Microporous membranes hollow fibre

Membrane gas absorption (MGA) is a gas-Hquid (G—L) contacting device that uses a microporous hydrophobic hollow fibre membrane element similar to the membrane contactors discussed earfter. The hydrophobic membrane barrier separates the gas phase from the absorption Hquid phase. The gas to be separated diffuses through the gas-fiUed pores of the membrane and is absorbed in the Hquid. Absorption is based on physical absorption or by a chemical reaction. Both phases should not mix in order for the operation to be efficient. 

Kong, J. and Li, K. (2001) An improved gas permeation method for characterising and predicting the performance of microporous asymmetric hollow fibre membranes used in gas absorption./owmaZ of Membrane Science, 182,271-281. 

Kuosmanen, K., T. Hyotylainen, K. Hartonen, and M.-L. Riekkola. 2003. Analysis of polycyclic aromatic hydrocarbons in soil and sediment with on-line coupled pressurised hot water extraction, hollow fibre microporous membrane liquid-liquid extraction and gas chromatography. Analyst 128 434 -39. 

Zorita, S., T. Barri, and L. Mathiasson. 2007. A novel hollow-fibre microporous membrane liquid-liquid extraction for determination of free 4-isobutylacetophenone concentration at ultra trace level in environmental aqueous samples. J. Chromatogr. A 1157 30-37. 

Wickramasinghe SR and Han B. Designing microporous hollow fibre blood oxygenators. Chem. Eng. Res. Des. 2005 83(A3) 256-261. Catapano C, Papenfuss HD, Wodetzki A, and Baurmeister U. Mass and momentum transfer in extra-luminal flow (ELF) membrane blood oxygenation. J. Membr. Sci. 2001 184 123-135. 

Zhang Q and Cussler EL. Microporous hollow fibres for gas-absorption 1. Mass-transfer in the liquid. J. Membr. Sci. 1985 23 321-332. Zhang Q and Cussler EL. Microporous hollow fibres for gas-absorption 11. Mass-transfer across the membrane. J. Membr. Sci. 1985 23 333-345. 

Lund LW, Hattler BG, and Federspiel WJ. Is condensation the cause of plasma leakage in microporous hollow fibre membrane oxygenators J. Membr. Sci. 1998 147 87-93. 

The oldest reported microporous membranes are based on carbon and are obtained by controlled pyrolysis of suitable polymeric precursors. Koresh and Soffer were the first to report properties of these membranes in a series of papers starting in 1980 (see refs, in Ref. [78]. Recently Linkov et al. [79] improved this method and arrived at mesoporous asymmetric hollow-fibre carbon membranes which could be transformed to microporous systems by coating the carbon membrane by e.g. vapour deposition polymerisation of polyimide forming precursors. 

S.P.J. Smith, V.M. Linkov, R.D. Sanderson, L.F. Petrik, C.T. O Connor and K. Keizer, Preparation of hollow fibre composite carbon zeolite membranes. Microporous Materials, 4 (1995) 385-390. 

An overview of microporous membrane types is given in Table 9.4. The oldest microporous membranes are based on carbon and are reported by Koresh and Softer in a series of papers from 1980 to 1987 (see overviews in Refs. [6,42]). They are made by pyrolysis of a suitable polymer (hollow fibre) as reviewed by Burggraaf and Keizer [9]. More recently Rao and Sircar [42] developed a new technique. A macroporous graphite sheet was coated with a suitable polymer (latex) which was pyrolysed subsequently. This process was repeated 4—5 times and resulted in a total carbon layer thickness of 2.5 pm with an average pore diameter between 0.5 and 0.6 nm. The membrane has interesting properties (see Section 9.4.3). 

Peters TA, Fontalvo J, Vorstman MAG et al. 2005. Hollow fibre microporous silica membranes for gas separation and pervaporation Synthesis, performance and stability. J. Membr. Sci. 248 73-80. 

Membrane contactor (MC) is a phase-contacting device for use in gas absorption and stripping (degassing) processes as well as in biomedical gas transfer processes [44, 46]. The function of the membrane is to facilitate diflfusive mass transfer between contactir phases such as liquid-liquid, gas-liquid and gas-gas. The membrane phase contactor uses polyolefins, e.g., polypropylene (PP) microporous hollow fibres membranes, which are packed densely in a high surface area module. Since membranes are hydrophobic and have small pores (0.05—0.1 3m), water does not pass through the membrane pores easily. The pressure required to force water to enter the pore is called the breakthrough pressure, which for a PP membrane with a pore size of 0.05 pm is greater than 10 bar g. 

A MC module contains thousands of microporous hollow fibres, which are knitted into a fabric that is wound around a distribution tube with a central baffle as shown in Figure 1.15. The baffle ensures the water is distributed across the fibres, and also results in reduced pressure drop across the contactor. The hollow fibres are packed densely in a membrane module with a surfrce area of up to 4000 n / m. The liquid flows outside (shell side) the membrane, while vacuum is appHed on the inside of the fibre (tube side) forming a film across the pores of the membrane. Mass transfer takes place through this film and the pores due to the difference in the gas partial pressure between the shell side and tube side. Since the membranes are hydrophobic, they are not wetted by water, thereby, efiectively blocking the flow of water through the membrane pores. The membrane provides no selectivity. Rather its purpose is to keep the gas phase and the Hquid phase separated. In effect, the membrane acts as an inert support that allows intimate contact between gas and liquid phases without dispersion. Vacuum on the tube side of the membrane increases the mass transfer rate as in a vacuum tower. The efficiency of the process is enhanced with the aid of nitrogen sweep gas flowing on the permeate side of the membrane. 

Osmotic distillation (OD), sometimes called isothermal membrane distillation, is a membrane process in which a liquid phase (usually an aqueous solution) containing one or more volatile components flows across one surface of a microporous membrane whose pores are not wetted by the hquid, while the opposing surfece is in contact with a second nonwetting liquid phase (usually an aqueous solution) in which the volatile components are soluble or miscible [35]. The device is similar to the membrane contactor (MC) discussed in Chapter 1, which contains hollow fibre membranes that are hydrophobic (non-wetting. 

Deng, Z., Nicolas, C.-H., Guo, Y., Giroir-Fendler, A., and Pera-Titus, M. (2010) Synthesis and characterization of nanocomposite B-MFl-alumina hollow fibre membranes and application to xylene isomer separation. Micropor. Mesopor. Mater., 133, 18-26. 

Microporous hollow fibre containing carrier solution acting as liquid membrane... 

Li Y, Chung T (2008) Exploratory development of dual-layer carbon-zeolite nanocomposite hollow fibre membranes with high performance for oxygen enrichment and natural gas separation. Microporous Mesoporous Mater 113(l-3) 315-324. doi 10.1016/j.micromeso. 2007.11.038... 

H. Kreulen, C.A. Smolders, G.R Versteeg, W.RM. van Swaaij, Microporous hollow fibre membrane modules as gas- liquid contactors. Part 1. Physical mass transfer processes A specific application Mass transfer in highly viscous hquids, J. Memb. Sci. 78 (1993) 197-216. 

Buetehorn, S, Brannock, M, Le-Clech, P, Leslie, G L, Vohnering, D, Vossenkaul, K, Wintgens, T and MeUn, T (2009), Observation of cake layer formation and removal on microporous hollow-fibre membranes . Desalination and Water Treatment, 9 82-85. 

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