Synthesis of Gd2O3 Nanoparticles and Their Photocatalytic Activity for Degradation of Azo Dyes

Gadolinium oxide (Gd2O3) nanoparticles were prepared via the reaction of gadolinium nitrate hexahydrate (Gd (NO3)(3)center dot 6H(2)O) and ethylamine (C2H5NH2), and their surface morphology, particle size, and properties were examined by using scanning electron microscopy, X-ray diffraction (XRD), Raman spectroscopy, Fourier transform infrared (FT-IR) spectroscopy, and ultraviolet visible (UV-vis) spectroscopy. The Gd2O3 nanoparticles were used as the photocatalyst for the degradation of various azo dyes, such as methyl orange (MO), acid orange 7 (AO7), and acid yellow 23 (AY23) under irradiation with UV light. The effect of the experimental parameters (initial concentration of azo dyes, dosage of catalyst, and wavelength of UV light) on the photocatalytic properties of the Gd2O3 nanoparticles were investigated. At a constant H2O2 concentration, the photocatalytic degradation efficiency of the Gd2O3 nanoparticles for various azo dyes was in the order: methyl orange > acid orange 7 > acid yellow 23. The kinetics study showed that the photocatalytic degradation of azo dyes was followed by a pseudo first-order reaction rate law.