Study of the solid-liquid extraction from two plants, Salvia coccinea (Lamiaceae) and Syzygium sakalavarum (Myrtaceae): modeling of isotherms

Chemical engineering

The aim of this work is to thermodynamically model the solid-liquid extraction of solutes from two plants Salvia coccinea and Syzygium sakalavarum in order to be able to determinate the most adequate extraction method. Two types of solvent were used, water and ethanol 20%. For this, the solid-liquid extraction is assimilated to desorption in the liquid phase. Several tests, with different masses of these plants powder, were carried out in order to obtain experimental points. These were introduced into software in order to obtain the corresponding isotherm for each test. The isotherms obtained experimentally are classified according to IUPAC classification. 4 of these isotherms are associated with the type VI isotherm. However, no model exists in the literature to present this type of isotherm. So a new model has to be created. The type VI isotherm is made up of a set of simple isotherms that make up a step. The modeling of each step has shown that these simple isotherms are type V which demonstrates the mesoporous nature of plant materials and therefore shows the usefulness of extracting solutes at high temperature.

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