Environmental photochemistry by cobalt doped magnesium ferrites: UV light assisted degradation of anionic azo and cationic thiazine dyes

Abstract

In the current study, cobalt magnesium ferrites (Mg_0.8-xCo_xFe₂O₄ for x values 0.2, 0.4 and 0.6) nanoparticles are prepared by combustion method. The morphology, optical, structural, photocatalytic, compositional and vibrational properties of Mg_0.8-xCo_xFe₂O₄ by the influence of cobalt doping is investigated. Fourier Transform Infrared (FTIR) Spectroscopy and X-ray diffraction (XRD) confirms the formation of spinel cubic phase of the prepared ferrites samples. The optical band gap energy shows a strong effect on crystallite size and increases from 4.2 to 4.4 eV as the concentration of cobalt gets increased. TEM images of Mg_0.8-xCo_xFe₂O₄ clearly reveal spherical nanoparticles with decreasing particle size which ranges from 16 to 10 nm. EDAX spectrum confirms the existence of Fe, Co, Mg and oxygen. The photocatalytic studies of Mg_0.8-xCo_xFe₂O₄ are performed for anionic and cationic dyes. The rate constant values of methylene blue are found as 0.017/min, 0.019/min and 0.022/min for Mg_0.8-xCo_xFe₂O₄ for x values 0.2, 0.4 and 0.6 respectively. The degradation efficacy of the prepared samples to degrade methylene blue is high (95%) and it indicates that they may be efficient in degrading environmental pollutants and may prove out to be competent photo-catalyst.

Keywords: Anionic azo dyes; Cobalt; Magnesium ferrite; Spinel; Thiazine dyes.