麦草乙醇法分解液中木素的分离和结构表征

Separation and Structural Characterization of Lignin from Black Liquor of Ethanol Pulping of Wheat Straw

通过加水、加酸和调节温度的方式回收麦草乙醇法分解液中的粗乙醇木素,并对制得的粗乙醇木素与工业碱木素分别进行FI-IR1、HNMR表征来确定粗乙醇木素的物理化学结构特征,并且进行了成分分析。结果表明,稀释比例为1∶1,pH值为2.5,温度为30℃时,粗乙醇木素的沉淀量最大,木素纯度更高,其物理化学结构特征与工业碱木素有所不同,乙醇木素含有更多的羟基、羰基和甲氧基,有利于改性利用。

The black liquor from wheat straw ethanol pulping was initially filtered to remove small fibers and impurities,then water was added into black liquor to adjust pH for lignin precipitation.The lignin obtained along with commercial alkaline lignin was characterized by FT-IR,1HNMR and their composition was analyzed.The results indicated that the largest amount of precipitated lignin was obtained when the dilution proportion,pH,temperature was 1,2.5,20℃ respectively.The physico-chemical properties and structural features of the precipitated ethanol lignin were better than that of the commercial alkaline lignin,which had high purity and contained more hydroxyl,carbonyl,methoxy structure,so ethanol lignin was good to be modified.