Gas dehumidification over supported nicotine-based ionic liquid membranes: Effect of alkyl chain length and ether group presence

In this work, supported nicotine-based IL membranes were synthesized and the effect of alkyl chain length and ether groups presence was examined on physicochemical as well as gas and water vapor separation properties. Gas permeation is mainly affected by diffusion, while solubility is the main factor for water vapor permeation. For this reason, alkyl chain lengthening contributed to the increase of all gas (CO2, CH4, N2) permeabilities due to IL viscosity reduction, while water vapor permeability decreased because of the concomitant increase in hydrophobicity. On the other hand, the membrane containing IL with ether groups exhibited the highest water vapor permeability of 141,000 Barrer with a H2O/CH4 selectivity of 126,000 and a H2O/N2 selectivity of 117,000. These permeation properties, which are the highest relative to other reported SILMs with TFSI- as counter anion, remained unchanged even under mixed gas/water vapor conditions, showing the potential for dehumidification processes.

Automated summary

Supported nicotine-based IL membranes were synthesized to investigate the effect of alkyl chain length and ether groups on physicochemical properties and gas/water vapor separation. Gas permeation was influenced by diffusion, while solubility played a major role in water vapor permeation. Increasing alkyl chain length enhanced gas permeabilities via reduced IL viscosity, but decreased water vapor permeability due to increased hydrophobicity. In contrast, membranes with IL containing ether groups showed the highest water vapor permeability and selectivity, making them suitable for dehumidification processes even under mixed gas/water vapor conditions.