Solid-liquid Extraction of Tannins from Geranium Sanguineum L. – Experimental Kinetics and Modelling

This paper is concerned with the investigation and the modelling of a solid-liquid extraction process and the importance of the influencing factors (solid phase, particle size and liquid-solid ratio). The studied system is a plant material (Geranium Sanguineum – L.) and a solvent mixture – 70 % ethanol in water. From the results, it is clear that the valuable compounds’ extraction rate is much more influenced by the solid particle size than the liquid-solid ratio. The process is described by a mathematical model which allows the determination of the effective diffusion coefficient (Deff) for the investigated solid-liquid system. Its values are compared with the Deff obtained by the methods of regular regime and the standard function. Very good correspondence is found.