Characterization of polysulfone/diisopropylamine 1-alkyl-3-methylimidazolium ionic liquid membranes: high pressure gas separation applications

Abstract

Membrane separation is gaining great attention in many applications, especially in gas separation. Polysulfone (PSF) is the most widely studied polymeric membrane material for CO2 in its pure or modified state. Ionic liquids supported membrane technology (SILMs) are now widely applied due to their unique properties at room temperatures. In our previous study, we proved the enhanced ability of ionic liquid enhanced PSF for the separation of CO2 from gas streams. In this study, the dielectric measurements (BDS) extending up to 107 Hz for different concentrations of ionic liquid into PSF matrix, are presented. Thermogravimetric analysis measurement (TGA), differential scanning calorimeter (DSC), dynamic mechanical analysis, and the tensile properties of the membranes are studied in order to optimize the efficiency of separating CO2 from CO2/N2 mixture and CO2/CH4. TGA showed that pure PSF is a highly thermostable polymer, of which the 5% weight loss temperature is above 150 C. DSC traces show that the Tg of PSF was 149.5 C and decreases gradually for the composites. This behavior was confirmed with BDS analyses, which also revealed important information about the chain motions dynamics and the fragility index.