Experimental Considerations of Solutocapillary Flow Initiation on Bubble/Drop Interface in the Presence of a Soluble Surfactant

The paper deals with the experimental study of the dynamics of generation of the solutocapillary flow at the air bubble or chlorobenzene drop interfaces in inhomogeneous aqueous solutions of ethyl or isopropyl alcohols, which have low surface tension and therefore are surface-tension active with respect to water. It has been found that the onset of the solutocapillary Marangoni convection is appreciably delayed relative to the moment at which a running flux of concentrated surfactant solution reaches the surface. Critical differences in surfactant concentrations (diffusion Marangoni numbers), which are responsible for initiation of the surfactant mass transfer along the interface, were determined depending on the rate of surfactant flux and alcohols initial concentration in the solution surrounding the bubble.