Sorption of Cesium on smectite-rich clays from the Bohemian Massif (Czech Republic) and their mixtures with sand

Sorption is an important process for the transport of radionuclides through backfill materials in a radioactive waste underground repository. Within this study, sorption of Cs on selected Czech clay materials and their mixtures with sand was investigated by batch tests. The experiments were performed under oxic conditions at 25°C. Synthetic groundwater as a liquid phase and unconditioned clays (as they were provided by their producer) were used to reach the natural conditions as close as possible. Distribution ratios (Rds) of Cs for all selected clays rise with increase of the clay fraction in clay/sand mixtures in agreement with previous works studying sorption behaviour of such mixtures. The rise of Rds is from 102 cm3 g−1 for mixtures with 80% of sand to 103 cm3 g−1 for pure clays. There are significant differences between natural and technologically modified clays.