A mass transfer model for type I facilitated transport in liquid membranes

Abstract

A model for the extraction with liquid surfactant membranes (LSM) has been developed to account for the simultaneous mass transfer both inside and outside emulsion globules and the reaction between the diffusing component and the internal reagent. A perturbation solution of the resulting nonlinear equations contains parameters Bi (Biot number), representing the ratio of the mass transfer resistance inside the globules to that of the external phase, and Da (Damköhler number), representing the ratio of the reaction rate to the diffusion rate inside the globules. The model predictions show that, when Da is less than five or larger than 200, the overall process will be controlled by reaction or diffusion, respectively, while for intermediate values of Da by reaction and diffusion jointly. In general, the zero-order, or pseudo-steady-state solution is adequate to describe the extraction process in LSM, and the model predictions are in good agreement with the experimental data on the batch extraction of acetic acid with LSM.