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13C-2H双同位素示踪法研究未漂硫酸盐浆中残余木质素的化学结构
Study on the Structure of Residual Lignin in Unbleached Kraft Pulp by 13C-2H Dual Isotope Tracer
收稿日期：2022-03-14  
DOI：DOI：10.11980/j.issn.0254-508X.2022.12.002
关键词:  银杏  双同位素示踪  木质素  木质素-碳水化合物复合体  硫酸盐法制浆
Key Words:ginkgo  dual isotope tracer  lignin  lignin-carbohydrate complex  kraft pulping
基金项目:国家自然科学基金项目（21878070）；湖北省高等学校优秀中青年科技创新团队计划项目（T201205）。
作者单位邮编
路德胜 湖北工业大学制浆造纸研究院，湖北武汉，430068 430068
张凯 湖北工业大学制浆造纸研究院，湖北武汉，430068 430068
陈旭东 湖北工业大学制浆造纸研究院，湖北武汉，430068 430068
谢益民* 湖北工业大学制浆造纸研究院，湖北武汉，430068 430068
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摘要:采用13C和2H分别标记裸子植物的木质素和碳水化合物，研究未漂硫酸盐浆中残余木质素的化学结构。向银杏（Ginkgo）植株中投入木质素前驱物松伯醇葡萄糖苷-[α-13C]、多糖前驱物D-葡萄糖-[6-2H2]及苯丙氨酸解氨酶（Phenylalanine Ammonialyas，PAL）的阻诘剂羧甲氧基胺半盐酸盐（AOA），获得双同位素标记的木材。将其制备的硫酸盐浆通过酶水解法分离得到纤维素酶解木质素（CEL），通过碱抽提纯化得到碱溶性CEL（CEL-Alk）。利用13C NMR对其结构进行分析，发现蒸煮前，天然银杏木质部中木质素结构单元间主要以β—1、β—5、β—O—4结构为主，少量木质素与多糖类物质以缩醛键连接。硫酸盐浆残余木质素中主要有β—5、β—1等缩合结构，部分木质素通过缩醛键与多糖类物质相连。1H NMR差示光谱显示，木质素单元Cα与葡萄糖或甘露糖之间形成了苯甲醚键连接。结果表明，银杏纤维中的木质素-碳水化合物复合体（LCC）中缩醛键和苯甲醚键结构在硫酸盐法蒸煮过程中较稳定。
Abstract:The chemical structure of residual lignin in unbleached kraft pulp was investigated using 13C and 2H labeling of lignin and carbohydrates from gymnosperms， respectively. And then the chemical structure of the residual lignin in the unbleached kraft pulp was studied. Dual isotope labeled wood was obtained by putting the lignin precursor coniferin-［α-13C］， the polysaccharide precursor D-glucose-［6-2H2］ and the carboxymethoxyamine hemihydrochloride as the inhibitor of phenylalanine ammonialyas （PAL） into Ginkgo. After kraft cooking， the pulp was separated by enzymatic hydrolysis to obtain cellulolytic enzymatic lignin （CEL）， which was purified by alkali extraction to further obtain alkali-soluble CEL （CEL-Alk）. The 13C NMR was used to analyze its structure. It was found that the lignin substructural units in natural ginkgo xylem before cooking were mainly composed of β—1， β—5， β—O—4 structure， while a small amount of lignin units related to polysaccharides by acetal bond. The residual lignin of kraft pulp was mainly connected by β—5， β—1 and a part of lignin related to polysaccharides through acetal bond. The results of 1H NMR difference spectra showed that Cα of lignin units were also linked to glucose or mannose by benzyl ether bond， indicating that the acetal and benzyl ether linkages in ginkgo lignin-carbohydrate complexes were relatively stable during kraft pulping.
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