Fabrication And Property Of Fixed Carrier Composite Membranes For CO₂/N₂ Separation

Membrane separation is considered to be a green and high-efficiency technology among CO2 separation and capture technologies. Therefore, developing CO2 separation membrane with low-cost and high-selectivity become a research focus nowadays. In this study,the commercial polysulfone(PS) ultrafiltration membrane was used as supporting layer, the Polydimethylsiloxane(PDMS) was served as“gutter layer”, which between the supporting layer and separation layer with polyvinylamine(PVAm) and high molecular weight Poly(propylene glycol)bis(2-aminopropyl ether)(PEA) by Dip-coating and Drop-coating. Finally,PVAm-PEA/PDMS/PS fixed carrier composite membranes were prepared simply.The optimal gases permeability of composite membranes, fabricating by the two methods,was chosen as the basement membrane,the difference contents of ZIF-8nano-particles were added into the basement membrane to prepare CO2/N2 gas separation membrane.(1) PDMS solution with different contents was coated on the surface of the PS ultrafiltration membrane by Dip-coating to fabricate PDMS/PS composite membranes.We could obtain the maximum CO2 and N2 permeability of PDMS/PS composite membranes at 0.1 MPa when the mass fraction of PDMS was 2%,which were 560 GPU and 95 GPU,respectively. Subsequently,PVAm-PEA was coated on the surface of 2% of PDMS/PS composite membrane to prepare PVAm-PEA/PDMS/PS fixed carrier composite membranes via the same coating method, the fixed carrier composite membranes containing 3% PVAm-PEA exhibited the highest CO2permeability(49 GPU) and CO2/N2 selectivity(92) through the gases permeability testing.(2) With reference to the part of research results,2% of PDMS which acting as inter-layer and PVAm-PEA which possessing facilitate transmit function were coated on the surface of commercial PS ultrafiltration membrane by Drop-coating,respectively. We also studied the exploring the formation mechanism of thecomposite membranes through comparing with the control experiment. The composite membrane having the optimal performance was received by gas permeability test, which existed the maximum CO2 permeability(103 GPU) and CO2/N2 selectivity(96). The CO2/N2 permeability of the composite membrane by Drop-coating was higher than the composite membrane by Dip-coating.(3) ZIF-8 nano-particles with an average size of 60 nm were rapidly and efficiently synthesized in aqueous solution at room temperature. The different contents of ZIF-8 nano-particles were added into the PVAm-PEA/PDMS/PS composite membranes by Drop-coating to prepare a variety of fixed carrier composite membranes. We could find that the fixed carrier composite membranes exhibited the maximum CO2 permeability(56 GPU) and CO2/N2 selectivity(203) when the mass fraction of ZIF-8 was 0.05%.The composite membranes would have a potential application in the separation of CO2 and N2 due to the high CO2 permeability and CO2/N2 selectivity.