Carbon dioxide solubility in amine-based deep eutectic solvents: Experimental and theoretical investigation

In this work, ammonium-based Deep Eutectic Solvents (DES) were successfully synthesized using Ethanol amine hydrochloride, and tetraethylenepenta amine (EAHC-TEPA) as a hydrogen bond donor (HBD) with the molar ratios of 1:1, 1:3, 1:6, and 1:9. Carbon dioxide (CO₂) solubility was measured in the synthesized DESs above ratios at different pressures and temperatures. The molar ratio of 1:9 showed the best solubility for CO₂ among other ratios and was chosen for more in-depth investigation in this work. Solubility data was correlated using response surface methodology (RSM) and ANOVA analysis was performed. The results showed that the temperature and pressure have a significant effect on CO₂ solubility and a correlation was successfully developed. The FTIR, NMR characterization and Henry's constant along with other thermodynamic properties such as enthalpy and entropy of absorption were calculated. The physicochemical properties such as density, refractive index, and viscosity were also measured and correlated using a modified Graber and Vogel-Tamman-Fulcher (VTF) equations respectively.