CO2 Separation Using Supported Deep Eutectic Liquid Membranes Based on 1,2-propanediol

In this work, deep eutectic solvents (DESs) composed of choline chloride, acetylcholine chloride or tetrabu-tylammonium chloride, and 1,2-propanediol were used as a liquid phase for polypropylene-based supported liquid membranes (SLMs) and evaluated for the separation of carbon dioxide from CO2/N2 mixtures. Fourier transform infrared spectra were obtained to confirm DES formation, and the thermal stability of solvents was investigated using thermogravimetric analysis. The physicochemical properties of DESs and carbon dioxide solubility were determined in a temperature range of 293.15-313.15 K. The effects of the hydrogen bond acceptor structure and the acceptor/ donor molar ratio in regard to properties and CO2 separation potential were discussed. The permeability of CO2 and N2 in DES-based SLMs was determined, and the ideal CO2/N2 selectivity was calculated. The gas permeation results of the 1,2-propanediol-based DES-based supported liquid membranes showed that the permeability of CO2 varied from 86 to 152 barrers in 293.15 K. Similarly, the ideal CO2/N2 selectivity varied from 21 to 30. The performance of DES-SLMs was compared with the competing imidazolium-based supported ionic liquid membranes and proved DES-SLMs as a promising alternative considering their green potential and comparable gas separation performance.