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Clays and Clay Minerals

, Volume 42, Issue 5, pp 526–533 | Cite as

Formation of Hydrotalcite-like Compounds During R7T7 Nuclear Waste Glass and Basaltic Glass Alteration

  • A. Abdelouas
  • J. L. Crovisier
  • W. Lutze
  • B. Fritz
  • A. Mosser
  • R. Müller
Article

Abstract

Alteration experiments have been performed using RTT7 and synthetic basaltic glasses in MgCl2−CaCl2 salt solution at 190°C. The duration of experiments ranged from 0.25 to 463 days. The alteration products were studied by Scanning Electron Microscope (SEM), Scanning Transmission Electron Microscope (STEM), X-ray diffraction (XRD) and Electron Spectrometry for Chemical Analysis (ESCA). For both glasses, the early alteration product is a hydrotalcite-like compound [Mg6Al2CO3(OH)16·4H2O] in which HPO42−, SO42− and Cl substitutes for CO32−. The measured basal spacing is 7.68 Å for the hydrotalcite formed from R7T7 glass and 7.62 Å for the hydrotalcite formed from basaltic glass which reflect the high Al/Al + Mg ratios x (0.34 ≤ x ≤ 0.46). The chemical microanalyses show that the hydrotalcite is subsequently covered by a silica-rich gel which evolves into saponite after a few months. These results support the use of basaltic glasses alteration patterns in Mg-rich solution, to understand the long-term behavior of R7T7 nuclear waste glass.

Key Words

Basaltic glass Experimental alteration Hydrotalcite-like compounds MgCl2-CaCl2 salt solution R7T7 nuclear waste glass Saponite 

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Copyright information

© The Clay Minerals Society 1994

Authors and Affiliations

  • A. Abdelouas
    • 1
    • 2
  • J. L. Crovisier
    • 2
  • W. Lutze
    • 1
  • B. Fritz
    • 2
  • A. Mosser
    • 3
  • R. Müller
    • 1
  1. 1.Kernforschungszentrum KarlsruheINEKarlsruheDeutschland
  2. 2.Centre de Géochimie de la SurfaceC.N.R.S.Strasbourg CedexFrance
  3. 3.IPCMS Groupe Surfaces-InterfacesStrasbourg CedexFrance

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