thermodynamic modeling of interfacial tension between di water and model oil by cubic-plus association (cpa) eos

Modeling of interfacial tension (ift) in liquid-liquid systems is of enormous importance in different contexts such as fluid flow in porous media, emulsion preparation, and foam stability# in this work, the equilibrium ift of de-ionized (di) water and model oil systems was measured by pendant drop tensiometry# cubic plus association equation of state (cpa eos) was employed to reproduce the experimental data and predict the equilibrium ift at different conditions# the model oil was prepared by dissolving asphaltene in a heptane-toluene solution# the modeling results indicate that the self-association energy of asphaltene molecules in the interface phase varies with the volume fraction of normal heptane in the bulk of the model oil# in addition, the dependency of the asphaltene self-association energy in the interface to the bulk volume fraction of heptane follows different trends before and after the asphaltene onset point# the asphaltene tendency to participate into the interface phase increases with a decrease in the aromaticity of the model oil#