Uptake of Eu(III) by C-S-H phases in CaCl2 solution in presence of EDTA: A molecular dynamics study

I Androniuk and AK Thumm and A Skerencak-Frech and M Altmaier and X Gaona, COMPUTATIONAL AND THEORETICAL CHEMISTRY, 1250, 115271 (2025).

DOI: 10.1016/j.comptc.2025.115271

The presence of organic ligands in radioactive waste influences radionuclide mobility and sorption in cement. Although EDTA is often assumed to have minimal impact, recent experiments indicate reduced Eu(III)/Cm(III) uptake by calcium silicate hydrate (C-S-H) at high EDTA concentrations in CaCl2 solutions. We used molecular dynamics (MD) simulations and potential of mean force calculations to investigate complexation and sorption mechanisms. Focusing on the (001) surface of C-S-H, we analyzed radionuclide behavior in the presence of organic ligands under repository-relevant conditions. Solution-phase simulations identified three probable Eu/ EDTA/Ca complexes. Sorption at two common sites was examined. Site-specific analysis shows that Ca-Eu(III)-EDTA complexes remain stable in solution, significantly reducing Eu(III) uptake by C-S-H. These findings align with experiments and highlight the role of ternary complex formation in limiting radionuclide retention in cementitious environments.

Return to Publications page