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

Author(s)

Lima, Cleilton S. ^{[1, 2]} ; Rabelo, Sarita C. ^[1] ; Ciesielski, Peter N. ^[3] ; Roberto, Ines C. ^[2] ; Rocha, George J. M. ^[2] ; Driemeier, Carlos ^[1]

Affiliation

^[1] Brazilian Ctr Res Energy & Mat CNPEM, Brazilian Bioethanol Sci & Technol Lab CTBE, BR-13083970 Campinas, SP - Brazil

^[2] Univ Sao Paulo, Engn Coll Lorena, Dept Biotechnol, BR-12602810 Lorena, SP - Brazil

^[3] Natl Renewable Energy Lab, Biosci Ctr, 15013 Denver West Pkwy, Golden, CO 80401 - USA

• Document type: Journal article
• Source: ACS SUSTAINABLE CHEMISTRY & ENGINEERING; v. 6, n. 3, p. 3796-3804, MAR 2018.
• Web of Science Citations: 1

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 degrees C, 3 h) as well as proximal conditions (0.1-0.7% NaOH, 55-85 degrees C, 1-5 h) chosen by 2(3) experimental design were evaluated. The deacetylation treatment removes similar to 90% of the acetyl groups and 20-30% of the lignin from both bagasse and straw, while removal of similar to 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. (AU)

• FAPESP's process: 15/50590-4 - Lignin valorization in cellulosic ethanol plants: biocatalytic conversion via ferulic acid to high value chemicals
• Grantee: Fábio Márcio Squina
• Support Opportunities: Program for Research on Bioenergy (BIOEN) - Thematic Grants