title: Experimental and Model Studies on Continuous Separation of 2-Phenylpropionic Acid Enantiomers by Enantioselective Liquid-Liquid Extraction in Centrifugal Contactor Separators.
abstract: Multistage enantioselective liquid-liquid extraction (ELLE) of 2-phenylpropionic acid (2-PPA) enantiomers using hydroxypropyl-β-cyclodextrin (HP-β-CD) as extractant was studied experimentally in a counter-current cascade of centrifugal contactor separators (CCSs). Performance of the process was evaluated by purity (enantiomeric excess, ee) and yield (Y). A multistage equilibrium model was established on the basis of single-stage model for chiral extraction of 2-PPA enantiomers and the law of mass conservation. A series of experiments on the extract phase/washing phase ratio (W/O ratio), extractant concentration, the pH value of aqueous phase, and the number of stages was conducted to verify the multistage equilibrium model. It was found that model predictions were in good agreement with the experimental results. The model was applied to predict and optimize the symmetrical separation of 2-PPA enantiomers. The optimal conditions for symmetric separation involves a W/O ratio of 0.6, pH of 2.5, and HP-β-CD concentration of 0.1 mol L(-1) at a temperature of 278 K, where eeeq (equal enantiomeric excess) can reach up to 37% and Yeq (equal yield) to 69%. By simulation and optimization, the minimum number of stages was evaluated at 98 and 106 for eeeq > 95% and eeeq > 97%.
authors.affiliation: College of Chemistry and Chemical Engineering, Hunan University, Changsha, People's Republic of China.
authors.forename: Xiaofeng
authors.initials: X
authors.lastname: Feng
authors.affiliation: Department of Chemistry and Chemical Engineering, Hunan Institute of Science and Technology, Yueyang, People's Republic of China.
authors.forename: Kewen
authors.initials: K
authors.lastname: Tang
authors.affiliation: Department of Chemistry and Chemical Engineering, Hunan Institute of Science and Technology, Yueyang, People's Republic of China.
authors.forename: Pangliang
authors.initials: P
authors.lastname: Zhang
authors.affiliation: College of Chemistry and Chemical Engineering, Hunan University, Changsha, People's Republic of China.
authors.forename: Shuangfeng
authors.initials: S
authors.lastname: Yin
keywords: 2-phenylpropionic acid; enantioselective liquid-liquid extraction; hydroxypropyl-β-cyclodextrin; multistage equilibrium model; simulation and optimization; symmetrical separation