A kind of silica-coated magnetic nanomaterials modified with 1-octyl-3-methylimidazolium hexafluorophosphate([OMIM]PF6) was prepared,and characterized by scanning electron microscope(SEM),Fourier transform infrared spectroscopy(FT-IR),vibrating sample magnetometer(VSM) and thermogravimetric analyzer(TGA).The synthetic material(Fe3O4-SiO2-IL) showed a good acid resistance.The adsorption behavior of cadmium ion onto Fe3O4-SiO2-IL was tested,and it was found that the equilibrium adsorption followed Langmuir isotherms well.Based on this,a new method for separation and preconcentration of Cd2+ in aqueous solution was developed by using modified silica-coated magnetic nanoparticle as the sorbent and flame atomic absorption spectrometry(FAAS) as detector.Effects of some factors on recovery of Cd2+ were investigated.The optimum conditions were as the follows:pH 6.0;eluent:1 mol/L HCl;oscillation time:10 min;standing time:20 min.Under the optimized conditions,the limit of detection(LOD) for Cd2+ was 0.2 μg/L,and relative standard deviation(RSD,n=6) for 15 μg/L Cd2+ was 2.5%.The proposed method was applied in the determination of Cd2+ in river and lake water with spiked recoveries of 84%-100%. |