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

The sorption of the uranium(VI)ions from aqueous solutions by diethylethanolammonium organovolcanics(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 as2.265and3.689m2/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 be25%±0.76and10.08mL/g,while the values for the DEEA-modified volcanics were88%±1.04and220mL/g,respectively.The pseudo-first-order and pseudo-secondorder 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(ΔG°,ΔH°,andΔS°)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.