Chiral separation of D,L-phenylglycine by cellulose triacetate membranes

Enantiopure pharmaceuticals are especially important in medicinal applications. Phenylglycine, as a critical pharmaceutical intermediate, is often utilized in single enantiomeric form for drug synthesis. Chiral membrane separation offers advantages such as simple operation, low energy consumption, and scalability, holding great potential for chiral drug separations. In this work, cellulose triacetate (CTA) membranes are prepared via phase inversion and used for permeation experiments driven by a concentration gradient to investigate selective permeation of D,L-phenylglycine solutions. Scanning electron microscopy reveals surface and cross-sectional morphologies of the fabricated membranes. After single-factor optimization, the CTA membrane exhibits an enantiomeric excess of 68.94% for D,L-phenylglycine separation. The membrane maintains its selective permeation capability after repeated use. This indicates the CTA membrane has favorable chiral selective permeation for D,L-phenylglycine solutions with stable performance. The chiral carbon on the six-membered ring of the CTA backbone, as well as the single-handed helical structure of the backbone, are thought to be responsible for the chiral selectivity of the membrane. This is the first report of using CTA membranes for chiral amino acid separation, providing experimental references and theoretical basis for membrane separation of racemic mixtures. It could facilitate scalable applications of chiral membranes.