The surface energy of hydrophilic and hydrophobic adsorbents

Water vapor adsorption and heats of water wetting are studied for hydrophilic quartz, hydrophobic-hydrophilic talc, and hydrophobized Silochrom samples. Water contact angles on the materials under examination are found. The surface thermodynamic parameters of the sorbents are calculated from the data obtained. It is shown that boundary water layers on hydrophilic quartz surface are ordered to a higher extent, while those on hydrophobic basal surfaces of talc particles and hydrophobic surfaces of modified Silochrom samples are ordered to a lower extent relative to liquid water. An empirical equation relating the surface pressure of water films adsorbed on hydrophilic high-energy surfaces with the surface free energy of the latter is proposed. The values of surface free energy are estimated from this equation for a number of important hydrophilic adsorbents.