期刊
INDUSTRIAL CROPS AND PRODUCTS
卷 32, 期 1, 页码 21-28出版社
ELSEVIER SCIENCE BV
DOI: 10.1016/j.indcrop.2010.02.008
关键词
Sweet sorghum stem; Lignin; Extraction; FT-IR; C-13 NMR
资金
- Major State Basic Research Projects of China [973-2010CB732204]
- National Natural Science Foundation of China [30930073]
- Ministries of Education [111, 2007B55, NCET-08-0728]
- Hei Long Jiang Province for Distinguished Young Scholars [JC200907]
Seven lignin fractions were isolated from dewaxed sweet sorghum stem and their physicochemical features were investigated. The dewaxed sweet sorghum stem was extracted sequentially with hot water, 50% dioxane and dimethyl sulfoxide (DMSO), and various concentrations of NaOH. The treatments resulted in dissolution of 0.5, 0.7, 0.2, 1.3, 1.6, 0.8, and 0.5% lignin, corresponding to release of 8.9, 12.5, 3.6, 23.2, 28.6, 14.3, and 8.9% of the total solubilized lignin, respectively. The seven lignin fractions were comparatively characterized by chemical composition, structural features, and molecular weights using alkaline nitrobenzene oxidation, acid hydrolysis, UV. FT-IR, H-1 and C-13 NMR spectroscopy. and GPC. The purity of the lignin fractions isolated by 50% dioxane and alkali was higher than that of the lignin preparations obtained by hot water and DMSO. in which the content of associated polysaccharides in the former lignin fractions (0.16-2.12%) was much lower than those of the latter lignin preparations (10.39 and 37.03%). It was found that the seven lignin fractions contained substantial amounts of non-condensed guaiacyl and syringyl units with fewer p-hydroxyphenyl units, and had weight-average molecular weights between 1270 and 3590 g mol(-1). No substantial differences in the main structural features between the lignin preparations isolated with 50% dioxane and alkali were found and these treatments did not result in significant changes in lignin composition and its structure. (C) 2010 Elsevier B.V. All rights reserved.
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