Optimizing Batch Liquid Liquid Extraction Separations

It is common in industry to mix two immiscible liquid phases together to facilitate the mass transfer of a dissolved component from one phase to the other.  This batch process is comprised of two stages, mass transfer and then separation. One of the problems typically found in employing this as a batch process is the long times required to separate the phases after the mass transfer stage.  The goal of this investigation is to minimize the total processing time.  Combining previous experimental work on liquid-liquid separations and a theoretical mass transfer analysis of this process has led to a recommendation to decrease the level of agitation during the mass transfer stage to minimize the overall time for this process.  One of the methods to reduce the level of agitation of the overall process is to move the agitator position the original 2 phase interface and operate it at a relatively low speed.  At the laboratory scale it was found that by moving the agitator from a standard industry position of 1/3 of the tank height from the bottom to the interface of the two fluids it is possible to reduce the total time of the process by 95%.  Comparisons with a model 3 component extraction system of butanol, acetic acid, water will be shown.