Theoretical evidence of charge transfer interaction between SO₂and deep eutectic solvents formed by choline chloride and glycerol

Abstract

Interaction nature between deep eutectic solvents (DESs) formed by ChCl and glycerol and SO 2 has been systematically investigated by using the M06-2X density functional combined with cluster models. Block-Localized Wavefunction energy decomposition (BLW-ED) analysis shows that the interaction between SO 2 and DESs is dominated by charge transfer interaction. After interaction, SO 2 molecule becomes negatively charged while the ChCl-glycerol is positively charged, which is the result of Lewis acid-base interaction. The current result affords a theoretical proof that it is highly useful and efficient to manipulate the Lewis acidity of absorbents for SO 2 capture.Moreover, hydrogen bonding as well as electrostatic interactions may also contribute to the stability of the complex. Structure analysis shows that solvent molecules will adjust their geometries to interact with SO 2 . In addition, the structure of SO 2 is barely changed after interaction. The interaction energy between different cluster models and SO 2 ranges from -6.8 to -14.4 kcal/mol. It is found that the interaction energy is very sensitive to the solvent structure. The moderate interaction between ChCl-glycerol and SO 2 is consistent with the concept that highly efficient solvents for SO 2 absorption should be not only solvable but also regenerable.

Vibrational analysis and formation mechanism of typical deep eutectic solvents: An experimental and theoretical study

“…Within DESs, there may be kinds of interactions, such as hydrogen-bonding interactions, electrostatic interactions and dispersion interactions. [41] It is noted that organic cations usually contain alkyl side chains and/or aromatic moieties with important contributions from dispersion forces to their equilibrium structures and interaction energies. [42] Moreover, the interaction between the cation and anion is significantly influenced by dispersion forces.…”

“…In the hydrogen bonds of Cl22•••H36 and Cl22•••H34, the hydrogen bond donors are the OH groups from glycerol, whereas the hydrogen bond donors of other hydrogen bonds are the CH groupsfrom ChCl. Therefore, the so-called hydrogen bond donor can also serve as the hydrogen bond acceptor and vice versa [41]. The most obvious difference between the two configurations is the numbers of hydrogen bonds, which indicates that the distance between ChCl and glycerol becomes shorter by B3LYP-D3.Secondly, there are three hydrogen bonds displayed inFig.…”

Quantum Chemistry Insight into the Interactions Between Deep Eutectic Solvents and SO2

“…The synthesis of DES via low-cost sources including natural HBA and HBD, predictable and almost null toxicity and total biodegradability have made both industry and academia consider DES as alternative solvents for gas capture and separation processes in within the green chemistry framework. Having said that, in recent years there has been increasing interest in the utilization of DES for gas capture especially on CO 2 capture and separation [37,38,39,40,41] however there are only a handful of studies that deal with the nature of the interaction between DES and SO 2 [14,20,21,22,42,43,44,45,46,47,48,49,50]. Most of the available few studies are in experimental basis and simply deal with determination of SO 2 solubility at low pressures in select DES systems [51].…”

Mechanistic Study on the Removal of NO2 from Flue Gas Using Novel Ethylene Glycol-tetrabutylammonium Bromide Deep Eutectic Solvents

“…These results demonstrate that the EG and Br – can form a hydrogen bond and an intermolecular force with NO 2 , which in turn may enhance the NO 2 absorption. 19 , 31 Also, it can be seen that the intensity of the peaks experienced a slight change in intensity. This phenomenon could be caused by the reaction of NO 2 and OH···Br – , which further indicates that the positive charge is not evenly distributed over the TBAB.…”