Surface-treated white pigment

Abstract

The effect of the form and the parameters of the atom-atom potential of intermolecular interaction, as well as that of the approximations used in its summation over the atoms of a solid, on the values of the Henry constant K1 for the adsorption of noble gases on the basal face of graphite has been examined. At fixed values of the depth and of the position of the atom-atom potential minimum, K1 values are only slightly sensitive to the form of this potential, if its summation is performed taking into account the layer structure of graphite. Disregarding the laminated structure of the graphite lattice leads to highly underestimated values of K1. The values of the parameter c1 of the attractive forces of the potential (6, 8, exp) for the intermolecular interaction of the atoms of noble gases with the carbon atom of graphite have been determined, using experimental values of K1 for the adsorption of these gases on graphitized thermal carbon blacks. The corresponding changes in internal energy, entropy and heat capacity have been calculated.The effect of the form and the parameters of the potential function φ of the intermolecular interaction of a monoatomic molecule with the basal face of graphite on the energy φo in the minimum of the potential curve φ(z), and on the product szo of the specific surface area s, and the equilibrium distance between the molecule and the surface zo, has been studied. φo and szo were determined from experimental values of the Henry adsorption constant K1 measured at different temperatures. From the experimental values of K1 for the adsorption of noble gases, the value of s for graphitized thermal carbon black Sterling PT, 2700 (P-33), has been determined. This value of s does not essentially depend on the adsorbate and lies within the limits of error of the s value, determined for this carbon black by the BET method. When determining s from K1, it is necessary to take into account the structure of the solid so as to choose the form of potential φ correctly. Values of zo should be determined from the atom-atom potential function of the adsorbate-adsorbent intermolecular interaction.