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  • 1
    Electronic Resource
    Electronic Resource
    S-GTASQUAC – A Group Contribution Method Based on a New Version of the quasi-Chemical Theory (1999)
    Springer
    Monatshefte für Chemie 130 (1999), S. 501-513 
    Details
    ISSN: 1434-4475
    Keywords: Keywords. Group contribution method; VLE data; Thermodynamic excess functions; quasi-Chemical method; Thermodynamics of mixtures.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Zusammenfassung.  In dieser Arbeit wird eine Gruppenbeitragsmethode auf der Basis einer neuen Version der quasi-chemischen Methode vorgestellt. Diese Gruppenbeitragsmethode hat eine präzise physikalische Basis und benötigt nur eine geringe Zahl von Modellparametern für die Beschreibung der Exzess-Funktionen. Für eine Reihe von Gruppen wurden die Gruppen-Wechselwirkungsparameter bestimmt. Mit diesen Parametern lassen sich die Phasengleichgewichte, Mischungsenthalpien und γ∞-Werte von Mischungen mit aliphatischen, aromatischen und cyclischen Kohlenwasserstoffen, Nitrilen und Ketonen berechnen. Die Leistungsfähigkeit der Gruppenbeitragsmethode S-GTASQUAC wurde durch Vergleich ihrer Ergebnisse mit jenen der UNIFAC- und mod. UNIFAC Modelle (Dortmund) getestet.
    Notes: Summary.  In this paper, a group contribution method based on a new quasi-chemical method (S-GTASQUAC) is introduced. This group contribution method has a precise physical back-ground and works with small number of model parameters for the description of excess functions. The group interaction parameters were determined for a collection of groups. On the basis of these parameters, the phase equilibria, enthalpies of mixing, and γ∞-values of mixtures containing aliphatic, aromatic, and cyclic hydrocarbons, nitriles, and ketones can be calculated. The potency of S-GTASQUAC was tested by comparing its results with those of the models UNIFAC and mod. UNIFAC (Dortmund).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/PL00010229
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  • 2
    Electronic Resource
    Electronic Resource
    Calculation and Prediction of Thermodynamic Properties of Non-Electrolyte Mixtures with a New quasi-Chemical Approximation (1999)
    Springer
    Monatshefte für Chemie 130 (1999), S. 485-499 
    Details
    ISSN: 1434-4475
    Keywords: Keywords. Theory; Methods of calculation; Vapour-liquid equilibria; quasi-chemical approximation; Gibbs free energy parameter.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Zusammenfassung.  Bei Verwendung des alten, modifizierten TASQUAC-Modells [1–3] können nur kleine negative Zusatz-Mischungsentropien näherungsweise beschrieben werden. Intra- und intermolekulare Schwingungen sowie die Rotation der Moleküle bleiben unberücksichtigt. In dieser Arbeit wurde daher eine neue From der Betrachung der Wechselwirkungsenergien, gekennzeichnet durch einen Enthalpie-(Δh) und einen Entropieparameter (Δs), vorgeschlagen. Die exakte Lösung für das quasi-chemische Gleichgewicht in einem Zweikomponentengemisch wird hergeleitet und ein neues Modell für die Beschreibung und die Vorhersage von Phasengleichgewichten in Mehrkomponentensystemen wird entwickelt. Es wird die Möglichkeit untersucht, S-TASQUAC für die Vorhersage von VLE-Daten zu verwenden. Anschließend werden die für binäre Gemische erhaltenen Ergebnisse mit denen anderer bekannter Modelle (Wilson, NRTL, UNIQUAC) für Flüssigkeitsgemische verglichen. Die Resultate beweisen, daß S-TASQUAC gut geeignet ist, um Phasengleichgewichte zu beschreiben bzw. vorherzusagen.
    Notes: Summary.  Using the old, modified TASQUAC model [1–3], only small negative excess entropies of mixing can be described with model assumptions. Intra- and intermolecular vibrations and the rotation of molecules are also not considered. In this work, therefore, a new relationship for the interaction energy with an enthalpy (Δh) and an entropy parameter (Δs) in the quasi-chemical approximation is suggested. The exact solution for the quasi-chemical equilibrium in the two-component mixture is given, and a new model for describing and predicting phase equilibria in multi-component systems S-TASQUAC is developed. We examined the possibilities of using S-TASQUAC to predict VLE data and compared the results of binary systems to the results of other known models of liquid mixtures (Wilson, NRTL, UNIQUAC). The results of the calculated data demonstrate the usability of S-TASQUAC as a qualified tool to describe and predict phase equilibria.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/PL00010228
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  • 3
    Electronic Resource
    Electronic Resource
    Crystallization of potassium chloride: The additives ZnCl2, Na6 [(PO3)6] and K4 [Fe(CN)6] (1995)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 18 (1995), S. 295-301 
    Details
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The batch crystallization of potassium chloride from aqueous solution is investigated without impurities, with zinc chloride I (30, 100, 1000 ppm), with sodium hexametaphosphate II (100 ppm) and potassium hexacyanoferrate (II) III (100, 500, 1000, 16 × 25 ppm). The dominant particle size of the pure system LN, D = 427 μm increases by 40% by addition of I and by 250% by addition of II. While I does not affect the habit II changes it from cubes to octahedrons. In cases of low concentration, III leads to dendrites.It is shown that addition of III decelerates growth and increases the metastable zone width. Hence a high supersaturation is formed, the solution impoverishes fast while III gets incorporated and therefore a strong nucleation starts in a relatively pure solution. By quasi-continuously adding 16 × 25 ppm of III the dominant particle size increases by 160% with little fines. In this case the content of III in the product is relatively low.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ceat.270180502
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  • 4
    Electronic Resource
    Electronic Resource
    Tailor-made additives to influence the habit of barite (BaSO4) obtained by precipitation (1996)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 19 (1996), S. 543-549 
    Details
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: In order to influence the habit of barite (BaSO4) single crystals obtained by precipitation, the tailor-made additives 2-aminomethanol, 3-aminoproponal, 5-aminopentanol, 4-aminobutane sulfonic acid, and several other growth inhibitors have been tested. The crystallization experiments have been carried out in a fully automated crystallizer with reproducible educt feed rates. The kinetics of the reaction has been measured by means of the conductivity. Scanning electron microscopic analysis of the obtained crystal habits led to the raesult that most of the additives tested did not influence the growth form of the crystals, but the predicted, tailor-made additives resulted in a more isometric crystal form.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ceat.270190612
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  • 5
    Electronic Resource
    Electronic Resource
    Secondary nucleation of sodium chlorate studied with the aid of asymmetric crystallization (1997)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 20 (1997), S. 633-640 
    Details
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The size-dependent breeding of sodium chlorate crystals can be determined by carrying out experiments with seed crystals of optical antipodes of different sizes that undergo absolutely identical experimental conditions. Small portions of right- and left-handed seed crystals of different sizes were used. The number density distributions of the two opposite forms led to the total numbers of D- and L-crystals. The nucleation from different seed sizes under identical experimental conditions was found to be proportional to L4 in agreement with Clontz et al. [1] and Bennett et al. [2]. A computer program for the modelling of batch crystallization was used to calculate the development of the nucleation process. The data for the supersaturation course and for the development of the population of the right- and left-handed crystals are in good agreement with the experimental results. Only few generations (one or two) of secondary nucleation are being built during the process because of the strong influence of the size of crystals on the nucleation rate. The formation of two generations of secondary nuclei could be observed during three-hour batch crystallization runs.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ceat.270200910
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  • 6
    Electronic Resource
    Electronic Resource
    Darstellung von beliebigen KristalloberflächenVortrag von W. Schröder auf der Arbeitssitzung des GVC-Fachausschusses „Kristallisation“ vom 29. bis 31. März 1993 in Freiberg/Sachsen. (1994)
    Weinheim : Wiley-Blackwell
    Chemie Ingenieur Technik - CIT 66 (1994), S. 211-213 
    Details
    ISSN: 0009-286X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cite.330660217
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  • 7
    Electronic Resource
    Electronic Resource
    Ein Vergleich zweier eng verwandter Stoffe bei der Kristallisation aus Lösungen: Hexatriakontan und StearinsäureVortrag von W. Beckmann auf der Sitzung des GVC-Fachausschusses „Kristallisation“, 11./12. März 1986 in Den Haag/Scheveningen. (1987)
    Weinheim : Wiley-Blackwell
    Chemie Ingenieur Technik - CIT 59 (1987), S. 82-83 
    Details
    ISSN: 0009-286X
    Keywords: Kristallisation ; Lösungskristallisation ; Wachstumsgeschwindigkeit ; Wachstumsmechanismen ; Übersättigung ; Temperatur-Abhängigkeit ; Stearinsäure ; Hexatriakontan ; Oktakosan ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cite.330590122
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  • 8
    Electronic Resource
    Electronic Resource
    Untersuchungen zur Sekundärkeimbildung von Natriumchlorat mit Hilfe der asymmetrischen KristallisationTeile dieser Arbeit basieren auf dem Vortrag anläßlich der gemeinsamen GVC-Fachausschußsitzung (Sitzung „Kristallisation“), 6./8. Mai 1996 in Schliersee. (1998)
    Weinheim : Wiley-Blackwell
    Chemie Ingenieur Technik - CIT 70 (1998), S. 396-400 
    Details
    ISSN: 0009-286X
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cite.330700407
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