Preparation of Thin Film Polymer Composite Membranes for Optical Resolution of Racemic Mixture of α-Amino Acids

Abstract

Thin film polymer composite membranes capable of resolving racemate of α-amino acids were prepared by coating a chiral selective layer on micro-porous polysulfone membrane in situ through interfacial polymerization of trans-1, 4-diaminocyclohexane (T-1, 4-DCH) with trimesoyl chloride (TMC). The chiral selective layer of membranes was extensively characterized by FTIR spectroscopy (ATR), Scanning Electron Microscopy (SEM), Atomic Force Microscopy (AFM), and Transmission Electron Microscopy (TEM). The membranes prepared from monomer solutions of low concentrations (T-1, 4-DCH, 2%, and TMC, 1%) rejected more solute with low enantioselectivity whereas the membranes prepared from monomer solutions of high concentrations (T-1, 4-DCH, 4% and 6% and TMC, 2%) rejected less solute with high enantioselectivity. The membrane prepared from 6% T-1, 4-DCH, and 1% TMC solutions exhibited maximum enantioselectivity (>92% ee). The membranes prepared from monomer solutions of low concentrations had very thin coating layer (<0.5 µm) whereas membranes prepared from concentrated monomer solutions had comparatively thick coating layer (>0.5 µm). The rejection of arginine increased marginally with permeation time but the enantioselectivity remained constant.

Keywords:

• 4-diaminocyclohexane
• enantioselective membrane
• enantioselectivity
• optical resolution
• Trans-1
• trimesoyl chloride

ACKNOWLEDGEMENTS

Department of Science and Technology (DST), New Delhi-India is gratefully acknowledged for financial assistance under the project (GAP-1025). Pravin G. Ingole acknowledges CSIR, New Delhi for award of SRF. We give special thank to analytical sciences discipline of the institute for support in analysis.