Quantifying the effect of polarity on the behavior of mixtures of n-alkanes with dipolar solvents using polar soft-statistical associating fluid theory (Polar soft-SAFT)

We present results concerning the phase equilibria and excess properties of binary mixtures of n-alkanes with a range of fluids from low to high dipolar strength, namely 1-hexene, chloroform, dichloromethane, tetrahydrofuran, acetone, dimethylformamide, and N-methyl pyrrolidone modeled by polar soft-statistical associating fluid theory. Polar interactions are considered through the theory of Gubbins and Twu, extended to chainlike fluids by Jog and Chapman, and a priori fixing the polar parameters of the pure fluids, instead of fitting to experimental data. The equation provides accurate predictions for low to moderate dipolar molecules with n-alkanes, while the induced dipoles created by very strong dipolar fluids (μ ≥ 3.5 D), is implicitly considered by the appropriate selection of pure component parameters and a binary parameter which can be transferred to predict other properties. The equation is used to systematically study the effect of asymmetrical energy scales between polar and nonpolar fluids on vapor–liquid equilibria and excess properties.