玉米秸秆苞叶与茎皮中磨木木质素和木素-碳水化合物复合体的傅里叶红外光谱分析
通过傅立叶红外光谱（FT-IR）对玉米秸秆苞叶和茎皮中的磨木木质素（MWL）和木素-碳水化合物复合体（LCC）的结构进行表征，旨在明确玉米秸秆不同部位木质纤维素的结构。采用改良的Bj?rkman方法，分别从玉米秸秆苞叶与茎皮部位提取分离到MWL和LCC，并通过FT-IR对其结构进行了表征和分析。结果表明：两个部位中的MWL组成明显不同。其中茎皮木质素中的苯丙烷侧链上的支链结构以及苯环结构比重均高于苞叶木质素，而羟基、甲基和共轭羰基结构则低于苞叶木质素。并且茎皮木质素结构中以紫丁香基结构单元为主，而苞叶木质素中则主要以愈创木基结构单元为主。两个部位的LCC结构也存在差异：苞叶LCC中的羟基含量高于茎皮LCC，而甲基、亚甲基含量较茎皮LCC低；而茎皮LCC中木质素与半纤维素连接强度明显高于苞叶LCC，因此可推断茎皮中木质素与纤维素的分离难度大于苞叶。研究结果为开发高效木质纤维素降解技术，提高玉米秸秆利用率奠定了基础。
英文摘要:
The structures of milled wood lignin (MWL) and lignin carbohydrate complex (LCC) in corn stalk ear husk and stem bark were characterized by FT-IR spectroscopy in order to clarify the difference of lignocellulosic structure in different sections of corn stalks. MWL and LCC were first extracted and separated from the corn stalk ear husk and stem bark by the improved method of Bj?rkman, and then were identified and analyzed by FT-IR. The results showed that the structure of MWL in the two sections was distinctly different. The concentration of branched chain structure and benzene ring structure of phenylpropane side chains in stem bark lignin were higher than those in ear husk, while the concentration of hydroxyl, methyl and conjugated carbonyl groups were lower than those of stem bark. The lignin in the stem bark was mainly composed by the syringyl structure units and the lignin in the ear husk was mainly composed by guaiacyl structure units. There are also differences between the LCC structure of two sections: the hydroxyl content of LCC in ear husk was higher and the methyl and methylene content was lower than those of LCC in the stem bark. In addition, the strength of the bond connecting the lignin and hemicellulose in stem bark LCC was significantly higher than that of ear husk LCC, which indicates that it is more difficult to separate lignin from the lignocellulose in stem bark than in the ear husk. The results have laid a foundation for the efficient degradation and effective utilization of corn stalk lignocellulose. The results laid the basis for the development of efficient lignocellulose degradation technology and the improvement of utilization rate of corn stalk.
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