Liquid-liquid extraction using vortex rings in a batch cell

Liquid-liquid vortex rings have been formed in a 19.5 cm diameter batch extraction cell by applying a periodic vertical impulse to a horizontal plate containing a single orifice (5.38 or 8.00 cm diameter) and located in the aqueous phase. The rings travel to the organic (kerosene) phase to form discrete rings of water rising through the kerosene phase. Unsteady mass transfer rates of benzoic acid from kerosene to water have been measured; the mass transfer efficiency, expressed as the fractional approach to equilibrium, depends upon the number of cycles of oscillation and upon a dimensionless rate constant k′ which increases with oscillation stroke and (in most cases) with the velocity of the plate impulse. When the plate is located at the liquid-liquid interface, the constant k′ is significantly increased due to the formation of discrete rings in both phases.