Determination of Surface Free Energy of Kaolinite

Authors:
  • ECEmil Chibowski
    Emil Chibowski
  • PSPiotr Staszczuk
    Piotr Staszczuk
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Abstract
The adsorption of n-octane and water vapor on natural kaolinite was measured. From adsorption isotherms film pressures were determined which were then used to calculate the dispersion and nondispersion components of the kaolinite surface free energy. In addition, thermodesorption of water from the kaolinite surface was determined. These results suggest that physically adsorbed water remained on the kaolinite surface, even at temperatures as great as 125°C. Therefore, experimentally determined dispersion and nondispersion components appear to relate to the surface precovered with a film of water. These values are: γSf(w)d = 34.4 mJ/m2 for dispersion interactions and γSf(w)n = 60.2 mJ/m2 for nondispersion interactions. Assuming a kaolinite surface precovered with a film of water, which decreased the free energy by the work of spreading, the following components of the energy for the bare surface were calculated: γSd = 67.6 mJ/m2 and γSn = 103.4 mJ/m2, for dispersion and nondispersion components, respectively.

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