Selective Recovery of n-Butanolfrom Aqueous Solutions with Functionalized Poly(epoxide ionic liquid)-BasedPolyurethane Membranes by Pervaporation

摘要

In this study, hydroxyl-terminated polybutadiene–poly(epoxide ionic liquid)–poly(urethane urea) (HTPB-PEIL-PU) membranes, HTPB-PEIL1-PU and HTPB-PEIL2-PU, were prepared by the reaction of functionalized PEIL, poly(1-methylimidazole-3-methyl-ethyloxy)hexafluorophosphate or poly(1-methylimidazole-3-methyl-ethyloxy)bistrifluoromethanesulfonimidate, respectively, with HTPB using 4,4′-diphenylmethane diisocyanate (MDI) as the chain extender. The HTPB-PEIL-PU and HTPB membranes were investigated for the selective recovery of n-butanol from aqueous solutions by pervaporation. PEIL was confirmed to be successfully embedded in the PU membranes by ¹H NMR, Fourier transform infrared, and differential scanning calorimetry measurements. According to our mechanical measurements, the HTPB-PEIL-PU membranes retain the mechanical properties of the original PU membrane. PEIL was shown to enhance the diffusion rate of n-butanol significantly based on swelling behavior tests. The pervaporation flux through the HTPB-PEIL1-PU membrane increased with increasingfeed temperature and feed concentration. In contrast, the separationfactor of the HTPB-PEIL1-PU membrane increased with increasing feedtemperature but decreased with increasing feed concentration. In addition,the HTPB-PEIL2-PU membrane exhibited an optimal separation factorof up to 29.2 at a feed concentration of 3% and a feed temperatureof 70 °C, which is superior to that (22.7) through pure HTPBmembranes. Furthermore, the HTPB-PEIL1-PU and HTPB-PEIL2-PU membranesshow better long-term stability than other supported ionic liquidmembranes.