Investigate the ability of deep eutectic solvent (ChCl-glycerol) to sense the sulphur dioxide using density functional theory calculations and molecular dynamics simulations

Abstract

SO2 gas is one of the major industrial pollutants, by-product obtained from the combustion of fossil fuels, is an indirect greenhouse gas. Hence, deep eutectic solvent can offer an inexpensive and efficient way for its sensing and removal. A theoretical investigation for deep eutectic solvent (DES) consisted of choline chloride and glycerol has been done with density function theory (DFT) calculations. DES was investigated for adsorption of SO2. Herein, feasibility of adsorption ability of the DES for different concentration or amount of SO2 was performed; on varying the ratio of DES: SO2 from 1:1 to 1:4. The change in feasibility of interaction of the DES and SO2 was also studied with the change in temperature using DFT computation. The study was done by analyzing the interactions, thermodynamic properties obtained from DFT calculations. The stability & interaction between DES and SO2 as well as the extent of charge transfer was analyzed with the help of natural bond orbital (NBO) analysis and density of states spectra (DOS). Molecular dynamic (MD) simulations of the DES and DES:SO2 (1:1 to 1:4) were performed and the interactions were analyzed using root mean square deviation (RMSD), root mean square fluctuation (RMSF) and radial distribution function (RDF). It was observed that the DES exhibited most stable interactions in the gaseous state. DES in gaseous state exhibited very stable interaction with the SO2 molecule as the concentration of the SO2 was increased the stability of interaction was also observed to increase. With the increase in temperature, the feasibility of interaction between DES and SO2 decreases.