电解法改性碱木质素及性能分析

发布时间：2018-06-10 08:10

  本文选题：电解 + 木质素　； 参考：《广西大学》2017年硕士论文

【摘要】：木质素广泛存在于自然界中是植物的三大组份之一。如何有效利用木质素是生物质材料和生物质能源这两个领域的研究热点。本文从制浆黑液中提取纯化木质素,继而利用电场诱导水溶液产生自由基的方法来改性木质素;其原理是通过氢自由基与木质素的自由基反应,和阴极反应来实现加氢效果;通过电场诱导和电极反应产生的羟基自由基破坏木质素分子之间的醚键等连接键,也可以与木质素发生氧化反应,使部分基团羧基化,从而达到改性的目的。研究结果如下:(1)经过EA分析,电解改性木质素的C、H元素含量增加,O元素含量减少,且XPS分析表明,木质素在电解改性后O/C值由28.22%变为27.63%,碳原子的电子结合能(eV)的峰位值从282.100 eV下降到281.9.00 eV(校正前),说明木质素电解后元素组成和比例发生了变化。(2)GPC分析表明,经过电解改性的木质素平均分子量呈现下降的趋势;利用STA得到电解改性木质素前后的TG和DSC曲线,发现电解改性的木质素玻璃态转化温度下降;NMR图谱显示电解改性木质素的β-0-4、甲氧基等结构醚键被大规模破坏,羧基等基团含量却增加,说明木质素电解后分子结构发生了变化。(3)通过GC-MS分析电解改性木质素产物中存在2,4-已二烯醇、十二烷、十三烷、正十五烷、2,6-二甲氧基苯酚、3-甲氧基-4-羟基苯甲醛4-羟基-3-甲氧基苯乙酮、丁香醛、3',5'-二甲氧基-4'-羟基苯乙酮、邻苯二甲酸正丁异辛酯、邻苯二甲酸单(2-乙基己基)酯等物质,通过氧弹热值仪测试电解前后的木质素的热值分别为20348 kJ·kg-1和20498 kJ·kg-1,说明木质素电解后组份物质发生了变化。(4)通过单因素实验,得到了电解法对木质素改性的最佳条件是:反应时间96 h,反应温度80℃,反应电压8 V,底物浓度2.5 g·L-1。
[Abstract]:Lignin is one of the three major components of plants in nature. How to utilize lignin effectively is the research hotspot in biomass material and biomass energy. In this paper, lignin was extracted and purified from the black liquor of pulping, and then the lignin was modified by the method of producing free radical in aqueous solution induced by electric field, which is based on the reaction of free radical of hydrogen with lignin and cathodic reaction to realize the hydrogenation effect. The hydroxyl radical produced by electric field induction and electrode reaction can destroy the bond such as the ether bond between lignin molecules, and it can also oxidize lignin and make some groups carboxylated, thus achieving the purpose of modification. The results are as follows: (1) after EA analysis, the content of Con H in electrolytic modified lignin increased and decreased, and XPS analysis showed that, After electrolysis modification, the O / C value of lignin changed from 28.22% to 27.63%, and the peak value of electron binding energy of carbon atom decreased from 282.100 EV to 281.9.00 EV. The TG and DSC curves before and after electrolytic modification of lignin were obtained by STA. It was found that the glass state transition temperature of electrolytic modified lignin was decreased by NMR, and the 尾 -0-4 of electrolytic modified lignin was found to be 尾 -0-4. The structure ether bond such as methoxy was destroyed on a large scale, but the content of carboxyl group was increased. The results showed that the molecular structure of lignin was changed after electrolysis. (3) by GC-MS analysis, there were 2k4- hexadienol, dodecane, tridecane in the products of lignin modified by electrolysis. N-pentadecane 6-dimethoxy phenol 3-methoxy-4-hydroxybenzaldehyde 4-hydroxy-3-methoxy acetophenone, eugenaldehyde 3- (5) -dimethoxy -4- (4) -hydroxyacetophenone, n-butyl phthalate (n-butyl) -isooctyl phthalate, mono-2-ethylhexyl phthalate, etc. The calorific values of lignin measured by oxygen bomb calorimeter were 20348 kJ kg-1 and 20498 kJ kg-1, respectively, which indicated that the composition of lignin electrolysis changed. The optimum conditions for the modification of lignin by electrolysis were obtained as follows: reaction time 96 h, reaction temperature 80 鈩，

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