【作者】 汤磊；

【导师】 刘本；

【作者基本信息】 浙江大学 ， 生物化工， 2010， 硕士

【摘要】 本文先通过响应面优化法优化了白芍中芍药苷的超临界流体萃取工艺条件,然后根据质量衡算规律建立了超临界流体萃取芍药苷的数学模型,最后分析总结了含夹带剂的超临界CO₂萃取传质过程。根据Box-Behnken的中心组合实验设计原理,在单因素试验的基础上,采用三因素三水平的响应曲面分析法,建立白芍饮片中芍药苷超临界流体提取的二次多项式数学模型,并以芍药苷提取率为响应值作响应面和等高线,考察萃取压力、萃取温度和甲醇浓度对芍药苷超临界流体提取的影响。芍药苷超临界流体提取的优化工艺条件为:萃取压力为18.9MPa,萃取温度为59.9℃,夹带剂甲醇浓度为68.5%,夹带剂流速0.4mL·min^-1,萃取时间为60min;在此工艺条件下,芍药苷的理论提取率可达7.85mg·g^-1。然后在此优化条件下进行验证实验,得到实际芍药苷的提取率为7.48mg·g^-1,与理论预测值相比,其相对误差约为4.71%。通过对响应曲面和等高线的分析可以得出芍药苷的超临界流体提取过程中萃取压力与甲醇浓度以及萃取温度和甲醇浓度之间相互影响比较明显,而萃取压力与萃取温度之间的相互作用不明显,说明夹带剂甲醇浓度对整个提取过程影响非常显著。进一步通过与索式提取和超声提取的比较可知,超临界流体提取的效果好、提取率高、时间短,是一种较为优秀的提取方法。在响应面实验的基础上根据分步萃取传质机理,建立了超临界流体萃取芍药苷的数学模型。通过模拟计算和模型的参数回归得到了不易萃取溶质的浓度x_k=5.243×10^-4kg·kg^-1,样品颗粒表面的外扩散传质系数K_f=8.598×10^-8m·s^-1以及样品颗粒内部的内扩散传质系数K_s=7.811×10^-10m·s^-1。通过模型检验得出模型能较好反映萃取的过程,为进一步优化模型参数和工艺研究提供了参考。更多还原

【Abstract】 This article optimized supercritical fluid extraction process conditions of paeoniflorin by using response surface methodolog at first, and then established the mathematical model of supercritical fluid extraction, finally summarized mass transfer process of supercritical CO₂ extraction containing entrainer.On the basis of one-factor tests and the Box-Behnken center-united experimental design principle, the method of response surface analysis with 3 factors and 3 levels was adopted. A second order quadratic equation for supercritical fluid extraction of paeoniflorin was built. Response surface and contour were graphed with the extraction rate of paeoniflorin as the response value. Based on the analysis of the response surface plots and their corresponding contour plots, the effects of extraction pressure, extraction temperature, and methanol concentration were explored. By using the new method discussed above, the optimum extraction condition was obtained as follows: extraction pressure 18.9MPa, extraction temperature 59.9℃, methanol concentration 68.5%, the flow rate of cosolvent mehtanol 0.4mL·min^-1, and extraction time 60min. Under the optimized condition, extraction rate of paeoniflorin on theoretical value was 7.85mg·g^-1. And the experimental extraction rate was 7.48mg·g^-1 with relative error 4.71%, compared with the predictive value.Through the analysis of response surface and contour lines, we can obtain the conclusion that the interaction between methanol concentration and extraction pressure or methanol concentration and extraction temperature is obvious, while is not obvious between pressure and temperature, indicating that methanol concentration has very significant impact on the extraction process. Compared with the soxhlet extraction and ultrasonic extraction, we can see that supercritical fluid extraction is an effective, high extraction rate and shorten time extraction method.According to fractional mass transfer mechanism on the basis of response surface analysis, established a mathematical model of supercritical fluid extraction about paeoniflorin. Through simulation obtained model parameters such as the solute concentration of difficult extraction x_k=5.243×10^-4kg·kg^-1, the mass transfercoefficient of the outer surface of sample particles K_f=8.598×10^-8m·s^-1, and the mass transfer coefficient of internal surface of sample particles K_s=7.811×10^-10m·s^-1. Through model checking, this model can reflect the process of extraction, it can be use as a reference for further optimizing the model parameters and technology research.更多还原