Preparation of water-swollen hydrogel membranes for the separation of carbon dioxide

Water-swollen hydrogel (WSH) membranes for the separation of carbon dioxide were prepared by dip-coating asymmetric porous polyetherimide (PEI) supporters with poly(vinyl alcohol) (PVA) - poly(acrylic acid) (PAA), followed by the thermal crosslinking of the PVA/PAA layer. The PVA/PAA layers with different blend compositions (PVA/PAA = 90/10, 80/20, 70/30 in wt %) were characterized with differential scanning calorimetry (DSC), infrared spectroscopy (IR) and the determination of their water swelling ratio. The permeabilities and the separation factors of carbon dioxide through these membranes were measured with a vacuum mode of downstream using a mass flow meter and gas chromatograph at different temperatures. When the feed composition of CO2/N-2 mixture was 20/80 (vol %), the separation factors toward carbon dioxide were about 100 and the permeabilities of CO2 ranged from 10(-5) to 10(-6) (cm(3)/cm(2) sec cmHg). These membranes were stable at least up to 12 h.