Microwave-synthesized eco‑friendly copper(II) oxide nanoparticles for photocatalytic dye removal

Copper(II) oxide (CuO) nanoparticles were synthesized via a microwave-assisted route using copper(II) nitrate and oxalic acid as precursors. The obtained material was characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive spectroscopy (EDS), Fourier-transform infrared spectroscopy (FT-IR), and thermogravimetric analysis (TGA). XRD analysis confirmed the formation of crystalline monoclinic CuO, while SEM images revealed particles in the size range of approximately 80–110 nm. The photocatalytic activity of the synthesized CuO nanoparticles was evaluated through the degradation of Orange G (OG) dye under 254 nm UV irradiation. Under the investigated experimental conditions, a maximum degradation of approximately 28% was achieved within 90 minutes. Kinetic analysis indicated that the degradation data showed the best linear fit with a second-order model (R² ≈ 0.94) among the evaluated kinetic models. The observed photocatalytic behavior is attributed to the generation of electron–hole pairs under UV irradiation, leading to the formation of reactive oxygen species responsible for dye degradation. While the obtained degradation efficiency is moderate, the results demonstrate that microwave synthesis provides a simple and rapid method for preparing CuO nanoparticles suitable for photocatalytic studies. Further optimization of catalyst properties and reaction parameters are required to enhance performance. • The potential of CuO nanoparticles as cost-effective, eco-friendly photocatalysts for wastewater treatment, aligning with green chemistry goals. • Microwave-Assisted and Dry Synthesis of CuO nps. • Different Characterization Techniques as XRD, EDS, FT-IR as well as TGA • CuO nps were utilized as efficient photocatalysts for the degradation of Orange G dye under UV light via the generation of reactive oxygen species (ROS). • The dye degradation rate fits a second-order model (R² = 0.94), suggesting the reaction depends on the concentration of both the dye and the photocatalyst. T