Acrylonitrile (AN) was graft-polymerized on micron-sized silicon particles, resulting in grafted particles PAN/SiO₂. Subsequently, the grafted PAN was converted to poly(amidoxime) (PAO) via amidoximation reaction, obtaining functional particles PAO/SiO₂. Then, the ionic imprinting towards the grafted PAO was performed with Gd^3＋ ion as template ion and glutaral as crosslinking agent by using the novel surface-molecular imprinting technique established by our research group, and the Gd^3＋ ion-imprinted material IIP-PAO/SiO₂ was prepared. Rare earth element Eu and Sm are adjacent to Gd in lanthanum elements, and the ionic radius difference between Eu^3＋ and Sm^3＋ ions and Gd^3＋ ion is only 1～3 pm. In this work, with Eu^3＋ and Sm^3＋ ions as contrast substances, both static and dynamic methods were adopted to study the binding properties and ion recognition character of IIP-PAO/SiO₂ for Gd^3＋ ion. The experiment results show that IIP-PAO/SiO₂ have specific recognition selectivity and excellent binding affinity for Gd^3＋ ion, and the selectivity coefficients of IIP-PAO/SiO₂ for Gd^3＋ ion with respect of Eu^3＋ ion and Sm^3＋ ion are 7.49 and 7.93, respectively. Besides, IIP-PAO/SiO₂ has excellent elution property, with diluted HCl solution as eluent, the desorption ratios of Gd^3＋ ion reach 99.54% in 29 BV.

Key words: poly(amidoxime), silica gel, ionic imprinting, surface imprinting, rare earth ion, ion recognition