Oxygen transfer enhancement in aqueous/perfluorocarbon fermentation systems: II. Theoretical analysis.

Two theoretical approaches were examined to quantify observed experimental oxygen transfer enhancements in aqueous/perfluorocarbon (pfc) fermentation systems. Steady-state macroscopic balance results indicated that enhancements in the presence of reaction were a function of the gas bubble-to-droplet diameter ratio for pfc-in-water dispersions, but primarily a function of only the droplet diameter for water-in-pfc dispersions. The problem of unsteady-state diffusion into a semi-infinite composite medium was employed to predict enhancements in the absence of reaction based on the relative permeabilities of the perfluorocarbon and water phases. Since potential enhancements exceeded actual enhancements in the presence of an oxygen consuming reaction for water-in-pfc dispersions, the use of less expensive, lower oxygen-permeable oil phases is recommended in practice.