Effect of nickel oxide nanoparticles as a photocatalyst in dyes degradation and evaluation of effective parameters in their removal from aqueous environments

The main goal of this work was to investigate the factors that can be effective on the photocatalyst degradation of azo dyes with nickel oxide nanoparticles (NiO-NPs) in aqueous solutions. Among the semiconductor oxides, nickel oxide is commonly utilized due to containing strong chemical stability and high catalytic activity as a competent photocatalyst material for environmentally friendly applications in regards to the degradation of azo dye. Throughout the process of degradation, we have also examined other varying factors such as the pH, light source, amount of photocatalyst, the initial concentration of dyes, light intensity, radiation time, the presence of mineral ions, and type of solvent. This review presents a detailed evaluation that had been performed on the photocatalyst degradation of azo dyes through the means of NiO-NPs and UV light irradiation in wastewater treatment.