槲皮素的热降解机理及其分解动力学研究

利用TG-DTG技术测得槲皮素在氮气气氛中不同升温速率β下的热分解曲线,协同使用Achar法、Coats-Redfern法、Kissinger法和Ozawa法等4种方法同时进行动力学处理,根据热分解的表观活化能Eα和指前因子A计算推断槲皮素的贮存期.随着升温速率的提高,槲皮素的热分解温度逐渐升高；槲皮素热二步分解的机理依次是随机成核与随后生长控制和化学反应控制,对应的函数名称是Avrami-Erofeev方程和反应级数方程；经Gaussian模拟和热重数据结合分析,槲皮素在第一步分解时,失去两个O原子；第二步分解时失去一个苯环；根据第一步热分解的表观活化能Eα和指前因子A推断,在室温25℃下,槲皮素的贮存期为1.5 ～2年.

Thermal Decomposition Mechanism and Kinetics of Quercetin

Thermal decomposing curves of quercetin in different heating rates were obtained in the nitrogen atmosphere by TG-DTG technique.Four thermal analysis kinetic methods(Achar,Coats-Redfern,Kissinger and Ozawa) were used to speculate the probable mechanism of thermal decomposing reaction and the kinetic parameters.The shelflife of quercetin at room temperature was calculated by the kinetic parameters of the first stage.With the improvement of the heating rate,thermal decomposing tempreture of quercetin rose.The most probable kinetic mechanisms of the two-stage thermal decomposition were nucleation and growth and chemical reactions,corresponding with Avrami-Erofeev Equation and Reaction Order.In accordance with the data of TG and Gaussian,one molecule of quercetin lost two oxygen atoms at the first stage of decomposition and lost one benzene ring at the second stage.The shelflife of quercetin at room temperature was about 1.5~2 years based on the apparent activation energy(Eα) and pre-exponential factor(A) of the first stage.