Photocatalytic degradation of direct blue 129 dye in the presence of nanostructured zinc chromite

A large variety of spinel-type families has been extensively studied, as to which the correlation between the substitute ions and the physical properties of the final compound has been reported. These materials are very attractive in both scientific and technological importance. Since the transport properties of this type of spinel vary when it comes into contact with gaseous atmospheres, it has been utilized as the basis for sensing devices, particularly in the regard to humidity [1]. The ability to obtain single-phase ZnCr2O4 nanoparticles with controllable particle size and size distribution improves its adequacy in an extensive range of innovative technological application. In order to obtain single-phase ZnCr2O4 with the appropriate physical and chemical properties, its synthesis via different methods has become an important area of research and development [2]. ZnCr2O4 crystallizes in the cubic system and has a normal spinel structure. In this mixed oxide ZnCr2O4 nonmagnetic Zn2+ and magnetic Cr3+ ions have a strong preference for the tetrahedral A-sites and the octahedral B-sites, respectively. It is a geometrically frustrated antiferromagnet with a first order transition at 12.5 K from paramagnetic phase with cubic structure to antiferromagnetic phase with tetragonal structure. The nanocrystalline ZnCr2O4 spinel has many applications, e.g., as catalysts, sensors for toxic gases and semiconductors. ZnCr2O4 is also very attractive as air depollution catalytic material, for a variety of reactions like oxidation of hydrocarbons, oxidative dehydrogenation of hydrocarbons, synthesis of methanol, as gas sensing, humidity sensing and photocatalyst [3-5]. In this work, zinc chromite nanostructures have been synthesized through sol-gel method. The synthesized products were characterized by field emission scanning electron microscopy (FESEM), X-ray diffraction (XRD), fourier transform infrared (FT-IR) spectra and X-ray energy dispersive spectroscopy (EDS). The X-ray powder diffraction (XRD) confirmed the formation of cubic spinel phase ZnCr2O4. The photocatalytic activity of ZnCr2O4 nanoparticles was confirmed by degradation of direct blue 129 under visible light irradiation. The effects of process parameters like, catalyst dosage, initial dye concentration, and visible light irradiation on dye degradation have been investigated.