Abstract
Magnetic Fe-SBA-15 mesoporous silica molecular sieves were prepared, characterized, and used for magnetic separation. Wet impregnation, drying, and calcination steps led to iron inclusion within the mesopores. Iron oxide was reduced to the metal form with hydrogen, and the magnetic Fe-SBA-15 was obtained. Fourier-transform infrared spectroscopy confirmed the preparation process from the oxide to metal forms. The structure of magnetic materials was confirmed by Mössbauer spectra. Powder X-ray diffraction data indicated that the structure of Fe-SBA-15 retained the host SBA-15 structure. Brunauer-Emmett-Teller analysis revealed a decrease in surface area and pore size, indicating Fe-SBA-15 coating on the inner surfaces. Scanning electron micrographs confirmed the decrease in size for modified SBA-15 particles. From scanning electron micrographs, it was found that the size of the modified SBA-15 particles decreased. Transmission electron micrographs also confirmed that modified SBA-15 retained the structure of the parent SBA-15 silica. Fe-SBA-15 exhibited strong magnetic properties, with a magnetization value of 8.8 emu g−1. The iron content in Fe-SBA-15 was determined by atom adsorption spectroscopy. Fe-SBA-15 was successfully used for the magnetic separation of three aromatic compounds in water. Our results suggest wide applicability of Fe-SBA-15 magnetic materials for the rapid and efficient separation of various compounds.
Highlights
Mesoporous SBA-15 silica molecular sieves of large pore diameter and area [1] show excellent homogeneity and stability and can be well controlled for adsorption/desorption processes [2]
The iron content in Fe-SBA-15 was determined by atom adsorption spectroscopy
The material was red after Fe(NO3)3-SBA-15 calcination at 750◦C, suggesting that iron oxide is mainly in the form of α-Fe2O3
Summary
Mesoporous SBA-15 silica molecular sieves of large pore diameter (up to 30 nm) and area (up to 1000 m2 g−1) [1] show excellent homogeneity and stability and can be well controlled for adsorption/desorption processes [2]. Inclusion of magnetic components in modified materials allows convenient and economical magnetic separation instead of centrifugation and filtration steps on application of an appropriate magnetic field [7,8,9]. Because of their potential applications in this approach, the preparation of Co, Co/Fe, α-Fe2O3, γ-Fe2O3, and Fe3O4 magnetic SBA-15 materials have been reported [10,11,12,13,14,15]
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