On Diffusion Processes and Medical Plants Processing

The paper concerns mathematical modeling of natural medical products processing. Fick's Laws are forming the core of our understanding of diffusion in solids, liquids, and gases. The drying models mainly Fick's Laws based are described in detail. The drying process of medical plants is relatively well studied. The extraction studies are not so well developed. The paper gives some insight in mathematical modeling for extraction. Phenomenological models of the extraction process consist of mass balance equations for solute in solid phase and in fluid phase. By integration of these differential equations time-dependent concentration profiles in both phases are obtained and the extraction curve is calculated from fluid-phase concentration at the extractor outlet. Phase equilibrium depends on extraction pressure and temperature and on the composition of solute, solvent, and matrix. Unfortunately, all these studies are yet very far from the ability to produce the practical recommendations for medical plants processing