Extending UNIFAC models for solid-liquid equilibria prediction and design of eutectic solvent systems

Although eutectic solvents (ESs) have received considerable attention as sustainable process fluids for various applications, discovering novel ESs remains challenging as computational methods for predicting the formation of eutectics are still scarce. In the present work, both the original and modified UNIFAC models are evaluated and extended for predicting the solid–liquid equilibria (SLE) of ES systems. The applicability of the two versions of UNIFAC models is first evaluated based on the SLE of 25 ES systems composed of only conventional components. Motivated by the good evaluation results, the SLE of 50 ES systems involving one salt component are employed to extend the UNIFAC models to include novel salt-component-related functional groups. The obtained models cover widely-reported salt components of choline/tetraalkylammonium chloride/bromide and conventional components of fatty alcohols and fatty/dicarboxylic/α-hydroxy acids. A theoretical design of novel ESs in a large scale is performed with the best-performing model extension, wherein four designed ES systems are validated experimentally.