Study on the adsorption L- and D- proline on MKN-MWCNT-P5000 carbon nanotubes from aqueous solutions

Carbon nanotubes (CNTs) are a new type of nano-adsorbent material with unique properties, which are promising adsorbents for the separation of enantiomers. Information regarding the interaction mechanism of enantiomers with carbon nanotubes has not yet been fully explored yet. In this work, we studied the adsorption of L and D-proline on carbon nanotubes in aqueous solution. Adsorption isotherms of enantiomers proline on multi-walled carbon nanotube MKN-MWCNT-P5000 from aqueous solution at 25℃ were constructed. The results of the experiments show that the adsorption capacity of the D-isomer is higher than that of the L-isomer. The separation coefficient of enantiomers on carbon nanotubes is in the range of 1.88–7.92. L-proline was adsorbed on CNTs as zwitterions and clusters of 62 molecules; and D-proline - in the form of zwitterions and clusters of 33 molecules. The results of quantum chemistry show that the adsorption energy of the D-proline monomer on carbon nanotubes is greater than that of the L-isomer. The nature of the bond between enantiomers and nanotubes was Van der Waals force.