Interaction of water molecules with hydrophilic and hydrophobic surfaces of colloid particles

Abstract

The hydrophobicity of talc basal surface and the hydrophilicity of silica gel surface have been considered. Ab initio calculations of energy and geometry of microclusters formed by water molecules on active centers of ideal basal surface of talc and silica gel surface were carried out. It was shown that the typical property of hydrophobic surface is the adsorption of single molecules on weak centers (oxygen atoms of siloxane group) of talc surface that next serve as secondary centers of adsorption of water molecules. At the same time the water adsorption on strong active centers (vicinal pairs) of silica gel surface leads to the formation of a cluster having the structure similar to that of liquid water. Accordingly an adsorption layer near the hydrophobic surface is depleted, while a layer near the hydrophilic surface is enriched with adsorbate molecules.