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CO2 solvation regimes in deep eutectic solvents revealed by internal-pressure profile
Yuto Ainai1, Chiaki Yokoyama1, Richard Lee Smith2
1Department of Chemical Biology and Applied Chemistry, College of Engineering, Nihon University, 1 Nakagawara, Tokusada, Tamura-machi, Koriyama 963-8642, Japan. kodama.daisuke@nihon-u.ac.jp.
Physical Chemistry Chemical Physics : PCCP
|July 17, 2026
Summary
Thermodynamic internal pressure reveals three CO2 solvation regimes in deep eutectic solvents (DESs). A secondary internal pressure rise indicates unique CO2-DES interactions, distinct from typical liquids.
Area of Science:
- Thermodynamics
- Physical Chemistry
- Materials Science
Background:
- Deep eutectic solvents (DESs) are novel solvents with tunable properties.
- Understanding CO2 solvation in DESs is crucial for applications like carbon capture.
- Internal pressure is a key thermodynamic parameter reflecting molecular interactions.
Purpose of the Study:
- To investigate CO2 solvation behavior in ethylene glycol-based DESs using thermodynamic internal pressure.
- To identify distinct thermodynamic response regimes of CO2 within DESs.
- To correlate internal pressure profiles with CO2-DES interactions and phase behavior.
Main Methods:
- High-pressure pvTx data acquisition for CO2-saturated DESs.
- Correlation of experimental data with a Hybrid-Tait equation.
- Analysis of internal pressure profiles to determine solvation regimes.
Main Results:
- Three distinct thermodynamic response regimes for CO2 solvation were identified.
- A secondary rise in internal pressure was observed at higher CO2 loadings.
- CO2-DES systems exhibit unique solvation behavior compared to conventional liquids.
Conclusions:
- Internal pressure profiles provide a quantitative framework for understanding CO2 solvation in DESs.
- The observed secondary rise in internal pressure highlights the coupling of non-volatile and supercritical phases.
- This study offers insights into cohesive energy density and thermodynamic response in DESs and similar systems.
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