Calculation of Vapor-Liquid and Liquid-Liquid Phase Equilibria for Systems Containing Ionic Liquids Using a Lattice Model

A lattice model developed previously is adopted to describe the vapor-liquid- and liquid-liquid-phase behavior of the systems containing ionic liquids that are treated as chainlike molecules with a chain length of r, while that of solvents is taken as 1. To take into account the impact of hydrogen bonds existing in the solutions to properties, the exchange energy in the model is expressed as a function of the temperature based on the concept of the double lattice model. It is found that this model can correlate infinite diluted activity coefficients, vapor pressures of solvents, and liquid-liquid equilibria of ionic liquid solutions successfully. Comparison between the calculated results and the experimental data shows the vigor of the model.