A comparative analysis of solar photocatalytic degradation of MB, RhB, and CV dyes with ZnO nanoparticles

This study reports the synthesis of ZnO nanoparticles via a simple co-precipitation method and their evaluation for solar-driven photocatalytic degradation of organic dyes. XRD analysis confirmed the formation of a hexagonal wurtzite phase with good crystallinity, while Raman spectroscopy further supported the structural integrity of ZnO. Transmission electron microscopy (TEM) revealed the morphology and particle-size distribution of the synthesized nanoparticles, and selected-area electron diffraction (SAED) indicated their polycrystalline nature. The photocatalytic performance of ZnO nanoparticles was investigated under natural sunlight using three model dyes: Methylene Blue (MB), Rhodamine B (RhB), and Crystal Violet (CV). UV–Visible spectroscopy showed a progressive decrease in dye concentration, following pseudo-first-order kinetics. The degradation efficiencies reached approximately 98% for MB, 93% for RhB, and 96% for CV within 160 min. XPS analysis suggests the presence of oxygen vacancy-related defect states, which may contribute to enhanced photocatalytic activity by influencing charge carrier dynamics. Overall, the study demonstrates the effectiveness of ZnO nanoparticles for solar-driven dye degradation under natural conditions. However, further investigations, including detailed optical characterization and stability studies, are required to fully assess their practical applicability in wastewater treatment.