Thermal analysis during partial carbonizing process of rhubarb, moutan and burnet

Abstract

Control of temperature and duration of partial carbonization for Chinese medicines have been mainly based on experience of the processors. No quantitative methods and parameters are available that can be used to precisely control the temperature and determine the energy changes during the process. In our research, with a simulated atmosphere air condition, the partial carbonization processes of three Chinese herb medicines rhubarb, moutan and burnet were simulated at different heating rates (5, 10 and 20°C • min-1) and analyzed by thermal gravimetric analysis (TGA) to quantify the upper limits of the temperature. The activation energy was calculated with Friedman, Kissinger-Akahira-Sunose (KAS) method and Ozawa-Flynn-Wall (OFW) methods in iso-conversional models and independent parallel reaction model (IPR). The upper temperatures were calculated to be 280, 184 and 246°C for rhubarb, moutan and burnet, respectively, at corresponding conversion rates of 0.4, 0.2 and 0.1. Calculation of the activation energy has been found impossible with the IPR model. Results obtained from the three iso-conversional methods were different. For rhubarb and burnet, the conversion rates at the upper temperature limits were at the highest or second highest activation energy, while for moutan, it was at the lowest value of activation energy. These results confirmed scientific rationales of traditional Chinese medicine theory that rhubarb and burnet be prepared at high temperature and moutan be prepared at medium temperature. Application of thermal analysis techniques would broaden and deepen traditional Chinese medicine research, and are applicable to the processing of medicinal materials including traditional Chinese medicines. Results obtained from the study could provide new ideas and methods for research to modernize the preparation of traditional Chinese medicines.

Investigation of the Effect of the Degree of Processing of Radix Rehmanniae Preparata (Shu Dihuang) on Shu Dihuangtan Carbonization Preparation Technology

“…Previously, we used TG/DTG methods to simulate the processing procedure of Zushima, in order to qualitatively demonstrate the overall compositional changes [10,11], and also analyzed the effects of pyrolysis in an inert Ar atmosphere on the preparation of gallic acid, rhubarb, mudan and burnet [12]. We also calculated the energy dynamics during the stir-frying process based on the data obtained from thermal analysis techniques [13]. These applications have greatly enhanced our experimental and theoretical understanding of the processing procedures of traditional Chinese medicines.…”

Chemical Property Changes and Thermal Analysis during the Carbonizing Process of the Pollen Grains of Typha

“…The mass conversion rates in the temperature from 200 to 450 °C were 74.13% (5 °C min −1 ), 71.72% (10 °C min −1 ), 66.87% (15 °C min −1 ), and 65.76% (20 °C min −1 ), respectively. Previous researches have demonstrated that the lower heating rate, the more compounds in the materials combusted and pyrolyzed because the constituents in herb medicine have sufficient time to react [13]. The peak 2 and peak 3 were known as oxidative pyrolysis.…”

“…Thermal analysis has been used as a method for evaluating the process technology of Chinese medicine in recent years [12]. This technology could provide various data to researchers including thermal gravimetry (TG), differential thermal analysis (DTA), derivative thermogravimetry (DTG), dynamic mechanical analysis (DMA), and thermo-mechanical analysis (TMA) for studying the changes of drugs during frying [13]. FTIR is one of the widely used methods for elucidating and identifying the components in herb medicine, and providing the date for the properties of the constituents in TCM [14,15].…”

An Example of a Novel Efficient Plant Extraction Technique: Electromagnetic Induction Heating

“…This positive trend may be explained by the most favorable features of electromagnetic induction heating in that a uniform heating across the whole of the extraction vessel can be achieved in a few seconds leading to a massive and rapid release of secondary metabolites from plant cells and preventing their chemical degradation, pending a short-lasting process being applied. Furthermore, this is particularly true in the case of anthraquinones from Chinese rhubarb, for which it has been demonstrated that heating represents an effective means to increase their extractive yields from rhizome [ 9 ].…”