Prediction of Density, Dynamic Viscosity, and Surface Tension of Seven Ionic Liquids [N222(n)][Tf2N] (n = 5,6,7,8,10,12,14)

In the present work, some thermophysical properties are correlated and predicted for seven Ionic Liquids (ILs) n-alkyl triethylammonium bis(trifluoromethylsulfonyl)imide ([N222(n)][Tf2N]). In this way, the Cubic Plus Association (CPA) Equation of State (EoS) singly, and in combination with the Free Volume Theory (FVT) and the modified Pelofsky models were employed to estimate the density, dynamic viscosity, and surface tension of the ILs, respectively. The properties of three of the ILs were correlated and the parameters of the models were optimized. Then, the achieved parameters were correlated as a unified-form function of carbon number in cationic alkyl chains of the ILs so that the model parameters could be predicted for the other four ILs. Indeed, three ILs with pentyl, octyl, and dodecyl alkyl chains were used in the correlation scenario, and the others were utilized in the predicting approach. According to the results, correlation, and prediction approaches present Absolute Average Deviations (AADs%) equal to 0.0207 & 1.1393 for density, 4.4478 & 12.8312 for dynamic viscosity, and 0.1632 & 1.3820 for surface tension, respectively. As can be concluded from the output, both correlative and predictive approaches demonstrate good accuracy. Therefore, the inter/extrapolation of the results could be performed for other ILs from this family.