RESUMO
To study the characteristics of adsorption and desorption of Scutellaria baicalensis pieces. On the basic thermodynamic theory, thestatic method was adopted to obtain S. baicalensis pieces' isothermal adsorption and desorption data at 25, 35, 45 ℃, with the water activity between 0.10 and 0.85. Eight moisture models were selected to fit the data and then evaluated to determine the thermodynamic properties of S. baicalensis pieces. The results show that, among the eight adsorption models, Peleg fit the best, in which absolutely-safe and the relatively-safe moisture contents of S. baicalensis pieces were around 9.22% and 13.51% respectively; the net equivalent heat adsorption and desorption and the differential entropy of S. baicalensis pieces were closely related to moisture content, and decrease within crease of water content; when drying the pieces, 12.0% of moisture content can be taken as the drying end; both of adsorption and desorption processes were driven by enthalpy and non-spontaneous. The study on S. baicalensis pieces' isothermal adsorption and desorption rules can help advance studies on adsorption and desorption rules of Chinese herbal pieces, and play a good guiding role in optimizing storage conditions and drying process of Chinese herbal pieces.
RESUMO
Based on the basic theory of thermodynamics, the thermodynamic parameters and related equations in the process of water adsorption and desorption of Chinese herbal decoction pieces were established, and their water absorption and desorption characteristics were analyzed. The physical significance of the thermodynamic parameters, such as differential adsorption enthalpy, differential adsorption entropy, integral adsorption enthalpy, integral adsorption entropy and the free energy of adsorption, were discussed in this paper to provide theoretical basis for the research on the water adsorption and desorption mechanism, optimum drying process parameters, storage conditions and packaging methods of Chinese herbal decoction pieces.