玉米秸秆半纤维素的逐级分离及其结构表征

Separation and Characterization of Hemicelluloses of Corn Stalks

中文关键词:  玉米秸秆  半纤维素  分离  结构表征

Key Words:corn stalk  hemicellulose  separation  structural characterization

中文摘要:

      将玉米秸秆进行苯-醇抽提和亚氯酸钠脱木素处理制取综纤维素，利用不同溶剂体系抽提综纤维素分离出不同特性的半纤维素，并对其化学结构进行表征。结果表明，经过二甲基亚砜、二氧六环-三乙胺、饱和Ba（OH）2、1 mol/L KOH、1 mol/L NaOH和3 mol/L KOH连续抽提，得到的乙醇沉淀半纤维素分别为玉米秸秆半纤维素总量的5.8%、0.3%、24.4%、38.6%、7.1%和12.2%。高效阴离子交换色谱（HPAEC）、傅里叶红外光谱（FT-IR）和核磁共振光谱（NMR）分析表明，二甲基亚砜和二氧六环-三乙胺提取所得半纤维素分枝度较高，无机碱体系抽提所得半纤维素分枝度较低；二甲基亚砜抽提所得半纤维素是以L-阿拉伯糖基和4-O-甲基-葡萄糖醛酸基为侧链的含有乙酰基的聚木糖半纤维素。热重分析（TGA）表明，无机碱抽提所得半纤维素的热稳定性高于有机溶剂抽提所得半纤维素。

Abstract:

      Holocellulose obtained by dewaxing and delignification of corn stalks were sequentially extracted and fractionated with different solvent systems to separate hemicelluloses. The chemical structures of the separated hemicelluloses were characterized. The results showed that the obtained hemicelluloses yields were 5.8%, 0.3%, 24.4%, 38.6%, 7.1% and 12.2% of total hemicellulose in corn stalk, respectively, after extracting sequentially by dimethyl sulfoxide, dioxane-triethylamine, saturated barium hydroxide, 1 mol/L KOH, 1 mol/L NaOH, and 3 mol/L KOH. The analysis of HPAEC, FT-IR, 1H-NMR and 13C-NMR indicated that the branching degree of hemicelluloses extracted by dimethyl sulfoxide and dioxane-triethylamine was high, while that of hemicelluloses extracted by inorganic alkali system was lower. The backbone chain of the hemicelluloses extracted by dimethyl sulfoxide was β-D-xylose with acetyl group, and the branched chains were L-Arabia sugar and 4-O-methyl glucose uronic acid. TGA analysis showed that the thermal stabilities of the hemicelluloses extracted by inorganic alkali were better than that of the hemicelluloses extracted by organic solvent.