Membranes polysulfone

Because membrane filtration is the only currently acceptable method of sterilizing protein pharmaceuticals, the adsorption and inactivation of proteins on membranes is of particular concern during formulation development. Pitt [56] examined nonspecific protein binding of polymeric microporous membranes typically used in sterilization by membrane filtration. Nitrocellulose and nylon membranes had extremely high protein adsorption, followed by polysulfone, cellulose diacetate, and hydrophilic polyvinylidene fluoride membranes. In a subsequent study by Truskey et al. [46], protein conformational changes after filtration were observed by CD spectroscopy, particularly with nylon and polysulfone membrane filters. The conformational changes were related to the tendency of the membrane to adsorb the protein, although the precise mechanism was unclear. 

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... 

Small-pore zeolite Nu-6(2) has a NSI-type structure and two different types of eight-membered-ring channels with limiting dimensions of 2.4 and 3.2 A [54]. Gorgojo and coworkers developed mixed-matrix membranes using Nu-6(2) as the dispersed zeolite phase and polysulfone Udel as the continuous organic polymer phase [55]. These mixed-matrix membranes showed remarkably enhanced H2/ CH4 selectivity compared to the bare polysulfone membrane. The H2/CH4 selectivity increased from 13 for the bare polysulfone membrane to 398 for the Nu-6(2)/ polysulfone mixed-matrix membranes. This superior performance of the Nu-6(2)/ polysulfone mixed-matrix membranes is attributed to the molecular sieving role played by the selected Nu-6(2) zeoHte phase in the membranes. 

Mixed-matrix membranes prepared from smaU-pore zeoHte Nu-6(2) and polysul-fone showed significantly enhanced H2/CH4 selectivity over the neat polysulfone membrane [55]. The H2/CH4 selectivity increased from 13 for the neat polysulfone membrane to 398 for the Nu-6(2)/polysulfone mixed-matrix membranes. 

Transport of Ions and Water in Sulfonated Polysulfone Membranes... 

Fig. 19 Scanning electron micrographs of the top surface and cross-section of polysulfone membranes (a,c) without and (b,d) with embedded luteolin-MIP particles. Reproduced with permission from [262]...

Figure 2.29 Scanning electron micrographs at approximately the same magnification of four microporous membranes having approximately the same particle retention, (a) Nuclepore (polycarbonate) nucleation track membrane (b) Celgard (polyethylene) expanded film membrane (c) Millipore cellulose acetate/cellulose nitrate phase separation membrane made by water vapor imbibition (Courtesy of Millipore Corporation, Billerica, MA) (d) anisotropic polysulfone membrane made by the Loeb-Sourirajan phase separation process...

Figure 6.3 Ultrafiltration membranes are rated on the basis of nominal molecular weight cut-off, but the shape of the molecule to be retained has a major effect on retentivity. Linear molecules pass through a membrane, whereas globular molecules of the same molecular weight may be retained. The table shows typical results obtained with globular protein molecules and linear polydextran for the same polysulfone membrane [8]...

Figure 6.24 Ultrafiltration flux in apple juice clarification as a function of the volumetric feed-to-residue concentration factor. Tubular polysulfone membranes at 55 °C [27]. Reprinted from R.G. Blanck and W. Eykamp, Fruit Juice Ultrafiltration, in Recent Advances in Separation Techniques-III, N.N. Li (ed.), AIChE Symposium Series Number 250, 82 (1986). Reproduced by permission of the American Institute of Chemical Engineers. Copyright 1986 AIChE. All rights reserved...

Figure 8.23 Hydrogen recovery from a hydrotreater used to lower the molecular weight of a refinery oil stream. Permea polysulfone membranes (PRISM ) are used [42]...

Figures 4A and 4B are scanning electron micrographs of a an ultrafilitration polysulfone membrane with a 30,000-Dalton mol wt cutoff at low and high magnification, respectively. The image was taken during the protein-filtration portion of cycle 10 ( 3100 s), for an SMY experiment with 5.0 g/L of cellulase in the primary feed, 5.36 of g/L yeast in the secondary feed, and Py=Ph = 15 psi. The majority of the membrane is covered by an SMY, but in a few places the SMY is absent or has been eroded. Note that the SMY is mostly monolayered, compared with the multilayered SMY seen during microfilitration. This difference is apparently due to the lower flux in ultrafiltration.

The goal of ultrafiltration, in contrast to microfiltration, is to retain protein molecules by the membrane while passing smaller solutes through the membrane with the permeate. Ultrafiltration experiments were performed with polysulfone membranes (30,000-Dalton mol wt cutoff). Figure 9 shows a comparison of the permeate flux vs time obtained during ultrafiltration of cellulase in the presence and absence of SMY that was periodically removed by backflushing and then replaced with a new SMY. 

The samples for on-line analysis were taken through a polysulfone membrane [37]. The seven channel automatic analyzer system consisted of six air-segmented continuous flow-wet chemical analyzers (Skalar analytics) to measure the concentration of ammonia with ion selective electrode (Philips IS-570), phosphate with ammonium molybdate at 880 nm, reducing sugar with pHBAH at 410 nm, methionine with Na-nitroprusside at 505 nm, cephalosporin C with... 

Flan, M., and Bhattacharyya, D. (1995), Changes in morphology and transport characteristics of polysulfone membranes prepared by different demixing conditions, / Membr. Sci., 98,191-200. 

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. 

Ismail, A. F., Ng, B. C., and Abdul Rahman, W. A. W. (2003), Effects of shear rate and forced convection residence time on asymmetric polysulfone membranes structure and gas separation performance, Sep. Purif. Technol, 33,255-272. 

Amin NB, Padhi ID, Touchette MA, Patel RV, Dunfee TP, Anandan JV. Characterization of gentamicin pharmacokinetics in patients hemodialyzed with high-flux polysulfone membranes. Am J Kidney Dis 1999 34 222-7. 

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. 

Reverchon E and Cardea S. Eormation of polysulfone membranes by supercritical CO2. J. Supercrit. Fluids 2005 35(2) 140-146. 

Han M-J. Effect of propionic acid in the casting solution on the characteristics of phase inversion polysulfone membranes. Desalination 1999 121(l) 31-39. 

The effect of different cleaning agents on the recovery of the fouled membrane was studied by Mohammadi et al. [78]. Results showed that a combination of sodium dodecyl sulfate and sodium hydroxide can be used as a cleaning material to reach the optimum recovery of the polysulfone membranes used in milk concentration industries. Also a mixture of sodium hypocholorite and sodium hydroxide showed acceptable results, where washing with acidic solutions was not effective. 

Higuchi, A, Mishima, S, and Nakagawa, T, Separation of proteins by surface modified polysulfone membranes, J. Membr. Sci., 57, 175, 1991. 

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