Synthesis Of Magnetic Nano-Materials And Applications In The Analysis

In recent years, Fe₃O₄ magnetic nanoparticles have been extensively studied and applied due to such notable properties as superparamagnetism, small-size effect, the high surface area to volume ratios, biosafety, biocompatibility, the ease of synthesis and subsequent coating and functionalization. The study of Fe₃O₄ magnetic nanoparticles is an active field of analytical chemistry and electroanalytical chemistry presently, involves relevant applications include: enzyme immobilization, electrochemical biosensors, wastewater treatment, protein separation and enrichment. In this thesis, we developed our work focusing on synthesis characterization, constructing electrochemical sensor based on direct electron transfer of Fe₃O₄ magnetic nanoparticles and its application in wastewater treatment field.1. The study of constructing oxygen and hydrogen peroxide sensor based on hemin grafted onto functionalized core-shell Fe₃O₄/SiO₂ magnetic composite materialsHemin that serves as is the active center of heme protein was directly grafted onto amino functionalized core-shell Fe₃O₄/SiO₂ magnetic composite materials by covalent bond. The synthesized Fe₃O₄/a-SiO₂/hemin composite magnetic materials was characterized by transmission electron microscopy (TEM),infrared (IR) and ultraviolet -visible (UV-vis )absorption spectroscopy. The resultant particles were deposited onto the glassy carbon electrode for constructing electrochemical sensor. This modified electrode had a good catalytic properties] towards oxygen and hydrogen peroxide and could be used as the determination of hydrogen peroxide and dissolved oxygen in water.2. The study of constructing glucose sensor based on Fe₃O₄/SiO₂/Au magnetic composite materials with core-shell structuresFirst, monodisperse Fe₃O₄ nanoparticles were synthesized by solvothermal method and Fe₃O₄/SiO₂ with core-shell structures were prepared by sol-gel method. Then Au nanoparticles were assembled onto the surface of Fe₃O₄/a-SiO₂ to form Fe₃O₄/a-SiO₂/Au magnetic composite materials. This composite materials employed to immobilize glucose oxidase (GOD) to construct glucose biosensor. The crystallization, morphology, structure, and electrochemistry of the magnetic materials were characterized by X-ray diffraction (XRD), transmission electron microscope(TEM), FT-IR (Fourier transform infrared) and (ultraviolet -visible ) UV–vis spectra, respectively. This materials could increase the amount of the immobilized material and its high surface average concentration was up to 3.92×10?9 mol·cm-2. In addition, the immobilized GOD retained its high bioactivity. The glucose biosensor showed wide linear range, low detection limit high sensitivity. The proposed method could be used for determination of glucose.3. The study of quickly magnetic absorption to remove pollutants from water based on monodisperse magnetic Fe₃O₄ NanoparticlesFirst, monodisperse Fe₃O₄ nanoparticles were synthesized by solvothermal method. The crystallization, morphology and structure were characterized by X-ray diffraction spectrum (XRD), transmission electron microscope (TEM) , Fourier transform infrared spectroscopy (FT-IR) and ultraviolet-visible spectroscopy (UV–vis), respectively. Fe₃O₄ magnetic NPs were used as adsorbent in wastewater treatment. Experiments examined in detail magnetic material remove to remove organic dye (BeryllonⅡ) by magnetic quickly adsorption under different conditions such as adsorption time, initial dye concentration, magnetic material concentration, temperature and solution pH. Adsorption data was made to fit the isothermal data using Langmuir and Freundlich equations. The experimental results have demonstrated that the equilibrium data are fitted well by a Freundlich equation. The results indicated that Fe₃O₄ magnetic nanoparticles could remove magnetically quickly organic pollutants in water.