粉丹竹磺化化学机械浆木素结构的31P-NMR和13C-NMR波谱分析

粉丹竹磺化化学机械浆（SCMP）的木素结构在漂白和老化过程中发生变化,使用纤维素酶酶解-弱酸水解的两步法对SCMP及其漂白浆、漂后老化浆中木素进行分离提纯,利用31P-NMR和13C-NMR波谱对木素样品中的结构及其比例进行研究。结果表明：SCMP木素样品中三种结构单元—对-羟苯基（H）、愈疮木基（G）和紫丁香基（S）的比例为G:S:H=30:42:28。在其漂白和漂白浆老化过程中,总酚羟基分别减少了30.7%和38.4%,而羧基的含量分别增加了53.2%和55.3%,木素结构中烷基芳基醚键和α-烷基醚键发生了断裂,γ-烷基醚键则比较稳定,同时木素侧链发生断裂,形成香草醛、Ar-COOH和Ar-CH2-COOR等结构。

The Analysis of Lignin Structure of Bamboo SCMP by Quantitative 31P-NMR and 13C-NMR

The lignin’s structure of bamboo (Bambusa Chung II) SCMP would change during its bleaching and ageing. Lignin samples of SCMP, bleached SCMP (BSCMP) and aged BSCMP was separated using the combined methods of mild enzyme hydrolysis and acid hydrolysis, and their structures were characterized by 31P-NMR and 13C-NMR. From the results, it can be found that the ratio of guaiacyl (G), syringyl (S) and p-hydroxylphenyl (H) unit in SCMP lignin sample is G:S:H=30:42:28. During the process of bleaching and ageing, total phenolic hydroxyl group in lignin sample decreased by 30.7% and 38.4%, carboxylic hydroxyl group increased by 53.2% and 55.3%, respectively. Aryl-O-alkyl and α–O-alkyl ethers in lignin samples were cleaved, butγ–O-alkyl ethers were stable. And the linkage of the side chain carbons in lignin samples were simultaneously cleaved, which formed some structures with short side chain, such as vanillin, Ar-COOH and Ar-CH2-COOH.