Carbon Dioxide Capture by Aqueous Ionic Liquid Solutions

Abstract

Confined water in aqueous solutions of imidazolium-based ionic liquids (ILs) associated with acetate and imidazolate anions react reversibly with CO₂ to yield bicarbonate. Three types of CO₂ sorption in these "IL aqueous solutions" were observed: physical, CO₂ -imidazolium adduct generation, and bicarbonate formation (up to 1.9 mol_bicarbonate mol^-1 of IL), resulting in a 10:1 (molar ratio) total absorption of CO₂ relative to imidazolate anions in the presence of water 1:1000 (IL/water). These sorption values are higher than the classical alkanol amines or even alkaline aqueous solutions under similar experimental conditions.