Modeling of P-ρ-T properties of ionic liquids using ISM equation of state: Application to pure component and binary mixtures

Abstract

Ihm-Song-Mason (ISM) equation of state (EOS) has been previously employed for modeling the volumetric properties of ionic liquids (ILs). The novelty of the present work is in replacing the macroscopic scaling constants with microscopic ones. Three temperature-dependent parameters that appeared in the EOS, which are universal functions of the reduced temperature, were determined using these new microscopic scaling constants. These parameters are the effective hard-sphere diameter (σ) and the non-bonded interaction energy between two spheres (ɛ). The present EOS is evaluated by examination of 3997 experimental density data points for five classes of ILs. The average absolute deviation (AAD) of the calculated densities from literature values was found to be of the order of 0.38%. Our calculations involved a broad range of temperature from 293 K to 472 K and pressures from 0.1MPa up to 200MPa. Another aspect of the present study is the extension of the proposed EOS to predict density of binary mixtures involving IL+ water and IL+ IL. In the case of binary mixtures, 898 data points were taken to assess the capability of the EOS. The overall AAD of the calculated mixture densities from the literature ones was within 0.43%.