Estimation of effective diffusion and transfer rate during the protopine extraction process from Fumaria officinalis L.

The kinetics of the solid–liquid extraction of protopine from Fumaria officinalis were examined in this study in order to deduce the diffusivity and explain the mass transfer. Extraction was carried out by varying the following operating conditions: temperature, solid/solvent ratio and percentage of ethanol in solvent. A simple method based on Fick's laws for predicting the effective diffusion coefficient and the rate transfer from the experimental kinetics is presented. The Biot number showed that intra-particle diffusion was the rate-governing step of the extraction process. It is shown that it is preferable to work with a moderate solid–liquid weight ratio at the highest possible temperature and with moderate ethanol content in water.

Graphical abstractFigure optionsDownload full-size imageDownload as PowerPoint slideResearch highlights▶ The protopine diffusion is promoted when the solid–liquid ratio is less than 5%. ▶ The increase in temperature enhances protopine diffusion. ▶ At the same temperature, coefficients (KT, Deff) are higher in water than in ethanol 44%. ▶ Fast dissolution of protopine is favoured by ethanol and water enhances its diffusion.