Carbon Dioxide Solubilities in Decanoic Acid-Based Hydrophobic Deep Eutectic Solvents

Area of Science:

• Chemical Engineering
• Materials Science
• Environmental Science

Background:

• Deep eutectic solvents (DESs) are emerging as tunable solvents for various applications.
• Hydrophobic DESs have been underexplored for gas solubility studies, particularly for carbon dioxide (CO₂) capture.
• Efficient CO₂ capture technologies are crucial for mitigating climate change.

Purpose of the Study:

• To measure and evaluate the solubility of CO₂ in a series of hydrophobic DESs for the first time.
• To compare the CO₂ solubility and absorption characteristics of these novel DESs with existing solvents.
• To assess the potential of these hydrophobic DESs as effective CO₂ capture agents.

Main Methods:

• Six different hydrophobic DESs were synthesized by combining decanoic acid with quaternary ammonium salts of varying halide anions and alkyl chain lengths.
• CO₂ solubility was measured across a temperature range of 298–323 K and CO₂ pressures up to 2 MPa.
• The experimental data were analyzed and compared against data for hydrophilic DESs, physical solvents, and fluorinated ionic liquids.

Main Results:

• The measured CO₂ solubilities in the studied hydrophobic DESs were found to be comparable to those of well-established fluorinated ionic liquids.
• The heats of CO₂ absorption for these DESs fall within the range typically observed for nonpolar solvents.
• The solubility data indicate that these hydrophobic DESs exhibit favorable characteristics for CO₂ absorption.

Conclusions:

• Hydrophobic deep eutectic solvents demonstrate significant potential as effective agents for CO₂ capture.
• The performance of these novel DESs in CO₂ solubility is competitive with current state-of-the-art materials.
• Further research into these DESs could lead to advancements in carbon capture technologies.