Title : Utilization of waste eggshell-supported ZnO photocatalyst for efficient photodegradation of methylene blue dye irradiation under sunlight

The increasing discharge of dye-containing wastewater from textile and related industries poses a significant threat to aquatic ecosystems and human health. In this study, a low-cost and eco-friendly ZnO/eggshell powder composite photocatalyst was synthesized and evaluated for the degradation of methylene blue (MB) dye under natural sunlight irradiation. Waste eggshells, primarily composed of calcium carbonate, were collected, cleaned, dried, and ground into fine powder before being used as a support material for zinc oxide (ZnO). The composite was prepared through a simple precipitation method followed by drying and calcination. The photocatalytic performance of the synthesized ZnO/eggshell powder was investigated using aqueous methylene blue solutions under sunlight exposure. The degradation efficiency was monitored by measuring the decrease in dye concentration at regular intervals using UV–Visible spectrophotometry. The results demonstrated that the ZnO/eggshell composite exhibited enhanced photocatalytic activity compared to untreated eggshell powder, owing to the synergistic effects of dye adsorption by the eggshell matrix and photocatalytic oxidation by ZnO. Reactive oxygen species generated upon sunlight irradiation effectively degraded the dye molecules into less harmful products. The study highlights the potential of utilizing waste eggshells as a sustainable support material for ZnO-based photocatalysts, providing an economical and environmentally friendly approach for the treatment of dye-contaminated wastewater.

Dr. Baskar Malathi is currently working as a Research Assistant in University of Sharjah, United Arab Emirates. She completed her Double Doctorate from Shizuoka University, Japan and SRM IST, India in the field of Optoelectrical and Nanotechnology. She obtained a B.Sc., degree from Bharathidasan Government college for women in India and an M.Sc., degree from Kanchi Mamunivar Centre for Post graduate studies and research in India. She was awarded Monbukagusho Japanese government fellowship. Her research interest includes Gas sensors, Photocatalysis, Nanomaterial synthesis and characterization.