CO2 removal with ‘switchable’ versus ‘classical’ ionic liquids

► Comparison of ionic liquid systems acting as chemical vs. physical solvents in practical terms. ► Recycling and reuse issues of ionic liquids in carbon dioxide capture. ► Introduction of new types of switchable ionic liquids. ► Studying the capture-release cycle behavior of the aforementioned ionic liquids. ► In essence, we have focused on engineering aspects. Switchable ionic liquids (SILs) are promising solvents for CO2 separation due to their high CO2 capturing efficiency and easy preparation compared to ‘classical’ ionic liquids. Considering viscosity, the present study has demonstrated that SILs formed at least two times stronger chemical bonds with CO2 than studied classical ionic liquids (ILs). Furthermore, the reversible properties of SILs were confirmed by evaluation of different regeneration methods. On average, molar fractions of CO2 were more than 0.3 outperforming acetate-based ILs (molar fraction of CO2 around 0.25) and more than ten times the capacity of physical ionic liquids (molar fraction 0.02). Consequently, SILs are found to be efficient CO2 absorbents operating at atmospheric pressure.