Enantioselective permeation of α-amino acid isomers through polymer membrane containing chiral metal–Schiff base complexes

Abstract

Herein we report the preparation of thin film composite membranes containing metal complexes with chiral ligands, their characterization and performance evaluation for resolution of racemic amino acids. Schiff base complexes of Cu and Zn metals with chiral ligand were synthesized and cross-linked through amide linkage on polysulfone ultrafiltration membrane by in-situ interfacial polymerization reaction. The membranes were characterized using ATR-FTIR Spectroscopy, Scanning Electron Microscopy and Atomic Forced Microscopy. The permeability and enantiomers selectivity of the membranes were determined in pressure driven process at 1034.64kPa pressure using aqueous solutions of racemic lysine and arginine as feeds. The effects of permeation process parameters such as, concentration of feed and permeation time, on the performance of membranes were determined. Membranes permeated d-enantiomers of α-amino acids preferentially. Membrane containing Zn complex exhibited better enantioseparation compared to that containing Cu complex. Both of the membranes exhibited higher enantiomeric excess (ee, >94%) for d-lysine.