Humanity's dependence on fossil fuel has led to a significant increase in amounts of CO2 in earth's atmosphere. Until clean energy is fully realized, CO2 capture remains a promising method of greenhouse gas mitigation. Traditional forms of carbon capture, such as amine scrubbing, require large amounts of energy and can release carcinogenic nitrosamines and nitramines into the atmosphere. In contrast, membrane-based separation processes are energy-efficient, yet suffer from lower selectivity in separation. To that end, supported ionic liquid membranes (SILMs) have emerged as a promising approach to enhance separation performance. SILMs are composed of ionic liquids (ILs) confined within a polymer membrane which harnesses the physical and chemical properties of the IL to capture CO2. Their lower operating costs, tunable structures, high CO2 affinity, and thermal stability make them appealing candidates for industrial applications. Recent advances in materials have demonstrated significant potential to enhance SILM performance through innovative membrane architectures. In parallel with these performance-focused innovations, there is a growing emphasis on sustainability, particularly designing SILMs from renewable, environmentally friendly materials without compromising efficiency. Several exciting green alternatives to traditional polymers and solvents have emerged in the past decade, including the Rhodiasolv® PolarClean solvent and PEBAX® RNEW block copolymer. The hard PA-block (Amino-11) in PEBAX® RNEW is derived from castor bean oil. compared to PEBAX® 1657, 1074, and 2533, PEBAX® RNEW outperformed its traditional block-copolymer counterparts at CO2 absorption across all pressures at °C. PEBAX membranes synthesized with Rhodiasolv® PolarClean showed similar CO2 sorption profiles as membranes synthesized with ethanol, absorbing 3.05 mol of CO2 per kg of IL. Our findings show that SILMs made from sustainable materials are a promising alternative to conventional SILM technology.
