On the role of chemical potentials in mass transfer processes in liquid systems with an interface: the case of diffusion from a drop

Abstract

An experimental study of the effect of chemical potentials on mass transfer processes in liquid systems with an interphase boundary was carried out. The study was performed for the case of surfactant mass transfer between a drop and the environment under conditions of maximum suppression of free convective motion (in a thin horizontal layer). The system of immiscible liquids was formed by water and a mixture of benzene with chlorobenzene; the diffusing surfactant was acetic acid, having significantly different solvation energies in the contacting liquids. Visualization of surfactant flows and concentration fields was performed using laser interferometry. We determined the characteristic times of surfactant extraction depending on the direction of its diffusion, the structure of the concentration field and the velocity of its propagation from the drop depending on the surfactant concentration and on the ratio of chemical potentials in the drop and the surrounding liquid. The role of gravitational effects and the resulting Marangoni convection was estimated for all the cases considered.