Modeling the Volumetric Properties of Ionic Liquids Using Modified Perturbed Hard-Sphere Equation of State: Application to Pure and Binary Mixtures

Abstract

In this paper, an alternative corresponding states correlation was applied to the perturbed hard-sphere equation of state (PHS EOS) to improve the predictive power of this EOS for modeling the volumetric properties of ionic liquids (ILs) and their mixtures. Two temperature-dependent parameters appearing in the EOS have been determined using two reliable scaling constants, the surface tension and the liquid density, both at room temperature. The predictive power of the proposed model has been assessed by comparing the results with 2366 experimental data points over a broad range of pressures and temperatures. The overall average absolute deviation (AAD) of the calculated densities from literature data was found to be 0.77%. Generally, this work shows that the PHS EOS based on the surface tension property of ILs outperforms the PHS EOS based on critical properties. Moreover, the improved PHS EOS has been applied to predict the volumetric properties of 16 binary mixtures involving ILs. The second partners of binary mixtures studied in this work are water, ethanol, methanol, acetone, acetonitrile, propylene carbonate, and 1-propanol. Furthermore, the binary mixtures of ILs have also been studied. From 1685 data points examined for the aforementioned binary mixtures, the AAD of the calculated densities and the excess volumes from those reported in the literature were found to be 0.38 and 0.56%, respectively. Finally, the nonadditivity behavior of the studied mixtures is also investigated. The sign of the nonadditivity parameter indicates a tendency toward attraction between the unlike molecules in the mixture. However, the value of this parameter is not large, which implies that the hard-sphere model is able to model the excess properties of the present mixtures.

Equation of state modelling of systems with ionic liquids: Literature review and application with the Cubic Plus Association (CPA) model

“…The obtained AAD values were between 0.8 and 2% for the first case [109] and between 0.3 and 3% for the second case [110]. Very recently [111], the same group applied an alternative corresponding-states correlation to the perturbed hard-sphere EoS to improve the model's capability of describing the volumetric properties of ionic liquids and their mixtures. Their main objective with this work was to apply the surface tension properties of ionic liquids (which can easily be measured experimentally) instead of the critical properties (which cannot be determined experimentally).…”

Density and isothermal compressibility of ionic liquids from perturbed hard-sphere chain equation of state

“…It should be mentioned that the extension of the proposed EOS for modeling the PVTx properties of mixtures involving ILs remains for future work. Table 4 Comparison of AAD calculated high-pressure densities of some studied ILs in this work, the preceding work of Hosseini et al [44] and those estimated by the method of G & C [9], compared with the experiment.…”

“…In order to assess further the reliability of the PHSC EOS, we have compared the present model with the group contribution method of Gardas and Coutinho (G & C) [9] as well as our previous model [44]. The outcomes of the calculations are given in Table 4.…”

“…The calculated results revealed that the predictive PHSC EOS can well represent the thermodynamic coefficients as well as densities of the studied systems. The predicted results were compared with those obtained from other approaches developed in the literature; e.g., the method of G & C [9] based on the use of group contributions and PHS EOS previously developed by Hosseini et al [44]. It should be mentioned that the extension of the proposed EOS for modeling the PVTx properties of mixtures involving ILs remains for future work.…”

Thermophysical properties of ionic liquids and their mixtures from a new equation of state

“…Aparicio et al [5] reviewed the available predictive models as well as experimental data reported in literature for the thermophysical properties and especially density and PVT behavior of ionic liquids. Further, a perturbed hard-sphere equation of state has been employed to predict the pressure-volume-temperature properties of some pure and mixture of ionic liquids [6][7][8][9]. Also, they predicted the volumetric properties of ILs using Ihm-Song-Mason (ISM) [10] and Tao-Mason [11] equations of state.…”