The effect of bentonite colloids on sorption of Eu in crystalline rock and its minerals

This study examines Eu(III) sorption on two Olkiluoto crystalline rocks and their minerals in low-salinity groundwater conditions. Sorption was studied as a function of 151 EuCl 3 molarity and pH. In addition, the competitive effect of MX-80 bentonite colloids on Eu(III) sorption was examined. To understand Eu(III)´s behavior in different experimental scenarios, the factors influencing Eu(III) sorption were further investigated by means of CEC, and zeta potential analysis of the materials used. The study revealed that the strongest sorbents for Eu(III) under the defined conditions were biotite and biotite-rich heterogeneous metatexitic gneiss. Depending on the rock matrix used and the colloid concentration of the solution, the introduction of bentonite colloids as a competing agent significantly reduced the sorption of Eu(III) on rock matrix. These findings provide insights into radionuclide mobility in natural and engineered systems. • RN sorption on BC compared to rock matrices in a low-salinity environment is high. • Increasing colloid concentration inhibited sorption on the rock matrices linearly. • Bentonite colloid enhance the transport of RN in the bedrock fracture system.