Representation of phase behavior of ionic liquids and their mixtures using various forms of cubic-two-state equation of state

Abstract

In this work, in addition of Soave-Redlich-Kwong (SRK) equation of state, two other alternative cubic models such as Peng- Robinson (PR) and Cubic Square Well (CSW) EoSs are combined with the Two-State Association Model (TSAM) and the new forms of the Cubic-Two-State equation of state (CTS EoS) as PR-TS and CSW-TS are presented. In the beginning, the present models are used to correlate the saturated vapor pressure and liquid density of pure water, alcohols and phenol. The models are also employed to predict vapor molar volume and second virial coefficients of pure compounds to explore the predictability of the different type of the CTS models. Also, the liquid density of different pure ionic liquids (ILs) at various temperatures from 298.15 K up to 500 K and pressure from 0.1 MPa up to 59.59 MPa is correlated and the parameters of the CTS models are obtained. Following successful application of the models for the pure components, using one temperature independent binary interaction parameter, the SRK-TS and PR-TS models are applied to predict the vapor-liquid equilibrium of the several binary mixtures consists of IL with non-association and association components at various temperatures from 298.15 K up to 363.15 K and pressure from 0.09 kPa up to 216 kPa. The results of the SRK-TS and PR-TS models for pure and binary systems containing ILs are in very good agreement with experiments and also are compared with various equations of states that show better results. In overall for the systems that are presented in this work, the PR-TS model shows slightly better results with respect to the SRK-TS model specially in prediction, and PR-TS and SRK-TS models present superiority with respect to the CSW-TS EoS.