New Functionalized Di-substituent Imidazolium Ionic Liquids as Superior Faster Absorbents for Carbon Dioxide Gas

Functionalization of room temperature liquids based on disubstituted imidazolium ionic liquids represents a promising avenue for tailoring their tunable physicochemical properties and expanding their potential application as green solvents to capture carbon dioxide as a greenhouse gas. In this work, new hydroxyl functionalized imidazolium ionic liquids were prepared from condensation of ethanolamine with glyoxal and formalin in the presence of acetic acid as catalyst. The chemical modification of the hydroxyl groups with epichlorohydrine added new hydroxylpropanoxychloride groups on the imidazolium cation that were quaternized with N-methylimidazolium chloride to produce new imidazolium acetate ionic liquids. The chemical structures, thermal stability, and thermal characteristics of the prepared imidazolium ionic liquids were evaluated. The incorporation of functionalized 1-chloro-2-hydroxypropanoxy and N-methylimidazolium chloride groups into the chemical structure of the imidazolium cations improved the thermal properties of the prepared ionic liquids. The application of the prepared ionic liquids as pure or mixed solvents with saline water to capture CO₂ under atmospheric and 55.2 bar pressures was evaluated at room temperature. The data indicate that the prepared ionic liquids have superior CO₂ adsorption/desorption rate in short time during 30 and 15 min and that their CO₂ capture efficiency increased from 6.2 to 16.8 mol_CO/kg_IIL and from 9.1 to 20.0 mol_CO/kg_IIL at atmospheric and 55.2 bar pressures, respectively.