Multiphase Behavior of the Water + 1-Butanol + Deep Eutectic Solvent Systems at 101.3 kPa

Area of Science:

• Chemical Engineering
• Thermodynamics
• Green Chemistry

Background:

• The chemical industry seeks sustainable separation and purification processes, driving interest in novel solvent alternatives.
• Deep eutectic solvents (DES) offer an environmentally friendly, cost-effective, and less toxic option compared to traditional solvents like ionic liquids (ILs).
• Understanding the thermodynamic behavior of DES in separation processes is crucial for their industrial application.

Purpose of the Study:

• To investigate the liquid-liquid equilibrium (LLE) and vapor-liquid equilibrium (VLE) of a water + 1-butanol + DES system.
• To evaluate the thermodynamic consistency and model the phase behavior using established approaches.
• To assess the potential of DES as extracting agents and compare them with ILs.

Main Methods:

• Experimental determination of LLE at 298.15 K and 101.3 kPa.
• Experimental determination of VLE at 101.3 kPa across a temperature range of 364.05 K to 373.85 K.
• Thermodynamic consistency tests (Marcilla et al. and Wisniak methods).
• Modeling using the gamma-gamma approach for LLE and gamma-phi for VLE with the NRTL model.

Main Results:

• Experimental LLE and VLE data were obtained and validated for thermodynamic consistency.
• The non-random two-liquid (NRTL) model effectively correlated the phase behavior of the studied system.
• Separation and distribution coefficients indicated the extractive potential of the DES.
• Relative volatility calculations assessed the presence of azeotropes, crucial for distillation design.

Conclusions:

• The studied DES (choline chloride + glycerol) demonstrates efficient phase behavior correlation using the NRTL model.
• DES show promise as effective and sustainable alternatives to ILs in separation and purification processes.
• This research provides a foundation for designing and optimizing industrial separation processes utilizing DES.