甲酸木质素的提

发布时间：2018-03-11 20:13

  本文选题：木质素　切入点：减水剂　出处：《青岛科技大学》2017年硕士论文　论文类型：学位论文

【摘要】：自然界中,木质素作为仅次于纤维素的第二大生物质资源,其具有含量丰富,环保,可再生的优点。但是,由于其结构复杂,分子量分布不均匀的特点,高值利用率低。所以,对木质素进行分级纯化改性,不仅能提高其利用率,还能降低石油等不可再生资源的消耗,对人类社会的可持续发展具有重要意义。本文采用甲酸提取针叶木中的木质素,再通过有机溶剂对木质素进行分子量分级,并进行化学改性,制备木质素基高效混凝土减水剂。将甲酸提取木质素实验条件优化后,将松木在140℃、L/S=6:1、H_2O_2溶液用量为5%(以绝干松木质量为基准)与88%甲酸反应40min可得甲酸木质素(FAL)。再利用有机溶剂溶解FAL进行分级处理可得到可溶木质素(S-FAL)和不溶木质素(I-FAL)。经元素分析,液相色谱、GPC、FT-IR、~1H-NMR测定分析可得:1、松木原料的最高脱木素率达到87.2%,所得纤维素纯度为89.3%、纤维素收率88.7%、半纤维素收率76.6%;2、分级的木质素具有更多的反应活性点(更多的亚甲基和羟基,和较少的甲氧基),更容易被改性(如磺化或磺甲基化),从而提高其工作性能。将改性实验条件优化后,将所得木质素与50%的H_2O_2溶液(以绝干FAL质量为基准)在100℃下反应1h进行氧化反应,然后,与100%HCHO溶液和50%的Na_2SO_3固体在150℃下反应2h进行磺甲基化反应制得分级改性木质素(MS-FAL、MI-FAL)。采用元素分析,液相色谱、GPC、FT-IR、~1H-NMR、水泥净浆流动度、磺化度和减水率测试对所有产品进行表征分析可得:经丙酮溶剂(分析纯)溶解分级的木质素改性后,当掺量为0.3%时,其水泥净浆流动度可达到178±2 mm,减水率可达21%,与商品萘系减水剂效果相当,达到高效减水剂的要求。实验所用的甲酸溶液和有机溶剂均可回收再利用,可减少污染,并降低生产成本。
[Abstract]:In nature, lignin, as the second largest biomass resource after cellulose, has the advantages of rich content, environmental protection and renewable. However, because of its complex structure, uneven molecular weight distribution, low utilization ratio of high value, The classification and purification modification of lignin can not only improve its utilization rate, but also reduce the consumption of non-renewable resources such as petroleum, which is of great significance to the sustainable development of human society. In this paper, formic acid was used to extract lignin from coniferous wood. Then the molecular weight of lignin was classified by organic solvent, and the lignin based high efficiency concrete water reducer was prepared by chemical modification. The experimental conditions of extraction of lignin by formic acid were optimized. After 40 minutes of reaction of pine wood with 88% formic acid for 40 minutes, soluble lignin S-FAL and insoluble lignin I-FALL can be obtained when the amount of solution is 5 (based on the mass of absolutely dried pine) and 88% formic acid, and the soluble lignin S-FAL and insoluble lignin I-FALL can be obtained by using organic solvent to dissolve FAL for 40 minutes. The highest delignification rate of pine wood was 87.2, the purity of cellulose was 89.33p, the yield of cellulose was 88.7%, the yield of hemicellulose was 76.6%, and the graded lignin had more reactive activity points (more methylene and hydroxyl). And less methoxy, it is easier to be modified (such as sulfonation or sulfomethylation), so as to improve its performance. The lignin was oxidized with 50% H _ S _ 2O _ 2 solution (based on the dry FAL mass) at 100 鈩，

本文编号：1599715