基于拉曼光谱快速检测亚氯酸钠法脱木素的动力学及选择性

doi:10.3964/j.issn.1000-0593(2020)09-2951-06

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Abstract Acid-chlorite delignification is the most popular and established laboratory method for the lignin removal from biomass with only trace degradation of the polysaccharides. However, the information on delignification kinetics and selectivity at the cellular level as the reaction proceeds is limited. Raman microscopy can be used to determine the dynamic changes of residual lignin and lignin monomer content in different cells and morphological areas in the delignification process quickly, qualitatively and semi-quantitatively. The average Raman spectra at 1 598, 1 270 and 1 331 cm^-1 in different cells of eucalyptus (angiosperms), coniferous fir (angiosperms) and bamboo (grass) were extracted, which were attributed to lignin, guaiacyl units (G) and syringyl units (S), respectively. It wasfound that the rules of delignification kinetics in the three kinds of wood were consistent, namelya large amount of lignin was rapidly removed at the initial stage of the reaction, and the efficiency of lignin removal decreased with the reaction progress. At the first 0.5 h, the average Raman intensity at 1 598 cm^-1 decreased more than 82%, while only 5%～15% of the average Raman intensity was decreased at the later stage of delignification. Particularly, the bamboo took significantly less delignification time than the wood under the same condition, which the Raman intensity at 1 598 cm^-1 of bamboo fiber decreased more than 88.65% within the first 10 minutes. Meanwhile, lignin removal was highly selective. At the initial stage of reaction, the removal rate of G and S lignin in ray cells was higher than that in the vessel and fiber cells, and in vessel and fiber cells more S lignin were removed than G lignin. In the whole process, the vessel was the most resistant to delignification, followed by ray and less resistant in fiber. In morphologically various areas, therate of lignin removal of the cell corner was the highest, followed by the compound middle lamella, and then the secondary wall of fiber. For lignin monomers, the S units were more prone to being removed than G units. The result showed that Raman spectroscopy could be used to detect the dynamic changes of residual lignin content in different tree species, tissues, cells and lignin units during the gradual delignification process, which could help to further understanding the selectivity and dynamics of delignification.

Key words：Delignification; Raman spectroscopy; Cell wall; Lignin monomers

Received: 2019-09-03 Accepted: 2020-01-12

ZTFLH:

O657.3

Corresponding Authors: LIU Xing-e E-mail: liuxinge@icbr.ac.cn

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https://www.gpxygpfx.com/EN/10.3964/j.issn.1000-0593(2020)09-2951-06 OR https://www.gpxygpfx.com/EN/Y2020/V40/I09/2951