桦木硫酸盐木素的分离及结构分析

用硫酸沉淀桦木硫酸盐制浆黑液中的木素，并对木素进行提纯及结构分析，同时还分析了原黑液及分离木素后上清液的各项指标。结果发现，黑液经分离木素后，ＣＯＤｃｒ及色度大大下降，分离的木素纯度为９０８３％。分离出的桦木硫酸盐木素中以紫丁香基单元为主，也含有一定数量的对羟苯基单元和愈创木基单元。

Isolation of White Birch Kraft Lignin and Relevant Structure

The main purpose of this paper is to investigate the isolation of kraft birch lignin(KBL) and its relevant structure KBL is precipitated from the black liquor through acidification with H2SO4. When the lignin was been isolated, the black liqour become clear, transparent, odorless and free from foams. The CODcr and color of the supernatant are much lower than those of the original black liquor. Lignin removal is claimed to be 90.84%, equavalent to 15.8% of that original birch. The lignin is further purified with a mixture of dichloroethane and ethanol. The yield of the purified lignin (P KBL) is 66%. Elementary analysis GPC, 1H NMR, nitrobenzene oxidation, potassium permanganate oxidation are employed for the structure studies. An empirical formula in terms of C9 unit for KBL is proposed as follows: C9H6.45O1.39(OCH3)1.11(Ph OH)0.63(Alc OH)0.58.The empirical formula for P KBL is: C9H6.17O1.39(OCH3)1.00(Ph OH)0.50(Alc OH)0.54. The molecular weight of P KBL is found to be greater than that of KBL, but the contents of OCH3,PH OH and ALc OH in P KBL are less then those in KBL. P KBL has more p hydroxypheny units and fewer syringe and guaiacyl units than KBL.