Transport of mass in ternary liquid‐liquid systems. Part II. Mass transfer and interfacial studies

The objective of this work is to experimentally examine mass transfer during liquid-liquid extraction in the system acetonitrile-benzene-n-heptane. The interfacial characteristics of the system are simultaneously investigated. (Part I deals with the diffusion properties of the system). The mass transfer experiments are conducted in a stirred extraction cell of the Lewis type. The transfer between an unsaturated and nearly saturated phase is studied. The mass transfer coefficients for the partially miscible binary system, and for those ternary experiments in which the slope of the operating line was negative are found to be independent of the driving force. A photographic investigation, which employed the schlieren technique, indicates that Marangoni-type instabilities are absent in such experiments. However, in ternary experiments, in which the slope of the operating line is positive and above a certain critical value the mass transfer coefficients decreases as equilibrium approached. The schlieren results confirm the presence of interfacial turbulence for this case. The driving-force dependence of the turbulent mass transfer coefficients is explaine using a surface renewal model. The model provides a correlation for the results of ternary experiments in which interfaical turbulence is present.