Impact of metal ions (Cr3+, Co2+, Ni2+, Cu2+ and Zn2+) substitution on the structural, magnetic and catalytic properties of substituted Co-Mn ferrites synthesized by sol-gel route

Manganese substituted cobalt ferrites (CoMn (x) Fe2-x O-4, x = 0.2, 0.4, 0.6, 0.8 and 1.0) synthesized using sol gel autocombustion method were used as photocatalysts for the degradation of both cationic and anionic dyes i.e Safranine-O and Remazol Brilliant yellow. CoMn0.4Fe1.6O4 exhibited maximum photocatalytic activity among all the synthesized ferrites. To further study the effect of metal ion doping on catalytic performance, substitution with different metal ions (Cr3+, Co2+, Ni2+, Cu2+ and Zn2+) was done in CoMn0.4Fe1.6O4 lattice. The structural and magnetic properties of prepared samples were investigated using powder X-ray diffraction, Fourier transform infrared spectroscopy and vibrating sample magnetometer. The average crystallite size of the synthesized nanoparticles was observed to be in the range of 39-52 nm. The saturation magnetization of the samples was found to decrease with the introduction of all metal cations (except Co2+) in the Co-Mn lattice. The changes in the catalytic activity were tested for degradation of Safranine-O and Remazol Brilliant yellow. Amongst the synthesized CoMn0.4M (x) Fe1.6-x O-4, Cu substituted Co-Mn ferrite exhibited maximum photocatalytic efficiency. All the magnetic nanoferrites were easily recovered by using an external magnet and could be reused without any remarkable change in catalytic efficiency.