Microporous hollow fiber membrane

Enzyme membrane reactor for production of diltiazem intermediate. A solution of the racemic ester in organic solvent enters the port at the bottom of the reactor and flows past the strands of microporous, hollow-fiber membrane that contain an enzyme. The enzyme catalyzes hydrolysis of one enantiomer of the ester that undergoes decarboxylation to 4-methoxyphenylacetaldehyde (which in turn forms a water-soluble bisulfite complex that remains in the aqueous phase). The other enantiomer of the ester remains in the aqueous stream that leaves the reactor via the port at the top. Courtesy of Sepracor, Inc. 

The core of double membrane stirrer perfusion bioreactors is a stirrer on which two microporous hollow fiber membranes are mounted, one of them being hydrophobic and used for bubble-free aeration, the second of them being hydrophilic and used for cell-free medium exchange [15]. This system has been reported to provide viable cell densities of 20 million cells per miUiliter for more than two months [106]. Although Lehmann et al. [15] have described the scale-up of this system to the 20-L and 150-L scale, it has been most commonly employed at the bench-scale. 

Tong, Y.P., Hirata, M., Takanashi, H. and Hano, T. (1999) Back-extraction of lactic-acid with microporous hollow-fiber membrane. Journal of Membrane Science, 157, 189. 

Nanoti, A., Ganguly S.K., Goswami, A.N. and Rawat, B.S. (1997) Removal of phenols from wastewater using liquid membranes in a microporous hollow fiber-membrane extractor. Industrial e[ Engineering Chemistry Research, 36, 4369. 

FIGURE 2.1 Microporous hollow fiber membrane in a membrane contactor. 

Semmens MJ, Qin R, and Zander A, Using a microporous hollow fiber membrane to separate VOCs from water. Journal of the American Water Works Association 1989, April, 162-167. 

Kreulen H, Smolders CA, Versteeg GF, and van Swaaij WPM, Microporous hollow fiber membrane modules as gas-bquid contactors. Part II, Mass transfer with chemical reactions. Journal of Membrane Science 1993, 78, 217-238. 

Kathios, D.J., Jarvinen, G.D., Yarbro, S.L., and Smith, B.F., A prehntinary evaluation of microporous hollow fiber membrane modules for the liquid-liquid extraction of actinides. J. Membr. Sci., 1994, 97 251-261. 

Malek A, Li K, and Teo WK. Modeling of microporous hollow fiber membrane modules operated under partially wetted conditions. Ind. Eng. Chem. Res. 1997 36 784-793. 

Chen and Lee [24] studied lactic acid production from dilute acid pretreated a-cellulose and switchgrass by L. delbruckii NRRL-B445 in the presence of a fungal cellulase in a fermentor extractor employing a microporous hollow fiber membrane (MHF). This reactor system was operated in a fed-batch mode with continuous removal of lactic acid by in situ extraction. A tertiary amine (alamine... 

Lasky, M. and Grant, D., Use of Microporous Hollow Fiber Membranes in... 

A. GoUchar, P. Keshavarz, D. Mowla, Investigation of COj removal by silica and CNT nanofluids in microporous hollow fiber membrane contactors. Journal of Membrane Science 433 (2013) 17-24. 

The microporous hollow-fiber membrane modules were employed for liquid-liquid extraction of neodymium as a surrogate for americium from 2 M nitric acid using dihexyl-A,A-diethylcarbamoylmethylphosphonate (DHDECMP) and CMPO extractants in diisopropylbenzene. These modules are applied for back extraction of neodymium from organic phase into 0.01 M nitric acid [149]. 

Ghasem, N., Al-Marzouqi, M., Duaidar, A. 2011. Effect of quenching temperature on the performance of poly(vinylidene fluoride) microporous hollow fiber membranes fabricated via thermally induced phase separation technique on the removal of CO2 from C02-gas mixture. Int. J. Greenh. Gas Control 5 1550-1558. 

A preliminary evaluation of microporous hollow fiber membrane modules for the liquid-liquid extraction of actinides. J. Membr. Sci. 97 251-261. 

Kreulen, H., Smolders, C.A., Versteeg, C.F., and Van Swaaij, W.R 1993. Microporous hollow fiber membrane modules as gas-liquid contactors. Part 2. Mass transfer with chemical reaction. 7. Membr. Sci. 78 217. 

Ahmed, T. and Semmens, M. J. 1992a. The use of independently sealed microporous hollow fiber membranes for oxygenation of water model development. Journal of Membrane Science, 69,11-20. 

Membrane contactors have also found some industrial applications, most commonly to deoxygenate ultrapure water for the electronics industry (96) or for boiler feed water and to adjust carbonation levels in beverages (97). Microporous hollow-fiber membrane modules are most commonly used. The aqueous phase is circulated on the shell side of the fiber and a gas sweep or vacuum flows down the inside of the fibers. 

The system consists of an aqueous phase containing solute flowing in the tube side of microporous hollow fiber membranes, the pores of which are filled with the organic extractant, which flows cocurrently or countercurrently in the shell side (Figure 4.8). The reaction takes place at the inside wall of membrane where the phase interface is located. The various steps in the extraction process are assumed to be as follows [89-91] ... 

A very common column configuration in elution chromatography is simply a tuhular column packed with porous particles, the packings, with or without a bonded liquid phase on the particle surfiices. Other column configurations include capillary columns or open tubular columns, in which a thin hquid film of adsorbents has been applied (or bonded) to the internal surface of the capillaries. A potential variation of this is the microporous hollow fiber membrane based column, wherein the stationary phase is heid in the pores of fiber wall and the eluent is passed through the bore of the fiber (Ding et al., 1989). 

FIGURE 78.1 Microporous hollow fiber membranes used in artificial lungs (a) Cross-sectional view of fibers, (b) Longitudinal view of fibers in Celgard fiber fabric, (c) Microporous outer wall surface of Celgard fiber. 

L. Shi, R. Wang, Y. Cao, D.T. Liang, and J.H. Tay. (2008). Eflect of additives on the fabrication of poly(vinylidene fluoride-co-hexafluropropylene) (PVDF-HFP) asymmetric microporous hollow fiber membranes, J. Memb. Sci. 315 195-204. 

In the fabrication of microporous hollow-fiber membrane, the development of membrane pores can be correlated to thermodynamic and kinetic effects of the polymer dope. When additives were introduced into the polymer dope, two significant effects transpired. First, instantaneous demixing would occur, which was due to the thermodynamic enhancement of phase separation by reducing the miscibility of the solution dope with the nonsolvent. Second, the increased viscosity of the solution would cause kinetic hindrance against the phase separation process, which resulted in a delay of solution demixing [45]. 

R. Wang, H.Y. Zhang, P.H.M. Feron, D.T. Liang, Influence of membrane wetting on C02 capture in microporous hollow fiber membrane contactors, Sep. Purif. Tech. 46 (2005) 33 0. 

S. Wongchitphimon, R. Wang, R. Jiraratananon, L. Shi, C.H. Loh, Effect of polyethylene glycol (PEG) as an additive on the fabrication of polyvinylidene fluoride-co-hexafluropropylene (PVDF-HEP) asymmetric microporous hollow fiber membranes. Journal of Membrane Science, 369 (2011) 329-338. 

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