Effect of thermal treatment on green synthesis of zinc oxide using cosmos caudatus leaf extract as photocatalyst for degradation of methylene blue dye

Water pollution caused by synthetic dyes such as methylene blue (MB) is a growing environmental concern due to its toxicity, stability, and resistance to degradation. Conventional water treatment methods often face limitations such as high costs, low efficiency at trace concentrations, and secondary pollution. Photocatalysis using semiconductor materials like zinc oxide (ZnO) presents as promising alternative for dye degradation, particularly under UV light exposure. This research focuses on the green synthesis of ZnO nanoparticles using Cosmos caudatus leaf extract as a natural reducing and stabilizing agent. The main objective of this study is to explore the potential of plant-based synthesis in developing effective photocatalysts for wastewater treatment. Specifically, the study aims to evaluate the effect of different calcination temperatures (450 °C, 500 °C, and 550 °C) on the photocatalytic degradation efficiency of methylene blue dye. The biosynthesized ZnO will be prepared through a green synthesis method followed by heat treatment at selected calcination temperatures. The resulting samples will be characterized using Energy Dispersive X-ray Spectroscopy (EDX) and Fourier-transform infrared (FTIR) spectroscopy to determine their morphology properties and functional groups. The photocatalytic performance of the ZnO nanoparticles will be tested by monitoring the degradation rate of methylene blue dye under irradiation light. The expected outcome of this study is the development of a cost-effective and eco-friendly photocatalyst with high degradation efficiency, contributing to sustainable wastewater treatment technologies.