Preparation Of Core-shell Magnetic Nano-composite And Research Their Antibacterial And Catalytic Properties

The level of production technology improving, along with the improvement of living standards, accompanied with more negative effects appear. Human pollution to the environment more and more serious, ultimately making the type of bacteria increase, accelerates the growth and reproduction of bacteria, resistance to antibiotics increase. This makes the emergence of new antimicrobial with strong antibacterial ability has become very necessary. The efficiency of nano-antibacterial agent is higher, but its recovery and management is inconvenience. In this paper, with magnetic particles as a carrier, modified its surface and loaded antibacterial agents on its surface. Lastly, magnetic composite antibacterial agent was prepared. This will not only ensure the high efficient and also the convenience of recovery and management the antibacterial agent. The structure, morphology and magnetic properties of the samples were characterized by means of X-ray diffraction (XRD),X-ray photoelectron spectroscopy (XPS),scanning electron microscopy (SEM). transmission electron microscopy (TEM). fourier transform infrared spectroscopy (FTIR),X-ray energy dispersive analyzer (EDX),magnetic measurement system (SQUID). We research the antibacterial property of the compound antibacterial agent under different conditions.The main work of this paper was developed from the following three aspects.1.Synthesis of Fe3O4@C@Ag and Fe3O4@Ag composites by solvothermal method, hydrothermal and chemical reduction. The size of the obtained Fe3O4@C@Ag composites is 250 nm, with strong ferromagnetic and a layer of compacted Ag nanoparticles deposited on its surface, the mean size of the Ag nanoparticle is 15 nm. Contrarily,the Ag nanoparticles on the surface of Fe3O4@Ag are loose and the size distribution is large. The antibacterial testing shows that:The antibacterial property of the compsosites is related to the concentration and size of Ag nanoparticles. When the concentration of Ag nanoparticle is 5μg/mL. the antibacterial properties of Fe3O4@C@Ag composites is the strongest. The magnetic composites can recycle the residual Ag nanoparticles and make the concentration of Ag nanoparticles is higher in special locality. The Fe3O4@C@Ag nanocomposites will have more potential uses in many fields for the catalytic and optical properties of the Ag nanopaerticles. 2. The magnetic particlesγ-Fe2O3 was synthesized by solvothermal method. We found that the reaction temperature and concentration of alkali resource have effect to the phase structure of the production. At 160℃. we obtained the pureγ-Fe2O3,By adjusting the concentration of the FeCl2 at 20,40 and 60 mmol/L. the particles size of theγ-Fe2O3 is 205, 280 and 403 nm respectively. The result of magnetism testing shown that the saturation magnetization of theγ-Fe2O3 was 77.3 emu/g,The strong magnetic makes the composites withγ-Fe2O3 as a carrier with stronger operability.3. Theγ-Fe2O3@SiO2@TiO2-Ag magnetic nanocomposites were synthesized by combining solvothermal,Stober method and sol-gel hydrothermal method. When the concentration of the methyl orange is 30μg/mL. the concentration of composites catalysts contained TiO2-Ag is 1 mg/mL,under the UV light (250 W) irradiation, after 1 h. almost all the methyl orange was decomposed. For the presence of the magnetic core, the composites catalyst can be efficient recovery and reused, after 18 cycles, the catalysis ability keep stable. For the presence of Ag nanoparticles. the composites has antibacterial ability under dark condition, also it can restrain the growth of all the bacteria under UV irradiation. Both the ability of photocatalytic degradation of organic pollutants and inhibit the growth bacterial, make the composites has broad application in the water treatment area.