Bentonite pore structure based on SAXS, chloride exclusion and NMR studies

Arto Muurinen, Torbjörn Carlsson

    Research output: Book/ReportReportProfessional

    Abstract

    Water-saturated bentonite is planned to be used in many countries as an important barrier component in high-level nuclear waste (HLW) repositories. Knowledge about the microstructure of the bentonite and the distribution of water between interlayer and non-interlayer pores is important for modelling of long-term processes. In this work the microstructure of water-saturated samples prepared from Namontmorillonite, Ca-montmorillonite, sodium bentonite MX-80 and calcium bentonite Deponit CaN were studied with nuclear magnetic resonance (NMR) and small-angle xray scattering spectroscopy (SAXS). The sample dry densities ranged between 0.3 and 1.6 g/cm3. The NMR technique was used to get information about the volumes of different water types in the bentonite samples. The results were obtained using 1H NMR spin-lattice T1ρ relaxation time measurements using the short inter-pulse method. The interpretation of the NMR results was made by fitting distributions of exponentials to observed decay curves. The SAXS measurements were used to get information about the size distribution of the interlayer distance of montmorillonite. The chloride porosity measurements and Donnan exclusion calculations were used together with the SAXS results for evaluation of the bentonite microstructure. The NMR studies and SAXS studies coupled with Cl porosity measurements provided very similar pictures of how the porewater is divided in interlayer and non-interlayer water in MX-80 bentonite. In the case where MX-80 of a dry density 1.6 g/cm3 was equilibrated with 0.1 M NaCl solution, the results indicated an interlayer porosity of 30 % and non-interlayer porosity of 12 %. The interlayer space mainly contained two water layers but also spaces with more water layers were present. The average size of the non-interlayer pores was evaluated to be 120 - 150 Å. From the montmorillonite surface area 98 % was interlayer and 2 % non-interlayer. Evaluation of the interlayer and non-interlayer porosities in the Deponit CaN based only on the SAXS measurements and on assumed number of layers per stack. The behaviour was rather similar as in MX-80.
    Original languageEnglish
    PublisherPosiva
    Number of pages74
    Publication statusPublished - 2013
    MoE publication typeD4 Published development or research report or study

    Publication series

    NameWorking Report
    PublisherPosiva Oy
    No.2013-53

    Fingerprint

    bentonite
    nuclear magnetic resonance
    spectroscopy
    scattering
    chloride
    porosity
    montmorillonite
    microstructure
    dry density
    water
    repository
    radioactive waste
    porewater
    surface area
    calcium
    sodium
    modeling

    Keywords

    • bentonite
    • pore structure
    • NMR
    • SAXS
    • exclusion

    Cite this

    Muurinen, A., & Carlsson, T. (2013). Bentonite pore structure based on SAXS, chloride exclusion and NMR studies. Posiva . Working Report, No. 2013-53
    Muurinen, Arto ; Carlsson, Torbjörn. / Bentonite pore structure based on SAXS, chloride exclusion and NMR studies. Posiva , 2013. 74 p. (Working Report; No. 2013-53).
    @book{85287ec0cb6a4a01b18a81f475385950,
    title = "Bentonite pore structure based on SAXS, chloride exclusion and NMR studies",
    abstract = "Water-saturated bentonite is planned to be used in many countries as an important barrier component in high-level nuclear waste (HLW) repositories. Knowledge about the microstructure of the bentonite and the distribution of water between interlayer and non-interlayer pores is important for modelling of long-term processes. In this work the microstructure of water-saturated samples prepared from Namontmorillonite, Ca-montmorillonite, sodium bentonite MX-80 and calcium bentonite Deponit CaN were studied with nuclear magnetic resonance (NMR) and small-angle xray scattering spectroscopy (SAXS). The sample dry densities ranged between 0.3 and 1.6 g/cm3. The NMR technique was used to get information about the volumes of different water types in the bentonite samples. The results were obtained using 1H NMR spin-lattice T1ρ relaxation time measurements using the short inter-pulse method. The interpretation of the NMR results was made by fitting distributions of exponentials to observed decay curves. The SAXS measurements were used to get information about the size distribution of the interlayer distance of montmorillonite. The chloride porosity measurements and Donnan exclusion calculations were used together with the SAXS results for evaluation of the bentonite microstructure. The NMR studies and SAXS studies coupled with Cl porosity measurements provided very similar pictures of how the porewater is divided in interlayer and non-interlayer water in MX-80 bentonite. In the case where MX-80 of a dry density 1.6 g/cm3 was equilibrated with 0.1 M NaCl solution, the results indicated an interlayer porosity of 30 {\%} and non-interlayer porosity of 12 {\%}. The interlayer space mainly contained two water layers but also spaces with more water layers were present. The average size of the non-interlayer pores was evaluated to be 120 - 150 {\AA}. From the montmorillonite surface area 98 {\%} was interlayer and 2 {\%} non-interlayer. Evaluation of the interlayer and non-interlayer porosities in the Deponit CaN based only on the SAXS measurements and on assumed number of layers per stack. The behaviour was rather similar as in MX-80.",
    keywords = "bentonite, pore structure, NMR, SAXS, exclusion",
    author = "Arto Muurinen and Torbj{\"o}rn Carlsson",
    year = "2013",
    language = "English",
    series = "Working Report",
    publisher = "Posiva",
    number = "2013-53",
    address = "Finland",

    }

    Muurinen, A & Carlsson, T 2013, Bentonite pore structure based on SAXS, chloride exclusion and NMR studies. Working Report, no. 2013-53, Posiva .

    Bentonite pore structure based on SAXS, chloride exclusion and NMR studies. / Muurinen, Arto; Carlsson, Torbjörn.

    Posiva , 2013. 74 p. (Working Report; No. 2013-53).

    Research output: Book/ReportReportProfessional

    TY - BOOK

    T1 - Bentonite pore structure based on SAXS, chloride exclusion and NMR studies

    AU - Muurinen, Arto

    AU - Carlsson, Torbjörn

    PY - 2013

    Y1 - 2013

    N2 - Water-saturated bentonite is planned to be used in many countries as an important barrier component in high-level nuclear waste (HLW) repositories. Knowledge about the microstructure of the bentonite and the distribution of water between interlayer and non-interlayer pores is important for modelling of long-term processes. In this work the microstructure of water-saturated samples prepared from Namontmorillonite, Ca-montmorillonite, sodium bentonite MX-80 and calcium bentonite Deponit CaN were studied with nuclear magnetic resonance (NMR) and small-angle xray scattering spectroscopy (SAXS). The sample dry densities ranged between 0.3 and 1.6 g/cm3. The NMR technique was used to get information about the volumes of different water types in the bentonite samples. The results were obtained using 1H NMR spin-lattice T1ρ relaxation time measurements using the short inter-pulse method. The interpretation of the NMR results was made by fitting distributions of exponentials to observed decay curves. The SAXS measurements were used to get information about the size distribution of the interlayer distance of montmorillonite. The chloride porosity measurements and Donnan exclusion calculations were used together with the SAXS results for evaluation of the bentonite microstructure. The NMR studies and SAXS studies coupled with Cl porosity measurements provided very similar pictures of how the porewater is divided in interlayer and non-interlayer water in MX-80 bentonite. In the case where MX-80 of a dry density 1.6 g/cm3 was equilibrated with 0.1 M NaCl solution, the results indicated an interlayer porosity of 30 % and non-interlayer porosity of 12 %. The interlayer space mainly contained two water layers but also spaces with more water layers were present. The average size of the non-interlayer pores was evaluated to be 120 - 150 Å. From the montmorillonite surface area 98 % was interlayer and 2 % non-interlayer. Evaluation of the interlayer and non-interlayer porosities in the Deponit CaN based only on the SAXS measurements and on assumed number of layers per stack. The behaviour was rather similar as in MX-80.

    AB - Water-saturated bentonite is planned to be used in many countries as an important barrier component in high-level nuclear waste (HLW) repositories. Knowledge about the microstructure of the bentonite and the distribution of water between interlayer and non-interlayer pores is important for modelling of long-term processes. In this work the microstructure of water-saturated samples prepared from Namontmorillonite, Ca-montmorillonite, sodium bentonite MX-80 and calcium bentonite Deponit CaN were studied with nuclear magnetic resonance (NMR) and small-angle xray scattering spectroscopy (SAXS). The sample dry densities ranged between 0.3 and 1.6 g/cm3. The NMR technique was used to get information about the volumes of different water types in the bentonite samples. The results were obtained using 1H NMR spin-lattice T1ρ relaxation time measurements using the short inter-pulse method. The interpretation of the NMR results was made by fitting distributions of exponentials to observed decay curves. The SAXS measurements were used to get information about the size distribution of the interlayer distance of montmorillonite. The chloride porosity measurements and Donnan exclusion calculations were used together with the SAXS results for evaluation of the bentonite microstructure. The NMR studies and SAXS studies coupled with Cl porosity measurements provided very similar pictures of how the porewater is divided in interlayer and non-interlayer water in MX-80 bentonite. In the case where MX-80 of a dry density 1.6 g/cm3 was equilibrated with 0.1 M NaCl solution, the results indicated an interlayer porosity of 30 % and non-interlayer porosity of 12 %. The interlayer space mainly contained two water layers but also spaces with more water layers were present. The average size of the non-interlayer pores was evaluated to be 120 - 150 Å. From the montmorillonite surface area 98 % was interlayer and 2 % non-interlayer. Evaluation of the interlayer and non-interlayer porosities in the Deponit CaN based only on the SAXS measurements and on assumed number of layers per stack. The behaviour was rather similar as in MX-80.

    KW - bentonite

    KW - pore structure

    KW - NMR

    KW - SAXS

    KW - exclusion

    M3 - Report

    T3 - Working Report

    BT - Bentonite pore structure based on SAXS, chloride exclusion and NMR studies

    PB - Posiva

    ER -

    Muurinen A, Carlsson T. Bentonite pore structure based on SAXS, chloride exclusion and NMR studies. Posiva , 2013. 74 p. (Working Report; No. 2013-53).