A perturbation solution for batch extraction with double emulsions: role of continuous phase mass transfer resistance

The effect of the continuous phase mass transfer resistance on solute extraction with double emulsions in a batch reactor is investigated. A model presented by Ho et al. (1982) for diffusion controlled mass transfer into the double emulsions is solved by perturbation analysis. In the case of a significant continuous phase mass transfer resistance, the extraction of solute is a function of the inverse Biot modulus, m. For values of m greater than 0.01 the external phase resistance must be taken into account in order to accurately predict extraction rates. Such conditions will exist when double emulsion drops are relatively small or when stirring rates in the batch extractor are low.