Mesostructural changes in cellulose within wood cell wall upon hydrothermal treatment at 200 °C

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A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä
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Cellulose, Volume 30, issue 13
Hydrothermal treatment between 150 °C and 230 °C is widely used in wood processing, from the steam treatment of timber for better dimensional stability and durability to the pretreatment for enzymatic saccharification and chemical pulping. Understanding the ultrastructural changes of wood cell walls through hydrothermal treatments is crucial for controlling and optimizing these hydrothermal treatment-based processes. Here, we studied the ultrastructure of wood cell walls of 24 hardwood species using simultaneous small- and wide-angle X-ray scattering measurements before and after the hydrothermal treatment at 200 °C. Most hardwoods show similar equatorial scattering features, representing the structure in the cross-section of the cell walls. In a water-saturated native state, there is a prominent correlation peak between 0.1 and 0.2 Å−1 and a second peak between 0.2 and 0.4 Å−1. The hydrothermal treatment above 160 ˚C drastically altered the structure at this nanometric scale: the two native correlation peaks disappeared, coincident with a buildup of a correlation peak in the 0.03–0.04 Å−1 range. The hydrothermal treatment likely removed the cell wall matrix component between the microfibrils through autohydrolysis and phase separation, leading to the collapse of microfibrils with each other in the normal wood. In cellulose-rich cell walls, such as the G-layer in tension wood, cellulose microfibrils are already collated in the native state.
Funding Information: This study was supported by JSPS KAKENHI Grant Number JP17J05156 (T.K.). The dried wood specimens were obtained through collaborative research using wood collection databases with Research Institute for Sustainable Humanosphere (RISH) (Y.M. and T.K.). We thank Prof. Junji Sugiyama and Hajime Sorimachi (Kyoto University, Japan) for advising us on the selection of wood specimens. We thank the support of Prof. Yukie Saito (The University of Tokyo, Japan) and The University of Tokyo Chichibu Forest and Arboricultural Research Institute (UTCF) during the sampling of beech green wood specimens. We acknowledge Glyco@Alps (ANR-15-IDEX-02) for the financial support. The wide-angle X-ray detector (WOS) was funded by the French National Research Agency (ANR) under the ‘Investissement d’Avenir’ program (Grant No. ANR-11-EQPX-0010). ESRF is acknowledged for the provision of beamtimes (experiment numbers A02-1-892 and A02-1-864, D2AM beamline). Publisher Copyright: © 2023, The Author(s).
Cellulose microfibril, Co-crystallization, Hydrothermal treatment, Mesostructure, Wood, X-ray scattering
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Kuribayashi, T, Ogawa, Y, Morfin, I, Matsumoto, Y & Nishiyama, Y 2023, ' Mesostructural changes in cellulose within wood cell wall upon hydrothermal treatment at 200 °C ', Cellulose, vol. 30, no. 13, pp. 8405–8413 .