Development of a modified van der Waals-type equation of state for pure and mixture of ionic liquids

The main aim of the present study is to modify the attractive part of van der Waals-type EOS to model the volumetric ionic liquids and their mixtures. The present study uses the Carnahan-Starling (CS) repulsion term and also focuses on introducing a variable parameter in the attractive term of modified vdW-type EOS. Investigation of the results obtained revealed that this variable is a function of temperature. Our results also show that employment of CS repulsion term together with an appropriately chosen exponent in the attractive term of EOS will greatly improve the accuracies of the calculated densities of various ionic liquids. The average absolute deviation (AAD) of the calculated densities from the experimental ones for 848 data points of pure ionic liquids was found to be 0.36. Further, in the case of mixtures, for 1014 data points the AAD was 0.20. (C) 2014 Elsevier B.V. All rights reserved.