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Gewählte Master / Diploma Thesis:

Renate Kepplinger (2016): Extraktion und Modifikation von Ligninen gewonnen aus hydrothermal vorbehandelter Biomasse.
Master / Diploma Thesis - Abteilung für Chemie nachwachsender Rohstoffe, BOKU-Universität für Bodenkultur, pp 127. UB BOKU obvsg

Data Source: ZID Abstracts
Abstract:
The objective of the thesis was to investigate whether a hydrothermal pre-treatment of lignocellulosic biomasses is capable of increasing the yield of lignin in subsequent isolation steps and how it would affects macromolecular features of the obtained lignins. The results confirmed that the application of a steam-explosion type hydrothermal pre-treatment increases the yield of lignin for both dioxan/water extraction and Organosolv pulping, most pronounced for hardwood biomass where the yield gain was almost 200%. Analytical Curie-Point-Pyrolysis GC/MS and 31P NMR spectroscopy of phosphitylated samples revealed that the distribution of H-, G- and S-units in lignin typical for a specific biomass is not significantly altered through pre-treatment, extration or pulping. In almost all cases the lignins originating from pre-treated biomasses possessed higher shares of phenolic OH-groups than the ones from untreated substrates. In the second part of the thesis, the isolated lignins were subjected to preliminary ammoxidation and aminoxidation testing aiming at their conversion to organo-mineral fertilizers featuring long-term nitrogen release and acting as humus surrogates. Additionally, first cross-linking experiments of the isolated lignins were conducted with the goal to develop water-storing hydrogels. While the tested reference lignins could be successfully ammoxidized in 5% aqueous ammonium hydroxide, homogeneous nitrogen enrichment of lignin isolated from hydrothermally treated biomass failed. Aminoxidation using DIMCARB as an ionic solvent and nitrogen source however afforded promising materials with regard to N-enrichment (ca. 5%) and content of different N-binding forms which mineralize in soil at different rates. The percentages of these binding forms can be varied to a certain extent by the choice of the used lignin, the nature of the nitrogen-source and the reaction conditions. With regard to the manufacture of lignin gels, oligo(propylene glycol)diglycidyl ether turned out to be a suitable cross-linking reagent as it affords swellable, free-standing monolithic gels of meso- and macroporous morphology.

Beurteilende(r): Liebner Falk

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