Structural, optical, and photocatalytic properties of Ni–Zn and Mg-Zn spinel ferrites

The present work describes the synthesis of spinal ferrite nanoparticles with the chemical formula: Ni_0.5Zn_0.5Fe₂O₄ (Ni-Zn) and Mg_0.5Zn_0.5Fe₂O₄ (Mg-Zn) by solution combustion technique and investigates its photocatalytic property for the removal of methylene blue (MB) and malachite green (MG) dye from the contaminated wastewater. The X-ray diffraction analysis revealed the arrangement of spinel cubic unit cell with space group fd-3 m. The crystallite size of 14.93 nm and 21.49 nm is calculated using Scherrer’s formula for Ni-Zn and Mg-Zn, respectively. Based on the Williamson-Hall plot analysis, the contribution of both crystallite size and strain were distinguished for the catalyst material. Energy dispersive spectroscopy results verify the existence of Mg and Ni as dopant in respective samples. The transmittance at 587 and 591 cm^− 1 in FTIR spectra supports the results with the formation of tetrahedrons in Ni-Zn and Mg-Zn ferrites, respectively. The optical properties of the prepared samples were evaluated using UV-visible spectroscopy and the band gap was calculated to be 1.73 eV and 1.98 eV for Ni-Zn and Mg-Zn ferrite, respectively. According to the photocatalytic study, under UV light irradiation removal rates for MB and MG were found to be 89.9% and 89.06% respectively. This concludes that Ni-Zn and Mg-Zn are suitable candidates for removal of MB and MG dye by photocatalytic reaction.