Chiral ionic liquid-multi walled carbon nanotubes composite membrane applied to the separation of amino acid enantiomers.

• New CIL-MWCNTs composite film was easily prepared for the first time. • Load capacity, stability and chiral recognition were well balanced for the film. • Membrane components can be flexibly adjusted to different separation objects. • Three enantioresolution modes based on the film was compared for the first time. • Characterization was comprehensive and mechanism was explored systematically. Various membranes are playing more and more important roles in the field of analytical and preparative applications of general interest, and some of them have been used in enantioresolution for amino acids (AAs) or similar bioactive molecules. In this study, a new composite membrane was prepared with chiral ionic liquid (CIL) of [BuPyro] [L-Pro] as chiral selector together with multi walled carbon nanotubes (MWCNTs) and additives through a simple way for the first time. Based on such a separation medium, the enantioresolution of amino acid enantiomers were achieved by forming ternary ligand complexes with Cu(II). It was comprehensively characterized by various ways, and key preparation conditions were discovered. After comparing the performance of three operation modes on the resolution of racemic phenylalanine, the effects of main influential factors were investigated and enantiomeric excess value (e.e.%) was 90.2% for the (D,L)-Phe aqueous solution (membrane thickness: 0.15±0.02 mm, total weight: 80 mg, CIL: 41.7%). Through effective desorption, up to 98.1% of the target was recovered. Finally, the mechanism of resolution was revealed by molecular simulation, kinetics and isotherm models, and the difference of interactive energy between ternary complexes of L-Phe-Cu(II)-CIL and D-Phe-Cu(II)-CIL was calculated as 1.56 kcal/mol. The membrane also remained stable after the post-treatment and showed good potential in chiral separation. [ABSTRACT FROM AUTHOR]