Hollow-fiber permeator, preparation

Hollow-fiber permeators, 26 22 Hollow fibers, 13 389-390 cellulose ester, 26 19 cellulosic, 26 18-20 ion-exchange, 26 15 mechanical considerations and dimensions for, 26 5-7 natural polymer, 26 23 polyacrylonitrile, 26 23 polyamide, 26 21-22 post-treatment of, 26 13-14 preparation of, 26 3 production of, 19 757 with sorbent walls, 26 26 technology of, 26 27 wet spinning of, 25 816, 817-818 Hollow-fiber spinning processes, 26 7-12 Hollow fiber spinning technology,... 

N. Tanihara, H. Shimazaki, Y. Hirayama, N. Nakanishi, T. Yoshinaga and Y. Kusuki, Gas Permeation Properties of Asymmetric Carbon Hollow Fiber Membranes Prepared from Asymmetric Polymer Hollow Fibers, 7. Membr. Sci. 160, 179 (1999). 

Tanihara, N.H., Shimazaki, Y., Hirayama, S., et al. (1999). Gas permeation properties of asymmetric carbon hollow fiber membranes prepared from asymmetric polyamide hollow fiber. J. Membrane Sci., 160(2), 179—86. 

Ogawa M, Nakano Y (1999) Gas permeation through carbonized hollow fiber membranes prepared by gel modification of polyanuc acid. J Membr Sci 162 (1-2) 189-198 Ogawa M, Nakano Y (2000) Separation of COJC l mixture through carbonized membrane prepared by gel modification. J Membr Sci 173 (1) 123-132... 

Soffer A, Azariah A, Amar A, Cohen H, Golub D, Saguee S (1997) Method of improving the selectivity of carbon membranes by chemical vapor deposition. US patent 5695618 Vu DQ, Koros WJ, Miller SJ (2002) High pressure CO /CH separation using carbon molecular sieve hollow fiber membranes. Ind Eng Chem Res 41 (3) 367-380 Ogawa M, Nakano Y (1999) Gas permeation through carbonized hollow fiber membranes prepared by gel modification of polyamic acid. J Membr Sci 162 (1-2) 189-198 Yamamoto M, Kusakabe K, Hayashi J, Morooka S (1997) Carbon molecular sieve membrane formed by oxidative carbonization of a copolyimide film coated on a porous support tube. J Membr Sci 133 (2) 195-205... 

The hollow fiber membranes are the optimum choice for gas separation modules due to their very high packing density (up to 30,000 m /m may be attained [1]). Figure 4.21 shows alternative configurations for such modules [108]. Modifications of this configuration exist, where possibility for introduction of sweep gas on permeate side is included, or fibers may be arranged transversal to the flow in order to minimize concentration polarization [109,110]. The hollow fiber membranes are usually asymmetric polymers, but composites also exist. Carbon molecular sieve membranes may easily be prepared as hollow fibers by pyrolysis. 

The history of the membrane developments for reverse osmosis and gas permeation shows that because of inherent differences, it is not possible to simply apply the techniques and materials from one separation technology to the other. The success of the resistance-model hollow-fiber technology which is based on the glassy-fiber technology invented for reverse osmosis, demonstrates the necessity to search for advanced techniques to prepare more selective membranes free of imperfections, rather than to look for new, unavailable materials. 

While the previously described three membrane modules required flat sheet membrane material for their preparation, special membrane configurations are needed for the preparation of the tubular, capillary, and hollow fiber modules. The tubular membrane module consists of membrane tubes placed into porous stainless steel or fiber glass reinforced plastic pipes. The pressurized feed solution flows down the tube bore and the permeate is collected on the outer side of the porous support pipe, as indicated in Figure 1.33 (d). The diameters of tubular membranes are typically between 1-2.5 cm. In some modules, the membranes are cast directly on the porous pipes and in others they are prepared separately as tubes and then installed into the support pipes. 

In order to determine whether the prepared anion-exchange porous membrane is superior to a gel-bead-packed bed in terms of protein recovery efficiency, an experimental comparison was performed with the same porous membrane and bead-packed bed volumes [12]. BSA in a buffer was permeated across the porous membrane and was made to flow downwards through the bed at a constant operating pressure of up to 0.1 MPa. The effluent was sampled from the outside of the hollow-fiber membrane, and from the bottom end of the bed. The effects of the protein solution flow rate on the dynamic binding capacity of the protein were compared between the membrane and the bed. The dynamic binding capacity is defined as the amount of protein adsorbed until the effluent concentration reaches 10% of the feed concentration. The SV as... 

K. Saito, M. Ito, H. Yamagishi, S. Furusaki, T. Sugo and J. Okamoto, Novel Hollow-Fiber Membrane for the Removal of Metal Ion during Permeation Preparation by Radiation-Induced Cografting of a Cross-Linking Agent with Reactive Monomer, Ind. Eng. Chem. Res., 28 (1989) 1808. 

Finally, it is important to notice the effect of the support in the pervaporation flux, analyzed by de Bruijn et al. [164] who proposed a model and evaluated the contribution of the support layer to the overall resistance for mass transfer in the selected literature data. They found that in many cases, the support is limiting the flux the permeation mechanism through the support corresponds to a Knudsen diffusion mechanism, which makes improvements in the porosity, tortuosity, pore diameter, and thickness necessary for an increase in the pervaporation flux. In fact, the researchers of Bussan Nanotech Research Institute Inc. (BNR), Sato et al. [165], designed and patented an appropriate asymmetric ceramic porous support to suppress pressure drop, and in this case, the water flux increased dramatically compared to previous reported results. Wang et al. [166] have clearly shown that the flux of the membranes increased with the porosity of the hollow fiber supports. In spite of the thin 1 pm zeolite layer, prepared by Zhou et al. [167], the flux enhancement compared to layers 10 times thicker [168] was not significant. 

Wang D, Tong J, Xu H, Matsamura Y (2004) Preparation of palladium membrane over porous stainless steel tube modified with zirconium oxide. Catal Today 93-95 689-693 Nair BKR, Harold MP (2007) Pd encapsulated and nanopore hollow fiber membranes synthesis and permeation studies. J Memb Sci 290 182-195... 

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