Correlation of three-liquid-phase equilibria involving ionic liquids

Area of Science:

• Thermodynamics
• Chemical Engineering
• Materials Science

Background:

• Accurate thermodynamic models for phase equilibria are challenging, especially for multi-phase systems and complex compounds like ionic liquids.
• Ionic liquids offer promising properties for future industrial applications, necessitating robust modeling approaches.

Purpose of the Study:

• To achieve the first simultaneous correlation of liquid-liquid and liquid-liquid-liquid equilibrium data for ternary systems involving ionic liquids.
• To determine the phase diagram of the water + [P66614][DCA] + hexane system at different temperatures.
• To correlate thirteen sets of equilibrium data for water + ionic liquid + oil ternary systems.

Main Methods:

• Determination of phase diagrams at 298.15 K and 323.15 K and atmospheric pressure.
• Correlation of equilibrium data using the NRTL model and isoactivity equilibrium condition.
• Analysis of geometric aspects of the Gibbs energy of mixing and common tangent plane condition.

Main Results:

• The phase diagram for the water + [P66614][DCA] + hexane system was determined.
• Good agreement was achieved between experimental and calculated data for all regions (triphasic and biphasic).
• The proposed strategies and NRTL model effectively correlated complex ternary systems involving ionic liquids.

Conclusions:

• The study successfully correlated complex multiphasic equilibrium data involving ionic liquids.
• The NRTL model and proposed strategies provide a reliable method for describing phase behavior in these systems.
• Accurate thermodynamic modeling is essential for advancing applications of ionic liquids, such as in enhanced oil recovery.