Elemental and particle size fractionation during the transport of Eu(III)-silicate colloids in water-saturated porous media.

Actinides (An)-bearing colloids could facilitate An migration in the environment. However, little is known about the transport behavior of An(III)-silicate colloids, which are readily formed by the reaction of An with silicic acid under environmental conditions. Column experiments were conducted to investigate the transport of Eu(III)-silicate colloids (chemical analog of An(III)-silicate colloids) in water-saturated porous media as a function of pH, ionic strength (IS) and the presence of fulvic acid (FA).

Stability of Eu(III)-silicate colloids: Effect of Eu content, pH, electrolyte and fulvic acid.

Dissolved silicic acid in the environment has strong affinity for actinides (An), but An(III)-silicate colloids have been scarcely investigated. In this study, Eu(III)-silicate colloids, an analogue to An(III)-silicate, were prepared and the aggregation kinetics of the colloids was investigated as a function of Eu content (Si/Eu molar ratio), pH, background electrolyte (NaCl, NaNO, NaClO, KCl and CsCl) and fulvic acid (FA). Results indicated that the colloids with higher Si/Eu molar ratio exhibited higher stability under the same conditions.