Terpene-Derived Low-Viscosity Deep Eutectic Solvent for Energy-Efficient CO₂ Absorption

Area of Science:

• Chemical Engineering
• Materials Science

Background:

• Deep eutectic solvents (DES) offer advantageous properties for mass transfer operations.
• Hydrophobic natural DES (HNDES) present a sustainable alternative for gas absorption.

Purpose of the Study:

• To investigate the CO2 absorption capacity of a novel hydrophobic natural DES (HNDES).
• To characterize the physicochemical properties of the HNDES and evaluate its CO2 solubility under varying conditions.

Main Methods:

• Preparation of HNDES using camphor (HBA) and menthol (HBD) at a 4:7 molar ratio.
• Measurement of HNDES properties: viscosity, vapor pressure, boiling point, and flash point.
• Investigation of CO2 solubility at temperatures from 298.15 K to 323.15 K and pressures from 0.2 to 0.6 MPa.
• Validation of CO2 physisorption using FTIR, Raman, and NMR spectroscopy.

Main Results:

• The HNDES exhibited a viscosity of 23 mPa.s at 298.15 K.
• The highest CO2 mole fraction achieved was 0.044 at 303.15 K and 0.6 MPa.
• The enthalpy of absorption was determined to be -14.7 kJ.mol-1, indicating decreased solubility with increasing temperature.

Conclusions:

• The synthesized HNDES shows promising CO2 absorption capabilities.
• The solvent's properties and CO2 solubility profile suggest its potential utility in carbon capture technologies.
• Physisorption of CO2 was confirmed through spectroscopic analysis.