Institut UTINAM - UMR 6213 - Etude expérimentale et par simulation numérique du système eau/cations alcalins en milieu nanoporeux. cas de deux exemples types : une zeolite et une argile

Résumé : Ionic conduction in nanopores is one of the primary “machinery” implicated in life, i.e.
cationic channels through phospholipidic membrane of biological cells and ionic transport
in soils that is the fate of major plant nutrients. In this “machinery”, the mobile ions
are located at the surface of open nanopores and their dynamics is directly related to
the presence of adsorbed molecules. Beside, many nanoporous materials, synthetic or
natural, as zeolites or clay minerals, possess ions at their inner-surface that play a
key role on their adsorption property and their ion exchange capacity.
Basically, ionic conductivity is particularly low at the dry state and increases
tremendously when small and polar molecules, e.g. water, are adsorbed at the ions
vicinity. It is thus well known that, on the one hand, the ions strongly influence the
adsorption of the polar molecules and on the other hand that the adsorbed molecules
permit the ions to diffuse over long distances. However, little is known about the exact
microscopic mechanisms involved in the adsorption phenomenon and further in the system,
i.e. ions and adsorbed molecules, dynamics. Fundamental work using model materials is
thus necessary. In this presentation, we will show how the combination of experimental,
i.e. dielectric relaxation spectroscopy and thermogravimetric analysis, and computational
methods, yields relevant information about ion dynamics in systems as zeolites and
smectites (clay minerals).The case of an idealized nanopore will also be discussed.

Institut UTINAM - UMR 6213

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Etude expérimentale et par simulation numérique du système eau/cations alcalins en milieu nanoporeux. cas de deux exemples types : une zeolite et une argile