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 °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...