Preparation And Recognition Performance Of The Magnetic Cadmium Ion Imprinted Polymer

Magnetic ion imprinted polymer(M-IIP) is one of high-molecular polymers prepared by molecular imprinting technique combined with magnetic material. it not only has a special selective adsorption capacity for the template ion, but also achieves fast separation by the action of an external magnetic field. In this paper, a magnetic ion imprinted polymer(M-IIP) was prepared by surface imprinting using cadmium ions as template, and the structure, recognition performance, recoveries of real samples of the M-IIP were studies. The main contents include:Magnetic ion imprinted polymers(M-IIP) with specific recognition were prepared using Fe3O4@Si O2 modified by vinyltrimethoxysilane as magnetic carrier, cadmium ion as a template, methacrylic acid(MAA) and arylamide(AM) as functional monomers, azodiisobutyronitrile as initiator,and ethylene glycol dimethyl acrylate as a cross-linker. The synthesis conditons(Solvent, functional monomer, crosslinking agent) were optimized in the process of preparation. The experiments results showed that the magnetic ion imprinted polymer had greater adsorption capacity when it was synthesized using acetonitrile / water(volume ratio 4: 1) as solvent, MAA-AM mixture(molar ratio 3: 1) as the functional monomer and the molar ratio of ion template and functional monomer was 1:20. And the prepared M-IIP were characterized by Transmission electron microscopy(TEM), infrared spectroscopy(FTIR), thermal gravimetric analysis(TGA) and vibrating sample magnetometer(VSM).The adsorption characteristics of the M-IIP were investigated in detail.The results showed that: the recovery rate could achieved 90% when hydrochloric acid of 2M was used as elute, which could meet the requirements of elution; the template ion could be washed throμghly in 8h; when the solution PH was less than 4,the adsorption properties of imprinted material would be affect. Compared with other metal ions, M-IIP have superior identification selectivity for Cd2+. Compared with langmuir and langmuir-Freundlih model, Freundlich model is more applicable to describe the static adsorption process, linear correlation coefficient is 0.9733; The magnetic ion imprinted polymer will reach adsorption equilibrium in 35 min, Then different kinetic models were selected to fititted the adsorption kinetics. Compared to the kinetics of primary model, the adsorption process is more suitable for Lagergren kinetic of secondary model, linear correlation coefficient is 0.9963. The selective adsorption of M-IIP was studied, The results showed that: the adsorption performance MIP and M-NIP for Pb, Cu, Zn was significantly lower than that of Cd, Pb, Cu, Ni selectivity factors are 3.17,2.97,2.57, respectively. The adsorption- stripping for M-IIP repeat 5 times after the experiment, It was found that the recovery rate still kept 90.67%。The cadmium in the digestion of rice samples was enriched throμgh the prepared M-IIP, then the concentration of cadmium in the elution was measured,and the content of cadmium in the rice was calculated.The LOD was 0.5 μg/kg, and the relative standard deviation(RSD) was 4.19%(n = 10, C = 1.5ng · m L-1); The recoveries were 80-103%, RSD was in the range of 1.15%-4.76%.