Page 166 - Chiral Separation Techniques

144 5 Membranes in Chiral Separations

Fig. 5-15. Enantiomer ratio
in the outflow versus time for
the separation of racemic
norephedrine.

at 1 wt- %, and the membrane life time is taken 1.5 years. As can be seen from Fig.
5-16, the separation costs are not extremely sensitive to the required optical purity
and the membrane life time. However, the achieved enantioselectivity and attainable
concentration of the drug (in the center of the column) determine separation costs to
a large extent. This is mainly due to the costs involved for product recovery from a
large, relatively diluted stream. Clearly, the effectiveness of this separation process
is predominantly determined by a proper selection and optimization of the selec-
tor–solvent combination.

Fig. 5-16. Sensitivity of separation costs to key process parameters.