Adsorption mechanism for imprinted ion (Ni2+) of the surface molecular imprinting adsorbent (SMIA)

The adsorption mechanism for the imprinted ion (Ni2+) of a novel surface molecular imprinting adsorbent (SMIA) prepared by the imprinting technique was studied. The interaction mechanism for the imprinted ion (Ni2+) with –OH and –NH2 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 –NH2 groups on the chitosan molecule. Most –NH2 groups showed higher adsorption activity owing to using the imprinting technique in the adsorbent preparation, whereas a few –NH2 groups displayed a lower adsorption activity because of being cross-linked in preparation, which caused different adsorption mechanisms for Ni2+. Compared with the surface molecular non-imprinting adsorbent (non-SMIA), both –OH and –NH2 groups on the imprinted adsorbent surface could provide higher adsorption activity to Ni2+ 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.