Journal of Nuclear Fuel Cycle and Waste Technology

In this study, a sorption experiment of multivalent nuclides such as Eu(III) and Th(IV) relatively stable for redox reactions was carried out for bentonite colloids which had been prepared from the domestic Gyeongju bentonite. The amounts of the nuclides lost by an attachment to bottle walls, by a precipitation, and by a colloid formation were estimated by performing blank tests for the sorption experiments. Sorption coefficients, Kd';s, reflecting the mass losses were obtained and investigated for the sorption of Eu(III) and Th(IV) onto the bentonite colloids. The net sorption coefficients Kd';s considering all the three mass losses were measured as about 106-107 mL/g and 7×106-107 mL/g for Eu(III) and Th(IV), respectively, depending on pH. In particular, a precipitation occurred mainly at a pH greater than 5 for Eu(III) and a precipitation and colloid formation significantly occurred at a pH greater than 3 for Th(IV). The precipitation and colloid formation of the multivalent nuclides of Eu(III) and Th(IV) therefore should be considered when Kd';s are rightly obtained over the pH range where their precipitation and colloid formation become significant at a given concentration.

Keywords

Europium,Thorium,Bentonite Colloids,Precipitation,Colloid Formation,Sorption,Coefficient Kd