Densities of ionic liquids from ion contribution-based equation of state: Electrolyte perturbation approach

- Development of electrolyte perturbed hard-sphere EOS based on MSA
- Parameterising the proposed EOS using ion-contribution method
- Density prediction of 29 ionic liquids
- Comparison with previous PHS model

In the present work, an ion contribution equation of state (EOS) based on the electrolyte perturbation theory is developed for 29 ionic liquids (ILs). According to this model, each ionic liquid is divided into two charged hard-spheres representing cation and anion. The ion parameters which reflect the hard-sphere diameter σ and the non-bonded interaction energy ε are optimised by the use of some pressure-volume-temperature (PVT) data. The performance of the model is examined by predicting the densities of 4353 experimental density data points over a wide range of temperatures within 272 K-472 K and pressures from 0.1 MPa up to 204 MPa. The studied ILs were imidazolium-, phosphonium-, pyridinium-, pyrrolidinium-, piperidinium-, and ammonium cation-based. The average absolute deviation (AAD in %) of the calculated densities from the literature values is found to be of the order of 0.64%.

Schematic representation of the physical basis of the electrolyte perturbed hard-sphere model.