Multilayer ultrathin-film composite membranes for oxygen enrichment

• Published in: Journal of applied polymer science Vol. 66; no. 11; pp. 2139 - 2147
• Main Authors: Li, Xin-Gui, Huang, Mei-Rong
• Format: Journal Article
• Language: English
• Published: New York John Wiley & Sons, Inc 19.12.1997; Wiley
• Subjects: air separation; Applied sciences; composite membrane; Exact sciences and technology; Exchange resins and membranes; Forms of application and semi-finished materials; multilayer; operating condition; oxygen enrichment; Polymer industry, paints, wood; solution casting; stability; Technology of polymers; ultrathin film; Oxygen; Sulfone polymer; 4-Methyl-1-pentene polymer; Temperature effect; Multiple layer; Cellulose(ethyl); Ethersulfone polymer; Air; Experimental study; Fabrication property relation; Time variation; Mixture; Gas permeability; Selective permeability; Membrane; Polycarbonate; Cellulose ether; Phenylene oxide(dimethyl) polymer
• ISSN: 0021-8995; 1097-4628
• DOI: 10.1002/(SICI)1097-4628(19971219)66:11<2139::AID-APP10>3.0.CO;2-X

Multilayer composite membranes were made of poly(4‐methylpentene‐1) (PMP), an ethyl cellulose (EC) + heptyl cellulose (HC) blend, polycarbonate (PC), polysulfone, poly(2,6‐dimethylphenylene oxide), cellulose triacetate ultrathin films as selective layers, and polysulfone, poly(ether sulfone), and poly(sulfone amide) ultrafiltration membranes with a 10–45 nm pore size and 100–120 μm thickness as porous support layers. The effects of the ultrathin‐film type and its casting solution concentration, operating pressure, temperature, as well as time on the oxygen‐enriched air (OEA) flux and oxygen concentration in the OEA permeated in a single step through the composite membranes were investigated using a constant pressure—variable volume method. The OEA flux increases significantly with an increasing transmembrane pressure difference and operating temperature. The oxygen concentration in the OEA also increases with an increasing pressure difference but decreases slightly with an increasing operating temperature. In long‐term tests, the oxygen‐enrichment properties were maintained almost constant for as long as 170 h. The composite membranes consisting of the bilayer ultrathin film cast from a more dilute solution (0.11–0.26 wt %) on the porous support with a smaller pore size combine a higher oxygen‐enriching ability and a higher stability than do those of monolayer and tetralayer ultrathin films. The maximum OEA flux and oxygen concentration produced at 20–75°C and a 500 kPa transmembrane pressure difference in a single pass across the PMP/98EC + 2HC bilayer and PC bilayer ultrathin‐film composite membranes are 3.1 × 10−3 cm3(STP)/s cm2 and 50%, respectively. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 66: 2139–2147, 1997