Polysulfone membranes properties

TABLE 20.5-1 Typical Unconted Porous Polysulfone Membrane Properties... 

Polysulfone hollow fibers, composite, 76 17 Polysulfone membranes, 75 811 Polysulfones, 70 202-204 properties of, 70 204t Polysulfone ultrafiltration hollow-fiber membrane, 76 4 Polyfsulfonic acid)s, 23 717-725 biomedical applications of, 23 722-723 uses for, 23 717... 

Pinnau, I., and Koros, W. (1991), Structures and gas separation property asymmetric polysulfone membranes made by dry, wet, and dry/wet phase-inversion, J. Appl. Polym. Sci., 43,1491-1502. 

More recently, composite membranes have been made by interfacial polymerization or by in situ polymerization A representative case is illustrated in F. 8. Here, a microporous polysulfone membrane is used as a substrate. This membrane is soaked in a dilute aqueous solution of a low molecular weight polyethylenimine (PEI). Without drying, this membrane is then contacted with a crosslinking agent such as toluene diisocyanate (TDI) or isophthaloyl chloride dissolved in hexane, after which the membrane is cured in an oven. A highly crosslinked, salt-rejecting interfacial layer is formed in this way. A summary of the properties of three of the more important composite membranes is presented in Table 10. 

Polysulfone membranes were prepared from 12.5, 13.75, and 15% (wt. %) polysulfone solution in dimethylformamide and formed on the surface of porous, sintered polymethyl methacrylate bars. An effective surface of each membrane was 49.2 cm. The effect of some casting parameters (composition and the temperature of the casting solution, time of solvent evaporation) and the pressure applied on the transport and separation properties of the membranes were analyzed. The experiments were carried out in a 1.2 dm pressure apparatus with continuous circulation of the permeate between feeding tank and the apparatus. It was found that membranes cast from 12.5% polysulfone solution of a temperature of 298 K with no solvent evaporation displayed the best properties. After 160 hours of operation at 0.18 MPa, the membranes in question showed an ability of a 97 to 99% rejection of 781.2 molecular-weight dye. The volume flux of the dye solution varied from 0.6 to 0.8m /m per day. 

The transport and separation properties of the polysulfone membranes depend on the polymer concentration in the casting solution, on the temperature of the casting solution, and on the time of solvent evaporation from the film surface. The best membrane properties were obtained, using a casting solution which consisted of 12.5 wt. % polysulfone (dissolved in dimethylformamide) and had a temparature of 298 K, with no evaporation of the solvent. 

Monsanto s Prism permeators for gas separation also employ composite membranes. Polyamide coatings are not used for the composite membrane in the Prism module. The Prism membrane consists of a coating of silicone rubber applied from an organic solvent on a porous polysulfone substrate. The Prism membrane is another good example of a composite membrane where Structure Level IV is used to obtain good membrane properties (22). 

Attempts to scale up the NS-300 membrane preparation from the laboratory scale to continuous machine production led to a high degree of variability in membrane properties ( ). The difference was attributed in part to the variability of machine-made polysulfone support film. Properties of the machine-made polysulfone supports differed from the laboratory cast support films. One of the major factors affecting this difference was that the machine-made support film was cast on a nonwoven polyester backing material which can vary in properties. Thus, the machine support film, which was quite adequate for NS-lOO type membranes using polymeric amine reactants, still remained a limitation for the monomeric amine reaction of NS-300. 

As indicated in Figure 10b, this membrane proved quite easy to clean. In contrast to the polysulfone membranes used in the cell separation step, the spiral ultrafilter showed 100% recovery of hydraulic permeability with a minimum effort to clean (i.e., no extra cleaning steps were ever used). Again, the ease of cleaning is related to both the nature of the process stream to which the unit was exposed, and the properties of the membrane itself. In the enzyme concentration step, solids load was very low (compared to the original cell broth). The membrane itself, on the other hand, exhibits much less tendency to adsorb protein than polysulfone because of the hydrophilic nature of regenerated cellulose. 

Knoell T., Safank J., Cormack T., Riley R., Lin S.W., Ridgway H. (1999), Biofouling potentials of microporous polysulfone membranes containing a sulfonated polyether-ethersulfone/polyethersulfone block copolymer correlation of membrane surface properties with bacterial attachment, J Membrane Science, 157, 117-138. 

ARO Aroon, M.A., Ismail, A.F., Monlazer-Rahmati, M.M., andMatsuura, T., Morphology and permeation properties of polysulfone membranes for gas separation Effects of non-solvent additives and co-solvent. Separation Purification Technol., 72, 194, 2010. 

The separation properties of these CMS membranes were compared with a very good asymmetric polysulfone membrane for air separation (Jones and Koros, 1994a). The polysulfone membrane has an O2/N2 selectivity ranging from 5.5 to 6.2, with an 62 flux between 20 to 30 GPU. Hence the CMS membrane has better separation properties. Jones and Koros also measured the separation properties of these CMS membranes for CO2/N2, CO2/CH4, and H2/CH4 and showed that the CMS membranes outperformed the traditional polymeric membranes. 

Reid B D, Ruiz-Trevino F A, Musselman I H, Balkus Jr K J, Ferrari P (2001) Gas Permeability Properties of Polysulfone Membranes Containing the Mesoporous Molecular Sieve MCM-41. Chemistry of materials 13 2366-2373. 

New versions of anion-exchange membranes were prepared via chlormethy-lation and amination of polysulfone. Amination using different diamines made it possible to investigate the effect of the length of the alkyl chain on membrane properties. The chain with the longest alkyl chain showed better hydroxyl ion conductivity and thermal stability than did those with a shorter chain (Park et al., 2008). 

There are several kinds of membrane characterization, depending on the information and knowledge required (morphological structure, chemical properties, permeability, selectivity, etc.). In this case, we focused on the morphological characterization of polysulfone membranes by using the SEM technique. 

Table 13.3 Outline of properties and structures of some representatives of polysulfone membranes... 

Yue W-W, Li H-J, Xiang T, Qin H, Sun S-D, Zhao C-S (2013) Grafting of zwitterion from polysulfone membrane via surface-initiated ATRP with enhanced antifouling property and biocompatibility. J Membr Sci 446 79-91... 

In this study, membrane properties were measured and correlated with various surface characteristics of dense sulfonated polysulfone (SPSF) membranes. Specifically, the analysis of dense SPSF membranes by electron spectroscopy for chemical analysis... 

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