Optimization of adsorption parameters for removal of 152+154Eu(III) from aqueous solutions by using Zn-Cu-Ni ternary mixed oxide

Abstract

A novel Zn-Cu-Ni ternary mixed oxide with a molar ratio of 1:4:1 was synthesized in the current study via coprecipitation method. The material was characterized by Fourier transform infrared (FTIR), scanning electron microscope and thermogravimetric-differential thermogravimetric (TG-DT) analysis and was employed as an adsorbent for removal of 152+154Eu(III) radionuclides from aqueous solutions. Various important parameters were studied to determine the optimum conditions for the studied adsorption process. The kinetic studies showed that the equilibrium was attained within 24 h. Both kinetic and equilibrium data were analyzed by several kinetic (modified second order, Lagergren, double exponential and intraparticle diffusion) and isotherm (Tempkin, Dubinin-Radushkevich, Freundlich and Redlich-Peterson) models. The maximum adsorption capacity achieved for Zn-Cu-Ni ternary mixed oxide (56.42 mg Eu(III)/g) was not only compared with those obtained by using its parent oxides (Zn-oxide, Cu-oxide, Ni-oxide and CuNi oxide), but also with those reported in literature for other adsorbents. The effect of the solution pH was studied in the range 2–8. The influence of temperature on adsorption process of 152+154Eu(III) radionuclides onto Zn-Cu-Ni ternary mixed oxide was studied and the thermodynamic parameters (enthalpy change ΔHo, free energy change ΔGo and entropy change ΔSo) were estimated. The performance of the irradiated adsorbent at different gamma doses was evaluated. Numerous reagents (HCl, NaCl, CaCl2, MgCl2 and AlCl3) at different concentrations were evaluated as desorbents for desorption of 152+154Eu(III) loaded onto Zn-Cu-Ni ternary mixed oxide. The obtained results in this study show the effectiveness of the synthesized material for removal of 152+154Eu(III) from aqueous solutions.