel synthesized MnFe2O4 ferrite nanoparticles is investigated in this study. Manganese (II) nitrate hexahydrate, ferric (III) nitrate nanohydrate and citric acid were used to synthesize ferrite nanoparticles via a facile sol-gel route. These ferrite nanostructures were heat-treated at 700°C and then given MW plasma treatment for 10 min. The pristine MnFe2O4 and plasma treated MnFe2O4 showed almost similar structural formation with a slight increase in crystallinity on plasma treatment. However, XRD peak intensity slightly increased after plasma treatment, reflecting better crystallinity of the nanostructures. The size of the particle increased from 35 nm to 39 nm on plasma treatment. It was challenging to deduce the surface morphology of the nanoparticles since both samples were composed of a mixture of big and small clusters. Clusters that had been treated with plasma were larger in size than pristine ones. The band gap energy of the pristine MnFe2O4 sample was about 5.92 eV, which increased to 6.01 eV after treatment with MW plasma. The saturation magnetization of MnFe2O4 sample was noted about 0.78 emu/g before plasma treatment and 0.68 emu/g after MW plasma treatment. [ABSTRACT FROM AUTHOR]