Synthesis of core-shell magnetic nanoparticles containing ultra-small domains of silicalite-1
Résumé
Synthesis of core–shell nanostructures with magnetic core and zeolitic shell is an ongoing challenge. Herein, a strategy is presented for preparation of γ-Fe2O3@mesoporous silica (mSiO2) core–shell nanoparticles containing ultrasmall domains of silicalite-1 in the shell (γ-Fe2O3@mSiO2/silicalite-1). The strategy consists in a solid-state reorganization of the precursor amorphous mSiO2 shell into silicalite-1 using a tetrapropylammonium hydroxide (TPAOH) as an organic structure-directing agent (OSDA) under mild hydrothermal (HT) conditions. The formation of silicalite-1 crystalline domains is investigated through the detailed characterization of products obtained at different times of HT treatment by X-ray diffraction (XRD), Raman spectroscopy, Fourier-transform infrared spectroscopy (FTIR), scanning electron microscope (SEM) with energy dispersive X-ray spectroscopy (EDS), transmission electron microscopy (TEM), and nitrogen physisorption. By careful tuning the time of HT treatment, the γ-Fe2O3@mSiO2/silicalite-1 nanostructures are prepared. Benefitting from the unique mesopores/microporous structure formed, the γ-Fe2O3@mSiO2/silicalite-1 core–shell nanostructure shows superior adsorption capacity to remove aniline from aqueous solutions than the γ-Fe2O3@mSiO2. Moreover, the γ-Fe2O3@mSiO2/silicalite-1 nanostructure is easily separated from aqueous solutions using magnetic separation technique within 1 min.
Domaines
Chimie
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