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@PHDTHESIS{Jestel:807408,
      author       = {Jestel, Tim Alexander},
      othercontributors = {Spieß, Antje Christine and Jupke, Andreas and Schwaneberg,
                          Ulrich},
      title        = {{A}dvanced chromatographic methods for lignin
                      characterization},
      school       = {RWTH Aachen University},
      type         = {Dissertation},
      address      = {Düren},
      publisher    = {Shaker Verlag},
      reportid     = {RWTH-2020-11334},
      isbn         = {978-3-8440-7676-9},
      series       = {Berichte aus der Verfahrenstechnik},
      pages        = {XV, 158 Seiten : Illustrationen, Diagramme},
      year         = {2020},
      note         = {Deutsche und englische Zusammenfassung; Dissertation, RWTH
                      Aachen University, 2020},
      abstract     = {Recent biorefineries employ renewable resources such as
                      lignocellulosic biomass for sustainable production of fuels
                      and chemicals. Efficient lignocellulose valorization
                      processes usually include thermochemical or electrochemical
                      lignin degradation. However, complex product mixtures and
                      low yields of target products are challenges in lignin
                      degradation. Furthermore, a qualitative and quantitative
                      assessment of lignin degradation processes is often not
                      possible, due to the lack of suitable analytical methods.
                      This work aims at improving and developing new
                      chromatographic methods for the analysis of lignin in
                      biorefineries and lignin valorizationprocesses. For the
                      analysis of lignin in raw lignocellulosic biomass, an
                      existing method based on high performance anion exchange
                      chromatography coupled to pulsed amperometric detection was
                      extended by the ability to detect lignin derived aldehydes
                      and alcohols that act as fermentation inhibitors. Gel
                      permeation chromatography (GPC) is the standard technique to
                      monitor the lignin molecular weight during lignin removal
                      and degradation. Here, secondary separation effects such as
                      column interactions and lignin association were reduced by
                      the addition of additives to GPC eluents. Liquid
                      chromatography electrospray ionization quadrupole
                      time-of-flight mass spectrometry (LC-ESI-Q-ToF-MS) was used
                      to elucidate the underlying mechanism of lignocellulose
                      treatment with laccases in combination with the mediator
                      1-hydroxybenzotriazole (HBT). Lignin surface modification by
                      HBT grafting led to reduced unspecific cellulase adsorption
                      and thus, increased glucose yields. Furthermore, Kraft
                      lignin was electrochemically depolymerized to produce
                      valuable degradation products such as carboxylic acids that
                      were detected and quantified by LC-ESI-Q-ToF-MS. To enable a
                      more facilitated analysis of complex lignin degradation
                      processes, GPC and LC-ESI-Q-ToF-MS were coupled. With the
                      help of the new method, the lignin molecular weight as well
                      as lignin degradation products could be determined in a
                      single step without labor intensive sample preparation and
                      dilution steps. Overall, the importance of efficient and
                      accurate analytical methods for lignin analysis during the
                      whole biorefinery process chain was highlighted in this
                      work. By refining existing analytical techniques and
                      coupling of methods, first important steps were successfully
                      taken for a facilitated and comprehensive lignin analysis.
                      Especially, the coupling of different analytical methods has
                      great potential to combine their respective advantages,
                      thereby providing a better understanding of lignin
                      chemistry.},
      cin          = {420110},
      ddc          = {620},
      cid          = {$I:(DE-82)420110_20140620$},
      typ          = {PUB:(DE-HGF)11 / PUB:(DE-HGF)3},
      url          = {https://publications.rwth-aachen.de/record/807408},
}