Adsorption of Cs and U(VI) on soils of the Australian arid zone

Abstract

Distribution coefficients (Kd values) for Cs and U(VI) on soils from an arid region of Australia were measured under a range of conditions. The Kd values for trace 137Cs in 0.02 M NaCl were typically around 104 mL/g, and were not affected by the pH. However, the Kd decreased with increasing ionic strength, and was strongly dependent on the total Cs concentration. Much lower Kd values (around 102 mL/g) were measured in systems containing total Cs of 1 mmol/L in a background electrolyte of 0.10 M NaCl. The main factor determining the sorption behaviour of U(VI) in systems equilibrated with air was the pH, with the Kd decreasing from above 103 mL/g at pH 7 to around 10 mL/g at pH 9.