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Mild depolymerization of alkaline lignin in a formic acid-choline chloride type deep eutectic solvent system

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Published/Copyright: January 26, 2023
Holzforschung
From the journal Holzforschung Volume 77 Issue 3

Abstract

The degradation of lignin can generate a variety of products with diverse applications. Lignin is abundant on earth; however, its high molecular weight and stable properties impede its development. Currently, acid-catalyzed degradation of lignin is a relatively common and promising catalytic method, particularly DES catalytic degradation, which is not only environmentally friendly but also features an excellent degradation effect. This report discusses the degradation mechanism and effect of the formic acid-choline chloride DES system for the degradation of alkaline lignin. According to fourier transform infrared spectroscopy (FTIR) and 1H-NMR spectroscopy, it is evident that the phenolic hydroxyl content of lignin increases after degradation, which indicates the cleavage of β-O-4′ ether bonds in the macromolecular structure. Gel permeation chromatography (GPC) was employed to determine the molecular weight of degraded lignin, and regenerated lignin with low molecular weight and low dispersibility was obtained. The minimum average molecular weight (M w ) was 2.3 × 103 g/mol. During the depolymerization process, it was also discovered that the repolymerization and degradation reactions formed a competitive relationship. The lignin oil contained primarily propanoic acid ethyl ester, acetic acid butyl ester, 2-methoxy-4-propyl phenol, 2-methoxy phenol, and apocynin, as determined by GC-MS.

Keywords: alkaline lignin; depolymerization; DES; formic acid
Corresponding author: Wenjuan Wu, Jiangsu Co-Innovation Center of Efficient Processing and Utilization of Forest Resources, Nanjing Forestry University, Nanjing, 210037, China, E-mail:

Funding source: National Natural Science Foundation of China

Award Identifier / Grant number: 31730106

Award Identifier / Grant number: 32271797

  1. Author contributions: All the authors have accepted responsibility for the entire content of this submitted manuscript and approved submission.

  2. Research funding: The authors are grateful for the support of the National Natural Science Foundation of China (32271797, 31730106).

  3. Conflict of interest statement: The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

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Received: 2022-09-16
Accepted: 2022-12-22
Published Online: 2023-01-26
Published in Print: 2023-03-28

© 2023 Walter de Gruyter GmbH, Berlin/Boston

Articles in the same Issue

  1. Frontmatter
  2. Original Articles
  3. Wood with improved hydrophobicity and thermal stability after depositing polydimethysiloxane/silica sol hybrid
  4. Evaluation of the dissolving ability of cellulosic pulps: investigation of a novel method using light scattering follow-up during classical cellulose carbanilation
  5. Mild depolymerization of alkaline lignin in a formic acid-choline chloride type deep eutectic solvent system
  6. On the hydrothermal depolymerisation of kraft lignin using glycerol as a capping agent
  7. Improved dimensional stability and mechanical properties of rubberwood via modification with maleated lignin and densification
  8. Insight into the mechanism underlying modification of Neosinocalamus affinis by hygrothermal treatment
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https://doi.org/10.1515/hf-2022-0145
Keywords for this article
alkaline lignin; depolymerization; DES; formic acid

Articles in the same Issue

  1. Frontmatter
  2. Original Articles
  3. Wood with improved hydrophobicity and thermal stability after depositing polydimethysiloxane/silica sol hybrid
  4. Evaluation of the dissolving ability of cellulosic pulps: investigation of a novel method using light scattering follow-up during classical cellulose carbanilation
  5. Mild depolymerization of alkaline lignin in a formic acid-choline chloride type deep eutectic solvent system
  6. On the hydrothermal depolymerisation of kraft lignin using glycerol as a capping agent
  7. Improved dimensional stability and mechanical properties of rubberwood via modification with maleated lignin and densification
  8. Insight into the mechanism underlying modification of Neosinocalamus affinis by hygrothermal treatment
  9. Degradation assessment of archaeological oak (Quercus spp.) buried under oxygen-limited condition
  10. Differences in dry shrinkage of bamboo rings with multiple heights and radians based on vascular bundle group
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