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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title = "Dissolution experiments of Na- and Ca-montmorillonite in groundwater simulants under anaerobic conditions",
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",
note = "Project code: 77467",
year = "2013",
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language = "English",
volume = "48",
pages = "295--308",
journal = "Clay Minerals",
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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 -