A Gibbs free energy minimization based model for liquid–liquid equilibrium calculation of a system containing oil, brine, and surfactant

Abstract

Accurate and reliable phase equilibrium calculations of microemulsion systems are of great importance. This study deals with the thermodynamic modeling of Liquid–Liquid Equilibrium (LLE) of a system including oil (n-decane), brine (containing CaCl2 salt), and ionic surfactant (sodium dodecyl sulfonate). Two models of UNIQUAC and UNIQUAC + Debye–Hückel were used for thermodynamic calculations. The LLE experimental data were utilized to estimate the binary interaction parameters of UNIQUAC model and the adjustable parameter, b, of the Debye–Hückel model. The thermodynamic model calculates the microemulsion phase’s compositions by minimizing the Gibbs free energy of the LLE system using a combination of genetic algorithm and fmincon function in order to prevent local minima. The thermodynamic modeling results show an appropriate agreement with the experimental data. Accordingly, the presented model of this study can be used as a suitable method to investigate the liquid–liquid equilibrium of systems containing oil, water, and surfactant.

Dissociative electron attachment to gold(I)-based compounds: 4,5-dichloro-1,3-diethyl-imidazolylidene trifluoromethyl gold(I)

“…The Gibbs free energy ( Salike and Bhatt, 2020 ; Lee et al, 2015 ; Martins and Cabral, 2019 ) of formation and reaction has been used multiple times to analyze the suitability of different complexes and organic or protein material for drug resistance ( Tahir et al, 2020 ), equilibrium calculations of emulsion systems ( Hosseini and Mohammadi, 2020 ), enthalpy of DNA formation ( Lomzov et al, 2015 ), calculations of different mineral formation ( Olivotos and Economou-Eliopoulos, 2016 ), and nanolithography (the present study). The Gibbs free energy of a compound is explained in terms of enthalpy (H), temperature (T), and entropy (S) by the relation: ΔG = ΔH–TΔS.…”