Derivation of a pH Dependent Solid-Liquid Interfacial Tension and Theoretical Interpretation of the Physicochemistry of Dewetting in the CO2-Brine-Silica System

The solid-liquid interfacial tension is a fundamental parameter in areas of wettability pertaining to adhesive bonds and petroleum engineering practice. In wettability issues related to surface functionalized polymeric materials design to achieve specific adhesive properties, the solid-liquid interfacial tension can be pH dependent due to amphoteric behavior. In this paper, we have used the theory of pH dependent surface charging and the 2-pk model as well as the site binding model of the electric double layer theory to derive a pH dependent solid-liquid interfacial tension equation. Following the fundamental relationship between solid-liquid interfacial tension and contact angle in light of Young’s equation, we have extended the theoretical basis of the derivation. Consequently, we have also derived a pH dependent cosine of the thermodynamic contact angle. Both equations give satisfactory explanations for observed experimental data available in the literature.