Preparation of chiral selective membranes for electrodialysis separation of racemic mixture

Chiral selective cation-exchange membrane (CSCM) and chiral selective anion-exchange membrane (CSAM) were prepared by blending poly(vinyl alcohol) (PVA) as basic material, β-cyclodextrin (β-CD) as chiral selector, and ion-exchange materials. Chiral selective capacities of these membranes were evaluated by electrodialysis resolution experiment. Electrodialysis separation of dl-4-hydroxyphenylglycine (HPG) racemic mixture showed that the chiral selective membranes had resolution effect. In acid medium, d-HPG+ took the precedence over l-HPG+ in passing through the CSCM and the selectivity αd/l of two kinds of CSCM were 1.21 and 1.34, respectively. In base medium, l-HPG− took the precedence over d-HPG− in passing through the CSAM and the selectivity αd/l was 0.84.