Optimum emulsion liquid membranes stabilized by non-Newtonian conversion in Taylor-Couette flow

The use of Taylor-Couette flow for extraction by emulsion liquid membranes has been characterized. In particular, the rate limiting step for the extraction of a weak acid (benzoic) in an aqueous continuous phase to a strong base (NaOH) in the encapsulated internal phase has been attributed to a surfactant resistance. Numerical and analytical solutions are developed to characterize the mass transfer at Biot numbers Bi < 10. It is demonstrated for fixed droplet composition that a single curve exists for all N for the extent of extraction by stretching the time coordinate by a function of the rotation rate proportional to N-1.2 that is proportional to the globule external area per unit total volume. Moreover, the leakage rate is shown to increase as t(0.6) and to be proportional to N-0.75, the Kolmogoroff eddy velocity. Comparison with stirred tank data demonstrates that greater droplet stability exists for Taylor-Couette flow. (C) 2004 Elsevier Ltd. All rights reserved.