Selective adsorption of metoprolol enantiomers using 2-hydroxypropyl-β-cyclodextrin cross-linked multiwalled carbon nanotube

Abstract

This study investigates the ability of functionalized multiwalled carbon nanotubes (MWCNTs) for enantio-separation of metoprolol chiral forms. 2Hydroxypropyl-β-cyclodextrin (2HP-β-CD) was applied as a chiral selector to functionalize carbon nanotubes (CNTs). The modified multiwalled CNT samples were characterized using scanning electron microscopy and Fourier transform infrared spectroscopy. The results of analyses showed that CNTs were successfully cross-linked with 2HP-β-CD. To evaluate the enantio-separation property of the products, the separation of metoprolol chiral forms on the initial and final products was examined. Further, UV-visible spectroscopy and polarimeter analyses were used for characterization. The results indicate that MWCNT does not have any intrinsic enantio-separation ability, although its selectivity for enantio-separation can be enhanced by cross-linking it to 2HP-β-CD. Moreover, the optimal mass of adsorbent as well as optimal mass of functional groups is estimated to achieve maximum enantio-separation efficiency. The results indicate that applying large amounts of 2HP-β-CD to CNTs functionalization decreases the cross-linking efficiency, which consequently reduces enantio-separation efficiency.