【作者】 何玉娟；

【导师】 李士雨；

【作者基本信息】 天津大学 ， 化学工程， 2004， 硕士

【摘要】 本文研究了天津地区野生黄花蒿植物中青蒿素的提取和分离过程,确定了一条由青蒿原料出发、较为合理的提取分离工艺路线,并通过误差反向传播(EBP)人工神经网络技术成功地对提取过程进行了模拟。主要研究内容和结果为: 1.在前人研究的基础上,本文对青蒿素测定方法进行了验证,研究表明,用紫外分光光度法测定青蒿素的含量,方法简便、准确,但NaOH溶液的质量浓度应控制在0.2%±0.02%范围之内,否则Q292的吸光值降低,测定结果不准确。2.根据文献,青蒿素含量达2mg/g以上的青蒿才有提取青蒿素的价值。本文采用紫外分光光度法,经五次平行实验,测得天津地区黄花蒿中青蒿素的含量平均为5.0377mg/g,由此认定该地区的青蒿素含量较高,有开发利用价值。3.比较了冷浸法、索氏提取和恒温搅拌三种提取方式对青蒿素的提取回收率(青蒿素提取量/原料青蒿素含量),结果分别为:46.48%、68.9%、79.60%,确认恒温搅拌提取方式回收率最高。对石油醚恒温搅拌提取方式利用单因素实验分析了温度、时间、搅拌速率、原料粒度、溶剂量等因素对青蒿素提取的影响,结果表明,各因素对青蒿素提取在一定程度上表现为促进的作用,在一定范围内回收率增加很快,但超过这个范围,提取回收率随之增加的趋势变缓且逐渐呈现下降的趋势。采用四因素四水平正交实验方法,得到了青蒿素较好的提取工艺条件,即提取时间180min,提取温度50℃,搅拌速度800r/min,原料粒度60目,每克青蒿叶粉溶剂用量为60mL。经五次实验验证,在该条件下青蒿素提取回收率平均为90%,文献报道的本工艺最好的提取回收率为83%。本实验结果为改进现有青蒿素石油醚提取工艺提供参考。4.本文采用质量浓度为70%的稀乙醇进行精制除蜡,效果较佳。采用正交实验方法,得到了适宜的青蒿素萃取条件,即萃取液中添加剂苯的质量比例为0.2、萃取液与原料液体积比例为1.0、萃取时间为3h,此时青蒿素的萃取质量比率高达83.52%。通过结晶和重结晶操作,得到了青蒿素粗晶体。5.通过对提取(恒温搅拌)、分离(溶剂萃取)、精制(结晶)工艺过程的研究,最终确定了一条总提取回收率为81.5%(折合成青蒿素提取量/原料量为0.41%)的青蒿素提取工艺路线,与文献报道的汽油法(青蒿素提取量/原料量为0.3%)、乙醇法(青蒿素提取量/原料量为0.24%)相比有了很大的提高。6.考虑到青蒿素提取其萃取产物和过程的复杂性,本文利用神经网络技术实现了青蒿素提取过程的模拟,模拟结果与实验数据吻合甚好,在此基础上分析了各因素对提取工艺的影响,结果表明提取温度、提取时间较其他因素对青蒿素提取回收率的影响显著,可很好的指导实验设计和实验操作。更多还原

【Abstract】 Extraction and separation of Artemisinin from wild Artemisia annua L. in Tianjin was studied in this dissertation, a rational extraction technical route based on Artemisinin raw material was established, and the simulation of the extraction process was achieved using the error back-propagation network. The main contents and results of the research included: 1. The measuration method of Artemisinin was verified based on previous studies, and the Ultraviolet Spectrophotometry was selected as a simple accurate method, but the mass concentration of NaOH solution should be within 0.2%± 0.02%, otherwise, the absorbance of Q292 would be reduced, and the accuracy of the content determination was also affected. 2. Artemisinin from Artemisia annua L. was only worth extracting when it’s content of Artemisinin was above 2mg/g according to literature. Using the Ultraviolet Spectraphotometry, the content of Artemisinin was determined as 5.0377mg/g after five parallel experiments. Thus the conclusion was confirmed that the content of Artemisinin in Tianjin was comparatively high, and Artemisia annua L. in Tianjin was worth exploiting and using. 3. The constant-temperature stirring extraction was affirmed having the highest extraction mass rate of recovery, compared with the infusing under room temperature and Soxhlet extraction methods, which mass rate of recovery was 46.48% and 68.9%. The effects of temperature, time, stirring speed, grinding drgree of material, quantity of solvent and other factors on the extraction rate of recovery were discussed, and the results were also given that those factors were beneficial to the extraction of Artemisinin within a certain range, and the extraction rate of recovery got a rapid increase within this range, then the increasing tendency slowed down and gradually presented the downtrend beyond this range. By the optimizing experiment, the appropriate technical conditions were established as extraction time at 180min, temperature at 50℃, stirring rate at 800 r/min, material grinding degree at 60 meshes,solvent quantity at 60mL/g.Under those conditions, the average extraction recovery rate of Artemisinin was 90%, but in literature was only 83%.These experiment results could be a guide for improving the extraction techniques. 4. The better result of refining and dewaxing was achieved by using the ethanol solution with mass concentration of 70%. By the optimizing experiment, the appropriate technical conditions were established as extraction time at 3 hours, mass proportion of additive benzene at 0.2, volume proportion of extraction solvent at 1.0. Under these conditions, the extraction rate was as high as 83.52%. The coarse crystal of Artemisinin was obtained by the crystallization and recrystallization. 5. A technical route to extract Artemisinin from Artemisia annua L. was established by the study of extraction (constant-temperature stirring), separation (extracting with solvent), and refine(crystallization) technical processes, which overall Artemisinin recovery rate was 81.5% (Artemisinin extraction quantity/raw material quantity amount to 0.41%). Contrast with the routes using gasoline (Artemisinin extraction quantity/raw material quantity amount to 0.3%) or ethanol (Artemisinin extraction quantity/raw material quantity amount to 0.24%) as solvent, this technics got a prodigious improvement. 6. Considering the complexity of the extraction production and process, a simulation of the extraction process was achieved using the error back-propagation network, and the simulation results were in accord with the experiment dates. The effects of those factors on the extraction process was discussed, and the results indicated that the temperature and the time of the extraction had a noticeable effect on the recovery rate of Artemisinin, thus the design and the operation of the experiment would be better supervised.更多还原