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Oxidative polymerization of lignins by laccase in water-acetone mixture

100%
Fiţigău I., Peter F., Boeriu C.
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2013
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vol. 60
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issue 4
817-822
EN
The enzymatic oxidative polymerization of five technical lignins with different molecular properties, i.e. Soda Grass/Wheat straw Lignin, Organosolv Hardwood Lignin, Soda Wheat straw Lignin, Alkali pretreated Wheat straw Lignin, and Kraft Softwood was studied. All lignins were previously fractionated by acetone/water 50:50 (v/v) and the laccase-catalyzed polymerization of the low molecular weight fractions (Mw < 4000 g/mol) was carried out in the same solvent system. Reactivity of lignin substrates in laccase-catalyzed reactions was determined by monitoring the oxygen consumption. The oxidation reactions in 50% acetone in water mixture proceed with high rate for all tested lignins. Polymerization products were analyzed by size exclusion chromatography, FT-IR, and 31P-NMR and evidence of important lignin modifications after incubation with laccase. Lignin polymers with higher molecular weight (Mw up to 17500 g/mol) were obtained. The obtained polymers have potential for applications in bioplastics, adhesives and as polymeric dispersants.
2
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The application of lignin as renewable raw material in chemical industry

88%
Goliszek M., Podkościelna B.
Annales Universitatis Mariae Curie-Skłodowska, sectio AA – Chemia
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2018
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vol. 73
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issue 1
EN
The overutilization of fossil fuels will inevitably cause the global environmental problems and dwindling of available resources. For that reason, identifying renewable sustainable alternatives has attracted an increasing attention. Lignocellulosic biomass has been considered to be one of the most logical feedstock to replace traditional fossil resources as one of the most accessible renewable forms of carbon. One of the primary components of lignocellulosic biomass, next to hemicellulose and cellulose is lignin. It is a by-product in paper and pulp industry. Lignin is mainly used as fuel directly, without further utilization which is suggested to be a waste of natural resources. With this purpose, the valorization of lignin into value-added products needs particular attention of researchers. This review article focuses on chosen possible applications of lignin in chemical industry.
3
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BIOPOLYMER COMPOSITES BASED ON LIGNIN AND MICROCRYSTALLINE CHITOSAN

88%
Kopania E., Wiśniewska-Wrona M.
Progress on Chemistry and Application of Chitin and its Derivatives
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2016
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vol. 21
122-134
EN
The article presents method of extracting lignin from hardwood and softwood after chemical treatment. Lignin fractions were extracted from black liquid (the by-product of pulp and paper industry), in a different reaction environment. Biopolymer composites were obtained by combining extracted lignin fraction and microcrystalline chitosan, which can be used as preparations for innovative biopolymer materials that are applicable in medical and hygienic products. The studies were performed in order to evaluate MCCh/Lignin composites to suitability to construction of dressing materials in the form of sponges. The MCCh/Lignin composites were tested for different properties: mechanical, sorption and absorption. The obtained lignin fractions and MCCh/Lignin composites were characterized by different structures and chemical purity as confirmed by FTIR spectra.
4
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Activation of phenylpropanoid pathway in legume plants exposed to heavy metals. Part I. Effects of cadmium and lead on phenylalanine ammonia-lyase gene expression, enzyme activity and lignin content

75%
Pawlak-Sprada S., Arasimowicz-Jelonek M., Podgórska M., Deckert J.
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2011
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vol. 58
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issue 2
211-216
EN
Species-specific changes in expression of phenylalanine ammonia-lyase (PAL) and lignin content were detected in roots of soybean (Glycine max L.) and lupine (Lupinus luteus L.) seedlings treated with different concentrations of cadmium (Cd2+, 0-25 mg/l) or lead (Pb2+, 0-350 mg/l). The stimulatory effect of both metals was observed in mRNA coding for PAL in soybean. In the case of lupine, changes of PAL mRNA level were dependent on the metal used: Cd2+ caused a decrease, whereas Pb2+ an increase of PAL transcript level. The activity of PAL was enhanced in both plant species at higher metal concentrations (15-25 mg/l of Cd2+ or 150-350 mg/l of Pb2+); however it was not directly correlated with PAL mRNA. This suggests a transcriptional and posttranscriptional control of PAL expression under heavy metals stress. In soybean, Cd2+ or Pb2+ treatment increased lignin content, while in lupine the effect was opposite. The decreased lignin accumulation in lupine roots in response to heavy metals, despite an increased PAL activity, suggests that the activated phenylpropanoid pathway was involved in the synthesis of secondary metabolites other than lignin.
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