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Tina Brueckner Anita Eberl Sonja Heumann Maike Rabe Georg M. Guebitz 《Journal of polymer science. Part A, Polymer chemistry》2008,46(19):6435-6443
Alkaline and enzymatic hydrolyzes of poly(ethylene terephthalate) fabrics (PET) were mechanistically compared based on released degradation products (HPLC‐UV‐RI) and changes in surface properties [hydrophilicity, cationic dyeing, X‐ray photoelectron spectroscopy (XPS)]. Enzymatic hydrolysis led to an increase in the amount of hydroxyl and carboxyl groups on the surface resulting in an enhanced water absorption and dyeability. Enzymes partially adsorbed to PET fabrics during hydrolysis were completely removed by subsequent extraction according to XPS analysis. In contrast to the enzyme treatment, alkaline hydrolysis did not lead to an increase of hydroxyl and acid groups according to XPS while both treatments caused a substantial increase in hydrophilicity and were more effective on amorphous fibers. Alkaline hydrolysis led to a greater increase in the K/S value after cationic dyeing due to enlarged surface area. Consequently, ESEM‐images demonstrated that alkaline treatment drastically affected the surface morphology of the polymer resulting in crater‐like structures of the fibers, whereas after enzymatic treatment the morphology of the fibers remained unchanged. To reach similar benefits in hydrophilicity, drastically higher amounts of degradation products were released during alkaline hydrolysis as also indicated by >6% weight loss compared to <1% after enzyme treatment. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 6435–6443, 2008 相似文献
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Justyna Korpecka Sonja Heumann Susan Billig Wolfgang Zimmermann Manfred Zinn Julian Ihssen Artur Cavaco-Paulo Georg M. Guebitz 《Macromolecular Symposia》2010,296(1):342-346
Functionalisation of synthetic polymers by using enzymes has been recently demonstrated. The major advantage of enzymes over chemical processes lies in their surface specific and endo-wise mode of action. Surface hydrophilisation of PET with lipases and cutinases leads to a dramatic increase of the surfacial acid and hydroxyl group content while conventional chemical treatment does not cause any change. However, this PET-hydrolysing activity by enzymes from distinct classes has not yet been correlated to activity on natural polyesters. Here, we show that lipases, cutinases and a PHA-depolymerase are all capable of hydrolysing PET, while only lipases and cutinases also hydrolysed cutin to various degrees. Lipases showed a higher specificity for terminal fatty acids while the cutinases preferred hydroxy fatty acids during cutin hydrolysis. 相似文献
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Carla Silva Teresa Matam Georg M. Guebitz Artur Cavaco‐Paulo 《Journal of polymer science. Part A, Polymer chemistry》2005,43(13):2749-2753
The stability of cutinase was measured in the presence of dimethylacetamide (DMA) and benzyl alcohol (BA). These solvents are known swelling agents of polyamide fibers. We found that cutinase retains some stability (half‐life of 14 h), enough for an enzymatic treatment with a solvent composition of 1.5% DMA + 10% BA. Enzymatic treatment in the presence of these solvent compositions yields more soluble amino groups as well as more amino end groups at the fiber level. We have shown evidence that the presence of minor quantities of solvent can increase the accessibility of the enzyme towards the polyamide fiber. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 2749‐2753, 2005 相似文献
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Nugroho Prasetyo E Kudanga T Steiner W Murkovic M Nyanhongo GS Guebitz GM 《Analytical and bioanalytical chemistry》2009,393(2):679-687
A novel antioxidant activity assay was developed using laccase-oxidized phenolics. In a three-step approach, phenolic compounds
were first oxidized by laccase. Laccase was then inhibited using 80% (v/v) methanol which also stabilized the oxidized phenolics
which were then used to measure antioxidant activities of ascorbic acid and Trolox. From a number of laccase-oxidized phenolics
screened for potential use in the measurement of antioxidant activities, syringaldazine emerged the best, giving results comparable
to the 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical, which is currently used in conventional methods. Like DPPH radicals,
two moles of stoichiometric oxidized syringaldazine were reduced by one mole of either ascorbic acid or Trolox. For the first
time we show that antioxidant activity can be correlated to oxygen consumption by laccase. Reduction of one molecule of oxygen
corresponded to oxidation of four molecules of syringaldazine which in turn is reduced by two molecules of Trolox or ascorbic
acid. This study therefore demonstrates the great potential of using laccase-oxidized syringaldazine for the measurement of
antioxidant activity. 相似文献
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The adsorption isotherms at 25, 45, and 65 degrees C of molybdenum solutions of concentration ranges between 10(-3) and 3x10(-2) M(Mo) (pH 4-5) on different alumina samples are investigated. The analysis is conducted using a modified Frumkin isotherm which takes a more realistic account of the lateral interaction between adsorbed species and considers that the adsorption takes place on the most basic OH groups on the surface of alumina. The results are discussed in view of the difference in solutions speciation, and the changes in the pH of the remaining supernatant solutions. The solution temperature, PZC of the used aluminas, the configuration of the basic OH groups on their surface, and the pore structure have been shown to intervene effectively. Copyright 2000 Academic Press. 相似文献
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Nagl Martin Haske-Cornelius Oskar Skopek Lukas Pellis Alessandro Bauer Wolfgang Nyanhongo Gibson Stephen Guebitz Georg 《Cellulose (London, England)》2021,28(12):7633-7650
Cellulose - With an annual production of more than 400 million tons, paper is the main product of the largest biorefinery process industrially implemented. Enzymes have been used for pulp refining... 相似文献