Coextraction during reactive extraction of phenylalanine using Aliquat 336: Modeling extraction equilibrium

Reactive liquid-liquid extraction can be used to recover hydrophilic fermentation products that would not otherwise partition into nonpolar solvents through an ion-exchange reaction at the two-phase interface. However, the ion-exchange reagent may not be specific to the solute of interest and other compounds present may also be extracted. In this study, the effect on solute extraction of other compounds present in the extraction medium was investigated for phenylalanine extraction using Aliquat 336. The extent of extraction at equilibrium was modeled using the equilibrium constants for the re- actions present in the process. The interaction of differ- ent species within a multicomponent medium was ex- amined using the model and experimental results. It was found that the extent of extraction and coextraction is controlled by the thermodynamics of each extraction re- action and, due to the formation of a common product, the interaction between each of the reactions. The main competition to reactive extraction will come from hydro- phobic anionic compounds that will be present in fer- mentation broth. © 2003 Wiley Periodicals, Inc. Biotechnol Bioeng 82: 533-542, 2003.