水热反应强化提取桑枝木质素过程解析

Analysis of extraction lignin from mulberry branch by hydrothermal reaction enhancement

采用水热反应强化碱溶酸析法提取废弃桑枝中木质素,运用均匀设计法优化获得提取桑枝木质素的适宜参数,运用FTIR分析木质素组分结构,解析桑枝木质素溶出过程。结果表明:加入2.25mol·L^-1的NaOH溶液体积(ml)与桑枝质量(g)比为15﹕1,于150℃的烘箱中水热反应80min后,经体积浓度为5%的盐酸溶液调节pH值为6.5,2.0000g桑枝能提取木质素121.5mg;解析红外光谱图可知,桑枝中C-O、O-H和C-H等键明显减弱或消失,表明水热反应可加强破坏桑枝细胞壁和糖类复合结构,加强桑枝植物组织中羧基、羰基、醚键等官能团结构裂解,有利于木质素碱溶酸析反应的进行;而影响木质素提取的反应条件主次因素顺序是pH值>NaOH浓度>水热反应温度>水热反应时间。

In order to utilize waste mulberry branches by resource,the lignin in abandoned mulberry branches was extracted by hydrothermal reaction and alkali-soluble acid precipitation method.To analysing of lignin dissolution process in mulberry branches,the suitable parameters for extracting mulberry lignin were optimized by uniform design method,and the lignin component structure was analyzed by FTIR.The results showed that the ratio of the volume(ml)of NaOH solution added with 2.25mol·L^-1 to the mass(g)of mulberry was 15∶1,and the hydrothermal reaction was carried out in an oven at 150℃for 80 min.The pH of the solution was adjusted to 6.5,and 2.0000g of mulberry could extract 121.5 mg of lignin.The analytical infrared spectrum showed that the C-O,O-H and C-H bonds in the mulberry branches were obviously weakened or disappeared,indicating that the hydrothermal reaction can strengthen the destruction of the mulberry cell wall and Thesaccharide composite structure strengthens the cleavage of functional groups such as carboxyl group,carbonyl group and ether bond in mulberry plant tissues,which is beneficial to the lignin alkalitic acid precipitation reaction;and the order of the primary and secondary factors affecting the extraction of lignin is pH>NaOH concentration>hydrothermal reaction temperature>hydrothermal reaction time.