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Title: Multiscale Alterations in Sugar Cane Bagasse and Straw Submitted to Alkaline Deacetylation

Alkaline deacetylation has emerged as a promising chemistry for pretreatments performed prior to enzymatic saccharification of lignocellulosic biomass. This process avoids complex pressurized reactors and opens new opportunities for lignin covalorization. In this work, we evaluate the chemical and morphological response of sugar cane bagasse and straw submitted to alkaline treatments. Alkaline solutions for deacetylation (0.4% w/w NaOH, 70 degrees C, 3 h) as well as proximal conditions (0.1-0.7% NaOH, 55-85 degrees C, 1-5 h) chosen by 23 experimental design were evaluated. The deacetylation treatment removes ~90% of the acetyl groups and 20-30% of the lignin from both bagasse and straw, while removal of ~20% of the xylan and glucan is observed in straw, but not in bagasse. Considering nanoscale structural alterations, neither cellulose cocrystallization (evaluated by X-ray diffraction) nor formation of lignin aggregates (evaluated by thermoporometric signature) are observed after the alkaline conditions, in contrast to observations after hydrothermal treatments. Furthermore, calorimetric thermoporometry as well as scanning and transmission electron microscopies show substantial introduction of nanoscale porosity and loosening of the tissue and cell wall structures, indicating desirable mechanical weakening and gains in enzyme accessibility. These results provide fundamental and practical knowledge for biorefineries based on alkaline deacetylation ofmore » sugar cane bagasse and straw.« less
Authors:
 [1] ;  [2] ;  [3] ;  [4] ;  [4] ;  [2]
  1. Brazilian Center for Research in Energy and Materials (CNPEM), Sao Paulo (Brazil); Univ.of Sao Paulo (Brazil)
  2. Brazilian Center for Research in Energy and Materials (CNPEM), Sao Paulo (Brazil)
  3. National Renewable Energy Lab. (NREL), Golden, CO (United States)
  4. Univ.of Sao Paulo (Brazil)
Publication Date:
Report Number(s):
NREL/JA-2700-71218
Journal ID: ISSN 2168-0485
Grant/Contract Number:
AC36-08GO28308
Type:
Accepted Manuscript
Journal Name:
ACS Sustainable Chemistry & Engineering
Additional Journal Information:
Journal Volume: 6; Journal Issue: 3; Journal ID: ISSN 2168-0485
Publisher:
American Chemical Society (ACS)
Research Org:
National Renewable Energy Lab. (NREL), Golden, CO (United States); Energy Frontier Research Centers (EFRC) (United States). Center for Direct Catalytic Conversion of Biomass to Biofuels (C3Bio)
Sponsoring Org:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
Country of Publication:
United States
Language:
English
Subject:
09 BIOMASS FUELS; bagasse; deacetylation; pretreatment; straw; sugar cane
OSTI Identifier:
1430818

Lima, Cleilton S., Rabelo, Sarita C., Ciesielski, Peter N., Roberto, Ines C., Rocha, George J. M., and Driemeier, Carlos. Multiscale Alterations in Sugar Cane Bagasse and Straw Submitted to Alkaline Deacetylation. United States: N. p., Web. doi:10.1021/acssuschemeng.7b04158.
Lima, Cleilton S., Rabelo, Sarita C., Ciesielski, Peter N., Roberto, Ines C., Rocha, George J. M., & Driemeier, Carlos. Multiscale Alterations in Sugar Cane Bagasse and Straw Submitted to Alkaline Deacetylation. United States. doi:10.1021/acssuschemeng.7b04158.
Lima, Cleilton S., Rabelo, Sarita C., Ciesielski, Peter N., Roberto, Ines C., Rocha, George J. M., and Driemeier, Carlos. 2018. "Multiscale Alterations in Sugar Cane Bagasse and Straw Submitted to Alkaline Deacetylation". United States. doi:10.1021/acssuschemeng.7b04158.
@article{osti_1430818,
title = {Multiscale Alterations in Sugar Cane Bagasse and Straw Submitted to Alkaline Deacetylation},
author = {Lima, Cleilton S. and Rabelo, Sarita C. and Ciesielski, Peter N. and Roberto, Ines C. and Rocha, George J. M. and Driemeier, Carlos},
abstractNote = {Alkaline deacetylation has emerged as a promising chemistry for pretreatments performed prior to enzymatic saccharification of lignocellulosic biomass. This process avoids complex pressurized reactors and opens new opportunities for lignin covalorization. In this work, we evaluate the chemical and morphological response of sugar cane bagasse and straw submitted to alkaline treatments. Alkaline solutions for deacetylation (0.4% w/w NaOH, 70 degrees C, 3 h) as well as proximal conditions (0.1-0.7% NaOH, 55-85 degrees C, 1-5 h) chosen by 23 experimental design were evaluated. The deacetylation treatment removes ~90% of the acetyl groups and 20-30% of the lignin from both bagasse and straw, while removal of ~20% of the xylan and glucan is observed in straw, but not in bagasse. Considering nanoscale structural alterations, neither cellulose cocrystallization (evaluated by X-ray diffraction) nor formation of lignin aggregates (evaluated by thermoporometric signature) are observed after the alkaline conditions, in contrast to observations after hydrothermal treatments. Furthermore, calorimetric thermoporometry as well as scanning and transmission electron microscopies show substantial introduction of nanoscale porosity and loosening of the tissue and cell wall structures, indicating desirable mechanical weakening and gains in enzyme accessibility. These results provide fundamental and practical knowledge for biorefineries based on alkaline deacetylation of sugar cane bagasse and straw.},
doi = {10.1021/acssuschemeng.7b04158},
journal = {ACS Sustainable Chemistry & Engineering},
number = 3,
volume = 6,
place = {United States},
year = {2018},
month = {1}
}