胡麻碱性亚硫酸钠-蒽醌法蒸煮机理的研究

A Study on Mechanism of Linum Usifalissmus Linn Pulping with Alkaline Sodium Sulfitc-Anthraquinone Process

本文研究了胡麻的原料组成,木素特性及胡麻碱性亚硫酸钠-蒽醌法蒸煮机理。 研究分析结果表明,胡麻中半纤维素主要由阿拉伯糖-葡萄糖醛酸-木糖组成。胡麻木素属GSH型,其中G>S>H;与麦草、竹子比较,胡麻木素中紫丁香基含量较高,而对羟苯基含量较少。胡麻的AS-AQ法蒸煮脱木素历程分为:(1)初始脱木素阶段,50℃升温到120℃;(2)大量脱木素阶段,120℃到165℃保温半小时;(3)补充脱木素阶段,165℃保温半小时到保温3小时。各微区木素的脱除也可分为三个阶段。碱在其中的作用,主要是使木素大分子发生某种程度的碎片化,木素的脱除主要是磺化溶出的结果。

In this paper, carbohydrate composition, lignin characteristics and the mechanism of Linum Usitatissmus Linn pulping with alkaline sodium sulfite-anthraquinone process were investigated.Analysis of carbohydrate composition of Linum Ustitatissmus Linn oy gas.chromatography indicates that the main component of hemicellululose in Linum Usitatissmus Linn is arabinose- glucuronic acid- xylose. Koxane lignin of Linum Usitatissmus Linn was investigated by UV, IR and 1HNMR, and compared with dioxane lignins of wheat straw and bamboo. The results obtained showed that Linum Usitatissmus Linn lignins are GSH-type lignins, and G>S>H. Linum Usitatissmus Linn lignin is rich in syringyl groups, but poor in p-hydroxyl benzaldehyde groups.No existence of ester linkages and lower content of phenolic hydroxyls in Linum Usitatissmus Linn lignin seem to be one of the most important causes that delignification is rather slower in cooking of Linum Usitatissmus Linn than that of other straw materials.The investigations show that dissolution of lignin can be divided into three phases during alkaline sodium sulfite-anthraquinone cooking of Linum Usitatissmus Linn: initial phase of delignification (below I20℃). bulk phase from 120℃ to 30min at 165℃. and supplementary phase from 30m in to 180minat 165℃. Before 30min at 165℃, dissolution of various polyoses is much faster and afterwards becomes slower. Dissolution amounts of all kinds of polyoses during the cooking period are: glucose about 30 % , xylose about 52%, arabinose and mannose about 70% , galactose about 74%.The topochemistry of delignification was investigated by the use of SEM- EDXA techniques. The results show that dissolution of delignification in different morphological regions also can be divided into three phases. Delignification rate in secondary wall is faster than those in cell corner and compound middle lamella before 1 40℃. After 165℃. cell corner and compund middle lamella have much higher delignification rates than secondary wall. At 165℃ for 30min, although lignin content is up to 14. 95% (as raw material), cell corner and compound middle lamela begin to seperate to some extent.Lignin extracted from waste liquor was examined by 1R and 1HNMR. Results show that the main effect of alkali could have degraded lignin to some extent. Bulk dissolution of lignin can be attributed to the sulfonation of lignin and dissolution of lignosulfonic acid.