Substituted Mg–Co-nanoferrite: recyclable magnetic photocatalyst for the reduction of methylene blue and degradation of toxic dyes

Abstract

Spinel structured CoFe₂O₄, have gained much importance in recent years due to their high coercivity, high Curie temperature, narrow bandgaps and, strong chemical and mechanical stability. In this work, we focus on the photocatalytic study by investigating the optical characteristics of Mg-substituted nano-crystallite CoFe₂O₄ with nominal compositions such as Co_1−xMg_xFe₂O₄ (x = 0.0, 0.3, 0.6, 0.9 and 1.0), prepared by sol–gel auto combustion method. As-prepared samples were then calcined at 600 °C for 6 h. X-ray diffraction determined a cubic spinel structure of all the samples. Microstructure observed using a scanning electron microscope revealed well-shaped, homogenously dispersed grains of almost uniform sizes. UV–Vis spectrophotometer was utilized to determine the energy band gaps of the samples. Magnetic and photocatalytic properties were discussed using vibrating sample magnetometer and a photoreactor, respectively. It has been observed that saturation magnetization and band gap values were decreased by increasing Mg concentration but at the same time enhanced the photocatalytic behaviour, with maximum activity at 60 % of Mg contents.