Hostname: page-component-848d4c4894-4rdrl Total loading time: 0 Render date: 2024-07-07T23:30:38.207Z Has data issue: false hasContentIssue false
  • English
  • Français

H2O self-diffusion coefficient of water-rich MX-80 bentonite gels

Published online by Cambridge University Press:  09 July 2018

Y. Nakashima
Y. Nakashima*
Affiliation:
Exploration Geophysics Research Group, National Institute of Advanced Industrial Science and Technology (AIST), Higashi 1-1-1 Central 7, Tsukuba, Ibaraki 305-8567
*
*E-mail: [email protected]
Get access Rights & Permissions [Opens in a new window]

Abstract

MX-80 is a bentonite clay from the Clay Spur bed, Wyoming, USA, consisting of ~80 wt.% Na-rich montmorillonite and is a leading candidate material for use in engineered barriers within underground nuclear waste disposal sites in Switzerland and Sweden. The diffusive invasion of groundwater into the engineered barriers is likely to cause the dry high-density bentonite to swell and evolve into a less-dense, water-rich gel during re-submergence of the shafts and galleries. Data on H20 diffusivity within water-rich bentonite gels are therefore essential to the safe design of the engineered barriers. To address this need, the self-diffusion coefficient, D, of 1H2O molecules in water-rich MX-80 bentonite gels was measured using the pulsed-gradient spin-echo method of 1H nuclear magnetic resonance spectroscopy at 0.47 T; D was measured over a wide range of temperatures (20.6–70.1°C) and of bentonite volume fractions (0 to 17.2 vol.%). The results showed that D increased markedly to values of bulk water self-diffusivity as the bentonite volume fraction decreased towards 0 vol.%. The activation energy of the diffusion process for the gels was approximately equal to that for bulk water. As a result, the normalized H20 self-diffusivity, D/D0, was approximately independent of temperature, where D0 is D in bulk water. The D/D0 data for ≤6.39 vol.% bentonite fraction were successfully fitted to a porous clay gel model that involves unbound water molecules that diffuse in the pore space by avoiding randomly placed discoidal obstacles (clay particles) of a high aspect ratio. The D/D0 data for MX-80 were similar to data for SWy-2 (Wyoming bentonite from the Newcastle formation) and Kunigel-Vl (bentonite from Yamagata, Japan), suggesting that all three bentonites are equally suitable candidate materials, in terms of water diffusivity performance, for use within engineered barriers.

Keywords

back-filling materialbuffer materialColony mineMX80PGSE NMRporous mediarandom walksurface relaxivitytortuosity.
Type
Research Article
Information
Clay Minerals , Volume 41 , Issue 2 , June 2006 , pp. 659 - 668
Copyright
Copyright © The Mineralogical Society of Great Britain and Ireland 2006

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

References

Balnois, E., S., Durand-Vidal & Levitz, P. (2003) Probing the morphology of laponite clay colloids by atomic force microscopy. Langmuir, 19, 6633—6637.Google Scholar
Bûcher, F. & Mtiller-Vonmoos, M. (1989) Bentonite as a containment barrier for the disposal of highly radioactive wastes. Applied Clay Science, 4, 157—177.Google Scholar
Cadene, A., S., Durand-Vidal, Turq, P. & Brendle, J. (2005) Study of individual Na-montmorillonite particles size, morphology, and apparent charge. Journal of Colloid and Interface Science, 285, 719—730.Google Scholar
Dunn, K.-J, Bergman DJ. & Latorraca, G.A (2002) Nuclear Magnetic Resonance, Petrophysical and Logging Applications. Pergamon, New York.Google Scholar
Elzea, J.M & Murray, H.H (1990) Variation in the mineralogical, chemical and physical properties of the Cretaceous Clay Spur bentonite in Wyoming and Montana (U.S.A). Applied Clay Science, 5, 229—248.Google Scholar
Fredrickson, G.H & Bicerano, J. (1999) Barrier properties of oriented disk composites. Journal of Chemical Physics, 110, 2181—2188.Google Scholar
Fripiat, J.J, Letellier, M. & Levitz, P. (1984) Interaction of water with clay surfaces. Philosophical Transactions of the Royal Society of London, A311, 287—299.Google Scholar
Grandjean, J. & Laszlo, P. (1989) Multinuclear and pulsed gradient magnetic resonance studies of sodium cations and of water reorientation at the interface of a clay. Journal of Magnetic Resonance, 83, 128—137.Google Scholar
Y., Guéguen & Palciauskas, V. (1994) Introduction to the Physics of Rocks. Princeton University Press, Princeton, New Jersey, USA.Google Scholar
Ichikawa, Y., Kawamura K, Nakano, M., Kitayama, K. & Kawamura, H. (1999) Unified molecular dynamics and homogenization analysis for bentonite behavior: Current results and future possibilities. Engineering Geology, 54, 21—31.Google Scholar
Ito, M., Okamoto, M., Suzuki K, Shibata, M. & Sasaki, Y. (1994) Mineral composition analysis of bentonite. Journal of the Atomic Energy Society of Japan, 36, 1055—1058.[in Japanese].Google Scholar
Japan Nuclear Cycle Development Institute (2000) Second progress report on research and development for the geological disposal of HLW in Japan H12: Project to establish the scientific and technical basis for HLW disposal in Japan, Supporting report 2 repository design and engineering technology. JNC Technical Report, JNC TN1410 2000—003. Google Scholar
Kim, J.K, Hu, C.G, R.S.C., Woo & Sham, M.L (2005) Moisture barrier characteristics of organoclay-epoxy nanocomposites. Composites Science and Technology, 65, 805—813.Google Scholar
Knechtel, M.M & Patterson, S.H (1962) Bentonite deposits of the northern Black Hills District, Wyoming, Montana, and South Dakota. US Geological Survey Bulletin, 1082-M, 893—1030.Google Scholar
Kozaki, T., Sato, Y., Nakajima, M., Kato, H., Sato, S. & Ohashi, H. (1999) Effect of particle size on the diffusion behavior of some radionuclides in compacted bentonite. Journal of Nuclear Materials, 270, 265—272.Google Scholar
Madsen, F.T (1998) Clay mineralogical investigations related to nuclear waste disposal. Clay Minerals, 33, 109—129.CrossRefGoogle Scholar
Melkior, T., Mourzagh, D., Yahiaoui, S., Thoby, D., Alberto, J.C, Brouard, C. & Michau, N. (2004) Diffusion of an alkaline fluid through clayey barriers and its effect on the diffusion properties of some chemical species. Applied Clay Science, 26, 99—107.Google Scholar
Mills, R. (1973) Self-diffusion in normal and heavy water in the range 1—45°. Journal of Physical Chemistry, 77, 685—688.Google Scholar
Miyahara, K., Ashida, T., Kohara, Y., Yusa, Y. & Sasaki, N. (1991) Effect of bulk density on diffusion for cesium in compacted sodium bentonite. Radiochimica Acta, 52/53, 293—297.Google Scholar
W.F., Moll Jr. (2001) Baseline studies of The Clay Minerals Society Source Clays: Geological origin. Clays and Clay Minerals, 49, 374—380.Google Scholar
Monma, T., Kudo, M. & Masuko, T. (1997) Flow behaviors of smectite/water suspensions in terms of particle-coagulated structures. Journal of the Clay Science Society of Japan, 37, 47—57.[in Japanese with English abstract].Google Scholar
Nakashima, Y. (2000) Effects of clay fraction and temperature on the H20 self-diffusivity in hectorite gel: A pulsed-field-gradient spin-echo nuclear magnetic resonance study. Clays and Clay Minerals, 48, 603—609.Google Scholar
Nakashima, Y. (2002) Self-diffusion of H20 in stevensite gel: Effects of temperature and clay fraction. Clay Minerals, 37, 83—2291.Google Scholar
Nakashima, Y. (2003) Diffusion of H20 in smectite gels: Obstruction effects of bound H20 layers. Clays and Clay Minerals, 51, 9—22.(erratum is available at http://staff.aist.go.jp/nakashima.yoshito/bin/errata. pdf).Google Scholar
Nakashima, Y. (2004) Nuclear magnetic resonance properties of water-rich gels of Kunigel-Vl bentonite. Journal of Nuclear Science and Technology, 41, 981—992 (Free download of the full text is available at http://www.jstage.jst.go.jp/article/jnst/41/10/981/_pdf).Google Scholar
Nakashima, Y. & Mitsumori, F. (2005) H20 selfdiffusion restricted by clay platelets with immobilized bound H20 layers: PGSE NMR study of waterrich saponite gels. Applied Clay Science, 28, 209—221.Google Scholar
Osman, M.A, Mittal, V. & Lusti, H.R (2004) The aspect ratio and gas permeation in polymer-layered silicate nanocomposites. Macromolecular Rapid Communications, 25, 1145—1149.Google Scholar
Osman, M.A, J.E.P., Rupp & Suter, U.W (2005) Gas permeation properties of polyethylene-layered silicate nanocomposites. Journal of Materials Chemistry, 15, 1298—1304.Google Scholar
Price, W.S (1997) Pulsed-field gradient nuclear magnetic resonance as a tool for studying translational diffusion. 1. Basic theory. Concepts in Magnetic Resonance, 9, 299—336.Google Scholar
Pusch, R. (1992) Use of bentonite for isolation of radioactive waste products. Clay Minerals, 27, 353—361.Google Scholar
Pusch, R. (2001) The buffer and backfill handbook part 2: Materials and techniques. SKB Technical Report, TR—02.12, 1—198.Google Scholar
Sato, H., Ashida, T., Kohara, Y., Yui, M. & Sasaki, N. (1992) Effect of dry density on diffusion of some radionuclides in compacted sodium bentonite. Journal of Nuclear Science and Technology, 29, 873—882.Google Scholar
Schramm, L.L & J.C.T., Kwak (1982) Influence of exchangeable cation composition on the size and shape of montmorillonite particles in dilute suspension. Clays and Clay Minerals, 30, 40—48.Google Scholar
Smellie, J. (2001) Wyoming bentonites: Evidence from the geological record to evaluate the suitability of bentonite as a buffer material during the long-term underground containment of radioactive wastes. SKB Technical Report, TR—01.26, 124.Google Scholar
Stejskal, E.O & Tanner, J.E (1965) Spin diffusion measurements: Spin echos in the presence of a timedependent field gradient. Journal of Chemical Physics, 42, 288—292.Google Scholar
C, Tournassat, Neaman, A., Villieras, F., Bosbach, D. & Charlet, L. (2003) Nanomorphology of montmorillonite particles: Estimation of the clay edge sorption site density by low-pressure gas adsorption and AFM observations. American Mineralogist, 88, 1989—1995.Google Scholar
Yu, J.W & Neretnieks, I. (1997) Diffusion and sorption properties of radionuclides in compacted bentonite. SKB Technical Report, TR—97.12, 1—98.Google Scholar