Thermodynamic study of interfacial tension between oil and aqueous phases composed of ionic liquids and brine

The first fundamental step in determining the physicochemical properties of an equilibrium system is to determine the activity coefficient of electrolyte and non-electrolyte ions. Based on understanding the importance of activity coefficient in thermodynamic systems in this study, in order to predict interfacial tension between oil and aqueous phases composed of ionic liquids and brine, a modified thermodynamic equation based on concentration and coefficient of activity of ionic liquids is defined. For this study, the Extended UNIQUAC model is desired and its adjustable parameters are optimized with Genetic + PSO algorithm. The modified model has practical features such as investigating the effect of concentrations of salts in the water of oil fields formation on the interfacial tension of the system, investigating the effect of concentrations of various organic compounds such as ionic liquids on the interfacial tension of the system and investigating the interaction energy between organic and inorganic ions. In this study, the optimization of the modified thermodynamic equation to predict the interfacial tension of solutions containing [C₈Py][Cl], [C₁₈Py][Cl], [C₁₂mim][Cl] and [C₁₈mim][Cl] with the presence of brine and distilled water is investigated. Also, the effect of ionic strength of the solution in 32 equilibrium systems on interfacial tension is investigated. According to the optimization results of this study, the design of a computer program can be considered to predict the interfacial tension with the presence of ionic liquids and salts.