麦草甲酸法制浆木素结构及分子质量变化

Changes of Lignin Structure and Molecular Weight in Wheat Straw Formic Acid Cooking

本研究采用甲酸法蒸煮麦草,首先对蒸煮废液的物理化学性质进行检测,分别对残余木素及溶出木素进行红外谱图分析,探讨木素在蒸煮过程中的结构变化通过凝胶渗透色谱(GPC)得出木素的分子质量分布及变化,并对其进行分析对比结果表明:25℃下废液黏度1.25mPa·s,有机物含量19.30g·L^(-1),占总固形物的82.8%,无机物含量4.18g·L^(-1);蒸煮过程中由于α-醚键或β-醚键断裂产生了较多的共轭和非共轭C=O基团,溶出木素含有较多的伯醇-OH和仲醇-OH,有利于木素的进一步加工利用;溶出木素的平均分子质量大于残余木素的平均分子质量,为甲酸法制浆的最佳工艺条件的确定提供理论参考。

This study use formic acid method to cook wheat straw, first of all, the physical and chemical properties of cooking waste were tested, respectively, the residual lignin and dissolved lignin were analyzed by the IR spectra, the structure transformation of lignin during cooking process was observed, and the changes of molecular weight of the lignin are studied and compared by GPC. The results showed that the viscosity of cooking waste was 1.25mPa＇s under 25℃, organic content was 19.30g·L-11, of 82.8% of the total solids, mineral content 4.18g·L-1; due to α-ether bond or β-ether cleavage have more non-conjugated and conjugated C=O group during cooking process, the dissolved lignin contain more primary alcohol-OH and secondary alcohol-OH, which was in favor of further utilization of lignin; the average molecular weight of dissolved lignin was higher than that of residual lignin, through this research, a foundation can be established for the optimization of formic acid pulping process, as well as for the industrialization of formic acid pulping of wheat straw in the future.