Dissolution experiments of Na- and Ca-montmorillonite in groundwater simulants under anaerobic conditions

Emmi Myllykylä, Merja Tanhua-Tyrkkö, A. Bouchet, M. Tiljander

    Research output: Contribution to journalArticleScientificpeer-review

    4 Citations (Scopus)

    Abstract

    The effects of simulant groundwater composition, pH and temperature on the dissolution and alteration of Na- and Ca-montmorillonite have been studied. Prior to the experiments, Wyoming type Na-montmorillonite, Swy-2, was purified to decrease the amount of accessory minerals. For Ca-montmorillonite experiments, the interlayer cation Na+ of purified Swy-2 was exchanged with Ca2+. The batch experiments were conducted with the purified montmorillonites in simulated fresh and saline waters at 25°C and 60°C under anaerobic conditions in an Ar atmosphere. The concentrations of Si, Al, Fe and Mg were analysed from ultra-filtered solution samples with High Resolution Inductively Coupled Plasma Mass Spectrometry (HR-ICP-MS) as a function of dissolution time. The pH evolution was also measured. The solid smectite phases were analysed with X-ray Diffraction (XRD) and Scanning Electron Microscopy (SEM). XRD analyses indicated that the nature of the smectite mineral did not change over 140 days. However, the experimental conditions, more or less, modified the structure (e.g. the layer stacking of montmorilllonite; the partial dissolution of the smectite), which cannot be detected by XRD but was evidenced by chemical data, and can be considered as a possible contributor to the stacking faults of the montmorillonite. The log rates (mol g-1 s-1), based on the dissolved amount of Si, varied between –10.64 and –12.13 depending on the experimental conditions.
    Original languageEnglish
    Pages (from-to)295-308
    Number of pages14
    JournalClay Minerals
    Volume48
    Issue number2
    DOIs
    Publication statusPublished - 2013
    MoE publication typeA1 Journal article-refereed

    Fingerprint

    Bentonite
    montmorillonite
    anoxic conditions
    Groundwater
    Dissolution
    dissolution
    smectite
    groundwater
    X-ray diffraction
    stacking
    X ray diffraction
    Minerals
    experiment
    Experiments
    Inductively coupled plasma mass spectrometry
    accessory mineral
    Stacking faults
    Accessories
    Cations
    mass spectrometry

    Keywords

    • montmorillonite
    • dissolution
    • groundwater
    • anaerobic conditions
    • bentonite buffer alteration

    Cite this

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    abstract = "The effects of simulant groundwater composition, pH and temperature on the dissolution and alteration of Na- and Ca-montmorillonite have been studied. Prior to the experiments, Wyoming type Na-montmorillonite, Swy-2, was purified to decrease the amount of accessory minerals. For Ca-montmorillonite experiments, the interlayer cation Na+ of purified Swy-2 was exchanged with Ca2+. The batch experiments were conducted with the purified montmorillonites in simulated fresh and saline waters at 25°C and 60°C under anaerobic conditions in an Ar atmosphere. The concentrations of Si, Al, Fe and Mg were analysed from ultra-filtered solution samples with High Resolution Inductively Coupled Plasma Mass Spectrometry (HR-ICP-MS) as a function of dissolution time. The pH evolution was also measured. The solid smectite phases were analysed with X-ray Diffraction (XRD) and Scanning Electron Microscopy (SEM). XRD analyses indicated that the nature of the smectite mineral did not change over 140 days. However, the experimental conditions, more or less, modified the structure (e.g. the layer stacking of montmorilllonite; the partial dissolution of the smectite), which cannot be detected by XRD but was evidenced by chemical data, and can be considered as a possible contributor to the stacking faults of the montmorillonite. The log rates (mol g-1 s-1), based on the dissolved amount of Si, varied between –10.64 and –12.13 depending on the experimental conditions.",
    keywords = "montmorillonite, dissolution, groundwater, anaerobic conditions, bentonite buffer alteration",
    author = "Emmi Myllykyl{\"a} and Merja Tanhua-Tyrkk{\"o} and A. Bouchet and M. Tiljander",
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    doi = "10.1180/claymin.2013.048.2.11",
    language = "English",
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    pages = "295--308",
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    Dissolution experiments of Na- and Ca-montmorillonite in groundwater simulants under anaerobic conditions. / Myllykylä, Emmi; Tanhua-Tyrkkö, Merja; Bouchet, A.; Tiljander, M.

    In: Clay Minerals, Vol. 48, No. 2, 2013, p. 295-308.

    Research output: Contribution to journalArticleScientificpeer-review

    TY - JOUR

    T1 - Dissolution experiments of Na- and Ca-montmorillonite in groundwater simulants under anaerobic conditions

    AU - Myllykylä, Emmi

    AU - Tanhua-Tyrkkö, Merja

    AU - Bouchet, A.

    AU - Tiljander, M.

    N1 - Project code: 77467

    PY - 2013

    Y1 - 2013

    N2 - The effects of simulant groundwater composition, pH and temperature on the dissolution and alteration of Na- and Ca-montmorillonite have been studied. Prior to the experiments, Wyoming type Na-montmorillonite, Swy-2, was purified to decrease the amount of accessory minerals. For Ca-montmorillonite experiments, the interlayer cation Na+ of purified Swy-2 was exchanged with Ca2+. The batch experiments were conducted with the purified montmorillonites in simulated fresh and saline waters at 25°C and 60°C under anaerobic conditions in an Ar atmosphere. The concentrations of Si, Al, Fe and Mg were analysed from ultra-filtered solution samples with High Resolution Inductively Coupled Plasma Mass Spectrometry (HR-ICP-MS) as a function of dissolution time. The pH evolution was also measured. The solid smectite phases were analysed with X-ray Diffraction (XRD) and Scanning Electron Microscopy (SEM). XRD analyses indicated that the nature of the smectite mineral did not change over 140 days. However, the experimental conditions, more or less, modified the structure (e.g. the layer stacking of montmorilllonite; the partial dissolution of the smectite), which cannot be detected by XRD but was evidenced by chemical data, and can be considered as a possible contributor to the stacking faults of the montmorillonite. The log rates (mol g-1 s-1), based on the dissolved amount of Si, varied between –10.64 and –12.13 depending on the experimental conditions.

    AB - The effects of simulant groundwater composition, pH and temperature on the dissolution and alteration of Na- and Ca-montmorillonite have been studied. Prior to the experiments, Wyoming type Na-montmorillonite, Swy-2, was purified to decrease the amount of accessory minerals. For Ca-montmorillonite experiments, the interlayer cation Na+ of purified Swy-2 was exchanged with Ca2+. The batch experiments were conducted with the purified montmorillonites in simulated fresh and saline waters at 25°C and 60°C under anaerobic conditions in an Ar atmosphere. The concentrations of Si, Al, Fe and Mg were analysed from ultra-filtered solution samples with High Resolution Inductively Coupled Plasma Mass Spectrometry (HR-ICP-MS) as a function of dissolution time. The pH evolution was also measured. The solid smectite phases were analysed with X-ray Diffraction (XRD) and Scanning Electron Microscopy (SEM). XRD analyses indicated that the nature of the smectite mineral did not change over 140 days. However, the experimental conditions, more or less, modified the structure (e.g. the layer stacking of montmorilllonite; the partial dissolution of the smectite), which cannot be detected by XRD but was evidenced by chemical data, and can be considered as a possible contributor to the stacking faults of the montmorillonite. The log rates (mol g-1 s-1), based on the dissolved amount of Si, varied between –10.64 and –12.13 depending on the experimental conditions.

    KW - montmorillonite

    KW - dissolution

    KW - groundwater

    KW - anaerobic conditions

    KW - bentonite buffer alteration

    U2 - 10.1180/claymin.2013.048.2.11

    DO - 10.1180/claymin.2013.048.2.11

    M3 - Article

    VL - 48

    SP - 295

    EP - 308

    JO - Clay Minerals

    JF - Clay Minerals

    SN - 0009-8558

    IS - 2

    ER -