| Research on the enantioseparation of drug enantiomers using liquid membrane and its mass transfer model has a great interesting potential. The basic concepts about chiral drug were expatiated, the importance of the determination of chiral drug was analyzed, and the present main methods of chiral separation and their research progress, the importance of the principle and mathematical model of mass transfer process were reviewed in this paper. The principle and mathematical model of mass transfer process using the chiral emulsion liquid membrane and the chiral supported liquid membrane were investigated and discussed in detail, the main content and results can be summarized as following:Chiral extraction of phenylalanine enantiomers in the emulsion liquid membranes system using copper (Ⅱ) N-decyl-L-hydroxyproline as chiral selector, Span-80 as surfactant and kerosene as organic solvent was studied. The effects of initial phenylalanine concentration, the direction of chiral extraction, the volume ratio of organic solvent and surfactant, the pH gradient from external to internal phase and the pH of external aqueous phase, on performances of selective extraction, were discussed, respectively. Consequently, appropriate extractive conditions were established: 8:92 (v/v) Span-80: kerosene; Initial concentration of phynelalanine is 1.0 mmol/L; External phase pH 4.8; Copper concentration 5 mmol/L; Chiral extraction from external phase to internal phase.The reaction-diffusion model was developed to analyze the concentration of enantiomers and the separation factor of the enantioseparation process of chiral emulsion liquid membrane by studying the principle and some factors of mass transfer process. The mass transfer resistance of boundary layer in outer aqueous phase and the interfacial chemical reactions at the liquid membrane interfaces were taken into account in the model equations. The concentration of D-phenylalanine in the external phase and the separation factorαcan be expressed as: The diffusion of boundary layer in outer aqueous phase is the controlled process while the concentration of D-phenylalanine in the external phase far less than the concentration of chiral carrier in the emulsion liquid membrane phase, then the diffusion coefficient k_e of boundary layer in outer aqueous phase can be achieved by data fitting.The improved reaction-diffusion model was developed by substituting the partition coefficient and the reaction equilibrium constant for the observed partition coefficient in the expression ofζ_j. The deviation of the computational results from the experimental data decreased from 20.4% to 10.7%. The expression ofζ_j can be deduced as:Resolution of racemicα-cyclohexyl-mandelic acid containing copper(Ⅱ) N-dodeecyl-(L)-hydroxyproline (CuN2) as a chiral carrier across hollow fiber supported liquid membrane was carried out successfully. The effects of velocity of feed phase and stripping phase and the pH of external and internal aqueous phase, on performances of selective extraction, were discussed, respectively. Consequently, appropriate extractive conditions which the velocity of feed phase and stripping phase is 3 mm/s and the pH of external and internal aqueous phase is 4.8 were established.The overall mass transfer model was developed to analyze the concentration of enantiomers in the stripping phase and the separation factor of the enantioseparation process. The observed partition coefficient between the feed phase and the membrane phase, the stripping phase and the membrane phase, mass transfer resistance of boundary layer in strip phase inside the hollow fibers, boundary layer in feed phase and mass transfer resistance of the membrane phase were taken into account in the model equations. The concentration of enantiomers in the stripping phase and the separation factorαcan be expressed as:Using the experimental results of the enantiomers concentration, several parameters of the proposed model had been achieved by nonlinear fitting method.The mechanism of mass transfer process across hollow fiber supported liquid membranes containing chiral carrier was investigated more detailedly. Partial differential equations describing the concentrations of enantiomers in the stripping phase, concentrations of enantiomers in the membrane phase and the separation factor of the enantioseparation process were deduced. The reaction-diffusion model has been developed according to some hypothesis and predigestion. The mass transfer resistance of boundary layer in the strip phase inside the hollow fiber and boundary layer in the feed phase, the diffusion in the membrane phase and the interfacial chemical reactions at the liquid membrane interfaces are taken into account comprehensively. The concentration of enantiomers in the stripping phase and the hollow fiber supported liquid membrane and the enantioseparation factor can be expressed as:The forward reaction rate and the backward reaction rate could be ignored because they have little influence on the concentrations of phenylalanine enantiomers and the separation factor of the enantioseparation process by the prediction of the reaction-diffusion model, so the rapid reaction-diffusion model of the enantioseparation process can be deduced. The expression ofλ_j can be deduced as:Substituting the reaction behavior between the enantiomers and the chiral carrier of the reaction-diffusion model for the observed partition behavior between the feed phase, the stripping phase and the liquid membrane phase, partial differential equations describing the concentrations of enantiomes in the stripping phase and the membrane phase were also deduced. The partition-diffusion model has been developed according to some hypothesis and predigestion. The observed partition coefficient between the feed phase and the membrane phase, the stripping phase and the membrane phase, mass transfer resistance of boundary layer in strip phase inside the hollow fibers, boundary layer in feed phase and the diffusion in the membrane phase are taken into account in the model equations. The concentration of enantiomers in the stripping phase and the hollow fiber supported liquid membrane and the enantioseparation factor can be expressed as: The mathematical model was used to predict the enantiomers concentration of (D/L)-phenylalanine and the separation factor of the enantioseparation process. The results indicate that the computational results of mathematical models were in good agreement with the experimental data and that the computational results of the overall mass transfer model, the reaction-diffusion model and the partition-diffusion model are almost the same. The effects of some factors such as pH of the feed phase and the stripping phase, mass transfer resistance of boundary layer and mass transfer resistance of liquid membrane on the enantiomers concentration of (D/L)-phenylalanine and the separation factor of the enantioseparation process were analyzed by those models. The results show that those mathematical models can be easily used to predict the concentration of (D/L)-phenylalanine and the separation factor of the hollow fiber liquid membrane resolution process.
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