Sorption of uranium(VI) from aqueous solutions by DEEA organo-volcanic: isotherms, kinetic and thermodynamic studies

The sorption of the uranium(VI) ions from aqueous solutions by diethylethanolammonium organo-volcanics (Kula-TURKEY) was investigated under different experimental conditions. DEEA was used to modify the surface of basaltic volcanics. The characteristic of basaltic volcanic was analyzed by XRF, SEM-EDS, FTIR, and XRD. The BET surface areas of unmodified volcanics and DEEA-modified volcanics were found as 2.265 and 3.689 m(2)/g, respectively. The volcanic samples were treated by using different concentrations of DEEA. The adsorption of U(VI) on natural and modified volcanics was examined as a function of the contact time, initial pH of the solution, initial U(VI) concentration, and temperature. Langmuir, Freundlich, and D-R adsorption isotherms were used to describe the adsorption. While examining the adsorption percentage and distribution coefficient, these values for unmodified volcanics were found to be 25% +/- 0.76 and 10.08 mL/g, while the values for the DEEA-modified volcanics were 88% +/- 1.04 and 220 mL/g, respectively. The pseudo-first-order and pseudo-second-order kinetic models were used to describe the kinetic data. In this study, it can be seen that the adsorption process is suitable for the pseudo-second-order kinetic model. Various thermodynamic parameters (Delta G degrees, Delta H degrees, and Delta S degrees) were calculated with the thermodynamic distribution coefficients obtained at different temperatures. The sorption process was a chemical adsorption process. The results indicated that the processes are spontaneous and endothermic.