Modeling Diluted Bitumen−Water Interfacial Compositions Using a Thermodynamic Approach

Abstract

A two-layer interfacial model was proposed to describe the layout of large and small surface-active species on a diluted bitumen/water interface. Based on this model, large asphaltene species “float” on the interface, with only “point contacts” with the actual interface, allowing small surface-active species to occupy almost the entire interfacial area at the same time. This interfacial model is able to reconcile the contradiction found in the literature (i.e., the small average molar area inferred from the interfacial tension data and the dominance of large asphaltene species on the interface, detected through chemical analyses). The multicomponent interface was further quantitatively modeled, using a modified Butler-type equation. The resulting parameters are consistent with many experimental findings in the literature.