Ultrathin and Stable Ionic Liquid Membranes with Bio-Inspired Interlocking Architecture for CO₂ Separation

Area of Science:

• Materials Science
• Chemical Engineering
• Environmental Science

Background:

• Supported ionic liquid membranes (SILMs) are crucial for energy-efficient carbon capture due to high CO2 solubility of ionic liquids (ILs).
• Conventional SILMs face limitations including thick IL layers (>50 µm) reducing CO2 permeance (<1 GPU) and mechanical instability under pressure.

Purpose of the Study:

• To engineer a novel membrane architecture that overcomes the thickness-stability limitations of conventional SILMs.
• To enhance CO2 permeance and selectivity for efficient gas separation in carbon capture applications.

Main Methods:

• Development of locked ionic liquid membranes (LILMs) inspired by Tenebrionidae beetle elytra.
• Fabrication of LILMs using two interpenetrating polyamide nanofilms with biomimetic protrusions to confine ILs.
• Characterization of IL layer thickness, CO2/N2 selectivity, CO2 permeance, and long-term stability.

Main Results:

• LILMs achieve sub-0.5 µm IL layers, significantly reducing thickness compared to conventional SILMs.
• Demonstrated CO2/N2 selectivity of 55 and enhanced CO2 permeance of 8.2 GPU, a ≈20-fold improvement.
• Maintained stability over 168 hours of continuous mixed gas separation, showcasing mechanical robustness.

Conclusions:

• The bio-inspired LILM architecture effectively overcomes thickness-stability limitations in SILMs.
• LILMs enable energy-efficient carbon capture by dual-purposing ILs as polymerization solvents and CO2 transporters.
• This approach offers a promising pathway for advanced gas purification technologies.