FRACTIONATION AND CHARACTERIZATION OF ALKALI-EXTRACTABLE HEMICELLULOSES FROM POPULUS GANSUENSIS
Populus gansuensis hemicelluloses were isolated with 10％ KOH at 25 oC for 16 h from the delignified materials. The hemicellulose B was sub-fractionated with graded alcohol precipitation at the final concentrations of 15％pre, 30％, 45％, 60％, 75％ and 90％, respectively. Together with hemicellulose A (Ha), all the seven hemicellulosic fractions were comparatively studied by sugar analysis, GPC, FTIR, 1D and 2D NMR spectra. The results showed that the molecular weights and the distribution of branches along the xylan backbone are different among the hemicellulosic fractions obtained in various ethanol concentrations. Macromolecular and more linear hemicelluloses were preferentially precipitated in relatively lower ethanol concentration, while with the increasing ethanol percentage, more branched hemicelluloses with low molecular weights were obtained. In addition, the hemicellulosic subfraction H30 precipitated at the ethanol concentration of 30％, was assumed to be 4-O-methyl-D-glucurono-D-xylans, with 4-OMeGlcA linked to C-2 of (1→4)-β-D-xylan. On average for every six D-xylopyranosyl residues, there is one uronic acid group.
Populus gansuensis ethanol precipitation hemicellulosic subfraction xylan
Bian Jing Peng Feng Peng Pai Xu Feng Sun Runcang
Institute of Biomass Chemistry and Technology,Beijing Forestry University, Beijing, 100083, China Institute of Biomass Chemistry and Technology,Beijing Forestry University, Beijing, 100083, China St State Key Laboratory of Pulp and Paper Engineering,South China University of Technology, Guangzhou,5
国际会议
广州
英文
85-88
2010-11-08（万方平台首次上网日期，不代表论文的发表时间）