Ionic transport in compacted bentonite: Preliminary equilibrium results

Jarmo Lehikoinen, Arto Muurinen, Markus Olin

    Research output: Chapter in Book/Report/Conference proceedingConference article in proceedingsScientificpeer-review

    2 Citations (Scopus)

    Abstract

    An attempt is made to decompose some quantities, most commonly integrated over the chemical composition, the structure of the pore network and the time scale, into their differential counterparts. Into this category typically fall, say, the apparent diffusivities of ionic species. To serve this objective, a two-dimensional unsteady molecular-level electrokinetic transport model for ionic species in bentonite clays will be developed. The model incorporates additional features to the conventional Gouy-Chapman (GC) theory: ionic hydration, dielectric saturation, and the volume exclusion of ions. The governing equations for the flow of electrolyte solution through the pores are solved by an iterative numerical scheme to relate the characteristics of the flow to the characteristics of the pores and to the composition of the external solution in contact with the clay. The pore geometry of the clay is modelled as an array of non-interconnected tortuous channels with no parallel or serial-type non-uniformities along the pathway. This roughly corresponds to the picture of clay particles of infinite extent aligned in parallel and spaced apart by a constant distance. The model aims to simulate and interpret equilibrium and transport experiments for bentonite clays containing different types of background electrolytes at various compactions. Specifically, emphasis is placed on quantifying the extent of co-ion exclusion and understanding the postulated surface diffusion mechanism on the basis of the well-established electric double-layer (EDL) theory. This contribution presents and discusses some preliminary results, based on the modified Boltzmann statistics, for the equilibrating part of the model.
    Original languageEnglish
    Title of host publicationScientific Basis for Nuclear Waste Management XXI, MRS Symposium Proceedings
    EditorsIan McKinley, Charles McCombie
    Place of PublicationWarrendale
    PublisherMaterials Research Society
    Pages383 - 390
    DOIs
    Publication statusPublished - 1998
    MoE publication typeA4 Article in a conference publication
    EventMRS Symposium: Scientific Basis for Nuclear Waste Management XXI - Davos, Switzerland
    Duration: 23 Sep 19973 Oct 1997

    Publication series

    SeriesMaterials Research Society Symposia Proceedings
    Volume506
    ISSN0272-9172

    Conference

    ConferenceMRS Symposium: Scientific Basis for Nuclear Waste Management XXI
    Country/TerritorySwitzerland
    CityDavos
    Period23/09/973/10/97

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