Hollow-fiber membrane separator

The various modifications of the polyethylene Ion-exchange hollow fiber membranes also proved that here we have a workable concept. From this family of special Interest membranes, results were obtained for anion-exchange hollow fiber membranes. Separation factors of 83, 18 and 3.5 were obtained for feed mixtures of 2-propanol, ethanol and methanol, respectively (each feed mixture was composed of 20 wt.X alcohol and the separation was conducted at 23°C). 

The first widespread commercial application of membrane separations is to use hollow-fiber membrane separators for hydrogen recovery from processes, ammonia plants and petrochemical purge streams, and H2/CO ratio adjustment in synthesis gas (Gardner et al., 1977 Bollinger et al., 1984 Koros and Mahajan, 2000). The reported ideal hydrogen selectivities with respect to different gases, such as CO2, CO, N2, and CH4, appear to be reasonable, ranging from 170 for H2/CH4 to 6.75 for H2/CO2. The operation of these permeators, however, is restricted to low temperatures because of the polymeric material used for the synthesis of hollow fibers. 

Hollow-fiber membranes may be run with shell-side or tube-side feed, cocurrent, countercurrent or in the case of shell-side feed and two end permeate collection, co- and countercurrent. Not shown is the scheme for feed inside the fiber, common practice in lower-pressure separations such as air. 

Nonselective membranes can assist enantioselective processes, providing essential nonchiral separation characteristics and thus making a chiral separation based on enantioselectivity outside the membrane technically and economically feasible. For this purpose several configurations can be applied (i) liquid-liquid extraction based on hollow-fiber membrane fractionation (ii) liquid- membrane fractionation and (iii) micellar-enhanced ultrafiltration (MEUF). 

Fig. 5-12. Separation of d,1-leucine in hollow-fiber membrane extraction using a Al- -dodecyl-l-hydrox-yproline solution in octanol as the enantioselective extraction liquid. The modules used were 32 cm long and contained 96 Celgard X-20 polypropylene fibers [57].

In the present study, we fabricated hollow fiber membrane modules and performed experiments at several conditions. The energy consumption of this process is compared to those of conventional gas absorption processes and membrane gas separation processes. 

Membranes offer a format for interaction of an analyte with a stationary phase alternative to the familiar column. For certain kinds of separations, particularly preparative separations involving strong adsorption, the membrane format is extremely useful. A 5 x 4 mm hollow-fiber membrane layered with the protein bovine serum albumin was used for the chiral separation of the amino acid tryptophan, with a separation factor of up to 6.6.62 Diethey-laminoethyl-derivatized membrane disks were used for high-speed ion exchange separations of oligonucleotides.63 Sulfonated membranes were used for peptide separations, and reversed-phase separations of peptides, steroids, and aromatic hydrocarbons were accomplished on C18-derivatized membranes. 

Okamoto, K.,S. Kawamura, M. Yoshino, H. Kita, Y. Hirayama, N. Tanihara, and Y. Kusuki, Olefin/ paraffin separation through carbonized membranes derived from an asymmetric polyimide hollow fiber membrane, Ind. Eng. Chem. Res., 38, 4424,1999. 

See also Gas separation adsorption adsorbents for, 1 612 coal gasification, 6 824 commercial separations, l 618t hollow-fiber membrane modules for, 15 823... 

High-pressure gas separation, hollow-fiber membrane modules for, 15 823 High pressure liquid chromatography (hplc), 9 234 21 275 in herbicide analysis, 13 312 polymer analysis using, 19 566 High-pressure methanol, production process, 16 300-301 High pressure methods, specialized, 13 430-431... 

Low polarity plasticizers, 74 479 Low power package, 74 863 Low pressure catalytic processes, 20 151 Low pressure chemical vapor deposition (LPCVD), 5 807, 811-812 Low-pressure gas separation, spiral-wound membrane modules for, 75 823-824 Low pressure hollow-fiber membranes, 76 24-26... 

Hydrogel membranes are particularly attractive because of high permeability and separation factor [300], and good stability for CO2/N2 separation [299], PVDF hollow fiber membrane modified by alkali was coated by PYA hydrogel on its surface and PVDF-PVA hydrogel membranes show better hydrophilic performance. For carbonate hydrogel (sodium carbonate concentration of 3.7 %) membrane, C02, concentration from 1.3 % to 0.6 % in feed gas could be decreased to 0.9-0.4 % at the outlet at 25 °C. 

Koresh and Soffer (1983) developed a hollow-fiber gas separation membrane. In principle, polymeric hollow fibers can be porous (macroporosity) or dense. On thermal treatment in vacuum (pyrolysis) a second structural feature, the so-called ultramicroporosity (Koresh and Soffer 1983) was observed. This is due to small gaseous molecules channeling their way out of... 

Mixed matrix hollow fiber membranes made with modified HSSZ-13 zeolite in polyetherimide polymer matrix for gas separation. /. Membr. Sd., 288, 195-207. 

Widjojo, N., Chung, T.S., and Kulprathipanja, S. (2008) The fabrication of hollow fiber membranes with doublelayer mixed-matrix materials for gas separation. J. Memhr. Sci., 325 (1), 326-335. 

Ekiner, O.M. and Kulkarni, S.S. (2003) Process for making mixed matrix hollow fiber membranes for gas separation. US Patent 5,553,805. 

Many nitrogen generator devices are commercially available to produce high purity gas in small amounts. In these, nitrogen is obtained from compressed air. It is separated from other air components by selective permeation through polymeric hollow fiber membranes after prefiltration. 

In order to develop the liquid membrane techniques, i.e., emulsion Hquid membrane (ELM), supported liquid membrane (SLM), non-dispersive extraction in hollow fiber membrane (HFM), etc., for practical processes, it is necessary to generate data on equilibrium and kinetics of reactive extraction. Furthermore, a prior demonstration of the phenomena of facilitated transport in a simple liquid membrane system, the so-called bulk liquid membrane (BLM), is thought to be effective. Since discovery by Li [28], the liquid membrane technique has been extensively studied for the separation of metal ion, amino acid, and carboxyHc acid, etc., from dilute aqueous solutions [29]. 

Blood cells are separated from blood (hematocrit 40%) by microfiltration, using hollow-fiber membranes with an inside diameter of 300 pm and a length of 20 cm. The average flow rate of blood is 5.5 cm s T Estimate the filtrate flux. 

The one-pass system consists of a feed tank, filter, pump, and membrane system (Fig. 6). The feed tank contains whiskey at approximately 100° proof. It is filtered through a cellulose filter and then pumped into the membrane system where the separation takes place. Dupont B-10 A ram id hollow fiber membranes are used in series or parallel and are able to withstand the high pressures, 689—1034 kPa (6.8—10 atm), necessary to achieve separation. 

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