Abstract: In this paper, jute fibers were catalytically oxidized by the laccase/TEMPO system, the lignin content in jute fibers before and after the treatment was determined through the Klason method, and the molecular weight and distribution, element content as well as the chemical structure of lignin extracted from jute fibers by the dioxane method were determined using gel permeation chromatography, organic elemental analysis and hydrogen nuclear magnetic resonance spectroscopy, respectively. The results showed that the lignin content in jute fibers decreased from 10.83% to 8.59% after the laccase/TEMPO treatment. The lignin remaining on jute fibers was also degraded, with the weight average molecular weight decreasing from 439,938 Da to 238,704 Da. For the lignin of laccase/TEMPO-treated jute fibers, its carbon content increased, oxygen content and OCH3 content decreased, and the number of alcohol hydroxyl groups decreased, while the number of phenolic hydroxyl groups decreased slightly. Besides, the connection type between structural units of lignin also changed, with the proportion of β-β, β-1and β-O-4 structure decreasing and the proportion of β-5 structure increasing. The results indicated that the laccase/TEMPO catalyzed oxidation reaction of jute fiber lignin was accompanied by some demethylation, and β-β, β-O-4 and β-1 bonds were mainly broken during lignin degradation and then β-5 links were formed.

Key words:

jute fiber, lignin, laccase, TEMPO, oxidation

摘要： 采用漆酶/TEMPO体系对黄麻纤维进行催化氧化处理，通过Klason法测定处理前后黄麻纤维中的木质素含量，分别利用凝胶渗透色谱法、有机元素分析法、核磁共振氢谱法测定以二氧六环法从黄麻纤维中提取木质素的分子量及分布、元素含量与化学结构。结果表明：经漆酶/TEMPO处理后黄麻纤维中木质素含量由10.83%降为8.59%，纤维上存留的木质素亦发生了降解，重均分子量由439938 Da降至238704 Da。黄麻纤维经过漆酶/TEMPO体系处理后，木质素的碳元素含量升高，氧元素和OCH3含量降低，醇羟基数目减少，酚羟基数目稍有下降，并且结构单元的连接方式有所转变，其中β-β、β-1和β-O-4结构比例有所降低，β-5结构增多，说明漆酶/TEMPO催化黄麻纤维木质素发生氧化反应并伴随有一定脱甲基化作用，木质素降解以β-β、β-O-4和β-1键断裂为主，而后形成β-5连接。

关键词:

黄麻纤维, 木质素, 漆酶, TEMPO, 氧化