Ion concentration caused by an external solution into the porewater of compacted bentonite

Arto Muurinen (Corresponding Author), Ola Karnland, Jarmo Lehikoinen

    Research output: Contribution to journalArticleScientificpeer-review

    29 Citations (Scopus)

    Abstract

    The concentrations caused by the external solution into the porewater were studied with compacted bentonite (MX-80), from which easily dissolving components had been removed in order to ensure that the ions in the porewater came from the external solution. The dry densities of the samples varied from 700 to 1700 kg/m3 and NaCl solutions of 0.1–3 M were used as the external solution for saturation. The concentrations in the porewater were determined by the direct analysis of the squeezed porewaters and by dispersing the sample in deionized water. At high concentrations, the Donnan model can predict the concentrations in the porewater rather well. At low concentrations, where the ion exclusion is stronger, the measured concentrations are clearly higher than the modelled values. One possible explanation for this discrepancy is the microstructure of the bentonite, and an attempt to couple the effects of the microstructure and the Donnan model was made. It was assumed that there are two pore types, interlamellar pores in the montmorillonite stacks and large pores in the gel between the stacks. The dimensions of the microstructure were obtained from SAXS and BET(N2) measurements. In this case, the fitting is much better, which supports the assumption of different pore types in bentonite.

    Original languageEnglish
    Pages (from-to)119 - 127
    Number of pages9
    JournalPhysics and Chemistry of the Earth
    Volume29
    Issue number1
    DOIs
    Publication statusPublished - 2004
    MoE publication typeA1 Journal article-refereed

    Fingerprint

    Bentonite
    bentonite
    ion concentration
    porewater
    Ions
    ion
    porosity
    microstructure
    Microstructure
    Saturation (materials composition)
    Deionized water
    dry density
    dispersing
    montmorillonite
    exclusion
    Gels
    low concentrations
    dissolving
    ions
    gel

    Keywords

    • bentonite
    • nuclear waste
    • porosity
    • exclusion
    • microstructure
    • Donnan model

    Cite this

    Muurinen, Arto ; Karnland, Ola ; Lehikoinen, Jarmo. / Ion concentration caused by an external solution into the porewater of compacted bentonite. In: Physics and Chemistry of the Earth. 2004 ; Vol. 29, No. 1. pp. 119 - 127.
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    abstract = "The concentrations caused by the external solution into the porewater were studied with compacted bentonite (MX-80), from which easily dissolving components had been removed in order to ensure that the ions in the porewater came from the external solution. The dry densities of the samples varied from 700 to 1700 kg/m3 and NaCl solutions of 0.1–3 M were used as the external solution for saturation. The concentrations in the porewater were determined by the direct analysis of the squeezed porewaters and by dispersing the sample in deionized water. At high concentrations, the Donnan model can predict the concentrations in the porewater rather well. At low concentrations, where the ion exclusion is stronger, the measured concentrations are clearly higher than the modelled values. One possible explanation for this discrepancy is the microstructure of the bentonite, and an attempt to couple the effects of the microstructure and the Donnan model was made. It was assumed that there are two pore types, interlamellar pores in the montmorillonite stacks and large pores in the gel between the stacks. The dimensions of the microstructure were obtained from SAXS and BET(N2) measurements. In this case, the fitting is much better, which supports the assumption of different pore types in bentonite.",
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    Ion concentration caused by an external solution into the porewater of compacted bentonite. / Muurinen, Arto (Corresponding Author); Karnland, Ola; Lehikoinen, Jarmo.

    In: Physics and Chemistry of the Earth, Vol. 29, No. 1, 2004, p. 119 - 127.

    Research output: Contribution to journalArticleScientificpeer-review

    TY - JOUR

    T1 - Ion concentration caused by an external solution into the porewater of compacted bentonite

    AU - Muurinen, Arto

    AU - Karnland, Ola

    AU - Lehikoinen, Jarmo

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    N2 - The concentrations caused by the external solution into the porewater were studied with compacted bentonite (MX-80), from which easily dissolving components had been removed in order to ensure that the ions in the porewater came from the external solution. The dry densities of the samples varied from 700 to 1700 kg/m3 and NaCl solutions of 0.1–3 M were used as the external solution for saturation. The concentrations in the porewater were determined by the direct analysis of the squeezed porewaters and by dispersing the sample in deionized water. At high concentrations, the Donnan model can predict the concentrations in the porewater rather well. At low concentrations, where the ion exclusion is stronger, the measured concentrations are clearly higher than the modelled values. One possible explanation for this discrepancy is the microstructure of the bentonite, and an attempt to couple the effects of the microstructure and the Donnan model was made. It was assumed that there are two pore types, interlamellar pores in the montmorillonite stacks and large pores in the gel between the stacks. The dimensions of the microstructure were obtained from SAXS and BET(N2) measurements. In this case, the fitting is much better, which supports the assumption of different pore types in bentonite.

    AB - The concentrations caused by the external solution into the porewater were studied with compacted bentonite (MX-80), from which easily dissolving components had been removed in order to ensure that the ions in the porewater came from the external solution. The dry densities of the samples varied from 700 to 1700 kg/m3 and NaCl solutions of 0.1–3 M were used as the external solution for saturation. The concentrations in the porewater were determined by the direct analysis of the squeezed porewaters and by dispersing the sample in deionized water. At high concentrations, the Donnan model can predict the concentrations in the porewater rather well. At low concentrations, where the ion exclusion is stronger, the measured concentrations are clearly higher than the modelled values. One possible explanation for this discrepancy is the microstructure of the bentonite, and an attempt to couple the effects of the microstructure and the Donnan model was made. It was assumed that there are two pore types, interlamellar pores in the montmorillonite stacks and large pores in the gel between the stacks. The dimensions of the microstructure were obtained from SAXS and BET(N2) measurements. In this case, the fitting is much better, which supports the assumption of different pore types in bentonite.

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