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Soil Science Society of America Journal Abstract -

Desorption of Glycerol from Clays as a Function of Glycerol Vapor Pressure1


This article in SSSAJ

  1. Vol. 30 No. 1, p. 30-34
    Received: May 3, 1965
    Accepted: Nov 8, 1965

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  1. B. F. Hajek and
  2. J. B. Dixon2



Glycerol desorption isotherms were developed for montmorillonite, vermiculite, kaolinite, and a mixture of montmorillonite and vermiculite at 95C and 80C. Application of the Langmuir equation to desorption data for montmorillonite indicated that 465 mg of glycerol was necessary for a complete monomolecular layer on all surfaces of 1 g of 2µ to 0.2µ clay. Although desorption data for vermiculite fitted the Langmuir equation, the adsorbed glycerol apparently was held at lower average density than for montmorillonite. Two intersecting straight lines fitted the desorption data for a montmorillonite and vermiculite mixture plotted according to the Langmuir equation, indicating that the two minerals could be distinguished quantitatively in the mixture. Multimolecular layers of glycerol appeared to be adsorbed on kaolinite at temperatures and pressures needed for duointerlayer (true monolayer) sorption by montmorillonite. Enthalpies of desorption from a Langmuir constant and from the Clausius-Clapeyron equation compared favorably. Enthalpies ranged from 40 to 55 kcal/mole of glycerol desorbed from kaolinite and expansible minerals, respectively.

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