离子液体负载修饰磁性纳米材料的制备及用于水样中痕量镉离子的测定

以四氧化三铁(Fe3O4)为载体包覆二氧化硅涂层,用1-辛基-3-甲基咪唑六氟磷酸盐(OMIM]PF6)负载修饰,制备了一种功能化磁性纳米材料,采用扫描电镜、傅立叶变换红外光谱仪、振动样品磁强计和热重分析仪对材料进行表征。材料显示出良好的耐酸性,其对镉离子的吸附符合Langmuir方程。将该材料用作固相萃取吸附剂萃取富集水中的痕量镉离子,之后用火焰原子吸收法测定,建立了一种分离富集和检测Cd2+的新方法。实验考察了水样酸度、吸附剂用量、振荡和静置时间、洗脱剂及共存离子等对Cd2+回收率的影响。结果显示,在pH 6.0、振荡10 min、静置20 min条件下,该材料对Cd2+具有较好的吸附性,用1 mol/L盐酸可完全洗脱。在优化实验条件下,方法对Cd2+的检出限为0.2μg/L,对15μg/L Cd2+测定结果的相对标准偏差(RSD,n=6)为2.5%。对河水和湖水样品中的Cd2+进行检测,加标回收率为84%～100%。

Preparation of Silica-coated Magnetic Nanomaterials Modified with Ionic Liquid and Its Application in Detection of Trace Cadmium Ion in Water

A kind of silica-coated magnetic nanomaterials modified with 1-octyl-3-methylimidazolium hexafluorophosphate(]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%.