Fundamental investigation on the development of composite membrane with a thin ion gel layer for CO2 separation

Abstract

A composite membrane with a thin defect-free ion gel layer was developed in this study. The ion gel layer containing an interpenetrating polymer network (IPN) and high ionic liquid (IL) content (80–90 wt%) was prepared on a poly(dimethylsiloxane) gutter layer by spin coating. The thickness of the IPN ion gel layer was reduced from 20 μm to 600 nm by increasing the dilution ratio of the ion gel precursor solution, and the CO2 permeance of the composite membrane was increased from 45 to 613 GPU. By increasing the IL content of the IPN ion gel layer to 90 wt%, the prepared composite membrane exhibited the CO2 permeance of 778 GPU and CO2/N2 selectivity of 15. The CO2 permeance and CO2/N2 permselectivity of the IPN ion gel layer alone having 90 wt% IL were respectively estimated to be 1860 GPU and 27. The excellent gas permeation performance proves that IPN ion gel is a good optional material as a selective layer of a composite membrane for efficient CO2 separation.