Preparation of chromate anion surface-imprinted material IIP-PVI/SiO2 based on polyvinylimidazole-grafted particles PVI/SiO2 and its ionic recognition characteristic

An anion-imprinted material with high performance for recognizing chromate anion was prepared by adopting the novel molecule surface-imprinting technique put forward by our research group previously. Functional macromolecule polyvinylimidazole (PVI) was first grafted on the surfaces of micron-sized silica gel particles, forming the grafted particle PVI/SiO2. Afterwards, the ion imprinting was carried out towards the grafted macromolecule PVI by using image anion as template and 1,6-dibromohexane as crosslinking agent, and chromate ion surface-imprinted material IIP-PVI/SiO2 was obtained. The binding characteristic of IIP-PVI/SiO2 towards image anion was studied with both static and dynamic methods. The experimental results show that IIP-PVI/SiO2 has excellent binding affinity and high recognition selectivity for chromate anion. Before imprinting, the grafted particles PVI/SiO2 have similar adsorption capacities for both two anions, chromate anion and phosphate anion that was used as a contrast anion. However, after imprinting, the binding capacity of IIP-PVI/SiO2 towards phosphate anion decreases remarkably, whereas the binding capacity of IIP-PVI/SiO2 for chromate anion still remains very high, leading to a high selectivity coefficient (7.78) of IIP-PVI/SiO2 for image anion with respect of image ion.