大黄酸和大黄素的热分析及其动力学研究(英文)  

Thermal Characterization and Decomposition Kinetics of Rhein and Emodin

作　　者：张黎明[1] 李霞[1] 孙茜[1] 戴玉杰[1] 

机构地区：[1]天津科技大学生物工程学院,天津300222

出　　处：《天然产物研究与开发》2007年第3期458-460,共3页Natural Product Research and Development

基　　金：This work was financially supported by the Science;Technology Development Fund of Tientsin University(20031210)

摘　　要：本文采用热重法(TG)和差热分析法(DTA)测定了大黄酸和大黄素的DTA,TG-DTG曲线。两者的DTA曲线中皆有两个较为明显的吸热峰,第一个在熔化过程中出现,第二个发生在热分解过程中并伴随有明显的失重现象。TG曲线均有一个失重平台,失重率在90%以上。用TG-DTG法对两者在非等温条件下进行热分解动力学研究,把从TG-DTG曲线中取得的数据和31个不同的方程采用Achar微分法和Madhusudanan-Krishnan-Ni-nan(MKN)积分法对其进行非等温分解动力学研究,得到动力学参数活化能(E和指前因子A)和分解动力学机理及方程。得出结论:大黄酸和大黄素的动力学方程为dα/dt=Aexp(-E/RT)3/2(1-α)4/3[1/(1-α)1/3-1]-1和dα/dt=Aexp(-E/RT)3/2(1-α)2/3[1/(1-α)1/3]-1,其分解等合3D抗理。二者的活化能E(kJ/mol)分别为117.6和86.79,lnA/s-1分别是36.72和27.44。The thermal behavior of Rhein and Emedin and their kinetics have been investigated under non-isothermal conditions by means of differential thermal analysis （DTA） and thermogravimetry （TG）. The thermal characteristics have been determined using the DTA and TG-DTG curves. The non-isothermal kinetics of the samples was studied by use of non-isothermal TG and DTG curves. The non-isothermal kinetics data were analyzed by Achar differential and Madhusudanan-Krishnan-Ninun （MKN） methods. The possible reaction mechanisms have been investigated by comparing the kinetics parameters. The kinetic equations for the Rhein and Emodin can be expressed as da/dt=Aexp（-E/RT）^3/2（1-α）^4/3[1/（1-α）^1/3-1]^-1 and da/dt=Aexp（-E/RT）^3/2（1-α）^2/3[1/（1-α）^1/3]^-1 respectively. The activation energy E/（kJ/mol） of the two free anthraquinones from Rheum are 117.6 and 86.79 and their lnA/（1/s） are 36.72 and 27.44, respectively.

关 键 词：大黄酸 大黄素 热重分析法(TG) 差热分析法(DTA) 非等温动力学 

分 类 号：Q946.91[生物学—植物学] TQ460.7[化学工程—制药化工]