دانلود رایگان مقاله تحقیقات تجربی و مدل سازی جذب سزیم و استرانسیم به خاک رس از دفع زباله

Abstract

Migration of strontium and cesium radionuclide in geohydraulic system is important for safety disposal of radioactive waste containing of these two radionuclides to prevent the migration of radionuclides from the disposal site to provide protection for man and his environment. Geochemical analysis was carried out to investigate the mineral composition of the clay taken from the site to predict the historical and environmental geology of Inshas disposal site. Batch experiments were carried out as a function of pH, solute concentration and under three different temperatures (298°, 313° and 333° K). Sorption capacity of Cs+ and Sr2 + onto clay sample was increased when initial metal ions concentration was increased. Increasing the temperature led to decrease in the sorption of Cs+ and Sr2 + ions. Several kinetic models were used to fit the experimental data and to examine the controlling mechanisms of the sorption processes. The kinetic study showed that sorption followed pseudo-second-order model with a good correlation coefficient (R2 = 0.999) for both studied ions. The experimental sorption data were fitted using Freundlich, Langmuir and Dubinin–Radushkevich (D–R) models. Results showed that the adsorption process was exothermic and favored at low temperature.

4. Conclusion

The level and the type of waste, the geochemistry of the clay and the role of climate, are important factors for controlling the geosphere medium of the studied area, as well as the selection of the site and method of burial of radioactive wastes. The kinetics of both metal ions was experimentally studied and the obtained rate data were analyzed using simple kinetic models. Results demonstrated that the pseudo second-order sorption mechanism is predominant and the over-all rate constant of each sorption process occurs to be controlled by chemical sorption process. The Cs+ and Sr2+ ions sorption data were described using Freundlich, Langmuir and Dubinin–Radushkevich (D–R) models. The sorption in both of them ions increased with increasing initial metal ions concentration and the amount of Cs+ ions sorbed onto clay is greater than that of Sr2+ ions, which it favored in the lower temperature of an aqueous solution. The maximum sorption capacity and the mean free energy of the studied ions have been determined. The sorption of each ion is an exothermic process. These results showed that natural materials an efficient ion exchange material for the behavior of cesium and strontium ions releasing on the surrounded geosphere of the disposal site.