Thermodynamic modeling of interfacial tension between DI water and model oil by cubic-plus association (CPA) EoS
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1Chemical/Petroleum Engineering, College of Engineering, Univ of Tehran, Tehran, Iran
2Institute of Petroleum Engineering, School of Chemical Engineering, College of Engineering, University of Tehran, P.O. Box 11155/4563, Tehran, Iran
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.