## Diffusion of ionic tracers in the Callovo-Oxfordian clay-rock using the Donnan equilibrium model and the formation factor

### Détails

ID Serval

serval:BIB_58B964ABFADF

Type

**Article**: article d'un périodique ou d'un magazine.

Collection

Publications

Fonds

Titre

Diffusion of ionic tracers in the Callovo-Oxfordian clay-rock using the Donnan equilibrium model and the formation factor

Périodique

Geochimica et Cosmochimica Acta

ISSN-L

0016-7037

Statut éditorial

Publié

Date de publication

2009

Peer-reviewed

Oui

Volume

73

Pages

2712--2726

Langue

anglais

Notes

Jougnot2009

Résumé

The transient diffusion of cationic and anionic tracers through clay-rocks

is usually modeled with parameters like porosity, tortuosity (and/or

constrictivity), sorption coefficients, and anionic exclusion. Recently,

a new pore scale model has been developed by Revil and Linde [Revil

A. and Linde N. (2006) Chemico-electromechanical coupling in microporous

media. J Colloid Interface Sci. 302, 682-694]. This model is based

on a volume-averaging approach of the Nernst-Planck equation. The

influence of the electrical diffuse layer is accounted for by a generalized

Donnan equilibrium model through the whole connected pore space that

is valid for a multicomponent electrolyte. This new model can be

used to determine the composition of the pore water of the Callovo-Oxfordian

clay-rock, the osmotic efficiency of bentonite as a function of salinity,

the osmotic pressure, and the streaming potential coupling coefficient

of clay-rocks. This pore scale model is used here to model the transient

diffusion of ionic tracers ((22)Na(+), (36)Cl(-), and (35)SO(4)(2-))

through the Callovo-Oxfordian clay-rock. Speciation of SO(4)(2-)

shows that similar to 1/3 of the SO(4) is tied-up in different complexes.

Some of these complexes are neutral and are therefore only influence

by the tortuosity of the pore space. Using experimental data from

the literature, we show that all the parameters required to model

the flux of ionic tracers (especially the mean electrical potential

of the pore space and the formation factor) are in agreement with

independent evaluations of these parameters using the osmotic pressure

determined from in situ pressure measurements and HTO diffusion experiments.

is usually modeled with parameters like porosity, tortuosity (and/or

constrictivity), sorption coefficients, and anionic exclusion. Recently,

a new pore scale model has been developed by Revil and Linde [Revil

A. and Linde N. (2006) Chemico-electromechanical coupling in microporous

media. J Colloid Interface Sci. 302, 682-694]. This model is based

on a volume-averaging approach of the Nernst-Planck equation. The

influence of the electrical diffuse layer is accounted for by a generalized

Donnan equilibrium model through the whole connected pore space that

is valid for a multicomponent electrolyte. This new model can be

used to determine the composition of the pore water of the Callovo-Oxfordian

clay-rock, the osmotic efficiency of bentonite as a function of salinity,

the osmotic pressure, and the streaming potential coupling coefficient

of clay-rocks. This pore scale model is used here to model the transient

diffusion of ionic tracers ((22)Na(+), (36)Cl(-), and (35)SO(4)(2-))

through the Callovo-Oxfordian clay-rock. Speciation of SO(4)(2-)

shows that similar to 1/3 of the SO(4) is tied-up in different complexes.

Some of these complexes are neutral and are therefore only influence

by the tortuosity of the pore space. Using experimental data from

the literature, we show that all the parameters required to model

the flux of ionic tracers (especially the mean electrical potential

of the pore space and the formation factor) are in agreement with

independent evaluations of these parameters using the osmotic pressure

determined from in situ pressure measurements and HTO diffusion experiments.

Mots-clé

TRIPLE-LAYER MODEL, COMPACTED BENTONITE, POROUS-MEDIA, ELECTRICAL-CONDUCTIVITY, , BURE MUDROCK, TRANSPORT, SORPTION, WATER, ARGILLITES, MEMBRANE

Création de la notice

25/11/2013 19:00

Dernière modification de la notice

18/11/2016 13:38