Layered double hydroxide nanosheets embedded β-cyclodextrin composite membranes with enhanced chiral separation performance

The technologies for enantiomeric resolution are essential to the development of pharmaceutical industry. The membrane technology has great potential in chiral separation owing to its low cost and high throughput; however, the enantioselective of membrane is limited by the thickness of the active layer, which is closely related to the number of theoretical separation plates. In this work, the layered double hydroxides (LDH) are synthesized by hydrothermal process and then vacuum filtrated with β-cyclodextrin (β-CD) and polyvinyl alcohol (PVA) on a porous substrate to fabricate chiral selective membranes. 2D channels with increased number of separation stages are formed in the selective layer after heat post-treatment. The enantiomeric excesses value is enhanced from 10.95% to 24.32% for racemic L/D- tryptophan resolution. This work provides a new approach for designing high performance chiral separation membranes from the aspect of increasing the transport path.