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  • 11
    Electronic Resource
    Electronic Resource
    Ethanol production in a microporous hollow-fiber-based extractive fermentor with immobilized yeast (1990)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 36 (1990), S. 826-833 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Microporous-membrane-based extractive product recovery in product-inhibited fermentations allows in situ recovery of inhibitory products in a nondispersive fashion. A tubular bioreactor with continuous strands of hydrophobic microporous hollow fibers having extracting solvent flowing in fiber lumen was utilized for yeast fermentation of glucose to ethanol. Yeast was effectively immobilized on the shell side in small lengths of chopped microporous hyrophilic hollow fibers. The beneficial effects of in situ dispersion-free solvent ex (oleyl alcohol and dibutyl phthalate) were demonstrated for a 300 g/L glucose substrate feed. Outlet glucose concentration dropped drastically from 123 to 41 g/L as solvent/ substrate flow ratio was increased from 0 to 3 at 9 mL/h of substrate flow rate with oleyl alcohol as extracting solvent. The significant productivity increase with in situ solvent extraction became more evident as solvent/ substrate flow ratio increased. A model of the locally integrated extractive bioreactor describes the observed fermentor performance quite well.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260360812
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  • 12
    Electronic Resource
    Electronic Resource
    Ternary gas mixture separation in two-membrane permeators (1987)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 33 (1987), S. 529-539 
    Details
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Single-stage separation of ternary gas mixtures of He, CO2, and N2 in a hollow-fiber permeator that simultaneously houses two different types of membranes, cellulose acetate and silicone rubber, was investigated. The two membranes have reverse selectivities with respect to He and CO2. Such a two-membrane permeator separates the feed into three streams, two permeates and one reject, each stream being enriched in a different component. The species permeabilities through each membrane were measured independently, and these values were utilized in a simulation that incorporates the fiber lumen pressure drops, the elastic deformation of the silicone capillaries, and the asymmetric structure of the CA membrane. Simulation results are compared with experimental data. Effects of flow pattern, relative permeation areas of the two membranes, permeate pressure ratios, feed composition, and membrane selectivities are studied. Advantages of the two-membrane scheme over the conventional permeators with only one kind of membrane are discussed.
    Additional Material: 16 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690330402
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  • 13
    Electronic Resource
    Electronic Resource
    Dispersion-free solvent extraction with microporous hollow-fiber modules (1988)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 34 (1988), S. 177-188 
    Details
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Extensive studies on dispersion-free solvent extraction have been carried out using modules made with either hydrophobic or hydrophilic microporous hollow-fiber membranes. Membrane and boundary layer resistances have been characterized for both kinds of hollow fiber using solvent extraction systems with a wide variation of distribution coefficients and interfacial tensions. It has been found that the Graetz solution for a constant wall concentration describes satisfactorily mass transfer on the lumen side of a hollow-fiber device. A correlation of the form NSh = [Dh(1 - φ)/L]NRe0.6NSc0.33 appears to provide a close fit to the shell-side mass transfer coefficient data. The perforamnce characteristics of dispersion-free extraction in hollow-fiber modules have been considered against those of commercial packed-bed extractors. A perspective has been provided on comparative utilities of hydrophobic or hydrophilic hollow fibers for a given solvent extraction problem.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690340202
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  • 14
    Electronic Resource
    Electronic Resource
    Nondispersive membrane solvent back extraction of Phenol (1990)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 36 (1990), S. 450-460 
    Details
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Nondispersive back extraction of phenol from methyl isobutyl ketone into caustic solutions has been studied using microporous polymeric membranes in flat as well as hollow-fiber form. Dispersion-free reactive back extraction was successfully achieved using the correct phase pressure difference. The predictive capabilities of the mathematical models developed for such a system have been investigated. This study indicates that the overall mass transfer can be controlled by boundary layer resistance and/or the membrane transfer resistance, depending on the flow configuration, the nature of the membrane, and the regime of caustic concentration. Individual film transfer coefficients on the shell side and the tube side have been isolated for different hollow-fiber modules. A commercially available 15 cm long module containing hydrophobic microporous hollow fibers has provided very low values of height of transfer unit (HTU) and very high phenol recoveries. The experimentally obtained HTUs of this module have been predicted with significant accuracy.
    Additional Material: 13 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690360314
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  • 15
    Electronic Resource
    Electronic Resource
    Separation of solutes from aqueous solutions by contained liquid membranes (1988)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 34 (1988), S. 1698-1708 
    Details
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The hollow fiber contained liquid membrane (CLM) is a thin liquid film contained in the interstices of two sets of intermingled microporous hollow fine fibers. Organic CLM-s have been used here for the separation of solutes from an aqueous feed into an aqueous strip. Solutes studied are phenol and acetic acid. The separations are carried out in either hydrophilic or hydrophobic hollow fiber CLM permeator modules, using a variety of organic liquids (e.g., decanol, methyl isobutyl ketone, xylene) as membranes. First-order models have been developed to predict the overall solute transfer coefficients adequately. The transfer coefficient can be enhanced significantly when a chemical reaction is carried out on the strip side using NaOH. The advantages of the CLM structure include operational stability, independent control of membrane phase pressure, automatic replenishment of the lost membrane liquid, and absence of the need for preequilibration. These features are demonstrated here, even for systems with considerable aqueous-organic mutual solubilities.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690341014
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  • 16
    Electronic Resource
    Electronic Resource
    An internally staged hollow-fiber permeator for gas separation (1989)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 35 (1989), S. 764-774 
    Details
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Conventional membrane permeation of gases employ a non-step process between the feed and the product on two sides of a membrane. By applying the overall driving force change through a two-step process using two membranes in one device, we illustrate theoretically the possibility of achieving a much higher enrichment without any extra energy consumption. Such an internally staged permeation is experimentally carried out in a hollow-fiber permeator with two sets of asymmetric cellulose acetate hollow fibers for the systems of O2—N2 (air) and CO2—N2. The superior enriching performance of the internally staged permeator over the same permeator operated in the conventional mode is demonstrated experimentally. A cocurrent flow pattern is found to be superior to a countercurrent flow pattern for the conditions employed. The simulation model incorporating fiber lumen pressure drop predicts the experimental performance quite well. A further improvement in performance can be achieved by recycling the intermediate pressure shell reject stream to the feed stream. The energy requirement in an internally staged permeator without recycle is less than that of a conventional permeator with permeate recycle.
    Additional Material: 15 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690350508
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  • 17
    Electronic Resource
    Electronic Resource
    Solvent extraction with microporous hydrophilic and composite membranes (1987)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 33 (1987), S. 1057-1066 
    Details
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Dispersion-free solvent extraction using microporous hydrophobic membranes has been extended to hydrophilic and composite hydrophobic-hydrophilic membranes. Excess phase pressure conditions, if needed for dispersion-free operation, have been identified. Boundary layer and membrane resistances to solute transport have been isolated and simple relations developed for the overall mass transfer coefficient in such systems. A variety of flat microporous membranes have been utilized. Previous investigations by others had interpreted the membrane mass transfer resistance using the notion of unhindered diffusion through tortuous pores of the membrane. We have studied here the applicability and limitations of such a model for a number of membrane-solute-solvent systems.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690330702
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  • 18
    Electronic Resource
    Electronic Resource
    Asymmetric cellulose acetate hollow fibers: Studies in gas permeation (1988)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 34 (1988), S. 417-425 
    Details
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Gas separation behavior of permeators containing asymmetric cellulose acetate hollow fibers with the dense skin on the outside, facing the feed gas, has been investigated experimentally and theoretically using a sweep gas technique. Two systems were studied: CO2-N2, and O2-N2 (air). If the membrane structure is assumed to be symmetric or homogeneous, the model complies with the present data much better, compared to the assumption that the membrane is asymmetric.Separation was carried out with the high-pressure feed outside the fibers as well as inside the fibers. In both cases the data were well predicted by the homogeneous model. No concentration polarization effects were found when the feed flowed inside the fibers. The inherent membrane separation capability appeared practically the same whether the feed was inside or outside the fibers. Internal pressurization did not damage the membrane performance for the low pressure range used.These findings enable the operation of asymmetric hollow-fiber permeators with the feed inside the fiber lumen, which gives better separation in high stage cut situations.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690340309
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