Optical Resolution of α-Amino Acids by Reverse Osmosis using Enantioselective Polymer Membrane Containing Chiral Metal-Schiff Base Complex

Abstract

The optical resolution of α-amino acids, arginine and alanine was performed by reverse osmosis at 517.10 kPa and 1034.21 kPa pressures using enantioselective composite nanofiltration membrane prepared by interfacial co-polymerizing, a mixture of Zinc metal Schiff's base complex and piperazine with trimesoyl chloride in-situ on the top of polysulfone ultrafiltration membrane. The chemical composition of the enantioselective layer was determined by ATR-FTIR and X-ray Fluorescence Spectroscopy and surface morphology was studied by scanning electron microscopy. The effect of process parameters such as the operating pressure, permeation time, and concentration of the feed on the performance of membrane was studied. The volumetric flux of aqueous solution of α-amino acids through membrane follows Hegen-Poiseuillie equation. The composite membrane permeates d-enantiomers of α-amino acids preferentially; 54% enantiomeric excess in for d-arginine was achieved. The enantioselective permeability of the membrane is found to be time dependent. The enantioselective property of the membrane has arisen due to a homo-Chiral environment created in the membrane by incorporating chiral ligand Schiff complex in thin film of poly (piperazine trimesamide) polymer on the top of the polysulfone membrane. The composite membrane also exhibits the separation of α-amino acids from their aqueous solutions.