玉米秆半纤维素的碱法提取与表征

Isolation and Characterization of Corn Stover Hemicellulose

中文关键词:  玉米秆  半纤维素  离子色谱  热重分析

Key Words:corn stover  hemicellulose  ion chromatography  thermogravimetric analysis

中文摘要:

      利用KOH溶液从玉米秆原料中提取了半纤维素，对半纤维素的主要成分和结构进行了研究，并对半纤维素进行了热重分析。离子色谱分析结果表明，75℃下利用80 g/L KOH溶液作用2 h，半纤维素溶出率接近95%，其中聚木糖占75.6%，是玉米秆半纤维素的主要成分，另外提取液中还含有聚阿拉伯糖、聚葡萄糖、聚半乳糖。凝胶渗透色谱结果显示，经提纯后的半纤维素的质均相对分子质量可达53431，多分散系数为1.07。核磁共振光谱与傅里叶红外光谱结果表明，玉米秆半纤维素可能是由(1→4)-β-D吡喃木糖为主链的聚阿拉伯糖木糖，在主链的C2、C3上的羟基分别连有α-L阿拉伯糖基和α-D葡萄糖醛酸基，另外，(1→4)连接的β-D-吡喃木糖残基可能含有取代的酚酸。热重分析结果表明，半纤维素的分解温度在190~350℃之间，267℃时失重速率最大，为0.89 %/℃。

Abstract:

      Hemicellulose was extracted from corn stover with potassium hydroxide, and the main composition and structure of the hemicellulose were studied，and thermogravimetric analysis was carried out to investigate its thermal stability. Results showed that KOH solution is an effective solvent for the dissolution of corn stover hemicellulose, almost 95% of the total hemicellulose was extracted when using 80 g/L KOH at 75℃ for 2h，among which 75.6% was xylan, the main component of corn stover hemicellulose. Besides, arabinan, glucan and galactan were also detectable. Molecular weight of the hemicellulose determined by gel permeation chromatography was 53431, with the polydispersity of 1.07. NMR and FT-IR analysis suggested the structure of the hemicelluloses from corn stover was assumed to be an arabinoxylan mainly consisting of (1→4)-β-D-xylan backbone substituted in hydroxy groups at C2 and/or C3 by single α-L-arabinose residue, single α-D-glucuronic acid residue. In addition, the (1→4)-linked β-D-xylopyranosyl residues in the backbone may contain substituted phenolic acids. Thermal analysis suggested that the decomposition temperature of hemicellulose was 190~350℃ and the maximum weight loss rate was 0.89%/℃, happened at 267℃.