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Oxidative Depolymerization of Kraft Lignin for Microbial Conversion

Abdelaziz, Omar Y. LU ; Ravi, Krithika LU ; Mittermeier, Fabian; Meier, Sebastian; Riisager, Anders; Lidén, Gunnar LU and Hulteberg, Christian P. LU (2019) In ACS Sustainable Chemistry and Engineering 7(13). p.11640-11652
Abstract

The valorization of lignin is being increasingly recognized as crucial to improve the economic viability of integrated biorefineries. Because of its inherent heterogeneity and recalcitrance, lignin has been treated as a waste product in the pulp and paper industry, but new technologies are now being explored to transform lignin into a sustainable resource and enhance its value chain. In the present study, alkaline oxidative depolymerization was investigated as a potential form of pretreatment to enable further biological conversion of LignoBoost kraft lignin (LB). LB lignin oxidation reactions were studied at various temperatures (120-200 °C) and O2 partial pressures (3-15 bar) to identify the optimal conditions for obtaining... (More)

The valorization of lignin is being increasingly recognized as crucial to improve the economic viability of integrated biorefineries. Because of its inherent heterogeneity and recalcitrance, lignin has been treated as a waste product in the pulp and paper industry, but new technologies are now being explored to transform lignin into a sustainable resource and enhance its value chain. In the present study, alkaline oxidative depolymerization was investigated as a potential form of pretreatment to enable further biological conversion of LignoBoost kraft lignin (LB). LB lignin oxidation reactions were studied at various temperatures (120-200 °C) and O2 partial pressures (3-15 bar) to identify the optimal conditions for obtaining a biocompatible, oxidatively depolymerized lignin (ODLB) stream. The low molecular weight compounds resulting from this treatment consisted mainly of aromatic monomers and carboxylic acids. The highest yield of aromatic monomers, 3 wt %, was obtained at 160 °C and 3 bar O2. The yield of carboxylic acids increased with both increasing temperature and O2 pressure, exceeding 13% under the harshest conditions investigated. The growth of four aromatic-catabolizing bacterial strains was examined on reaction product mixtures, all of which showed growth on agar plates utilizing ODLB as the sole source of carbon and energy. Rhodococcus opacus and Sphingobium sp. SYK-6 were found to consume most of the aromatic monomers present in the ODLB (e.g., vanillin, vanillate, acetovanillone, and guaiacol). The findings of this study indicate that pretreatment by oxidative depolymerization has potential in the biological valorization of technical lignin streams, for the production of valuable chemicals and materials.

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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
Alkaline oxidation, Aromatic monomers, Bacterial conversion, Lignin valorization, LignoBoost, Softwood, Sustainable resources
in
ACS Sustainable Chemistry and Engineering
volume
7
issue
13
pages
13 pages
publisher
The American Chemical Society (ACS)
external identifiers
  • scopus:85067959986
ISSN
2168-0485
DOI
10.1021/acssuschemeng.9b01605
language
English
LU publication?
yes
id
c75c17a1-f8a6-47af-b28e-19c9e3b7524c
date added to LUP
2019-07-11 09:18:40
date last changed
2019-10-06 04:42:41
@article{c75c17a1-f8a6-47af-b28e-19c9e3b7524c,
  abstract     = {<p>The valorization of lignin is being increasingly recognized as crucial to improve the economic viability of integrated biorefineries. Because of its inherent heterogeneity and recalcitrance, lignin has been treated as a waste product in the pulp and paper industry, but new technologies are now being explored to transform lignin into a sustainable resource and enhance its value chain. In the present study, alkaline oxidative depolymerization was investigated as a potential form of pretreatment to enable further biological conversion of LignoBoost kraft lignin (LB). LB lignin oxidation reactions were studied at various temperatures (120-200 °C) and O<sub>2</sub> partial pressures (3-15 bar) to identify the optimal conditions for obtaining a biocompatible, oxidatively depolymerized lignin (ODLB) stream. The low molecular weight compounds resulting from this treatment consisted mainly of aromatic monomers and carboxylic acids. The highest yield of aromatic monomers, 3 wt %, was obtained at 160 °C and 3 bar O<sub>2</sub>. The yield of carboxylic acids increased with both increasing temperature and O<sub>2</sub> pressure, exceeding 13% under the harshest conditions investigated. The growth of four aromatic-catabolizing bacterial strains was examined on reaction product mixtures, all of which showed growth on agar plates utilizing ODLB as the sole source of carbon and energy. Rhodococcus opacus and Sphingobium sp. SYK-6 were found to consume most of the aromatic monomers present in the ODLB (e.g., vanillin, vanillate, acetovanillone, and guaiacol). The findings of this study indicate that pretreatment by oxidative depolymerization has potential in the biological valorization of technical lignin streams, for the production of valuable chemicals and materials.</p>},
  author       = {Abdelaziz, Omar Y. and Ravi, Krithika and Mittermeier, Fabian and Meier, Sebastian and Riisager, Anders and Lidén, Gunnar and Hulteberg, Christian P.},
  issn         = {2168-0485},
  keyword      = {Alkaline oxidation,Aromatic monomers,Bacterial conversion,Lignin valorization,LignoBoost,Softwood,Sustainable resources},
  language     = {eng},
  number       = {13},
  pages        = {11640--11652},
  publisher    = {The American Chemical Society (ACS)},
  series       = {ACS Sustainable Chemistry and Engineering},
  title        = {Oxidative Depolymerization of Kraft Lignin for Microbial Conversion},
  url          = {http://dx.doi.org/10.1021/acssuschemeng.9b01605},
  volume       = {7},
  year         = {2019},
}