Effect of aqueous acetic, oxalic, and carbonic acids on the adsorption of europium(III) onto α-alumina

Abstract

Chemical retention, i.e., partition of the element between aqueous solution and mineral surface, is a key phenomenon for assessing the safety of possible nuclear waste disposal. For this purpose, the sorption of Eu(III) onto a model mineral— α-alumina—is studied here, including the effects of groundwater chemistry: pH and concentrations of small organic and inorganic ligands (acetate, oxalate, and carbonate anions). This work presents some experimental evidence for a synergic mechanism of sorption of europium–ligand complexes onto the alumina. Only cationic complexes were necessary to consider to model experimental results. Using the ion-exchange theory (IET) and a corresponding restricted set of parameters—exchange capacities and thermodynamic equilibrium constants—the whole set of sorption experiments of Eu(III) cationic species onto the α-alumina was modeled under various chemical conditions.