Physical absorption and thermodynamic modeling of CO2 in new deep eutectic solvents

Abstract

Due to the advantages of deep eutectic solvents (DESs), such as good CO2 absorption performance, excellent biodegradability, low cost, and simple synthesis, attention has been drawn to selecting DESs with high efficiency for capturing CO2 in a green and environmentally compatible context. In the present study, acetamide as the hydrogen bond acceptor (HBA) and diethylene glycol, 1,2-propanediol, and 1,3-propanediol as the hydrogen bond donors (HBD) for the synthesis of DESs. First, the density and viscosity of these prepared DESs were measured under standard ambient pressure and at temperatures ranging between 293 K and 343 K. Subsequently, the CO2 solubility in DESs was ascertained by the isovolumetric saturation experimental method. The results indicated that all synthesized DESs exhibited physical absorption of CO2 and the diethylene glycol-based DESs had the highest dissolvability for CO2. For the DES with diethylene glycol and 1,2-propanediol as HBD, the CO2 solubility increased as the molar ratio of HBD decreased. On the contrary, the amount of CO2 adsorbed by 1,3-propanediol-based DES increased with increasing 1,3-propanediol content. The semi-empirical Jou and Mather model allows for an efficient correlation to be made among experimentally determined CO2 solubilities, temperatures, and the CO2 partial pressures. Comparing the deviations between the experimental and fitted values, the average relative deviation is small. By estimating the Henry constants and Manuscript File Click here to view linked References comparing them with the literature, it was demonstrated that the synthesized DESs are competitive in absorbing CO2.