Interfacial stability of binary liquid—liquid systems—I. Stability analysis

Abstract

Temperature gradients, resulting from thermal effects due to heats of solution and mixing, which accompany mass transfer in partially miscible liquid pairs, were found to be of the same order of magnitude as those leading to thermal instability in shallow liquid layers. Linearised perturbation analysis was therefore applied to such binary liquid systems, using linearised profiles, and the characteristic equation was analysed for the onset of spontaneous Marangoni-type interfacial convection. The stability criteria indicate that binary systems may be stable or unstable in both directions of transfer or unstable in only one direction of transfer. They also suggest that stationary instability is promoted when the heat of solution and the rate of change of interfacial tension with temperature are of opposite signs and that instabilities of oscillatory character are most likely to occur for mass transfer out of the phase of higher viscosity