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Introducing interacting diffuse layers in TLM calculations: A reappraisal of the influence of the pore size on the swelling pressure and the osmotic efficiency of compacted bentonites

J. Goncalves 1 P. Rousseau Gueutin 1, 2 A. Revil 3, 4
1 SISYPHE - Structure et fonctionnement des systèmes hydriques continentaux
2 ANDRA - Agence Nationale pour la Gestion des Déchets Radioactifs
3 Department of Geophysics [Golden CO]
4 LGIT - Laboratoire de Géophysique Interne et Tectonophysique
Abstract : The truncation of the Gouy-Chapman diffuse part in compacted clay-rocks and bentonite is introduced into the electrical triple-layer model (TLM) recently developed by P. Leroy and A. Revil [J. Colloid Interface Sci. 270 (2004) 371]. The new model is used to explain the dependence of the osmotic efficiency and the swelling pressure as functions of the mean pore size of the medium, determined from the porosity and the specific surface. The truncation of the diffuse layer introduces a new variable in the system of equations to be solved, the electrical potential at the midplane between adjacent charged surfaces. This new variable is evaluated through a Taylor expansion of the electrical potential. The present model is able to capture the variation of the osmotic efficiency and the swelling pressure with the mean pore size. The partition of counterions between the Stern layer and the diffuse layer as a function of the pore size calculated by the TLM also shows a good consistency with the model. This implies that more than 90% of the counterions are located in the Stern layer.
Keywords : Pore size Truncation Triple-layer model Osmotic efficiency Swelling pressure
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https://hal-insu.archives-ouvertes.fr/insu-00346080
Contributor : Pascale Talour <>
Submitted on : Thursday, December 11, 2008 - 9:40:17 AM
Last modification on : Tuesday, July 27, 2021 - 9:36:02 AM

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CNRS | UNIV-SAVOIE | INSU | OSUG | EPHE | PARISTECH | INSTITUT-TELECOM | IFSTTAR | METIS_UMR7619 | UPMC | EHESP | DSETGS | USPC | SORBONNE-UNIVERSITE | SU-SCIENCES | IRSTEA | INRAE | PSL | UGA

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J. Goncalves, P. Rousseau Gueutin, A. Revil. Introducing interacting diffuse layers in TLM calculations: A reappraisal of the influence of the pore size on the swelling pressure and the osmotic efficiency of compacted bentonites. Journal of Colloid and Interface Science, Elsevier, 2007, 316 (1), pp.92-99. ⟨10.1016/j.jcis.2007.07.023⟩. ⟨insu-00346080⟩

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