Valorization of Lignin via Oxidative Depolymerization with Hydrogen Peroxide: Towards Carboxyl-Rich Oligomeric Lignin Fragments
The extraction and characterization of defined and carboxyl-rich oligomeric lignin fragments with narrow molecular weight distribution is presented herein. With regard to the well-known pulp bleaching process, oxidative lignin depolymerization was investigated using hydrogen peroxide in an aqueous a...
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| Format: | Article |
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MDPI AG
2020-06-01
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| Series: | Molecules |
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| Online Access: | https://www.mdpi.com/1420-3049/25/11/2717 |
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| author | Ulrike Junghans Justin J. Bernhardt Ronja Wollnik Dominik Triebert Gerd Unkelbach Daniela Pufky-Heinrich |
| author_facet | Ulrike Junghans Justin J. Bernhardt Ronja Wollnik Dominik Triebert Gerd Unkelbach Daniela Pufky-Heinrich |
| author_sort | Ulrike Junghans |
| collection | DOAJ |
| description | The extraction and characterization of defined and carboxyl-rich oligomeric lignin fragments with narrow molecular weight distribution is presented herein. With regard to the well-known pulp bleaching process, oxidative lignin depolymerization was investigated using hydrogen peroxide in an aqueous alkaline solution (i.e., at T = 318 K, t = 1 h) and subsequent selective fractionation with a 10/90 (<i>v</i>/<i>v</i>) acetone/water mixture. While the weight average molecular weight (M<sub>W</sub>) of lignin in comparison to the starting material was reduced by 82% after oxidation (T = 318 K, t = 1 h, c<sub>lignin</sub> = 40 g L<sup>−1</sup>, c<sub>H2O2</sub> = 80 g L<sup>−1</sup>, c<sub>NaOH</sub> = 2 mol L<sup>−1</sup>) and subsequent solvent fractionation (T = 298 K, t = 18 h, c<sub>cleavage product</sub> = 20 g L<sup>−1</sup>), the carboxyl group (–COOH) content increased from 1.29 mmol g<sup>−1</sup> up to 2.66 mmol g<sup>−1</sup>. Finally, the successful scale-up of this whole process to 3 L scale led to gram amounts (14% yield) of oligomeric lignin fragments with a M<sub>W</sub> of 1607 g mol<sup>−1</sup>, a number average molecular weight (M<sub>N</sub>) of 646 g mol<sup>−1</sup>, a narrow polydispersity index of 3.0, and a high –COOH content of 2.96 mmol g<sup>−1</sup>. Application of these oligomeric lignin fragments in epoxy resins or as adsorbents is conceivable without further functionalization. |
| first_indexed | 2024-03-10T19:14:33Z |
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| id | doaj.art-e86e55d4015a47959f203a55735396a3 |
| institution | Directory Open Access Journal |
| issn | 1420-3049 |
| language | English |
| last_indexed | 2024-03-10T19:14:33Z |
| publishDate | 2020-06-01 |
| publisher | MDPI AG |
| record_format | Article |
| series | Molecules |
| spelling | doaj.art-e86e55d4015a47959f203a55735396a32023-11-20T03:33:19ZengMDPI AGMolecules1420-30492020-06-012511271710.3390/molecules25112717Valorization of Lignin via Oxidative Depolymerization with Hydrogen Peroxide: Towards Carboxyl-Rich Oligomeric Lignin FragmentsUlrike Junghans0Justin J. Bernhardt1Ronja Wollnik2Dominik Triebert3Gerd Unkelbach4Daniela Pufky-Heinrich5Fraunhofer Center for Chemical-Biotechnological Processes CBP, Am Haupttor, Bau 1251, 06237 Leuna, GermanyFraunhofer Center for Chemical-Biotechnological Processes CBP, Am Haupttor, Bau 1251, 06237 Leuna, GermanyFraunhofer Center for Chemical-Biotechnological Processes CBP, Am Haupttor, Bau 1251, 06237 Leuna, GermanyFraunhofer Center for Chemical-Biotechnological Processes CBP, Am Haupttor, Bau 1251, 06237 Leuna, GermanyFraunhofer Center for Chemical-Biotechnological Processes CBP, Am Haupttor, Bau 1251, 06237 Leuna, GermanyFraunhofer Center for Chemical-Biotechnological Processes CBP, Am Haupttor, Bau 1251, 06237 Leuna, GermanyThe extraction and characterization of defined and carboxyl-rich oligomeric lignin fragments with narrow molecular weight distribution is presented herein. With regard to the well-known pulp bleaching process, oxidative lignin depolymerization was investigated using hydrogen peroxide in an aqueous alkaline solution (i.e., at T = 318 K, t = 1 h) and subsequent selective fractionation with a 10/90 (<i>v</i>/<i>v</i>) acetone/water mixture. While the weight average molecular weight (M<sub>W</sub>) of lignin in comparison to the starting material was reduced by 82% after oxidation (T = 318 K, t = 1 h, c<sub>lignin</sub> = 40 g L<sup>−1</sup>, c<sub>H2O2</sub> = 80 g L<sup>−1</sup>, c<sub>NaOH</sub> = 2 mol L<sup>−1</sup>) and subsequent solvent fractionation (T = 298 K, t = 18 h, c<sub>cleavage product</sub> = 20 g L<sup>−1</sup>), the carboxyl group (–COOH) content increased from 1.29 mmol g<sup>−1</sup> up to 2.66 mmol g<sup>−1</sup>. Finally, the successful scale-up of this whole process to 3 L scale led to gram amounts (14% yield) of oligomeric lignin fragments with a M<sub>W</sub> of 1607 g mol<sup>−1</sup>, a number average molecular weight (M<sub>N</sub>) of 646 g mol<sup>−1</sup>, a narrow polydispersity index of 3.0, and a high –COOH content of 2.96 mmol g<sup>−1</sup>. Application of these oligomeric lignin fragments in epoxy resins or as adsorbents is conceivable without further functionalization.https://www.mdpi.com/1420-3049/25/11/2717Kraft ligninoxidative depolymerizationhydrogen peroxidesolvent fractionationoligomeric lignin fragments |
| spellingShingle | Ulrike Junghans Justin J. Bernhardt Ronja Wollnik Dominik Triebert Gerd Unkelbach Daniela Pufky-Heinrich Valorization of Lignin via Oxidative Depolymerization with Hydrogen Peroxide: Towards Carboxyl-Rich Oligomeric Lignin Fragments Molecules Kraft lignin oxidative depolymerization hydrogen peroxide solvent fractionation oligomeric lignin fragments |
| title | Valorization of Lignin via Oxidative Depolymerization with Hydrogen Peroxide: Towards Carboxyl-Rich Oligomeric Lignin Fragments |
| title_full | Valorization of Lignin via Oxidative Depolymerization with Hydrogen Peroxide: Towards Carboxyl-Rich Oligomeric Lignin Fragments |
| title_fullStr | Valorization of Lignin via Oxidative Depolymerization with Hydrogen Peroxide: Towards Carboxyl-Rich Oligomeric Lignin Fragments |
| title_full_unstemmed | Valorization of Lignin via Oxidative Depolymerization with Hydrogen Peroxide: Towards Carboxyl-Rich Oligomeric Lignin Fragments |
| title_short | Valorization of Lignin via Oxidative Depolymerization with Hydrogen Peroxide: Towards Carboxyl-Rich Oligomeric Lignin Fragments |
| title_sort | valorization of lignin via oxidative depolymerization with hydrogen peroxide towards carboxyl rich oligomeric lignin fragments |
| topic | Kraft lignin oxidative depolymerization hydrogen peroxide solvent fractionation oligomeric lignin fragments |
| url | https://www.mdpi.com/1420-3049/25/11/2717 |
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