Current status and prospects for development of research on the hydrophilicity of disperse systems

The current status of research on the hydrophilicity of disperse systems was discussed. The criterial values of the surface pressure of the adsorbed water film, heat and contact angle of wetting with water which separate the hydrophilic and hydrophobic surfaces were determined. An analysis of the thermodynamic characteristics showed that the boundary layers of water are more ordered near a hydrophilic surface (mica, kaolinite) and less ordered near a hydrophobic surface (organokaolinite, graphite) in comparison to liquid water. The biexponential character of the change in the structural component of the disjoining pressure with the thickness of the water film was demonstrated for disperse materials with a hydrophilic surface (kaolinite). The classification of the forms of water bound by hydrophilic disperse materials was discussed. The changes in the thermodynamic functions of vermiculite in adsorption of water were found with complex adsorptioncalorimetric and dilatometric measurements. This adsorbent undergoes a first-order phase transition during adsorption. The prospects for use of the adsorption-calorimetric method for determining the amount and energy characteristics of hydrophilic sites was demonstrated for ZSM-5 hydrophobic zeolite.Presented to the meeting of the Chemistry Section of the Academy of Sciences of the Ukraine on October 27–29, 1992.Translated from Teoreticheskaya i Eksperimental'naya Khimiya, Vol. 29, No. 2, pp. 100–115, March–April, 1993.