Water Vapor Separation from Gas Streams Using Nicotine-Based Ionic-Liquid Membranes

In this study, nicotine-based ionic liquid (IL) membranes were prepared, and the impact of the counteranion was investigated regarding their physicochemical characteristics and their performance in gas and water vapor separation. IL structures were verified by using NMR and ATR-FTIR spectroscopy. Rheological and thermal properties of the ILs were also studied. Considering water vapor permeability, it can be adjusted by selecting counteranions with high hydrophilicity. For this reason, the [HexNic][MeSO3] membrane exhibited the highest water vapor permeability of 8 × 105 barrer, one of the highest reported in the literature. It should be noted that the water vapor permeability increases with feed relative humidity (RH). At 65% RH, H2O/CH4 selectivity of 1.5 × 107 was acquired, and it was reduced by one order of magnitude under mixed gas and water vapor permeation conditions. Because the [HexNic][MeSO3] membrane maintains its position among the best reported membranes for water vapor separation, it could potentially be used in low-pressure dehumidification processes (e.g., biogas production and air dehumidification).