Abstract
Herein the novel natural bimetallic oxides of perovskite oxides (CaTiOx) and calcium aluminum oxides (CaAlOx) were fabricated by one-step calcination-oxidation process under air conditions and were characterized using zeta potential, FT-IR, SEM, TEM, XRD, and XPS techniques. Potous and cotton-shaped irregular surface morphologies of CaTiOx and CaAlOx could provide excellent active sites and large specific surface area for the removal of U(VI) from wastewater. Based on FT-IR, XRD and XPS analyses, the enrichment of U(VI) was attributed to the abundant adsorption sites (e.g., M-O groups) of CaTiO, and CaAlOx. The consequences demonstrated that the sorption of U(VI) on CaTiOx and CaAlOx were strongly dependent on pH and weakly dependent on ionic strength at pH < 4.0, while strongly dependent on pH and ionic strength at pH > 4.0. The accordance of sorption kinetic data with the pseudo-second order model suggested that the sorption reaction was multi-stage controlled chemical process. The sorption isotherms of U(VI) can be satisfactorily simulated by the Langmuir model and the maximum monolayer sorption capacities of U(VI) were 241.71 mg.g(-1) on CaTiOx and 258.29 mg.g(-1) on CaAlOx at 298.15 K. In addition, the thermodynamic results pointed out that the sorption reaction was spontaneous and endothermic process. The sorption mechanism was interpreted as surface complexation and electrostatic interactions. The results demonstrated that CaTiOx and CaAlOx could be widely used as promising and cost-effective materials for the treatment of U(VI) of aqueous solutions in environmental management and pollution prevention and cure. (C) 2017 Elsevier B.V. All rights reserved.