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  • 1
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 20 (1974), S. 1206-1212 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: An experimental study of the ultrafiltratin of several ionic inorganic soluted, using a negatively-charged membrane, is detailed. Both single salt and multi-salt systems are investigated in a continuous flow, thin chappel unit, with and average transmembrane pressure difference of 2.76 × 105N/m2 and a channel Reynolds number of 2800, The solute rejection is predictable to some extent in terms of Donnan ion exclusion theory, and the water flux is dictated by the combined effects of osmotic pressure and membrane-cation interaction.In the single salt experiments, the anion rejections can be related to the inlet (feet) concentration by power functions of the form: rejection = 1 - K Cia, in which 0 〈 a 〈 1.0. The power a is 0.4 chloride salts 0.25 fo monovalent oxyanion salts, and 0.1 fir divalent oxynion salts, but a is indepedent of the cationn present (Na+, Ca2+, or La3+). The constant K is generally a function of both the anion (except in the case of SO42-, HPO42-, and CrO42-) and the cation, being determined by such factors as sistance to water flux is found to depend on cation charge and cation radius. For systems containing two or more salts, the presence of a divalent anion decreses the rejection of the monovalent anion. For multi-salt systems, a rejection of Ca2+ plus Mg2+ of 0.82 and a water flux of 12.9 × 10-4 cm/s (27.2 gal/ft2-day) are achieved at a transmembrane pressure difference of 4.10 × 105 N/m2 (4.1atm), indicating that the process has considerable potential for industrial water softening.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
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  • 2
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 42 (1996), S. 3351-3363 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Noncohesive granular materials in slowly rotated containers mix by discrete avalanches; such a process can be described mathematically as a mapping of avalanching wedges. A natural decomposition is thus proposed: a geometrical part consisting of a mapping wedge → wedge, which captures large-scale aspects of the problem; a dynamical part confined to the avalanche itself, which captures details emanating from differences in size/density/morphology. Both viewpoints are developed and comparisons with experiments are used to verify the predictions of the models. In this article, we develop a model of granular mixing and show how to extend the model in order that it may: (1) handle complicated geometries, (2) be applicable for 3-D mixers, (3) rapidly test mixing enhancement strategies, and (4) incorporate differences in particle properties. In addition, an optimal fill level is determined for several 2-D mixing geometries, and a novel hybrid - geometrical/dynamical - computational technique is proposed. By merging the geometrical and dynamical viewpoints, this technique reduces the computational time of a typical molecular-dynamics-type simulation by a factor of 15. The ultimate goal is to provide fundamental understanding and tools for the rational design and optimization of granular mixing devices.
    Additional Material: 18 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
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