Volumetric properties of mixtures involving ionic liquids from improved equation of state

The present work aims to propose alternative corresponding states correlations for temperature-dependent parameters appeared in perturbed hard-sphere equation of state (PHS EOS). The microscopic scaling constants sigma, the effective hard-sphere diameter, and epsilon, the non-bonded interaction energy between two spheres are employed to construct the correlations. The modified PHS EOS is applied to model the volumetric properties of pure and mixtures containing ionic liquids (ILs). For 3127 experimental density data points examined for the studied pure ILs, the total average absolute deviation (AAD) of the predicted densities from the literature data is found to be 0.52%. Also, 978 data points for binary mixtures is examined, the AAD of the calculated densities of mixtures from those reported in the literature is found to be 0.79%. Several thermodynamic coefficients have also been successfully determined by the use of the present PHS EOS. The effect of the solvent on the excess functions of the studied binary mixtures has also been investigated using the proposed model. (C) 2012 Elsevier B.V. All rights reserved.