Supported Imidazolium-Based Ionic Liquids on a Polysulfone Matrix for Enhanced CO₂ Capture

The present work demonstrates the potential for improved CO₂ capture capabilities of ionic liquids (ILs) by supporting them on a polysulfone polymeric matrix. CO₂ is one of the main gases responsible for the greenhouse effect and is a focus of The European Commission, which committed to diminishing its emission to 55% by 2023. Various ILs based on combinations of 1-butyl-3-methyl- imidazolium cations and different anions (BMI·X) were synthesized and supported on a polysulfone porous membrane. The influence of the membrane structure and the nature of ILs on the CO₂ capture abilities were investigated. It was found that the membrane's internal morphology and its surface characteristics influence its ILs sorption capacity and CO₂ solubility. In most of the studied configurations, supporting ILs on porous structures increased their contact surface and gas adsorption compared to the bulk ILs. The phenomenon was strongly pronounced in the case of ILs of high viscosity, where supporting them on porous structures resulted in a CO₂ solubility value increase of 10×. Finally, the highest CO₂ solubility value (0.24 mol_CO2/mol_IL) was obtained with membranes bearing supported ILs containing dicarboxylate anion (BMI.MAL).