Hostname: page-component-78c5997874-lj6df Total loading time: 0 Render date: 2024-11-10T07:12:13.806Z Has data issue: false hasContentIssue false
  • English
  • Français

Effects of Relative Humidity on the Basal Expansion of Mg-Smectite Equilibrated with Ethylene Glycol at Low Vapor Pressure

Published online by Cambridge University Press:  02 April 2024

Y. P. Hsieh
Y. P. Hsieh*
Affiliation:
Wetland Ecology Program, Florida A&M University, Tallahassee, Florida 32307
Rights & Permissions [Opens in a new window]

Abstract

Core share and HTML view are not available for this content. However, as you have access to this content, a full PDF is available via the ‘Save PDF’ action button.

The effects of relative humidity (RH) on the expansion of Mg-smectite, equilibrated with low vapor pressure of ethylene glycol (EG), was studied. Four smectite samples were equilibrated with EG vapor from: (1) saturated vapor of pure EG, (2) an EG-CaCl2 solvate, and (3) 0.05 relative EG vapor pressure at 65°C. X-ray powder diffraction (XRD) analyses of the clays under different RH conditions indicated that without EG, the basal spacing of Mg-smectite samples could only be expanded to 16 Å, even at 0.97 RH. The basal spacing of Mg-smectite samples equilibrated with saturated EG vapor was expanded to 17.1 Å and was not significantly affected by RH in the range 0.1–0.9. The basal spacing of the Mg-smectite samples equilibrated with vapor from the EG-CaCl2 solvate and 0.05 relative EG pressure at 65°C was expanded by an amount that depended on the RH during the XRD analysis. The basal spacing increased from 14.2 to 17.1 Å as the RH increased from 0.6 to 0.75, except for sample API 23, which expanded to 17.1 Å at RH > 0.9. This sample did not expand beyond 16 Å when it was equilibrated with 0.05 EG relative vapor pressure. Sorption of moisture from air caused the one-layer EG-Mg-smectite complex (basal spacing = 14.1 Å) to rearrange itself to a double-layer EG-Mg-smectite complex (basal spacing = 17.1 Å). A small amount of the adsorbed EG in Mg-smectite, much less than was needed to cover a one-layer of the interlayer surfaces, caused an expansion of the basal spacing to 17.1 Å at high RH during the XRD analysis. The minimum amount of adsorbed EG which caused the one-/two-layer EG complex conversion was about 20–30 mg EG/g. The conversion was fast (<5 min) and was relatively reversible.

Keywords

Basal expansionEthylene glycolRelative humiditySmectiteX-ray powder expansion
Type
Research Article
Information
Clays and Clay Minerals , Volume 37 , Issue 5 , October 1989 , pp. 459 - 463
Copyright
Copyright © 1989, The Clay Minerals Society

References

Boublick, T., Fried, V. and Hala, E., 1973 The Vapor Pressure of Pure Substances New York Elsevier 98.Google Scholar
Dyal, R. S. and Hendricks, S. B., 1950 Total surface of clays in polar liquids as a characteristic index Soil Sci 69 421 – 432.CrossRefGoogle Scholar
Hsieh, Y. P., Tsai, P. P. and Hsu, P. H., 1984 Expansion of smectites as a function of vapor pressure of ethylene glycol Soil Sci. Soc. Amer. J 48 935 – 939.CrossRefGoogle Scholar
Jackson, M. L., 1969 Soil Chemical Analysis–Advanced Course 127 – 141.Google Scholar
Keren, R. and Shainberg, I., 1975 Water vapor isotherms and heat of immersion of Na/Ca-montmorillonite systems–I: Homoionic clay Clays & Clay Minerals 23 193 – 200.CrossRefGoogle Scholar
Kunze, G. W., 1955 Anomalies in the ethylene glycol solvation technique used in X-ray diffraction Clay and Clay Minerals 395 88 – 93.Google Scholar
Mooney, R. W., Keenan, A. E. and Wood, L. A., 1952 Adsorption of water vapor by montmorillonite–II. Effect of exchangeable ions and lattice swelling as measured by X-ray diffraction J. Amer. Chem. Soc 74 1371 – 1374.CrossRefGoogle Scholar
Morin, R. E. and Jacobs, H. S., 1964 Surface area determination of soils by adsorption of ethylene glycol vapor Soil Sci. Soc. Amer. Proc 38 190 – 194.CrossRefGoogle Scholar
Shainberg, I., Kemper, W. D. and Bailey, S. W., 1966 Electrostatic forces between clay and cations as calculated and inferred from electrical conductivity Clays and Clay Minerals New York Pergamon Press 117 – 132.CrossRefGoogle Scholar