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  • 1
    Electronic Resource
    Electronic Resource
    Liquid chromatographic studies for essential fatty acids on a commercial alkyl phenyl bonded silica column (1993)
    Springer
    Chromatographia 35 (1993), S. 399-402 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Polyunsaturated fatty acids ; Direct injection ; Enthalpy of adsorption
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Retention studies on arachidonic acid 5, 8, 11, 14 all cis eicosatetraenoic acid, C20:4ω6), eicosapentaenoic acid (5, 8, 11, 14, 17 all cis eicosapentaenoic acid, C20∶5ω3) and docosahexaenoic acid (4, 7, 10, 13, 16, 19 all cis docosahexaenoic acid C22∶6ω3) were performed on a commercial μBondapak free fatty acid analysis column. The ternary mobile phase consisting of acetonitrile, water and tetrahydrofuran was used in an isocratic mode with differential refractometry detection. Retention data were mesured at various flow rates with two different, mobile-phase compositions. Capacity factors and enthalpy of adsorption were calculated from the retention data. Finally the retention mechanism is explained.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02278593
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  • 2
    Electronic Resource
    Electronic Resource
    Modelling of a fixed bed and a fluidized bed immobilized enzyme reactor (1988)
    Springer
    Applied microbiology and biotechnology 29 (1988), S. 316-322 
    Details
    ISSN: 1432-0614
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Summary An axial dispersed plug flow model incorporating mass transfer limitations was established to predict the substrate conversion of an immobilized enzymatic reaction in a packed bed and a fluidized bed reactor. The model equations were solved by the method of orthogonal collocation. The enzymic system evaluated was glucose isomerase on porous support, catalysing the isomerization of glucose to fructose. Two types of glucose isomerase immobilized on particles of regular and irregular shape were used. Satisfactory agreement was obtained in the comparison of calculated conversions and experimental data for the packed bed and the fluidized bed loaded with regular spherical particles. In the packed bed and fluidized bed loaded with particles of irregular shape, the two-phase model did not furnish a satisfactory description of the system.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00265813
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  • 3
    Electronic Resource
    Electronic Resource
    Flow dynamics of immobilized enzyme reactors (1984)
    Springer
    Applied microbiology and biotechnology 20 (1984), S. 303-309 
    Details
    ISSN: 1432-0614
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Summary Enzymic conversion of glucose to fructose was carried out in a packed bed and in a fluidized bed reactor. The flow dynamics of these two flow systems, loaded with two different types of immobilized loaded with two different types of immobilized glucose isomerase particles, were studied. The theoretical RTD curve calculated from the axial dispersed plug flow model equation was matched to the experimental RTD curve by an optimization technique. The effect of fluid velocity on the extent of liquid dispersion was established. Theoretical predictions on the conversion of glucose to fructose were calculated using three mathematical models, namely, a plug flow model, a continuous stirred tank reactor (CSTR) model and an axial dispersed plug flow model. The experimental results showed that the axial dispersed plug flow model was superior in predicting the performance of both the packed bed and fluidized bed reactor.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00270590
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  • 4
    Electronic Resource
    Electronic Resource
    Comparative study of flow schemes for a simulated countercurrent adsorption separation process (1992)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 38 (1992), S. 1744-1750 
    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: Continuous separation of three carbohydrate mixtures [fructose-dextran (M. W. ≈ 9,400), raffinose-dextran (M. W. ≈ 6,000), and fructose-raffinose] has been carried out using a simulated countercurrent process with silica gel as the sorbent and deionized water as the eluent. Experiments were conducted using the commercial four-section arrangement and a modified three-section flow scheme which does not recycle part of the eluent for reuse. Data for the four-section flow scheme reflect a much higher product concentration in the raffinate and a substantially lower rate of fresh eluent consumption than for the three-section scheme. It is concluded that when both the extract and raffinate products are desired, the four-section scheme should be used for the separation of a mixture with a small separation factor which usually requires a large quantity of eluent to achieve an efficient separation. The behavior of the simulated countercurrent process was simulated theoretically by representing the process in terms of an equivalent true countercurrent system. A good fit to the experimental data was obtained when the process was configured in the four-section mode. However, the same theoretical approach failed to provide a good representation of the behavior of the three-section scheme in one respect: predicted concentrations of the raffinate product were about two times higher than experimental values. The discrepancy may be attributed to the periodic switching of fluid inlet and outlet points in the operation of the three-section simulated countercurrent unit.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690381107
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  • 5
    Electronic Resource
    Electronic Resource
    Multicomponent separation using a column-switching chromatographic method (1994)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 40 (1994), S. 1843-1849 
    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: A cyclic chromatographic process based on the method of column switching was used to separate a three-component carbohydrate mixture. It permits continuous introduction of the feed and is designed to produce higher product concentration compared to a normal elution cyclic process. A fixed-bed model incorporating axial dispersion and a linear driving force for mass transfer was successfully used to estimate optimum operating conditions (switch times and fluid-flow rates). Its experimental setup can be easily constructed by modifying the apparatus of a simulated countercurrent process since both systems comprise segmented columns equipped with on-off valves for fluid-flow control. This allows one to conduct either multicomponent separation based on elution operation or binary separation based on countercurrent operation using essentially the same set of experimental apparatus with minor modification.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690401108
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  • 6
    Electronic Resource
    Electronic Resource
    An improved adsorption process for the production of high-fructose syrup (1986)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 32 (1986), S. 1876-1880 
    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: By applying a temperature profile to the system, the concentration of the extract product in a countercurrent adsorption separation process may be increased relative to the maximum concentration attainable under isothermal conditions. To achieve the required temperature profile in a simulated countercurrent system it is necessary to heat and cool the columns in sequence as the feed and product draw-off points are switched through the bed. The practical feasibility of operating the system in this way has been demonstrated experimentally for the separation of glucose-fructose mixtures. By maintaining a temperature difference of 30-35°C across the bed an extract product containing 28% fructose and about 1% glucose was obtained, at steady state, from a feed containing 25 wt. % of each sugar.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690321113
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  • 7
    Electronic Resource
    Electronic Resource
    Solvent concentration dependence of solute distribution coefficient (1995)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 41 (1995), S. 1146-1152 
    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: A simple method for modeling the solvent concentration dependence of solute distribution coefficient is described. Ideal and modified distribution models are proposed based on the mechanism of multicomponent competitive adsorption and the theory of solvent association. The system cresol-methanol/water-β-CD-silica is tested using the models, which compared with other experimental results show that the ideal distribution model fails at higher water concentrations and that the modified model can describe well the observed solute distribution behavior over the entire concentration range. The relative impact of nonideal factors in the adsorbed phase and the solvent association in the mobile phase on the distribution dependence shows that the limitation of the ideal model at higher water concentrations results mainly from uneven saturation capacities of the solute and solvent components for the system studied here.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690410510
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  • 8
    Electronic Resource
    Electronic Resource
    Isomerization of glucose to fructose in a fluidized bed reactor (1984)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 26 (1984), S. 820-823 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260260733
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  • 9
    Electronic Resource
    Electronic Resource
    A chromatographic analysis of hindered diffusion of saccharides in silica gels (1989)
    Springer
    Chromatographia 28 (1989), S. 370-374 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Diffusion coefficients ; Distribution coefficients ; Dextran
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The chromatographic technique as a means for experimental studies of diffusion in porous solids has been demonstrated. In this paper we report the effective diffusion coefficients which we have chromatographically obtained for two dextran samples and three low molecular weight solutes. The chromatographic method of measuring diffusional resistances in porous solids has the advantages of rapidity and simplicity. This method also provides information on the axial dispersion and distribution of a solute between the moving phase and the solvent held stationary in the pore. The elution curves of a packed column in pulse response experiments were analyzed by the method of moments to give the parameters of interest. The results indicate that pore diffusion of the solutes was appreciably restricted in comparison with diffusion in bulk solution. The degree of hindrance depended on the size of the diffusing substances.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02261017
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