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  • 1
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 44 (1994), S. 557-562 
    ISSN: 0006-3592
    Keywords: membrane-fixed enzymes ; invertase ; amyloglucosidase ; enzyme distribution ; enzyme reactor ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Invertase as well as as amyloglucosidase were immobilized within asymmetyric ultrafiltration membranes that were prepared from polysulfone or homogeneously modified polysulfone. The chemical modification was carried out by sulfonation and halomethylation. This additional change of the surface properties of the capillaries within the membrane offers the possibilities for various types of enzyme fixation, namely adsorption, charge interactions, or covalent bonding. By variation of the immobilization conditions the distribution of the enzyme could be adjusted over the membrane's cross section. At a distinct enzyme concentration in the loading solution a homogeneous enzyme distribution within the membrane could be verified. This was shown by diffusion experiments. Under ultrafiltration conditions using a solution that contains membrane-impermeable macromolecules as well as a membrane-permeable solute like saccharose the residence time within the membrane was increased due to gel formation atop the membrane yet the kinetic was no affected. The nonpermeable soluble starch was not reacted by the amyloglucosidase membrane, indicating that the skin layer was free of enzymes. © 1994 John Wiley & Sons, Inc.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 39 (1992), S. 725-731 
    ISSN: 0006-3592
    Keywords: urease ; ultrafiltration membranes ; covalent bonding ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Asymmetric ultrafiltration membranes suitable for covalent bonding of urease can be prepared from membranes based upon polyamide or polysulfone. Because the original membrane polymers are not chemically reactive, they have to be converted in such a way that known reactions for enzyme fixation can be used such as the diazo, the acyl-acid, the carbodiimide, and the methylbromide reaction. The enzyme was fixed within the porous substructure of the membrane. The amount of enzyme immobilized at the membrane dense skin was found to be negligible. The kinetics can be described according to the Michaelis-Menten model. Compared to the native urease, the activity of the membrane-bonded enzyme was very low. The reasons can be sought in the transmembrane transport and in the fixation procedure as well.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 46 (1995), S. 503-509 
    ISSN: 0006-3592
    Keywords: affinity membrane ; epoxidized polysulfone ; iminodiacetic acid ; Cu chelate ; amino acid separation ; streaming potential ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Affinity membranes for the treatment of solutions containing amino acids were obtained via lithiating polysulfone that was subsequently converted with glycidylether. From this polymer asymmetric ultrafiltration membranes were cast. The membranes were reacted with iminodiacetic acid yielding membranes fitted out with bidentate chelates. The same reaction path was applied to commercially available symmetric microfiltration membranes. The chelate-bearing membranes were complexed with Cu, Ni, and Zn ions. For the experiments with amino acids only the Cu-complexed membranes were used. The complexation constants for histidine and tryptophan for six different membranes were determined. Because of the affinity of these two amino acids for the complexed Cu ions, they could easily be separated from solutions containing amino acids such as alanine, glycine, and valine. Also, concentrating very dilute amino acid solutions was carried out successfully. © 1995 John Wiley & Sons, Inc.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 119 (1983), S. 105-123 
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: A new heterogeneous ultrafiltration membrane for covalent immobilization of enzymes is described. The matrix of the membrane consists of polysulfone, likewise the active compound for coupling is a polyarylic ether with a suitable substituent. The behaviour as genuine ultrafiltration membrane as well as active enzymatic membrane was investigated. The covalent immobilization was carried out by diazo compounds. The enzyme dextranase is coupled only to the supporting layer of the asymmetric membrane. In this case a model of an ideal biological membrane reactor is realized.
    Notes: Eine neue heterogene Ultrafiltrationsmembran zur kovalenten Kupplung von Enzymen wird beschrieben. Die Membranmatrix besteht aus Polysulfon, die aktive Kupplungskomponente ist ebenfalls ein Polyarylether mit entsprechendem Substituenten. Das Verhalten als reine Ultrafiltrationsmembran sowie als aktive Enzymmembran wurde untersucht. Die kovalente Immobilisierung erfolgte durch Diazotierung der aktiven Komponente. Das Enzym Dextranase ist nur in der Stützschicht der asymmetrischen Membran fixiert. Damit ist das Model1 eines idealen Membranbioreaktors realisiert.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 221 (1994), S. 165-176 
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Die Charakterisierung der Oberflächeneigenschaften von porösen Membranen für die Ultrafiltration läßt sich über Messungen des Strömungspotentials vornehmen. Die untersuchten Membranen waren aus chemisch modifiziertem Polysulfon gefertigt. Je nach Reaktion waren sie entweder neutral infolge von Chlormethylgruppen oder positiv geladen nach Aminolyse des Chlors. Die Membranen adsorbieren in wäßriger Lösung Ionen, zumeist OH-Ionen, aber auch Dissoziation kann erfolgen. Dies läßt sich durch Messungen des Strömungspotentials bei konstanter Ionenstärke in Abhängigkeit vom pH-Wert Kenntlich machen. Ausgehend vom Zetapotential lassen sich mit einem jüngst entwickelten Modell die elektrokinetischen Größen berechnen, die für die Oberflächeneigenschaften der Membranen von Bedeutung sind, wie Dissoziationskonstanten der sauren oder basischen funktionellen Gruppen oder die maximale Ladungs-dichte in der Scherebene an der Membran. Werden Lösungen mit geladen, grenzflächenaktiven Substanzen verwendet, lassen sich qualitative Informationen über den Ladungszustand in den Membrankapillaren erhalten. Eine Temperaturabhängigkeit besagter Größen konnte bis 70°C nicht beobachtet werden.
    Notes: The surface properties of porous ultrafiltration membranes were determined by means of the streaming potential. The membranes were prepared from chemically modified polysulfone through a phase inversion process. The chemical reactions were carried out in such a way that the resulting polysulfone either was fitted out with chloromethyl substituents or with quaternary ammonia groups. Due to this, the surface of the membranes cast from these materials were either neutral or positively charged. In aqueous solution, ion adsorption as well as dissociation can occur at the surface of the membranes. This can be demonstrated by streaming potential measurements at different pH values, but constant ionic strength. From the calculated zeta potential using a recently developed model, evidence can be given on the dissociation constants of acidic and basic functional groups on the surface of the membranes and on the amount of charges within the shear plane adjacent to the membrane. Using solutions which contained surfactants, qualitative information on the amount of charges within the capillaries of the membrane can be obtained. In the range from 20 to 70°C no temperature dependency of the zeta potential could be observed.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
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  • 6
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: The separation with membranes has made evident progress. The knowledge of permeation through membranes is well established, even the process design and development of technical application has reached a high level. This is above all the result of intense search for new polymers suitable for the production of more efficacious membranes, but last this could succeed in the introduction of new membrane forming procedures. The now used and promising polymers for membranes are discussed to the respective separation processes hyperfiltration, ultrafiltration, dialysis and gaspermeation.
    Notes: Die Separation mit Membranen hat Fortschritte gemacht nicht nur hinsichtlich des Verständnisses über die Art der Permeation durch die Membran, sondern auch auf dem Gebiet der Verfahrensentwicklung und der technischen Realisierbarkeit. Dies ist nicht zuletzt der intensiven Suche nach Polymeren für wirksamere Membranen zu danken. Positiv wirkte sich zudem aus, daß neue Verarbeitungsverfahren für neue Polymere eingeführt wurden. Getrennt nach den Prozessen Hyperfiltration, Ultrafiltration, Dialyse und Gaspermeation werden die bislang eingeführten und Erfolg verheißenden Kandidaten für die entsprechenden Membranen behandelt.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
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  • 7
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: The redoxreaction H2O2-rongalite was investigated in the presence of catalytic amounts of iron. Radicals responsible for initiation of polymerization are produced only when at least traces of heavy metals are available. For the above reaction iron is the most effective one. Reaction rates for the consumption of H2O2 and rongalite with respect to complexbound and free iron, without and with the addition of acrylonitrile, are provided. A scheme of reactions is being presented which helps to unterstand the reaction rates, reaction products aldehyde bisulphite and sulphate, as well as the mode and degree of polymerization.
    Notes: Die Redoxreaktion H2O2/Rongalit läuft nur dann über Radikale ab, die die Polymerisation starten, wenn Schwermetalle zumindest in Spuren vorhanden sind. Am wirksamsten ist Eisen. Die Zeitgestze für den Umsatz von H2O2 und Rongalit in Abhängigkeit von komplexgebundenem und freiem Eisen ohne und mit Zusatz von Acrylnitril werden ermittelt. Ein Reaktionsschema wird angegeben, das die Zeitgesetze, die Umsetzungsprodukte Aldehydbisulfit und Sulfat, sowie Ablauf und Grad der Polymerisation verstehen läßt.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 10 (1970), S. 97-107 
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: The addition of propylene oxide to monophenyl monopropylene glycol in the presence of cesium phenolate as catalyst was investigated under pressure up to 1 000 at.Experiments carried out in substance have proved a first order in the catalyst, a pseudo zeroth order with respect to the epoxide and the hydroxyl component, respectively. The activation energy has been found to be 14.8 kcal/mole. The very high activation volume of -55 cm3/mole rules out the possibility of an ionic mechanism under these conditions. The reaction takes place via a ternary transition state preceded by associates. The results with 14C-marked phenolate as well as paper chromatographic experiments show that there is no phenolate-glycolate transformation. The phenolate as catalyst maintains its original form in the course of the reaction.
    Notes: Die Anlagerung von Propylenoxid an Monophenylmonopropylenglykol mit cäsiumphenolat als Katalysator wurde bei Drücken bis 1000 at untersucht. Die in Substanz vorgenommenen Versuche ergaben für den Katalysator eine erste Ordnung. für das Epoxid wie auch für die OH-Komponente eine pseudonullte Ordnung; die Aktivierungsenergie wurde zu 14,8 kcal/Mol ermittelt. Das sehr hohe Aktivierungsvolumen von -55 cm3/Mol schließt einen ionischen Mechanismus unter den angewandten Bedingungen aus; die Reaktion verläuft über einen ternären Übergangskomplex, dem Assoziate vorgelagert sind. Die Ergebnisse bei Anwendung von markiertem Phenolat sowie papierchromatographische Unter suchungen sprechen gegen eine Phenolat-Glykolatumwandlung. Das Phenolat liegt als solches über den gesamten Ablauf der Reaktion vor.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 184 (1991), S. 183-196 
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Oft reichen für spezielle Anwendungen die Eigenschaften von Membranen, die für die unterschiedlichsten Stofftrennungsvorhaben verwendet werden, nicht aus. Deshalb ist es üblich, Membranpolymere chemisch so zu modifizieren, daß z. B. die Selektivität oder das Sorptionsverhalten geändert werden. Dabei sollten aber die Filmbildungseigenschaften nicht beeinträchtigt werden. In dieser Untersuchung werden Methoden beschrieben, wie kommerzielle Polysulfon-Membranen für die Ultrafiltration mittels chemischer Umsetzung ohne Verlust der mechanischen Eigenschaften funktionalisiert werden können. Geeignete Verfahren sind die Sulfonierung, Halomethylierung, Aminomethylierung und Lithiierung. Von den entsprechenden Substituenten ausgehend, lassen sich weitere Umsetzungen vornehmen; somit können Membranen mit ganz speziellen Gruppen hergestellt werden.
    Notes: In recent years efforts have been increased to work with more intelligent membranes which render more than normal filtration properties. Thus, membranes have been prepared using chemically modified polymers or have been furnished with additives in order to increase their selectivity and/or special sorbing capabilities. In this paper, methods are described how commercially available polysulfone membranes can be functionalized by chemical reactions without disintegrating their mechanical properties. For this purpose, Sulfonation, chloromethylation, aminomethylation, and lithiation reactions were applied. A broad spectrum for further conversions modified membranes is opened by these chemical reactions which allow an individual fitting of the membranes with special substitutes. The chemical reactions and the analytical procedures are also described.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 96 (1981), S. 21-36 
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Cellulose acetate as well as polysulphon are well established polymers for the production of ultrafiltration membranes. Contrary to the former polysulphon is not suitable for enzyme immobilization. These difficulties can be eliminated by introduction of distinct substituents, but by this process the film forming tendency is lost. By mixing the original polymer with the substituted material a casting solution can be obtained to producing heterogeneous membranes. The enzymes dextranase and urease were fixed and the activated membranes were tested using dextrane and urea as substrates.
    Notes: Im Gegensatz zu Celluloseacetat ist Polysulfon, ebenfalls ein Polymeres zur Herstellung von Ultrafiltrationsmembranen, für Kupplungsreaktionen mit Enzymennicht geeignet. Die Einführung von entsprechenden Substituenten ist möglich, dabei gehen aber die Filmbildungstendenzen verloren. Im Gemisch mit originalem Polymeren wurden Gießlösungen erhalten, die heterogene Membranen ergeben, an die Dextranase und Urease fixiert wurden. Die Wirkungsweise der aktiven Membranen wurde mit Dextran und Harnstoff untersucht.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
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