Adsorption mechanism for imprinted ion (Ni 2+) of the surface molecular imprinting adsorbent (SMIA)

Abstract

The adsorption mechanism for the imprinted ion (Ni 2+) of a novel surface molecular imprinting adsorbent (SMIA) prepared by the imprinting technique was studied. The interaction mechanism for the imprinted ion (Ni 2+) with –OH and –NH 2 groups on the chitosan molecules was testified by Fourier transform-infrared spectrometry (FT-IR) and X-ray photoelectron spectroscopy (XPS). By the means of FT-IR and XPS analysis, there exist two kinds of –NH 2 groups on the chitosan molecule. Most –NH 2 groups showed higher adsorption activity owing to using the imprinting technique in the adsorbent preparation, whereas a few –NH 2 groups displayed a lower adsorption activity because of being cross-linked in preparation, which caused different adsorption mechanisms for Ni 2+. Compared with the surface molecular non-imprinting adsorbent (non-SMIA), both –OH and –NH 2 groups on the imprinted adsorbent surface could provide higher adsorption activity to Ni 2+ based on FT-IR and XPS analyses. SMIA had more pores and bigger specific surface area than non-SMIA according to the distribution of the pore diameter and specific surface area analyses. Based on the above research, a higher adsorption capacity and a better selectivity for the imprinted ions of SMIA could be interpreted.