An analytical expression for the vapor pressure of ionic liquids based on the Peng-Robinson equation of state is proposed. The method uses the concept of zero-pressure fugacity previously presented in the literature and that has been found to work well in the range of low vapor pressures (lower than 0.1. Pa), where the values of vapor pressure of ionic liquids, up to moderate temperatures, are found. The parameters of the equation of state are generalized in terms of ionic liquid properties and results are compared with experimental data, showing average absolute deviations below 8%. The advantage of the proposed analytical expression is its solid thermodynamic foundation, the generalization of the model parameters, and its acceptable accuracy for engineering calculations.
Bibliographical noteFunding Information:
The authors thank the support of the Direction of Research of the University of La Serena and of the Center for Technological Information of La Serena-Chile, for special support. J.O.V. thanks the National Council for Scientific and Technological Research (CONICYT) for its research grant FONDECYT 1120162 . L.A.F. thanks the Administrative Department of Science, Technology and Innovation (Colciencias-Colombia) , for financial support through the program National Doctorates-Bicentennial Generation 2009.
- Equations of state
- Ionic liquids
- Vapor pressure
- Zero-pressure fugacity