Synthesis, Characterization And Application Of Mesoporous Superparamagnetic Nanoparticles

Magnetic inorganic nanoparticles especial spinel-type ferrites as akind of magnetic materials have been attracting much attention both inindustrial and science research. Core-shell magnetic materials have beenattracting more attention in recent years because the coating shell canprevent magnetic nanoparticles' aggregation, improve their chemicalstability, and be functionalized. At the same time, the magnetic core canbe endowed with new functionality.In this paper, a novel approach for preparing mesoporoussuperparamagnetic nanocomposite was proposed. The cores, a series ofoxalate modified spinel-type ferrites MFe₂O₄(M=Fe²⁺,Co²⁺,Zn²⁺), weresuccessfully obtained by homogeneous precipitation in aqueous solution.Then mesoporous silica was self-assembled on the surface of nanoparticalsMFe₂O₄(M=Fe²⁺,Co²⁺,Zn²⁺) with the help of organic templates CTAB and TBABdirectly by sol-gel process. The particle size and morphology were studiedby means of transmission electron microscopy (TEM) and X-raydiffraction (XRD); energy diffraction spectroy (EDS) was used toinvestigate their compositions, and N₂ adsorption-desorption tocharacterize their cores structures. Their magnetic property weremeasured with Superconducting Quantum Interference Device(SQUID). Somenew results were obtained.Based on the previous work, mesoporous superparamagneticnanocomposite CuO-MSCNSM was prepared by impregnation. The surfacemorphology, its compositions and magnetic susceptibility werecharacterized by SEM,XRD,EDS,BET and SQUID, respectively. CuO-MSCNSM was tested to be a desulfurizer in petroleum aether, It was found thatas shown by gas chromatography (GC), the CuO-MSNSM as a desulfurizerperformed excellently in an artificial mixture, CH₃(CH₂)₁₁SH-addedpetroleum aether. CuO-MSCNSM can be easily collected and separated fromthe liquid fuel by an external magnet. The absorbing mechanism ofCuO-MSCNSM was also discussed.Ag-MSCNSM was obtained when ig was embedded into the mesoporous shellof superparamagnetic nanocomposite MSCNSM. Then Ag-MSCNSM was treatedwith silane coupling agent(KH—570). The modified particles wereco-polymerized with MMA and BPO via bulk polymerization to form thenanocomposite Ag-MSCNSM-doped PMMA, which were characterized by DSC, TGAand vector network analyzer. It was noted that the core-shell magneticparticles acted as crosslinking points in the nanocompositeAg-MSCNSM-doped PMMA. The thermal stability and the glass transitiontemperature of the composites increased with the addition of thecore-shell particles. Acorroding to the results of vector networkanalyzer, the nanocomposite Ag-MSCNSM-doped PMMA has a better microwaveabsorbing property than single PMMA within the microwave range of0.3-3.5GHz. The probable absorbing mechanism of the nanocompositeAg-MSCNSM-doped PMMA was discussed.