The aim of this work is the synthesis of NiFe₂O₄ and Co-doped NiFe₂O₄ nanoparticles to catalyze photodegradation of direct red 264 under visible light. So, NiFe₂O₄ and Co-doped NiFe₂O₄ nanoparticles were synthesized by a sol-gel auto-combustion method. The catalysts were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), Fourier transform infrared (FT-IR) and diffuse reflectance spectra (DRS).

In recent years, the waterways polluted with azo dyes cause serious environmental problems, so they must be removed. Direct Red 264 (DR264) was used as a model. The effects of NiFe₂O₄ and Co-doped NiFe₂O₄ nanoparticles as catalysts were studied on photocatalytic degradation of DR 264 in typical wastewater using visible light irradiation. UV-vis spectrophotometer was used to measure concentration of dyes before and after degradation.

The effects of doping on dye degradation were investigated. The results shows doping did not remarkable effect on photocatalytic properties.