中药提取过程的动力学

药学学报 Acta pharmaceutica sinica20023x7)559-562559中药提取过程的动力学储茂泉,刘国杰华东理工大学化学与制药学院,上海200237)摘要:目的为中药提取工艺设计提供理论依据。方法基于Fick扩散第二定律,建立中药提取过程的动力学方程并以实验对其进行检验。结果中药提取过程的动力学服从一级动力学方程甘草、五味子、麦冬中有效成分以及丹参中丹参酮的提取等实验结果与动力学方程能较好地吻合乙醇提取丹参酮的过程为內扩散控制的其提取表观活化能为20.26 kJ mol-l。结论建立的中药提取过程的动力学方程是可靠的。关键词∶中药;提取;动力学方程;Fick扩散第二定律;丹参酮中图分类号:TQ461;R969.1;R921文献标识码:A文章编号:0513-48702002)7-0559-04在中药生产工艺中从药材中提取有效成分是一r处的溶质质量浓度为c,固相外溶液体积为V液相个重要的组成部分。怎样提高有效成分的提取得率直主体溶质质量浓度为C内扩散系数为Ds,则根据接关系到中药生产的成本和经济效益。因此提供可Fick扩散第二定律有靠的中药提取过程动力学方程是十分必要的。然而D(1)由于中药提取过程的复杂性目前这方面的研究不多已提出的模型1-5还不足以全面反映中药提取过程令u=cr'则的动力学规律。at(2)本工作试图以Fick扩散第二定律为基础,导得个形式简单的新动力学方程旨在为中药提取工艺的边界条件为0(3)最优化提供有价值的理论依据。(?C)V=-Ds()=r(4)模型与动力学方程的建立式中,S为药材颗粒与溶剂的接触面积。若t=0时药材颗粒内溶质平均质量浓度为coκ测则初始条件为5中药提取实质上是使有效成分即溶质从固相向对于药材其与溶液主体之间有无数毛细孔相连平衡液相转移的传质过程。其过程的物理化学模式一般可时固体内外溶质质量浓度可认为相等即设想分3步完成溶剂向药材内部的渗透和药材的t= oo(6)润湿②药材内部溶质的溶解③溶质从药材内部向式中c和C分别为提取平衡时固相内、外溶质质量药材表面以及由药材表面向溶液主体的扩散。其中内浓度。扩散常被认为是整个提取过程的速率控制步骤6如果溶液中溶质的初始质量浓度为Cσ用分离变假定药材颗粒为球形半径为r渗入药材内的溶量法可解得液体积为v′在提取过程中,t时刻颗粒内距球心为Dexp((7)[1+1+。)ki其中,TYH中国煤化工CNMHG收稿日期:2001-08-24通讯作者Te:(021423092662932831-16Fax:(0212933466l: machu@mail.stu.edu,cmn的根式中a=V/V'。药学学报 Acta pharmaceutica sinica20023x7)559-562因提取是內扩散控制,可认为溶质一经扩散到颗取首项即i=1就足够了。这样式14)简化为粒表面就立即进入溶液主体。于是在r′=r处,CCx-C 2c又C2=c因此由式7)可得[1+d(19[1+以1+?ex(-122)(15)2Dst(9)根据质量守恒得(10)上式两边同除以V′得o+aC0=c∞+aCa(11)由式11不难得到co-Co=Ca+1 Co-Co)(12)将式(12代入式9)得da+1)Figure 1 Schematic digram of equation ytgm; and y=1/(1+am, 2exp([1+d因t=0时,C=C0于是由式15河得药材內部结构是极其复杂的如果溶质从药材颗2a+1)1(16)粒中心向颗粒表面扩散则要经过曲折的孔隙所经过的路径要比颗粒半径大。因此,可假定溶质是通过半从而式15地也可表示为径为Kr的理想球体直线向外扩散的其中K被称为CD、孔隙的形状因子。于是式13)可修正为(17)C∞-C对式17筹号两边取对数则得d(18))(14)+d1+-。)]其中k为表观速率常数其值为D式14还可进一步加以简化。若令y=tgm;则(19)式8地可联立表示为式18)进一步整理为CIn()(20)=1/(1+这便是本工作建立的动力学方程前已述及,m是这组联立方程的根,它可由图1所的两条曲线的交点示意地表示新动力学方程在中草药提取中的应用不难看出随着m;的增大两曲线的交点y值逐渐减小。因溶剂提取时药材固相所含的溶液体积远1甘草中国煤化工分提取小于固相外溶液的体积a是一个很大的值因此交点CNMH甘阜、丑咻丁和爱零中背双成分是以水为溶剂提的y值将随m;的增大而快速地逼近于0。由此可见,取的89。文献89卫分别发表了提取动力学数式14冲中的11+1+“0)地将随着m,的增大据图2是它们的C2(C=-C)对t作图而衰减卉快的速度逼近于0以致其多项式只由图可见它们均呈线性关系。由于这些提取实药学学报 Acta pharmaceutica sinica20023x7)559-562561验都没有经过预浸泡故Co=0直线通过坐标原点Figure 4 Relationship between In[ CoA Co-C)]and t at different temperature(r=90. 5 umT=313KT=323K;▲-▲T=333Kt/min0→0T=348K从图3A可见除了初始阶段实验尚未稳定外,它们的C。(C-C)]~t均成较好的线性关系。Figure2 Relationship bet ween In[C=XC=-C)]由于预漫泡,Co≠0故直线不再通过原点nd t for extracting actiGlycyrrhiza uralensis Fisch(■■), Schisandra由此可见本工作建立的动力学方程能够广泛地chinesis(··) and Ophiopogon japonicus( Thunb.)适用于药材的提取过程。不仅如此由图34中的直Ker-Gawl(c-o )with water respectively线斜率还能得到它们的速率常数与药材颗粒大小和2乙醇提取丹参酮温度的关系如表1所示为了更广泛地检验所建立的动力学方程,作者还进行了以乙醇为溶剂提取中药丹参中的有效成分丹参 Table 1 values of k(×105s-1) at different particle酮的动力学实验。先将干燥丹参颗粒用少量乙醇进行 size and temperature了预浸泡然后再加入乙醇在三口烧瓶中加热回流提T/K取搅拌器转速为100rmin-常压。考察了药材颗68.75137.50181.25255.50313323333348粒大小以颗粒半径r表示提取温度以T表示对176.007.508.3313.17浸出丹参酮质量浓度的影响。实验详细过程可参考文根据式(19),/Kr与r应呈比例关系。由表1列献10图34分别为不同颗粒大小和温度下测得的动力出的数据还能获得乙醇提取丹参酮的活化能。因为在学实验数据的HCAC-C)对t作图。般情况下速率常数与温度的关系服从 Arrhenius方程即lnk对1/T作图应是一条直线,它可表示成如下方程lnk=-2436.3/T-1.9594(21)据此可得乙醇提取丹参酮过程的活化能为20.26综上所述利用Fick扩散第二定律建立了一个中药提取过程的动力学方程这个方程具有较普遍的适用性它中国煤化工方程其速率常数不00400500仅与温HCNMH半径的平方成反比Figure3 Relationship between Inl[CaKC-C)与内扩散系数成正比。只要实验提供完整的动力学数and t at different particle size( T=343K)据便能获得提取过程的速率常数和活化能等动力学参数r=137.背数据r=6875m药学学报 Acta pharmaceutica sinica20023x7)559-562REFERENCES[6]Spiro M, Page CM. The kinetics and mechanism of caffeineI 1] SpiI wood RM. The kinetics and equilibria of teainfusion from coffee: hydrodynamic aspects[ J]. J Sci Foodinfusion. Part 3. Rotating-disc experiagric,198435925-930steady-state mode[J]. J Chem Soc Faraday Trans,1982[7] Piret EL, Ebel RA, Kiang CT, et al. Di78:95-305extraction of porous solids. I. Single phase extractions[ JI2 I Spiro M, Selwood RM. The kinetics and mechanism ofChem Eng Progr, 1951 Ax 8)405-414affeine infusion from coffee: the effect of particle size[ J][8] Hou SX, Li ZW, He Q, et al. Studies on the influentialJ Sci Food Agric, 1984 35 915-924factors affecting the efficiency of Chinese material medical[3]Li YR, Cheng S. Simulation and optimization of herbtraction[J. Chin Tradit Herb Drugs(中草药),1996,extraction process[ J]. Chin Tradit Herb Drugs(中草药)273):43-14199728(7)399-401[9 J Cheng ZY, Liu L, Liu DS, et al. Variational disciplinarianand approximate calculating method of theconcentrationof4] Hou KF, Zheng Q, Li YR, et al. Modeling andoptimization of herb leaching processes[ J ] Comput Chemactive components in solution during the Chinese traditionalEng,2000242-7):1343-1348herbs leaching processes with water[ J ]. Chin Tradit Pat[5] Yin YX. Study on microwave-assisted extraction of activeMed(中成药),1994,166)component tanshinone from Salvia miltiorrhiza Bge[ A10 J Chu MQ. Studies on the kinetics of Chinese traditionalMaster' s Thesis east China Uniy Sci Technol(华东理工medicine extraction process and new dosage forms of大学硕士论文川[D] Shanghai: East China University oftanshinone[ A ] Doctors Thesis East China Univ SciTechnot(华东理工大学博士论文)[D] Shanghai:Eastcience and Technology 1997 20-50China University of Science and Technology 2001 20-22KINETIC MODEL FOR EXTRACTION PROCESS OFCHINESE TRADITIONAL MEDICINECHU Mao-quan, LIU Guo-jieChemical and Pharmaceutical College, East China University of Science and Technology Shanghai 200237, ChinaABSTRACT: AIM To present a theory bases for Chinese traditional medicine extraction process. METHODSA kinetic equation for Chinese traditional medicine extraction process was presented based on Fick s second law ofdiffusion. Experiments for extracting tanshinone from Salvia miltiorrhiza bge with ethanol under different particlesizes and temperatures were studied. In addition the data of extraction process of three kinds of herbs includinGlycyrrhiza uralensis Fisch, Schisandra chinesis and Ophiopogon japonicus( Thunb. ) Ker-Gawl were introducedto evaluate the kinetic equation. RESULTS The kinetic of Chinese traditional medicine extraction process agreedwith the first-order rate equation. Experiment data of active components extracted from the herbs above couldperfectly match with the kinetic equation. The rate-determining step for extracting tanshinone from Salviamiltiorrhiza Bge was the diffusion of tanshinone through the herb particles. The apparent activation energy fortanshinone diffusion process was 20.26 kJ mol". CONCLUSION The relation between the concentration of activecomponent and extraction time size of herb particles and temperature could be got from this kinetic equation. Theextraction process of other herbs besides the above could be described by this equationKEY WORDS Chinese traditional medicine extraction kir中国煤化工d law of diffusiontansTHCNMHG