Adsorption and retarded diffusion of EuIII-EDTA- through hard clay rock

JOURNAL OF HYDROLOGY

卷:544

Article

Descostes, Michael^1,3  Pointeau, Ingmar^1,4  Radwan, Jean¹  Poonoosamy, Jenna^1,5  Lacour, Jean-Luc²  Menut, Denis^2,6  Vercouter, Thomas²  Dagnelie, Romain V. H.¹ 

[1] Univ Paris Saclay, CEA, DEN Serv Etud Comportement Radionucleides SECR, F-91191 Gif Sur Yvette, France

[2] Univ Paris Saclay, CEA, DEN Serv Etud Analyt & Reactivite Surfaces SEARS, F-91191 Gif Sur Yvette, France

[3] AREVA Mines, R&D Dept, F-92084 Paris, France

[4] CEN Cadarache, DEN Serv Exploitat Expertise & Caracterisat SEEC, F-13108 St Paul Les Durance, France

[5] Forschungszentrum Julich, D-52425 Julich, Germany

[6] Univ Paris Saclay, CEA, DEN Serv Rech Met Appl SRMA, F-91191 Gif Sur Yvette, France

关键词: Europium;    EDTA;    Organic;    Diffusion;    Adsorption;    Clay rock;   

DOI  :  10.1016/j.jhydrol.2016.11.014

来源: Elsevier

【 摘 要 】

Adsorption and diffusion experiments of Eu-III were performed in Callovo-Oxfordian (COx) clay rock in the presence of EDTA. The predictive model based on binary system parameters (Eu/COx and EDTA/COx) was in good agreement with the results for the Eu/EDTA/COx ternary system. At low EDTA concentrations, the behaviour of Eu-III was mainly driven by Eu3+ adsorption and complexation by carbonates and EDTA. At higher EDTA concentrations, the behaviour of Eu-III was driven by the adsorption of [Eu-III-EDTA](-) anions. Europium was then used as a probe to estimate the transport of EDTA. Three through-diffusion experiments of EDTA were compared with 14C, Eu and 152Eu tracers. Eu-III-EDTA was not quantitatively dissociated by diffusion through the rock. The effective diffusion coefficients quantified D-e(Eu-III-EDTA) = 1.5-1.7.10(12) m(2) s(-1) were an order of magnitude lower than that of water, evidencing the anionic exclusion of [Eu-III-EDTA](-) within the clay rock. Break-through curves and diffusion profiles confirmed retardation due to significant adsorption on the clay rock (R-d(Eu-III-EDTA)similar to 6-14 L kg(-1)) in comparison with inorganic anions. However, the model based on batch adsorption measurements failed to predict the diffusion results. All experiments displayed an early break-through of EDTA complexes. This behaviour contrasted with results on iron oxides rich sediments, which usually led to higher retardation than expected from the batch studies. (C) 2016 Elsevier B.V. All rights reserved.

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