| 基于全溶体系的毛竹竹材木质素分离方法 |
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| 引用本文： | 吴文娟,闫雪晴,邹春阳,王博伟,何贤.基于全溶体系的毛竹竹材木质素分离方法[J].浙江农林大学学报,2020,37(2):335-342. |
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| 作者姓名： | 吴文娟 闫雪晴 邹春阳 王博伟 何贤 |
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| 作者单位： | 南京林业大学 江苏省林业资源高效加工利用协同创新中心, 江苏 南京 210037 |
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| 基金项目： | 国家自然科学基金青年基金资助项目21704045江苏省高等学校大学生创新创业训练计划项目201910298034Y |
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| 摘 要： | 目的 以毛竹Phyllostachys edulis竹材为原料，经球磨分别通过LiCl/DMSO溶剂体系的溶解、再生处理、纤维素酶水解，得到的酶解残渣进行溶剂抽提、纯化，分离出竹材中的再生酶解木质素（RCEL）。 方法 木质素化学成分按照标准方法测定，木质素结构单元的变化通过红外、碱性硝基苯氧化、核磁共振波普分析，采用X射线衍射比较再生前后的纤维素结晶区变化。用凝胶渗透色谱测定木质素的分子量及其分布。 结果 经由化学成分结果得知:RCEL的得率和纯度都较高。经红外、元素分析、硝基苯氧化、凝胶渗透色谱、核磁共振等手段表征表明:分离得到的竹材RCEL为GSH型木质素，缩合程度略高于纤维素酶解木质素（CEL），其中，紫丁香基结构单元含量较高，达50%，分离过程中结构单元比例没有变化。从分子量及其分布来看，竹材RCEL数均分子量和重均分子量都较高，分离过程中木质素降解较少。经X射线衍射分析，经LiCl/DMSO体系溶胀处理后纤维素的结晶度有所下降。RCEL木质素热失重温度为200~600℃，600℃后失重趋于稳定，木质素缩合程度不同会导致不同的热解特性。 结论 基于LiCl/DMSO溶剂体系的分离方法，对木质素大分子结构有较好的保护作用，对碳水化合物有很好的降解作用，可以改变纤维素结晶区的结构，降低结晶度，从而能促进纤维素的降解，提高酶解效率，有利于高效分离CEL。与传统分离方法得到的球磨木质素（MWL）、CEL相比，经过LiCl/DMSO溶剂体系处理后得到的竹材RCEL，能较好地代表竹材的木质素。
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| 关 键 词： | 林业工程 木质素 LiCl/DMSO 分离 竹材 |
| 收稿时间： | 2019-05-27 |
A isolation method of lignin from bamboo based on complete dissolution |
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| WU Wenjuan,YAN Xueqing,ZOU Chunyang,WANG Bowei,HE Xian.A isolation method of lignin from bamboo based on complete dissolution[J].Journal of Zhejiang A&F University,2020,37(2):335-342. |
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| Authors: | WU Wenjuan YAN Xueqing ZOU Chunyang WANG Bowei HE Xian |
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| Affiliation: | Jiangsu Co-Innovation Center of Efficient Processing and Utilization of Forest Resources, Nanjing Forestry University, Nanjing 210037, Jiangsu, China |
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| Abstract: | Objective To obtain regenerated cellulolytic enzyme lignin (RCEL), ball-milled bamboo (Phyllostachys edulis) was dissolved, regenerated, and subjected to cellulose enzymatic hydrolysis in a lithium chloride/dimethyl sulfoxide (LiCl/DMSO) solvent system before the enzymatic residue is extracted and purified in the solvent. Method First, the chemical composition of lignin was determined with the standard method. Then, the structures and contents of the isolated lignin were analyzed by means of Fourier transform infrared(FT-IR)spectroscopy, alkaline nitrobenzene oxidation and proton nuclear magnetic resonance(1H NMR). Afterwards, gel permeation chromatography(GPC) was conducted to analyze the molecular weight and polydispersity of lignin while X-ray diffraction was used to evaluate the effect of dissolution and regeneration of bamboo on the cellulose crystallinity. Result (1) In terms of the chemical composition, the yield and purity of RCEL were higher. (2) The isolated bamboo RCEL lignin was GSH lignin whose condensation degree was slightly higher than that of cellulolytic enzyme lignin(CEL), the content of Syringyl structural unit was higher, almost reaching 50% (w/w), and the proportion of structural unit did not change during the separation process. (3) In terms of molecular weight and its distribution, both of the average molecular weight and weight average molecular weight of bamboo RCEL lignin were high, and there was no occurrence of lignin degradation during the separation process. (4) The crystallinity of cellulose decreased after swelling treatment of LiCl/DMSO solvent system with X-ray diffraction. (5) The thermogravimetric temperature of RCEL lignin was between 200℃ and 600℃ and different pyrolysis features are presented with different condensation degrees of lignin. Conclusion This separation method based on LiCl/DMSO solvent system had a good protective effect on the macromolecular structure of lignin while caused damage in carbohydrates structure. It could change the cellulose crystallization region and reduce the degree of crystallization, thus promoting the degradation of cellulose and improving the efficiency of enzyme hydrolysis, which were beneficial to the efficient separation of CEL. Compared with milled wood lignin (MWL) and CEL isolated with the traditional separation method, the RCEL lignin separated using the current separation method could better represent the protolignin of bamboo. |
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