The efficient separation of gases has industrial, economic, and environmental importance. Here, we report the improvement in gas separation performance of a polyimide-based matrix (Matrimid^®5218) filled with a Cu-based metal organic framework [MOF, Cu₃(BTC)₂] with two different ionic liquids (ILs) confined within the pores. The chosen ILs are commonly used in gas solubilization, 1-ethyl-3-methylimidazolium tetrafluoroborate ([EMIM][BF₄]) and 1-Ethyl-3-methylimidazolium trifluoromethanesulfonate ([EMIM][OTf]), and the incorporation of the [EMIM][BF₄]@Cu-BTC and [EMIM][OTf]@Cu-BTC composites in Matrimid^®5218 proved to be an efficient strategy to improve the permeability and selectivity toward CO₂/N₂ and CO₂/CH₄ mixtures.

Iongel-based CO₂ separation membranes were prepared by fast (< 1 min) UV-initiated polymerization of poly(ethylene glycol) diacrylate (PEGDA) in the presence of different ionic liquids (ILs) with the [C₂mim]⁺ cation and anions such as [TFSI]⁻, [FSI]⁻, [C(CN)₃]⁻ and [B(CN)₄]⁻. The four ILs were completely miscible with the non-ionic PEGDA network. Transparent and free-standing iongels containing between 60 and 90 %wt of IL were obtained and characterized by diverse techniques (FTIR, TGA, DSC, DMTA, SEM, CO₂ solubility and pure gas permeability). The thermal and mechanical stability of the iongels, as well as CO₂ solubility, were found to be strictly dependent on the IL content and the anion’s nature. The TGA results indicated that the iongels mostly follow the thermal profile of the respective neat ILs. The DMTA analysis revealed that the iongels based on fluorinated anions have higher storage modulus than those of cyano-functionalized anions. Conversely, the PEGDA–C(CN)₃ iongels presented the highest CO₂ solubility values ranging from 72 to 80 mmol/g. Single CO₂ permeabilities of 583 ± 29 Barrer and ideal CO₂/N₂ selectivities of 66 ± 3 were obtained with the PEGDA–70 C(CN)₃ iongel membrane. This work demonstrates that the combination of PEGDA with high contents of the best performing ILs is a promising and simple strategy, opening up new possibilities in the design of high-performance iongel membranes for CO₂ separation.

The extensive use of organic solvents in industrial processes contributes to environmental pollution, resource depletion, and human health hazards, incentivizing the development of more sustainable alternatives. In response, bio‐based “green” solvents have emerged as environmentally benign substitutes, offering reduced toxicity and lower carbon footprints. However, their industrial implementation is challenged by high viscosity, energy‐intensive recovery, and limited life‐cycle sustainability when employed in single‐use processes. Herein, organic solvent nanofiltration (OSN) as an energy‐efficient and selective membrane‐based technology for recycling green solvents is explored. OSN membranes enable solvent purification by selectively removing impurities while preserving solvent integrity, reducing waste generation and energy consumption. OSN performance in the recovery of widely used green solvents, including acetone, acetonitrile, ethyl acetate, Cyrene, dimethyl isosorbide (DMI), and γ‐valerolactone (GVL), is evaluated. The potential of OSN for in‐process solvent recycling is demonstrated, with a case study on the recycling of Cyrene in synthetic leather production, demonstrating the feasibility of OSN membranes in maintaining solvent purity and enabling a more sustainable manufacturing process.