ABSTRACT
Liquid-liquid extraction is of great importance in the isolation of chemical and biological products. The area of liquid-liquid extraction for protein isolation on a large scale encompasses, for the most part, aqueous two-phase extraction. The practical considerations associated with liquid-liquid extraction will be developed with examples given to emphasize both beneficial and problem areas. Computer methods to derive or predict liquid phase activity coefficients are in place to select the proper solvents for separation processes, or at least narrow the field of choice. In addition to the time needed to develop a process, often the time of the liquid extraction itself is of extreme importance in minimizing the degradation of the product protein due to the presence of proteases in the cell extracts. Liquid membrane separation, a rate process, is accomplished by a driving force rather than equilibrium between phases.
