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Title: The Nature of Hololignin

Abstract

Acid chlorite delignification is frequently used to obtain a mixture of cellulose and hemicellulose known as holocellulose from biomass. While a majority of lignin is removed after holocellulose pulping, there appears to be a minor fraction of lignin that is more resistant to acid chlorite treatment and remains in the holocellulose even after repeated delignification treatment. This type of lignin, defined as hololignin, has not been characterized, is likely to contribute to biomass recalcitrance and is clearly of fundamental interest to understand its structural characteristics. In this study, hololignin isolated from poplar holocellulose was characterized with a wide array of techniques including GPC, quantitative 13C, DEPT-135, HSQC, and 31P NMR. The results were then compared to those from milled wood lignin (MWL), the representative native lignin isolated from poplar. NMR analysis demonstrated a depletion of cinnamyl aldehyde, acetyl group, and decrease of p-hydroxybenzoate structural units in hololignin. An enrichment of condensed structures in hololignin was observed. Hololignin also had a significantly lower molecular weight than MWL. Finally, hololignin is relatively enriched in guaiacyl units and has a lower S/G ratio, lower β-O-4 ether linkages, fewer aliphatic and phenolic hydroxyl groups, and more carboxylic acid groups than MWL.

Authors:
 [1]; ORCiD logo [2];  [3]; ORCiD logo [2];  [4]; ORCiD logo [5]
  1. Univ. of Tennessee, Knoxville, TN (United States). Dept. of Chemical and Biomolecular Engineering
  2. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Biosciences Division
  3. Georgia Inst. of Technology, Atlanta, GA (United States). School of Chemistry and Biochemistry
  4. Fujian Agriculture and Forestry Univ., Fuzhou (China). College of Material Engineering
  5. Univ. of Tennessee, Knoxville, TN (United States). Center of Renewable Carbon, Inst. of Agriculture and Dept. of Chemical and Biomolecular Engineering and Dept. of Forestry, Wildlife and Fisheries; Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Biosciences Division
Publication Date:
Research Org.:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Sponsoring Org.:
USDOE Office of Science (SC), Biological and Environmental Research (BER) (SC-23)
OSTI Identifier:
1427613
Grant/Contract Number:  
AC05-00OR22725
Resource Type:
Journal Article: Accepted Manuscript
Journal Name:
ACS Sustainable Chemistry & Engineering
Additional Journal Information:
Journal Volume: 6; Journal Issue: 1; Journal ID: ISSN 2168-0485
Publisher:
American Chemical Society (ACS)
Country of Publication:
United States
Language:
English
Subject:
09 BIOMASS FUELS; 37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY; Acid chlorite; Delignification; Holocellulose pulping; Hololignin; Milled wood lignin

Citation Formats

Meng, Xianzhi, Pu, Yunqiao, Sannigrahi, Poulomi, Li, Mi, Cao, Shilin, and Ragauskas, Arthur J. The Nature of Hololignin. United States: N. p., 2017. Web. doi:10.1021/acssuschemeng.7b03285.
Meng, Xianzhi, Pu, Yunqiao, Sannigrahi, Poulomi, Li, Mi, Cao, Shilin, & Ragauskas, Arthur J. The Nature of Hololignin. United States. doi:10.1021/acssuschemeng.7b03285.
Meng, Xianzhi, Pu, Yunqiao, Sannigrahi, Poulomi, Li, Mi, Cao, Shilin, and Ragauskas, Arthur J. Tue . "The Nature of Hololignin". United States. doi:10.1021/acssuschemeng.7b03285. https://www.osti.gov/servlets/purl/1427613.
@article{osti_1427613,
title = {The Nature of Hololignin},
author = {Meng, Xianzhi and Pu, Yunqiao and Sannigrahi, Poulomi and Li, Mi and Cao, Shilin and Ragauskas, Arthur J.},
abstractNote = {Acid chlorite delignification is frequently used to obtain a mixture of cellulose and hemicellulose known as holocellulose from biomass. While a majority of lignin is removed after holocellulose pulping, there appears to be a minor fraction of lignin that is more resistant to acid chlorite treatment and remains in the holocellulose even after repeated delignification treatment. This type of lignin, defined as hololignin, has not been characterized, is likely to contribute to biomass recalcitrance and is clearly of fundamental interest to understand its structural characteristics. In this study, hololignin isolated from poplar holocellulose was characterized with a wide array of techniques including GPC, quantitative 13C, DEPT-135, HSQC, and 31P NMR. The results were then compared to those from milled wood lignin (MWL), the representative native lignin isolated from poplar. NMR analysis demonstrated a depletion of cinnamyl aldehyde, acetyl group, and decrease of p-hydroxybenzoate structural units in hololignin. An enrichment of condensed structures in hololignin was observed. Hololignin also had a significantly lower molecular weight than MWL. Finally, hololignin is relatively enriched in guaiacyl units and has a lower S/G ratio, lower β-O-4 ether linkages, fewer aliphatic and phenolic hydroxyl groups, and more carboxylic acid groups than MWL.},
doi = {10.1021/acssuschemeng.7b03285},
journal = {ACS Sustainable Chemistry & Engineering},
issn = {2168-0485},
number = 1,
volume = 6,
place = {United States},
year = {2017},
month = {11}
}

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