Photocatalytic activity of cobalt substituted zinc ferrite for the degradation of methylene blue dye under visible light irradiation

Highlights: • Cobalt zinc ferrite catalyzes the removal of methylene blue dye from the water. • Degradation efficiency get enhanced with an increase in the cobalt ion concentration. • 77% of the methylene blue was removed by using cobalt zinc ferrite under visible light. • FT-IR patterns showed metal stretching vibrations at tetrahedral and octahedral sites. -- Abstract: Cobalt-zinc ferrite with composition Co_xZn_1-xFe₂O₄ (x = 0.0, 0.1, 0.2, 0.3, 0.4 and 0.5) was synthesized using citrate precursor method and the prepared samples were characterized by using X-ray powder diffractometry (XRD), Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM), Fourier Transform Infrared Spectroscopy (FT-IR) techniques. Single phase spinel structure was confirmed by the XRD patterns having (311) characteristic peak. SEM images showed the agglomeration of the powdered samples of cobalt-zinc ferrite. TEM images record an average crystallite size of 52 nm. Visible range light was used for the photocatalytic degradation of methylene blue by creating a Fenton-type system. It was observed that the degradation of methylene blue was enhanced with an increase in cobalt concentration. The degradation efficiency reached a maximum (77%) for x = 0.5 while it was the smallest (∼65%) for x = 0.0 in 1 h under visible light irradiation. Hence, we conclude that cobalt-zinc ferrite can be used as a potential material for purification of water and its degradation efficiency increased with an increase in cobalt concentration.