Isomer separation membrane stability

The use of two types of liquid membranes is described in [302] liquid emulsion membranes (LEMs), and supported liquid membranes (SLMs), where isoparaffin or kerosene and their mixtures were used as organic phases. A surfactant of the type of Span 80 served as emulsifier. LEMs are used, for example, for selective separation of L-phenylalanine from a racemic mixture of L-leucine biosynthesis as well as conversion of penicillins to 6-APA (6-aminopenicillanic acid). SLMs have a higher stability. A number of their commercial applications have been studied, e.g. in separation of penicillin from fermentation broth, as well as in the recovery of citric acid, lactic acid and some aminoacids. Compared with other separation methods (ultrafiltration, ultracentrifugation and ion exchange), LEMs and SLMs are advantageous in the separation of stereospecific isomers in racemic mixtures. 

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