Comprehensive exploration of the adsorption capacity of innovative betaine-based deep eutectic solvents for carbon dioxide capture

Compared with traditional organic solvents and ionic liquids, deep eutectic solvents (DESs) as innovative emerging solvents has attracted widespread attentions in the field of CO 2 absorption due to its remarkable advantages, such as low melting point, cheapness, easy preparation, regeneration and biodegradation. Herein the halogen-free DESs constituting of betaine as hydrogen bond acceptor, 1,2-propanediol and diethylene glycol as hydrogen bond donor were employed to absorb CO 2 . The CO 2 absorption capacity of DESs with different molar ratios was measured at a certain temperature (303.15–348.15 K) and pressure (180–770 kPa). The results show that the solubility of CO 2 in DESs can be improved by decreasing the temperature and increasing the pressure. The solubility of CO 2 in DESs increases with increasing mole ratio of 1,2-propanediol, but decreases with increasing mole ratio of diethylene glycol. The Jou and Mather model was used to calculate the CO 2 solubility data, which was compared with the experimental results. Through the estimated Henry's constant, the gibbs free energy, enthalpy and entropy of absorption were calculated and the results indicate that the CO 2 dissolution in DESs is a non-spontaneous exothermic process. Regeneration can be achieved by depressurizing and heating the DES-CO 2 system. By comparing with the Henry's constant H m of the reported solvents, this work provides the possibility and space for further optimizing the use of new materials DESs to capture CO 2 .