乙醇-水抽提法分离毛竹枝桠材组分的研究

Study on Separation of Moso Bamboo Branch Components by Ethanol-water Extraction Method

关键词:  毛竹枝桠材  乙醇-水  木素  寡木糖  纸浆

Key Words:moso bamboo branch  ethanol-water  lignin  oligoxylose  pulp

摘要:以废弃的毛竹枝桠材为原料进行间歇三段乙醇-水抽提，从各段抽提液中回收多糖、溶剂和木素，考察了第一段抽提温度对主产品（多糖）和副产品（木素、纸浆）指标的影响。结果表明，乙醇-水抽提法进行组分分离是可行的，在保温温度为一段170℃、二段145℃、三段120℃，保温时间依次为2.5、1.0、0.5 h，每段液比1∶10和乙醇体积分数为65%的条件下，粗糖总得率25.12%，含少量杂质，略高于原料聚戊糖含量24.86%；精制糖总得率22.26%，其中寡木糖（DP₂-DP₇）占比59.09%；抽提所得木素占原料总木素的48.04%；细浆得率49.59%。离子色谱和纸浆纤维形态以及成纸性能分析表明，在170~180℃范围内，一段保温温度升高对粗糖、精制糖和木素的得率影响不大，但会导致寡木糖得率、纸浆得率及纸浆强度的下降；乙醇-水抽提法所得纸浆杂细胞含量高且强度较低，可筛分后与优质浆进行配抄使用。

Abstract:Intermittent three-stage ethanol-water extraction was carried out using discarded Moso bamboo branch as raw materials. Lignin, solvent, and polysaccharide were recovered from the extraction solution of each stage. The effects of extraction temperature on the yields and properties of the main product polysaccharide, the by-products lignin and pulp were investigated. The results showed that this component separation method was feasible. When the extraction temperatures were respectively kept at 170℃ for 2.5 h for the first stage, at 145℃ for 1.0 h for the second stage and at 120℃ for 0.5 h for the third stage, the liquid ratio of each stage of 1∶10 and the ethanol volume fraction of each stage of 65%, the total yield of raw sugar containing a small amount of impurities was 25.12%,which was slightly higher than the raw material pentose content of 24.86%; the total yield of refined sugar was 22.26%, of which oligoxylose (DP₂-DP₇) accounted for 59.09%; the lignin obtained by extraction accounted for 48.04% of the total lignin in the raw materials; screened pulp yield was 49.59%.Ion chromatography and pulp fiber morphology and resultant paper performance analyses showed that the increase of the first stage extraction temperature in the range of 170 ℃ to 180 ℃ had little effect on the yields of raw sugar, refined sugar and lignin, but would lead to a decrease of the oligosaccharide’ s yield, the pulp’ s yield and paper strength; the pulp obtained by the separation of components with ethanol-water method had high content of non-fibrous cells and low paper strength, and it could be mixed with high-quality pulp to make paper after screening.