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Porosities accessible to HTO and iodide on water-saturated compacted clay materials and relation with the forms of water: A low field proton NMR study
Montavon G., Guo Z., Tournassat C., Grambow B., Le Botlan D.
Geochimica et Cosmochimica Acta Acta 73, 24 (2009) 7290-7302 - http://hal.archives-ouvertes.fr/hal-00450881
Chimie/Chimie théorique et/ou physique
Chimie/Chimie analytique
Porosities accessible to HTO and iodide on water-saturated compacted clay materials and relation with the forms of water: A low field proton NMR study
Gilles Montavon ()1, Z. Guo1, Christophe Tournassat2, 3, B. Grambow1, D. Le Botlan ()4
1 :  SUBATECH - Laboratoire SUBATECH Nantes
http://www-subatech.in2p3.fr/
CNRS : UMR6457 – IN2P3 – Université de Nantes – École Nationale Supérieure des Mines - Nantes
4, rue Alfred Kastler - 44070 Nantes Cedex 03
France
2 :  LGIT - Laboratoire de géophysique interne et tectonophysique
http://www-lgit.obs.ujf-grenoble.fr/
CNRS : UMR5559 – Institut de recherche pour le développement [IRD] – LCPC – OSUG – INSU – Université de Savoie – Université Joseph Fourier - Grenoble I
Maison des Géosciences 1381 Rue de la piscine - BP 53 38041 GRENOBLE CEDEX 9
France
3 :  BRGM - Bureau de recherches géologiques et minières
http://www.brgm.fr/
Bureau de Recherches Géologiques et Minières (BRGM)
France
4 :  LAIEM - Laboratoire d'analyse isotopique et électrochimique de metabolismes
http://www.sciences.univ-nantes.fr/laiem/LAIEMweb.html
CNRS : UMR6006 – Université de Nantes
2 Rue de la Houssinière - BP 92208 44322 NANTES CEDEX 3
France
The aim of the present work was to quantify accessible porosities for iodide and for a water tracer (HTO) on water-saturated compacted clay samples (illite, montmorillonite and MX-80 bentonite) and to relate these macroscopic values to the forms of water in these porosities (surface/bulk water, external/internal water). Low field proton NMR was used to characterize and quantify the forms of water. This enabled the three different populations (structural OH, external surface and internal surface water) to be differentiated on hydrated clays by considering the difference in proton mobility. An accurate description of the water forms within the different populations did not appear possible when water molecules of these populations were in contact because of the occurrence of rapid exchange reactions. For this reason, it was not possible to use the low resolution NMR method to quantify external surface and bulk water in fully water-saturated compacted clay media at room temperature. This latter information could however be estimated when analyzing the samples at -25°C. At this temperature, a distinction based on the difference in mobility could be made since surface water remained in a semi-liquid state whereas bulk water froze. In parallel, accessible porosities for anions and HTO were determined by an isotopic dilution method using capillaries to confine the materials. HTO was shown to probe the whole pore volume (i.e. the space made of surface and bulk water). When the surface water volume was mainly composed of interlayer water (case of montmorillonite and bentonite), iodide was shown to be located in the pore space made of bulk water. When the interlayer water was not present (case of illite), the results showed that iodide could access a small fraction of the surface water volume localized at the external surface of the clay particles.
Anglais

Geochimica et Cosmochimica Acta Acta
internationale
Articles dans des revues avec comité de lecture
15/12/2009
73
24
7290-7302

European Commission, IP FUNMIG ACTINET network of excellence 05-21 French National Agency for Radioactive Waste Management (ANDRA)
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