1,3-Propanediol-Based Supported Deep Eutectic Liquid Membranes as an Efficient Material for Carbon Dioxide Separation

In this study, new polypropylene-based supported liquid membranes (SLMs) with a liquid phase composed of deep eutectic solvents (DESs) containing choline chloride, acetylcholine chloride, or tetrabutylammonium chloride and 1,3-propanediol were introduced. Fourier transform infrared spectroscopy was employed to verify DES formation, and the thermal stability was assessed using thermogravimetric analysis. The physicochemical properties, namely, density, refractive index, and viscosity, of DESs and their carbon dioxide capacities were measured across a temperature range of 293.15–313.15 K. The study examined how the structure of the hydrogen bond acceptor and the molar ratio of acceptor to donor influenced the properties and potential for CO2 separation. The permeability of CO2 and N2 through DES-based SLMs was measured, and the ideal selectivity for CO2 over N2 was evaluated. Results indicated that the permeability of CO2 through SLMs containing 1,3-propanediol-based DES ranged from 89 to 123 barrer at 293.15 K, with an ideal CO2/N2 selectivity between 22 and 32. The performance of the studied DES-SLMs demonstrates that they are a viable alternative to commercially used CO2 separation methods due to their environmentally friendly nature and comparable gas separation capabilities.