| Magnetic nanomaterials can be used as solid-phase extraction adsorbents for separation enrichment of trace components in environmental water. Due to the excellent properties shch as small size effect, large specific surface area, high adsorption capacity, and with superparamagnetism, magnetic nanomaterials can easily separated from the solution in the presence of an external magnetic field. And after modification, magnetic nanoparticles can be realized the selective adsorption of the specific components. This paper studied the synthesis and characterization of magnetic composite nanomaterials, as well as used as adsorption agent for separation and preconcentration of trace components. The main parts of the results are summarized below:1. Magnetic multiwalled carbon nanotubes were synthesized, and used as a solid-phase extraction sorbent for extraction and preconcentration of trace amounts of Se (IV) with detection by hydride generation atomic fluorescence spectrometry. The prepared nanoparticles were confirmed by Fourier transform infrared spectra, X-ray diffraction spectrometry, vibrating sample magnetometry, and transmission electron microscopy. The main factors affecting the signal intensity such as sample pH value, adsorbent amount, eluent concentration and volume, sample volume, and coexisting ions have been investigated and established. The absorbent could be repeatedly used at least100times. The enhancement factor of the proposed method for Se(IV) was100. The method had a linear calibration plot in the range from0.05to10.0μg L-1with a standard deviation of2.3%at0.5μg L-1(n=11). The limit of detection was as low as0.013μg L-1. Accuracy of the method was evaluated by the analysis of water samples and certified reference materials.2. A novel material, Fe3O4functionalized iso-reticular metal-organic framework-3nanocomposites (Fe3O4/IRMOF-3), was synthesized by a simple hydrothermal reaction. The magnetic nanocomposites are characterized in detail and further applied as solid-phase extraction sorbents to extract trace levels of Cu(II) with detection by electrothermal atomic absorption spectrometry. Parameters such as the amount of Fe3O4/IRMOF-3, pH, extraction time, eluent concentration and volume, and desorption time were optimized. Under the optimum conditions, the adsorption capacity of Fe3O4/IRMOF-3was found to be2.38mg g-1. The method had a linear calibration plot over the range of0.1to10.0μg L-1with a relative standard deviation of0.4%at0.1ug L-1(n=10). The detection limit was as low as0.073μg L-1. It can be concluded that the Fe3O4/IRMOF-3nanocomposites could be used as a very promising and high effective materials for metal determination.3. Dithizone functionalized magnetic metal-organic frameworks (Fe3O4/Cu3(BTC)2-H2Dz) were successfully synthesized for the determination of trace levels of lead based on magnetic solid-phase extraction. The properties of the hybrid nanoparticles were characterized in detail. The metals were quantitatively desorbed and quantified by electrothermal atomic absorption spectrometer. The factors affecting the extraction process such as pH, adsorbant amount, sample volume, eluent concentration and volume, and interfering ions had been investigated and optimized. The adsorption capacity of Fe3O4/Cu3(BTC)2-H2Dz was found to be1.58mg g-1for lead. The method had a linear calibration plot over the range from0.01to5.0μg L-1with a relative standard deviation of3.2%at0.5μg L-1(n=10). The detection limit was as low as0.046μg L-1. The results indicated that the proposed method based on was a novel, rapid analysis, high selectivity, and reliable assay for lead detection. |
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