Selective permeation of L-tyrosine through functionalized single-walled carbon nanotube thin film nanocomposite membrane

In the present work, we demonstrated a strategy to render an enantioselective nature to otherwise hydrophobic Single-walled carbon nanotubes (SWCNTs) via a simple covalent functionalization. The covalent functionalization was initiated on the SWCNTs surface by incorporating a COOH group followed by chlorination of the carboxylic group into acid chlorides and terminated with an amidation reaction using D-tryptophan as the chiral probe. Subsequently, the functionalized SWCNTs were assembled into a thin film nanocomposite membrane following a phase inversion method. Finally, the enantioselectivity of the developed membrane was tested by treating a racemic mixture of tyrosine on the membrane, where the D-isomer was preferentially adsorbed on the membrane while the L-isomer was selectively allowed to transport through it. In order to optimize the permselective properties of the membrane, different process parameters such as mass loading of SWCNTs, concentration of feed, applied pressure and reaction temperature were varied in a pressure-driven membrane process and highest enantiomeric excess up to 98.86% was obtained under optimized conditions which include the concentration of FSWCNTs as 0.2% in the membrane, operation pressure of 4 bar, feed concentration less than 0.1 mmol·L−1 and operation temperature of 35 °C. Moreover, the effect of concentration of FSWCNT in the dope solution was also examined to increase the thermal as well as mechanical properties and antifouling behavior of the membrane.