(384e) Corresponding States Principle and Group Contribution Method for the Prediction of Physicochemical Properties of Ionic Liquids

Ionic liquids (ILs) refer to liquids composed entirely of ions that are fluid around or below 100°C¹ and continue to attract burgeoning interest in both academic research and industrial field which often requires knowledge of their physicochemical properties. It is difficult to measure all the properties of different ILs at wide conditions due to the vast amount of possible combination of cations and anions. Alternatively, generalized reliable predictive models for physicochemical properties are of fundamental importance in exploiting new ionic liquids and process design or simulation. Group contribution method has been extended to predict the thermophysical properties of ionic liquids², but the research on the critical properties is scarce, which are essential for the calculation of physicochemical properties using the generalized equations or appropriate equation of state. A new method combined Group Contribution with Corresponding States Principle (GC-CSP) method is developed herein to predict the normal boiling temperatures, the acentric factors and the critical properties (namely, critical temperature, pressure and volume) of ILs. The reliability of the GC-CSP method developed here is verified by the prediction of density and surface tension which used the critical properties predicted using this method. With the calculated critical properties, new equations based on corresponding states principle for the estimation of density, surface tension, heat capacity and thermal conductivity are proposed via data regression. The results show that the GC-CSP method gives reliable critical properties of ILs which can be successfully applied to density and surface tension prediction. The calculated density, surface tension, heat capacity and thermal conductivity by the proposed equations display a good agreement with the corresponding experimental densities with the average absolute relative deviation all less than 4%.

References

1. Rogers RD, Seddon KR. Ionic liquids - Solvents of the future?. Science. Oct 31 2003;302(5646): 792-793.

2. Gardas RL, Coutinho JAP. Group Contribution Methods for the Prediction of Thermophysical and Transport Properties of Ionic Liquids. Aiche Journal. May 2009;55(5):1274-1290.