Preparation And Adsorption Study Of Functionalized Nanomaterials

Nanotechnology is a fast-growing area, involving the preparation and applications of nano-sized materials and devices. Various nanomaterials play various roles in modern nanoscience and nanotechnology. Quantum dots, magnetic nanoparticles, magnetic-fluorescent multifunctional nanocomposites and magnetic carbon nanotube are particularlly important due to their broad range of potential applications in nanoscience, environment, biomedical and other fields.In view of this, innovation works, focusing on quantum dots, magnetic nanoparticles, magnetic-fluorescent multifunctional nanocomposites and magnetic carbon nanotube nanocomposites, were carried based on the previous work. This dissertation consists of four chapters:Chapter 1 The properties, preparation and application potential of nanomaterials, such as quantum dots, magnetic nanoparticles, magnetic-fluorescent multifunctional nanocomposites and magnetic carbon nanotube, are briefly summerized.Chapter 2 In this study, hollow citrate-stabilized cadmium selenide (CdSe) quantum dots were prepared by a novel, facile one-pot synthetic route, which need not inert atmosphere protection. The synthesis conditions for CdSe quantum dots in aqueous solution were investigated. The as-prepared quantum dots were fully characterized by X-ray diffraction (XRD), transmission electron microscope (TEM), ultraviolet and visible absorption spectrum (UV-vis), fluorescence spectrum (FL) and Fourier transform infrared spectroscopy (FT-IR). The prepared CdSe quantum dots were hollow with an average particle diameter of ca.20 nm and exhibited an emission peak located at 525 nm when excited at 360 nm. The fluorescent intensity of CdSe quantum dots was strong and could be stable in water for more than 30 days without any change. This method was a mild, simple, cheap and efficient "green" route for producing quantum dots in aquepus solution.Chapter 3 Fe3O4/CdSe/SiO2 bifunctional nanocomposites were successfully synthesised based on a feasible electrostatic self-assembly method at room temperature. Both the pH value of the system and the adsorption of cetyltrimethy ammonnium bromide onto the Fe3O4 nanoparticles played essential roles in directing the structure of the bifunctional nanocomposites. Fourier transform infrared spectroscopy, X-ray diffraction, transmission electron microscopy, fluorescence spectroscopy and magnetometry were applied to fully characterise the prepared nanocomposites. The dispersion of the nanocomposites was stable, and the nanocomposites were found to exhibit fluorescent and magnetic properties favorable for a myriad of applications in guiding as well as fluorescent imaging and magnetic separation.Chapter 4 In the present study, Multiwall carbon nanotube (MWCNT)/iron oxide magnetic nanocomposites (MMWCNTs) were prepared by solvothermal approach and characterized by transmission electron microscope, Fourier transform infrared spectroscopy and vibrating sample magnetometer. The results revealed that MWCNT and iron oxide were successfully fabricated. The obtained composites were used to as an absorbent to extract aromatic amines at trace levels from aqueous solution. Capillary zone electrophoresis (CZE) was employed to determine the aromatic amines after preconcentration with the MMWCNTs as absorbent. Under the selected conditions, the enrichment factor could be achieved as 18,40,154 and 181-fold for p-Chloroaniline,3-bromoaniline,3-Nitroaniline and 2,4-Dichloroaniline respectively.