Fourier Transform Infrared Spectroscopic Techniques to Investigate Surface Hydration Processes on Bentonite

Author: Shewring N.I.E.   Jones T.G.J.   Maitland G.   Yarwood J.  

Publisher: Academic Press

ISSN: 0021-9797

Source: Journal of Colloid and Interface Science, Vol.176, Iss.2, 1995-12, pp. : 308-317

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Abstract

Hydration processes at the bentonite surface have been investigated using Fourier transform infrared transmission and attenuated total reflection (ATR) spectroscopic techniques. Significant differences in the silicate nu(Si-O) stretching region (1150 to 950 cm -1 ) have been consistently observed between the spectra of bentonite powder with its natural water content and the spectra of bentonite freshly deposited on a substrate by evaporating the water from an aqueous bentonite suspension. The origin of these differences (and in particular the appearance of two "new" bands at 1086 and 1018 cm -1 ) is discussed in terms of variations in the silicate structure as a function of the variation of electrical double layer properties. Differences of interfacial distances which result from the variations in interplatelet repulsion are thought to be responsible for the spectral changes and this idea is supported by spectral correlations with variations of exchangeable cation and ionic strength of the aqueous environment of the dispersed bentonite.

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