Thermodynamic Parameters of the Extraction of Three Nicotiana Species

The thermodynamic parameters - Gibbs free energy, entropy and enthalpy, were calculated for the extraction of tannins from the leaves of three tobacco species (Nicotiana alata Link&Otto, N. rustica L. and N. tabacum L.). The extraction was carried out with ethanol solvent at 30, 50, 70 and 95% concentration, duration of 1, 3, 5 and 7 hours and temperature range from 20 to 60 °C. Those thermodynamic parameters were used to determine the stability of the system and the type of the process of tobacco leaf extraction.