Project Details Critical evaluation of data on solubility and liquid-liquid equilibria in binary mixtures of 1-alkyl-3-methylimidazolium based ionic liquid and molecular solvent

Project No.:
Start Date:
01 May 2016
End Date:


The objective of this project is a critical evaluation of solubility data of binary mixtures of 1-alkyl-3-methylimidazolium-based ionic liquids mixed with molecular solvents. These data have been compiled in the IUPAC project 2011-065-3-500 Database on liquid-liquid equilibria of binary mixtures of ionic liquids and molecular compounds.


Since ionic liquids are classified as novel designer solvents with perspective of many possible applications, an evaluation of their mutual solubilities with traditional solvents is of interest for different technological point of views. In fact, mutual solubilities of ionic liquids as well as the solubility of molecular solvents in ionic liquids are of critical importance in the design and optimization of liquid separation processes, as well as in environmental remediation. Due to the increasing number of published datasets, which range significantly in their quality and robustness, a critical evaluation of this data is needed urgently for the field to move into practical application.

The proposed evaluation will include a critical review of the apparatuses used to measure the solubility data. In addition, the data will be critically assessed with the respect to the experimental techniques used as well as the purity of the ionic liquid/solvent measured. The compiled data will be also evaluated using a robust gnostic method. Mathematical gnostics provides a non-statistical approach to data uncertainty treatment, without an a priori assumption of the error distribution. UNIFAC model parameters will be estimated and methods applying results of the theory of critical phenomena to provide a statistical analysis and estimates for equations of state will be used. Based upon the different analyses carried out during this project, a set of recommended values will be finally presented. A critical overview of the ionic liquids phase behavior in the presence of molecular solvents will be addressed to develop a structure-property relationship including the ion interactions and structure as well as the polar/associating nature of the molecular solvent. The obtained results will provide a framework for process design and a critical assessment of the ability of ionic liquids to be used in separation processes.


The collected data will be processed into a review paper in Journal of Physical and Chemical Reference Data, as a volume of the Solubility Data Series. For this purpose, the collected data will be critically assessed by means of correlations by the modified Flory-Huggins equation. A robust gnostic regression method will be used to obtain equation parameters, enabling us at the same time to evaluate the agreement between individual datasets for systems measured by different authors and/or methods. The experimental data will also be compared with molecular simulations or relevant predictions where available in literature. Eventually, in the planned publication, chemical-engineering aspect of the data will be discussed.

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Feb 2021 update
– The project that has been on hold until the end of 2020, and just restarted. An early-stage researcher will join the Task Group to contribute to the data mining and critical evaluation of the data.

page last updated 17 April 2021