Effect of [BMIM][BF4] ionic liquid on performance of poly (ether-block-amide) membrane for gas separation applications
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Abstract
The main purpose of this study was to employ the 1-butyl-3-methylimidazolium tetrafluoroborate ([BMIM][BF4]) ionic liquid for the modification of polyether-block-amide (PEBAX) membranes for the gas separation application. Accordingly, dual-layer PEBAX/polyethersulfone (PES) membranes containing the ionic liquid were fabricated to investigate its performance. These membranes were then examined for the separation of CO2/N2 and O2/N2 gas mixtures. The ionic liquid was added in 0.5, 1, and 1.5% of the polymer. The experiments were conducted at the temperature of 25 ºC and pressures of 2, 4, and 6 bar. It was found that the incorporation of [BMIM][BF4] ionic liquid into the PEBAX matrix had significant effect on the permeation of CO2. Based on the results, the optimal addition of 1%wt. ionic liquid has increased the selectivity of carbon dioxide rather than nitrogen by 4.8 times. Further addition of ionic liquid has caused a competitive behavior between carbon dioxide and the ionic liquid to have an interaction with PEO segment in copolymer resulting in reduced selectivity.
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