Kinetic dependences for the extraction of apricot pits kernels with ethanol-water solvent

Abstract

During the extraction of a capillary-porous body, such as the nuclei of fruit seeds, the movement of the distributed substance in the solid phase is carried out by means of molecular diffusion. The amount of material flow in a solid per unit surface is determined by Fick’s law using the diffusion coefficient. The molecular diffusion coefficient depends on the structure of the solid, temperature and soluble substances, and does not depend on the hydrodynamic conditions on the surface of solid particles and the design of the apparatus. The article studies the kinetics of extraction of petals of apricot kernels with ethanol-water solvent. When calculating the value of the residual mass content of plant raw materials during the extraction process, an interval calculation method was used. Based on the experimental data of the extraction kinetics, the molecular diffusion coefficient was determined, which significantly increases during 600-700 s of extraction, and then decreases by 2 times after 1800 s. After 3000 s from the beginning of the process, the diffusion coefficient decreases less sharply. A significant increase in the diffusion coefficient at the beginning of the extraction process, including the impregnation stage, is associated with the uneven distribution of the extracted components in the initial sections of the capillaries. In the studies carried out, the nature of the change in the diffusion coefficient over time does not contradict modern concepts of the mechanism of extraction of a porous structure from plant raw materials.