Polysulfone membranes, effect

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]...

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. 

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. 

While a-lactalbumin (a-La) was found to have the greatest gel-forming tendency in UF of whey using polysulfone membranes and is the cause of immediate loss of initial flux, /3-lactoglobulin (/3-Lg) has great effect on long-term fouling... 

A 17-year-old anuric woman with end-stage renal insufficiency received a massive overdose of vancomycin (40 mg/kg/day for 8 days) and was treated three times with high-flux hemodiafUtration with a polysulfone membrane (134). The vancomycin concentration fell from 101 to 17 mg/1 at the end of the procedure. There were no adverse effects of either vancomycin or hemodiafUtration. 

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. 

Figure 4.9. Effect of papain loading on modified polysulfone membrane on the activity. activity corrected by the adsorption of the reaction product, -nitroaniline. O activity. Adapted from Ganapathi et al [4.77], with permission from the American Chemical Society and the American Institute of Chemical Engineers.

In concentrating WPs, DF is employed, in which water or buffer is continually added to the retentate while lactose and minerals are simultaneously removed in the filtrate, to increase WP purity [4,52,61]. This is commonly done in constant-volume mode where water or buffer is added to the retentate at the same rate as permeation. There is an optimum protein concentration in the retentate at which DF can be commenced where the trade-off between permeate flux and the number of diavolumes is balanced and only the minimum membrane area or process time is necessary [62,63]. Using 20 kDa MWCO polysulfone membrane sheets, Nilsson [18] found that, in the UF of reconstituted whey protein concentrate (WPC)-80, the relative flux reduction (RFR) increased with protein concentration and then plateaued up to about 3.2% protein concentration in the retentate. Beyond this concentration, the RFR increased sharply. Cheryan and Kuo [22] showed that at 335 kPa TMP and 50°C, the flux approached a minimum when the retentate reached about 3% protein concentration using polysulfone spiral wound membrane while the flux in the polysulfone hollow fiber is four times higher (Figure 19.1). This suggests that DF may be effectively carried out until 3% protein concentration in the retentate is reached. 

According to the method, a relatively thick silicone rubber layer is coated on a thin selective layer of an asymmetric polysulfone membrane. The thickness of silicone rubber is about 1 ttm while the effective thickness of the selective polysulfone layer is one tenth of 1 p,m. While being coated, silicone rubber penetrates into the pores to plug them. Thus, feed gas is not allowed to leak through the defective pores. The selectivity of the membrane approaches that of the defect-free polysulfone layer. Moreover, since the permeabihties of siHcone rubber for gases are orders of magnitudes higher than those of polysulfone, the permeation rate is not affected very much even when a relatively thick silicone rubber layer is coated. 

Gancarz, I., Pozniak, G., Bryjak, M. and Tylus, W. 2002. Modification of polysulfone membranes. 5. Effect of -butylamine and allylamine plasma. 38 1937-1946. 

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. 

A hollow fibber polysulfone membrane with an effective area of 0.42 m was used throughout this study. The internal diameter of the fibers is 0.5 mm. The membrane molecular weight cut-off is 500 kDalton to completely retain suspended solids, supracolloidal material, and micro-organisms. The hydraulic permeability of the membrane at 28°C is 875 L/m h bar. 

McGinniss and Whitmore studied thin polysulfone membranes formed under high and low g environments on parabolic airplane flights, sounding rockets and on the Space Shuttle (42). The most important effect of acceleration level was on the solvent gas transfer coefficient and not on the components in the membrane. Tan et al. considered the same issue theoretically (43). 

BA2 Barth, C., Goncalves, M.C., Pires, A.T.N., Rbder, J., and Wolf, B.A., Asyrrrmetric polysulfone and polyethersulfone membranes effects of thermodynamic corrditiorrs during formation on their performance, J. Membrane Sci., 169, 287, 2000. 

Nagarale, R.K., Gohil, G.S., Shahi, V.K., Rangarajan, R. (2005) Preparation and electrochemical characterization of sulfonated polysulfone cation-exchange membranes effects of the solvents on the degree of sulfonation. Journal of Applied Polymer Science, 96, 2344-2351. 

Rahbari-Sisakht et al. [54] investigated the effect of novel surface modifying macromolecules (nSMMs) on the morphology and performance of PSf hollow-fiber membrane for CO2 absorption. The performance of surface-modifled membrane in contactor application for CO2 absorption through distilled water as absorbent was studied. The results show that surface-modified membrane had higher performance compared to plain polysulfone membranes. With the membrane prepared from SMM in the spinning dope, a maximum CO2 flux of 5.8 X 10 mol/m s was achieved at 300 ml/min of absorbent flow rate, which was almost 76% more than the other membrane. In a long-term stability study, the initial flux reduction was found to be about 18% after 50 h of operation of the surface-modified membrane. 

The effect of substrate membranes on the performance of SPPO TFC membranes was reported." Using porous polysulfone membranes prepared in their own laboratory under different conditions and commercial polypropylene membranes for substrate membranes, they obtained SPPO thin film composite (TFC) membranes with markedly different performances. Some of their results are reproduced in Table 6. 

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