The effect of calcination temperatures on the structural and optical properties of zinc oxide nanoparticles and their influence on the photocatalytic degradation of leather dye

Abstract

The challenge of dealing with synthetic dye pollution in waste from the leather industry requires continual research and development. Although numerous dyes used in the textile, food, and other industries have been found to be degraded by photocatalyst based on zinc oxide nanoparticles (ZnO NPs), no thorough studies on the degradation of leather dye from dye-containing wastewaters from tanneries have been reported to date. Hence, this study investigates the efficient photocatalytic destruction of leather dye using ZnO NPs produced by chemical precipitation method. The influence of calcination temperatures ranging from 400 to 600 °C on the structural and optical characteristics of ZnO NPs was investigated. XRD examination revealed an increase in crystallite size as the calcination temperature increased, presumably due to the merger of smaller crystallites into larger ones. Meanwhile, the polycrystalline and wurtzite structure of the synthesized ZnO NPs was observed, with particle diameters ranging from 40 to 90 nm and an average size of around 62 nm. UV–vis spectra revealed a decrease in energy band gap (3.15 to 3.05 eV), which was ascribed to an increase in crystallite size produced by higher calcination temperature from 400 to 600 °C. The photocatalytic degradation of leather dye was studied further. It has been demonstrated that ZnO NPs synthesized at a calcination temperature of 400 °C can remove 90% of the leather dye in 30 min. The dynamics of deterioration were also studied. It was discovered that the degradation of leather dyes best fitted the pseudo-first-order kinetics, with superoxide ions being the most likely species.