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

Abstract : 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.
Type de document :
Article dans une revue
Geochimica et Cosmochimica Acta, Elsevier, 2009, 73 (24), pp.7290-7302. <10.1016/j.gca.2009.09.014>


https://hal.archives-ouvertes.fr/hal-00450881
Contributeur : Gilles Montavon <>
Soumis le : mercredi 27 janvier 2010 - 15:37:20
Dernière modification le : vendredi 22 mai 2015 - 13:14:00
Document(s) archivé(s) le : jeudi 17 juin 2010 - 21:25:08

Fichier

GCA_2009.pdf
Fichiers produits par l'(les) auteur(s)

Identifiants

Collections

Citation

Gilles Montavon, Z. Guo, Christophe Tournassat, B. Grambow, D. Le Botlan. 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. Geochimica et Cosmochimica Acta, Elsevier, 2009, 73 (24), pp.7290-7302. <10.1016/j.gca.2009.09.014>. <hal-00450881>

Exporter

Partager

Métriques

Consultations de
la notice

543

Téléchargements du document

247