Adsorption and Effect of Very Low-Level Radioactive Waste Site Soil on U and Sr

The adsorption behaviors of uranium and strontium were investigated on soil of very low-level radioactive waste (VLLW) in a preelection site by the static experimental method. The effects of the various experimental conditions such as pH, coexist iron and colloid on the adsorption were investigated with the 238U and 90Sr as indicator respectively. The maximum adsorption distribution coefficient (Kd) of U and Sr on the site’s soil are 11 300 and 723 mL/g, respectively. The concentration relationship in aqueous solutions and the adsorption capacities of U and Sr can be described by the Freundlich adsorption equation. The Kd of U is maximum when the pH is 4-8, however, the Kd of Sr is minimal. It is also noted that the Kd of U and Sr drops obviously when the solution contains Ca2+ or Mg2+, even the influence on Sr is more than U. The Kd of U reduces remarkably when adding in CO2－3 or C2O2－4, but the Kd of Sr increases. The ferric hydroxide colloid would make the Kd of U and Sr drop. The Kd of U decreases while the Kd of Sr increases when the humic acid exists in solution.