Industrial & Engineering Chemistry Research, Vol.52, No.10, 3893-3902, 2013
Continuous Separation of alpha-Cyclohexyl-mandelic Acid Enantiomers by Enantioselective Liquid-Liquid Extraction in Centrifugal Contactor Separators: Experiments and Modeling
Multistage enantioselective liquid-liquid extraction (ELLE) in centrifugal contactor separators was developed for separation of enantiomers. Performance of the process was evaluated by product purity (enantiomeric excess, ee) and yield (Y). Enantioselective liquid-liquid extraction of alpha-cyclohexyl-mandelic acid (alpha-CHMA) enantiomers with hydrophilic hydroxyphenyl-beta-cyclodextrin as extractant (C) was performed in a countercurrent cascade of 10 centrifugal contactor separators (CCSs) at 278 K to investigate the influence of the operation variables including phase ratios and concentrations on extraction efficiency. On the basis of a single stage equilibrium model and the law of conservation of mass, a multistage equilibrium model of enantioselective liquid-liquid extraction was developed to investigate the influence of changes in the process parameters such as phase ratios and concentrations on extraction efficiency. The multistage model predicted the experimental data accurately and was applied to optimize the symmetrical separation of alpha-CHMA enantiomers. By modeling, the minimum number of stages for ee(eq) > 97% and ee(eq) > 99% was predicted as 42 and 48, respectively.