Abstract
The accumulation of greenhouse gases, leading to global warming, necessitated the research for efficient and recyclable CO2 capture solvents. A variety of solvents were tested. Among all, amine-based solvents have been used often to capture CO2 from the post-combustion process. However, the current process has led to several issues that have led many researchers to pose new alternatives [1]. The literature studies revealed that liquid salt-based absorbents, such as ionic liquids (ILs) and deep eutectic solvents (DES), had been discovered as a possible alternative for effective CO2 capture, and it performed better than traditional absorbents (organic solvents such as amines) [2]. Our aim is to develop task-specific ILs and DES to capture efficient CO2 from the flue gases. We have synthesized amine-based ILs and deep eutectic solvent containing a series of polyamines as a cation and different carboxylate varied from formate to octanoate as anions due to their distinctive features, including selective reactivity with CO2 under moderate conditions, a wide liquidus range, minimal vapour pressure, high thermal decomposition temperature, and superior solvating capabilities. The presence of -OH group and co-solvent addition in ionic liquids has drastically increased CO2 absorption capacity. The synthesized ILs were subjected to CO2 absorption at different temperature, pressure, and flow rate, and results revealed that the CO2 absorption increases with increasing alkyl chain length of the anion [3]. The CO2 absorption capacity varied with different molar ratios of DES. The derived thermodynamic properties of ILs/DES, such as thermal expansion coefficient, isentropic compressibility, intermolecular free length, free volume and change of standard entropy, enthalpy, gibbs free energy, were calculated from experimental data to predict the intermolecular interactions and space between constituent ions in the ILs/DES [4].
References
[1] Bates, E.D.; Mayton, R.D.; Ntai, I.; Davis, J.H., J. Am. Chem. Soc. 2002, 124, 926-927.
[2] Blanchard, L.A., Hancu, D., Beckman, E.J. and Brennecke, J.F., Nature. 1999, 399, 28-29.
[3] Ramkumar, V.; Gardas, R.L., J.Chem. Eng. Data. 2019, 64, 4844-4855.
[4] Das, I., Swami, K.R. and Gardas, R.L., J. Mol. Liq. 2023. 371, 121114.