Sol-Gel Synthesis of NiO/CuO Nanocomposites for Uptake of Rare Earth Elements (Ho, Yb, and Sm) from Aqueous Solutions

Abstract

NiO/CuO nanocomposites are synthesized successfully by sol-gel method and employed for the uptake of rare earth elements (Ho, Yb, and Sm) from aqueous solutions. NiO/CuO nanocomposites have been characterized by FT-IR, SEM-EDAX, and X-ray diffraction (XRD). Results of XRD analysis show the crystal structure of NiO/CuO with average sizes between 50–80 nm. The SEM photographs show granular and plate morphology of nanoparticles with high uniformity. FTIR spectra show a broad band at 480–486 cm–1, which are corresponded to the Cu–O bond in the CuO structure and a broad band in the range of 440–470 cm–1, this band is assigned to the Ni–O bond stretching vibrations. Various parameters including pH, contact time; initial concentration and temperature were optimized to achieve maximum adsorption capacity. The adsorption efficiency of Yb(III), Sm(III), and Ho(III) are 97, 96, and 96% on NiO/CuO-500 and 92, 94 and 93% on NiO/CuO-800, respectively, under room temperature, pH 5 and 300 min. The adsorption kinetics of Ho(III), Yb(III), and Sm(III) have been described by pseudo-first order mechanism. The thermodynamics studies confirm that the adsorption is exothermic. The results indicate that the nanocomposite is an efficient adsorbent with good adsorption capacity for Ho(III), Yb(III), and Sm(III).