Preparing Surface Anion-imprinted Material Based on Ion Exchange and Surface-initiated Graft-polymerization and Studies on Its Recognition Character

The molecularly imprinted polymers (MIPs) synthesized by conventional bulky imprinting methods suffer from several limitations, such as time-consuming preparation process, poor site accessibility to the target molecules and the lower binding capacity for the target molecules. To overcome these problems in bulking imprinting, in this work, a novel surface-ion imprinting method that not only is simple but also highly effective, is put forward and found. The coupling agent gamma-aminopropyltrimethoxysilane (AMPS) was bond onto the surface of silica gel particles, and amino groups were introduced onto the surfaces of silica gel particles, obtaining the modified particles AMPS-SiO2. In aqueous solution, the molecules of the cationic monomer methacryloxyethyltrimethyl ammonium chloride (DMC) were first combined around the template ion, phosphate ion, by right of ion exchange action. A redox initiating system was constructed by the amino groups on AMPS-SiO2 and ammonium persulphate in the solution, and free radicals were produced on the surfaces of silica gel particles. These free radicals initiated the monomer DMC and the crosslinker N,N'-methylene bisacrylamide (MBA) to be graft-copolymerized and crosslinked, and the surface-imprinting of phosphate ion was realized. After removing the template ions, PO43- surface-imprinted material IIP-PDMC/SiO2 was obtained. Both permanganate ion, MnO4- ion, and PO43-, ion are isoelectronie bodies. Their chemical structures are similar and their configurations are the same, but their sizes are different. In this work, MnO4- ion was used as contrast ion, and both static and dynamic methods were adopted to study the binding properties and ion recognition character of IIP-PDMC/SiO2 for PO43- ion. The experiment results show that IIP-PDMC/SiO2 have specific recognition selectivity and excellent binding affinity for PO43- ion, and its selectivity selectivity coefficients for PO43- ion with respect of MnO4- ion is 9.58. Besides, IIP-PDMC/SiO2 has excellent elution property, with NaCl solution as eluent, the desorption ratio of PO43- reach 99.53% in 20 BV.