Effect of aqueous acetic, oxalic, and carbonic acids on the adsorption of europium(III) onto alpha-alumina.
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-alpha-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 alpha-alumina was modeled under various chemical conditions.
Alliot
Cyrille
C
CEA--DEN/DPC/SECR/LSRM, Bât 391, Centre d'Etudes de Saclay, 91191 Gif-sur-Yvette Cedex, France. cyrille.alliot@subatech.in2p3.fr
Bion
Lionel
L
Mercier
Florence
F
Toulhoat
Pierre
P