ABSTRACT
Surface phenomena can and often do exert a significant influence on the traditional fluid phase separation processes of chemical engineering. The rate of mass transfer of a solute across a liquid interface may be increased over that of molecular diffusion by as much as an order of magnitude by spontaneous interfacial turbulence. Traces of surfactant may likewise enhance the efficiency of sieve trays by increasing the froth height on them, but under slightly different conditions may cause the unit to fill completely with stable foam. In attempting to sort out these and other interfacial effects in fluid phase mass transfer processes, the chapter focuses on a consideration of the underlying thermodynamic and hydrodynamic fundamentals. It includes discussion of analytical studies of model systems and experimental studies of flow and mass transfer under controlled conditions. The chapter examines some of the empirical observations that have been made concerning the interfacial phenomena in actual distillation, absorption, and extraction units.
