Effective photocatalytic degradation of methylene blue (MB) and reactive red 120 (RR120) using Al substituted ZnO nanoparticles

Abstract

The discharge of dyes into the environment from industries can have an adverse impact on human and aquatic health, even at low concentrations. Therefore, this work aims to eliminate the toxic dyes using aluminium (Al) substituted ZnO nanoparticles (NPs) before they mix into the water bodies. The substitution of Al modifies its crystal structure and extends its optical absorption, that improves the photocatalytic activity of ZnO NPs. The X-ray diffraction of the prepared NPs exhibited a well-defined wurtzite phase of ZnO. The crystallite size of ZnO nanoparticles decreases with an increase in Al concentration. The scanning electron microscopic images of Al substituted ZnO NPs revealed vertically aligned rod-like particles. The size of synthesized particles decreased by rising the concentration of Al, and this impact was due to the inhibition of particle growth. The band gap of the Al substituted ZnO decreased compared to pure ZnO. The 20 mg of Al (5%) substituted ZnO catalysts degrade 99.7% of methylene blue (MB) and 99.6% of reactive red 120 (RR120) with rate constants of 0.01701 min−1 and 0.0680 min−1. The 5% Al substituted ZnO NPs were found to be an efficient catalyst for the removal of toxic contaminants in water.