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Title: Fractionation and characterization of lignin streams from unique high-lignin content endocarp feedstocks

Abstract

In this paper, lignin is a promising source of building blocks for upgrading to valuable aromatic chemicals and materials. Endocarp biomass represents a non-edible crop residue in an existing agricultural setting which cannot be used as animal feed nor soil amendment. With significantly higher lignin content and bulk energy density, endocarps have significant advantages to be converted into both biofuel and bioproducts as compared to other biomass resources. Deep eutectic solvent (DES) is highly effective in fractionating lignin from a variety of biomass feedstocks with high yield and purity while at lower cost comparing to certain ionic liquids. In the present study, the structural and compositional features of peach and walnut endocarp cells were characterized. Compared to typical woody and herbaceous biomass, endocarp biomass exhibits significantly higher bulk density and hardness due to its high cellular density. The sugar yields of DES (1:2 choline chloride: lactic acid) pretreated peach pit ( Prunus persica) and walnut shell ( Juglans nigra) were determined and the impacts of DES pretreatment on the physical and chemical properties of extracted lignin were characterized. Enzymatic saccharification of DES pretreated walnut and peach endocarps gave high glucose yields (over 90%); meanwhile, compared with dilute acid and alkalinemore » pretreatment, DES pretreatment led to significantly higher lignin removal (64.3% and 70.2% for walnut and peach endocarps, respectively). The molecular weights of the extracted lignin from DES pretreated endocarp biomass were significantly reduced. 1H– 13C HSQC NMR results demonstrate that the native endocarp lignins were SGH type lignins with dominant G-unit (86.7% and 80.5% for walnut and peach endocarps lignins, respectively). DES pretreatment decreased the S and H-unit while led to an increase in condensed G-units, which may contribute to a higher thermal stability of the isolated lignin. Nearly all β-O-4' and a large portion of β-5' linkages were removed during DES pretreatment. In conclusion, the high lignin content endocarps have unique cell wall characteristics when compared to the other lignocellulosic biomass feedstocks. DES pretreatment was highly effective in fractionating high lignin content endocarps to produce both sugar and lignin streams while the DES extracted lignins underwent significant changes in SGH ratio, interunit linkages, and molecular sizes.« less

Authors:
 [1];  [1]; ORCiD logo [2]; ORCiD logo [3];  [1]; ORCiD logo [2]; ORCiD logo [1]
  1. Univ. of Kentucky, Lexington, KY (United States)
  2. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Univ. of Tennessee, Knoxville, TN (United States)
  3. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Publication Date:
Research Org.:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Sponsoring Org.:
USDOE
OSTI Identifier:
1492154
Grant/Contract Number:  
AC05-00OR22725
Resource Type:
Accepted Manuscript
Journal Name:
Biotechnology for Biofuels
Additional Journal Information:
Journal Volume: 11; Journal Issue: 1; Journal ID: ISSN 1754-6834
Publisher:
BioMed Central
Country of Publication:
United States
Language:
English
Subject:
09 BIOMASS FUELS; Endocarp; Deep eutectic solvent; Pretreatment; Lignin; Biofuel; Biorefinery

Citation Formats

Li, Wenqi, Amos, Kirtley, Li, Mi, Pu, Yunqiao Joseph, Debolt, Seth, Ragauskas, Arthur J., and Shi, Jian. Fractionation and characterization of lignin streams from unique high-lignin content endocarp feedstocks. United States: N. p., 2018. Web. doi:10.1186/s13068-018-1305-7.
Li, Wenqi, Amos, Kirtley, Li, Mi, Pu, Yunqiao Joseph, Debolt, Seth, Ragauskas, Arthur J., & Shi, Jian. Fractionation and characterization of lignin streams from unique high-lignin content endocarp feedstocks. United States. doi:10.1186/s13068-018-1305-7.
Li, Wenqi, Amos, Kirtley, Li, Mi, Pu, Yunqiao Joseph, Debolt, Seth, Ragauskas, Arthur J., and Shi, Jian. Thu . "Fractionation and characterization of lignin streams from unique high-lignin content endocarp feedstocks". United States. doi:10.1186/s13068-018-1305-7. https://www.osti.gov/servlets/purl/1492154.
@article{osti_1492154,
title = {Fractionation and characterization of lignin streams from unique high-lignin content endocarp feedstocks},
author = {Li, Wenqi and Amos, Kirtley and Li, Mi and Pu, Yunqiao Joseph and Debolt, Seth and Ragauskas, Arthur J. and Shi, Jian},
abstractNote = {In this paper, lignin is a promising source of building blocks for upgrading to valuable aromatic chemicals and materials. Endocarp biomass represents a non-edible crop residue in an existing agricultural setting which cannot be used as animal feed nor soil amendment. With significantly higher lignin content and bulk energy density, endocarps have significant advantages to be converted into both biofuel and bioproducts as compared to other biomass resources. Deep eutectic solvent (DES) is highly effective in fractionating lignin from a variety of biomass feedstocks with high yield and purity while at lower cost comparing to certain ionic liquids. In the present study, the structural and compositional features of peach and walnut endocarp cells were characterized. Compared to typical woody and herbaceous biomass, endocarp biomass exhibits significantly higher bulk density and hardness due to its high cellular density. The sugar yields of DES (1:2 choline chloride: lactic acid) pretreated peach pit (Prunus persica) and walnut shell (Juglans nigra) were determined and the impacts of DES pretreatment on the physical and chemical properties of extracted lignin were characterized. Enzymatic saccharification of DES pretreated walnut and peach endocarps gave high glucose yields (over 90%); meanwhile, compared with dilute acid and alkaline pretreatment, DES pretreatment led to significantly higher lignin removal (64.3% and 70.2% for walnut and peach endocarps, respectively). The molecular weights of the extracted lignin from DES pretreated endocarp biomass were significantly reduced. 1H–13C HSQC NMR results demonstrate that the native endocarp lignins were SGH type lignins with dominant G-unit (86.7% and 80.5% for walnut and peach endocarps lignins, respectively). DES pretreatment decreased the S and H-unit while led to an increase in condensed G-units, which may contribute to a higher thermal stability of the isolated lignin. Nearly all β-O-4' and a large portion of β-5' linkages were removed during DES pretreatment. In conclusion, the high lignin content endocarps have unique cell wall characteristics when compared to the other lignocellulosic biomass feedstocks. DES pretreatment was highly effective in fractionating high lignin content endocarps to produce both sugar and lignin streams while the DES extracted lignins underwent significant changes in SGH ratio, interunit linkages, and molecular sizes.},
doi = {10.1186/s13068-018-1305-7},
journal = {Biotechnology for Biofuels},
number = 1,
volume = 11,
place = {United States},
year = {2018},
month = {11}
}

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