In this research, structural, magnetic properties and photocatalytic activity of cobalt ferrite spinel (CoFe₂O₄) nanoparticles were studied. The samples were characterized by X-ray powder diffraction (XRD), energy dispersive X-ray (EDX), scanning electron microscopy (SEM), transmission electronic microscopy (TEM), Brunauer–Emmett–Teller (BET), Fourier transform infrared spectroscopy (FTIR), and UV-visible diffused reflectance spectroscopy (DRS) analysis. The XRD analysis revealed the formation of the single-phase CoFe₂O₄ with a cubic structure that is annealed at 500–700 °C in 3 h. The optical band gap energy for CoFe₂O₄ was determined to be in the range of 1.57–2.03 eV. The effect on the magnetic properties of cobalt ferrites was analyzed by using a vibrating sample magnetometer (VSM). The particle size and the saturation magnetization of cobalt ferrite nanoparticles increased with increasing annealing temperature. The photocatalytic activity of CoFe₂O₄ nanoparticles was investigated by using rhodamine B dye under visible light. The decomposition of rhodamine B reached 90.6% after 270 min lighting with the presence of H₂O₂ and CF500 sample.

In this study, nanocrystalline ZnNd_xFe_2−xO₄ ferrites with x = 0.0, 0.01, 0.03 and 0.05 were fabricated and used as a catalyst for dye removal potential. The effect of Nd³⁺ ions substitution on the structural, optical and photo-Fenton activity of ZnNd_xFe_2−xO₄ has been investigated. The addition of Nd³⁺ ions caused a decrease in the grain size of ferrites, the reduction of the optical bandgap energies and thus could be well exploited for the catalytic study. The photocatalytic activity of the ferrite samples was evaluated by the degradation of Rhodamine B (RhB) in the presence of H₂O₂ under visible light radiation. The results indicated that the ZnNd_xFe_2−xO₄ samples exhibited higher removal efficiencies than the pure ZnFe₂O₄ ferrites. The highest degradation efficiency was 98.00%, attained after 210 min using the ZnNd_0.03Fe_1.97O₄ sample. The enhanced photocatalytic activity of the ZnFe₂O₄ doped with Nd³⁺ is explained due to the efficient separation mechanism of photoinduced electron and holes. The effect of various factors (H₂O₂ oxidant concentration and catalyst loading) on the degradation of RhB dye was clarified.

In this study, we adopted the solution combustion method to synthesize magnesium ferrite (MgFe₂O₄) using urea as the fuel. Various techniques including TGA, XRD, SEM, TEM, FTIR, UV-Vis DRS, and EDS were employed to characterize the synthesized MgFe₂O₄ nanoparticles. The XRD analysis revealed that single-phase MgFe₂O₄ was formed at a calcination temperature of at 500–600°C for 3 hours in the absence of an intermediate phase. TEM analysis also revealed the formation of monodisperse magnesium ferrite nanoparticles, averaged at 30 nm in size. The photocatalytic activity of the synthesized MgFe₂O₄ nanoparticles against methylene blue dye under visible light was investigated, showing the efficiency of 89.73% after 240 minutes of light irradiation with the presence of H₂O₂.

Many organic dyes including rhodamine B are persistent or degraded slowly, leading to long-term retention in the aquatic environment. Here, NiFe₂O₄/g-C₃N₄ was synthesized for the photocatalytic degradation of rhodamine B dye efficiently.

Doping of neodymium ions into CoFe ₂ O ₄ nanoparticles significantly boosted the photocatalytic activity of CoNd _x Fe _{2− x} O ₄ for the degradation of Rhodamine B dye. Up to 94.7% of dye was degraded under CoNd _0.05 Fe _1.95 O ₄ /H ₂ O ₂ /visible-light system.