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

Cleilton S. Lima, Sarita C. Rabelo, Peter N. Ciesielski, Inês C. Roberto, George J.M. Rocha, Carlos Driemeier

Research output: Contribution to journalArticlepeer-review

22 Scopus Citations

Abstract

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 °C, 3 h) as well as proximal conditions (0.1-0.7% NaOH, 55-85 °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.

Original languageAmerican English
Pages (from-to)3796-3804
Number of pages9
JournalACS Sustainable Chemistry and Engineering
Volume6
Issue number3
DOIs
StatePublished - 2018

Bibliographical note

Publisher Copyright:
Copyright © 2018 American Chemical Society.

NREL Publication Number

  • NREL/JA-2700-71218

Keywords

  • Bagasse
  • Deacetylation
  • Pretreatment
  • Straw
  • Sugar cane

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