Saien - Department of Applied Chemistry, University of Bu-Ali Sina, Hamadan ۶۵۱۷۴, Iran,
Riazikhah - Department of Applied Chemistry, University of Bu-Ali Sina, Hamadan ۶۵۱۷۴, Iran,
Ashrafizadeh - Faculty of Chemical Engineering, Iran University of Science and Technology, Narmak, Tehran ۱۶۸۴۶, Iran

The variation of overall mass transfer coefficient in liquid-liquid extraction was investigated using single drop experiments with the chemical system of tolueneacetone- water, having the advantage of high accuracy and repeatability in using GC for analysis. Three surfactants: SDS, Triton X-100 and DTMAC were used to study the effects of the contaminant type and their concentration on this system; each of them with two solute mass transfer direction. The overall mass transfer coefficient, od K , decreases rapidly with adding surfactants and then remains with low variations and the rate of mass transfer is more for dispersed to continuous phase direction. The order of effectiveness of contaminants was found to increases in the order: DTMAC < SDS < Triton X-100, which represents the more activity of the non-ionic surfactant. Adding contaminants do not change the trend of variation with respect to drop size; however, the percentage of reduction is more significant for small drops, resulting a number of drops to find rigid behavior at high contaminant concentrations. A combined mass transfer coefficient could be applied to describe the variation of mass transfer coefficient with the aid of an empirical coefficient developed for different cases.

liquid extraction, contamination, mass transfer direction, combined model