Recent advances in the formation of ultrathin polymeric membranes for gas separations

Abstract

During the past 20 years membrane systems have been applied to a limited number of commercial gas separations. To further advance membrane‐based gas separations, current research efforts focus on optimization of (i) membrane materials, (ii) membrane structures and (iii) membrane system design. In this overview, recent developments in the formation of high‐performance gas separation membranes are discussed. The gas separation properties of state‐of‐the‐art integrally skinned asymmetric membranes and thin‐film composite membranes are summarized. Future directions for the preparation of advanced gas separation membranes are highlighted.

Gas permeation in amine functionalized silicon rubber membranes

“…This could be explained based on the combined effect of pore size and the solution viscosity. At 4% concentration, the increase in solution viscosity lowered solution penetration in to the pores of lower size and thus did not follow the trend observed for PAN 17 . This indicated that at certain coating solution viscosity and support pore size, the pore penetration can be restricted.…”

“…The hydrophobic nature of PSF would also enable deeper passage of SR (hydrophobic) solution into the pores, leading to increase in effective thickness, though PSF 20 exhibited the lowest water flux and porosity. In case of TFC membranes prepared using ASR (1-4%) on PAN 17 and PAN 20 UF support with same dip time of 40 min, effective thickness of defect-free TFC ranged from 1 to 2.2 m and 1.17 to 2.6 m, respectively (Fig. 10).…”

“…The gelation was done using water as non-solvent at 20 • C and curing at 40 • C in case of dope solution containing PAN. In case of PSF-dope solution, gelation was done at 6-8 • C in water and curing at 60 • C. The formed membranes were washed under running water for 12 h. The membranes were designated as PAN 15 , PAN 17 , PAN 20 and PSF 20 ; where the suffix denotes the concentration of polymer in the dope solution. These UF membranes were characterized for water flux, bubble point and solute rejection using proteins of different molecular weight (0.1% aqueous solution at 7.5 pH using McIlvaine buffer) as detailed earlier [19].…”

“…The solvent-exchanged UF membrane pieces (PAN 15 , PAN 17 , PAN 20 or PSF 20 ) were dipped for 2 min in ASR solutions in hexane of different concentration (0.5%, 1%, 2% or 4%, w/v). This was followed by dipping the membrane pieces in 2% aqueous glutaraldehyde solution for varying time (2, 10, 20 and 40 min).…”

“…Lundy and Cabasso [7] demonstrated TFC membrane having poly(dimethylphenylene oxide) as the selective layer and toluene diisocyanate crosslinked poly(aminosiloxane) as the gutter layer. Though the gas separation properties through the composite membrane are controlled by the coating layer, its formation is affected by the structure, porosity and substructure resistance of the support asymmetric membrane [17].…”