ISOLATION AND FRACTIONATION OF HEMICELLULOSES FROM SALIX PSAMMOPHILA
Water- and alkali-soluble hemicelluloses were isolated with hot water and 10％ KOH at 25 ℃ from dewaxed and delignified Salix psammophila, respectively. The alkali-soluble hemicelluloses were then successively sub-fractioned by neutralization and graded precipitation at final ethanol concentrations of 15％, 30％, 45％, 60％, 75％ and 90％, respectively. Chemical composition, physico-chemical properties, and structures of eight precipitated hemicellulosic fractions were elucidated by a combination of sugar analysis, molecular determination, FT-IR, 1H, 13C 2D HSQC NMR. It was found that water-soluble hemicelluloses were more branched, and had low molecular weights (6060 g/mol), whereas the alkali-soluble hemicelluloses were less branched, and had high molecular weights (17110-85540 g/mol), in which xylose and uronic acid are the main sugar component. In addition, the less branched hemicelluloses with large molecules were precipitated in lower ethanol percentages, while with the increasing ethanol concentrations, more branched hemicelluloses with low molecular weights were obtained. That is, linear hemicelluloses could be recovered at lower ethanol concentrations, and more branched hemicelluloses could be obtained at the higher ethanol concentrations. Based on the FT-IR, 1H, 13C and 2D HSQC NMR studies, the alkali-soluble hemicelluloses had a main structure composed of the (1→4)-linked β-D-xylopyranosyl backbone with 4-O-methyl-αD-glucuronic acid attached to O-2 of the xylose residues.
Salix psammophila hemicelluloses alkali fractionation xylans
Feng Peng Ning Jia Jing Bian Pai Peng Feng Xu Runcang Sun
Institute of Biomass Chemistry and Technology, Beijing Forestry University, Beijing 100083, China St Institute of Biomass Chemistry and Technology, Beijing Forestry University, Beijing 100083, China State Key Laboratory of Pulp and Paper Engineering, South China University of Technology, Guangzhou
国际会议
16th International Symposium on Wood,Fiber and Pulping Chemistry(第十六届木材、纤维及制浆化学国际会议)
天津
英文
439-444
2011-06-08（万方平台首次上网日期，不代表论文的发表时间）