Abstract

Environmental pollution caused by untreated effluents from Paper, textile, printing, and several other industries is of serious concern. These industries generate a tremendous amount of wastewater contaminated with harmful chemicals. Methylene blue dye finds important application in pharmaceuticals to treat methemoglobinemia: a rare blood disorder. However, while present in drinking water or food material, methylene blue (MB) dye is a serious health hazard as it is carcinogenic and non-biodegradable that can cause a threat to human health and environmental safety. Hence, there is a need to develop an environmental friendly, and efficient technology for removing MB from wastewater. The usual physical and chemical methods employed for the removal of dyes are less efficient, costlier, and generate solid waste with adverse environmental impact. In the present work, Zinc oxide (ZnO) nanoparticles were synthesized by hydrolysis and oxidative method. As-synthesized ZnO powder was characterized using X-ray diffraction, and UV visible spectroscopic techniques. Photocatalytic degradation of methylene blue dye, catalyzed by as-synthesized ZnO nanoparticles, has been carried out in aqueous medium under UV radiation. The effects of operating parameters, such as amount of ZnO catalysts, pH, and initial concentration of dye on MB degradation, were investigated. The photo-catalytic degradation of MB was found to follow the pseudo-first-order kinetic model. Using ZnO optimum load 250 mgL1 , solution pH 10, the degradation of 20 mgL-1 MB was 85% at 3 hrs. Keeping in view its low cost, and high photocatalytic efficacy, the nanosize ZnO can be used for a large scale treatment of wastewater contaminated with methylene blue dye as pollutant.

Keywords

nanoparticles, methylene blue, kinetic, photocatalytic, degradation