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

Area of Science:

• Materials Science
• Chemical Engineering
• Environmental Science

Background:

• Carbon dioxide (CO2) is a major greenhouse gas, with global efforts focused on emission reduction.
• Ionic liquids (ILs) show promise for CO2 capture but often suffer from high viscosity and limited surface area.
• Polysulfone membranes offer a potential matrix for immobilizing ILs to improve their CO2 capture efficiency.

Purpose of the Study:

• To investigate the enhanced CO2 capture capabilities of ionic liquids supported on polysulfone polymeric matrices.
• To explore the impact of IL structure and membrane properties on CO2 sorption and solubility.
• To identify optimal IL-membrane configurations for efficient carbon dioxide capture.

Main Methods:

• Synthesis of various ionic liquids (ILs) based on 1-butyl-3-methylimidazolium cations and different anions (BMI·X).
• Immobilization of synthesized ILs onto porous polysulfone membranes.
• Investigation of membrane morphology and IL nature's influence on CO2 capture performance.
• Quantification of CO2 solubility and adsorption capacity for supported ILs compared to bulk ILs.

Main Results:

• Supporting ILs on polysulfone membranes increased their contact surface area and CO2 adsorption capacity.
• The membrane's internal morphology and surface characteristics significantly influenced IL sorption and CO2 solubility.
• A tenfold increase in CO2 solubility was observed for high-viscosity ILs supported on porous structures.
• The highest CO2 solubility (0.24 molCO2/molIL) was achieved using membranes with supported ILs containing the dicarboxylate anion (BMI.MAL).

Conclusions:

• Supporting ionic liquids on polysulfone matrices is a viable strategy for enhancing CO2 capture.
• The immobilization of ILs on porous membranes overcomes limitations associated with high viscosity and low surface area.
• The specific choice of IL anion, particularly dicarboxylate anions like MAL, is crucial for maximizing CO2 capture efficiency.