Copper oxide nanoparticles (CuO-NPs): Synthesis, characterization and evaluating their ability to remove methylene blue from aqueous solutions without UV irradiation and in the absence of H2O2

Abstract

In this work, CuO nanoparticles (CuO-NPs) were synthesized at 400 °C using a modification of the polymer complex-Pechini method. Considering the procedure used, a mechanism was proposed to explain the formation of CuO-NPs. The synthesized nanoparticles were characterized using IR, Raman and UV–Vis spectroscopies, X-ray diffraction (XRD) and scanning electron microscopy (SEM). The results indicated that the sample synthesized contained CuO as the only crystalline phase, with a crystallite size between 9.17 and 14.95 nm, depending on the crystallographic direction and gap energy values of ∼4 eV and ∼5.86 eV. The CuO powder had agglomerates, in the order of microns, and primary particles smaller than 100 nm, with irregular morphology. The CuO synthetized was not stoichiometric and that it had an excess of oxygen, indicating the presence of cation vacancies and/or interstitial oxygen. The study of the capacity of CuO-NPs to remove methylene blue (MB), without irradiating the system with UV–Vis and without the presence of H2O2, showed that these promoted a percent removal of ∼39% in a basic medium (pH ∼9.7).