Amino-functionalized magnetic mesoporous microspheres with good adsorption properties

• Synthesis of amino-functionalized magnetic mesoporous microspheres.
• The excellent adsorption capacity of Fe3O4@SiO2@meso-SiO2-NH2 on heavy metal ions.
• Magnetically recoverable property of Fe3O4@SiO2@meso-SiO2-NH2 microspheres.
• The regeneration of Fe3O4@SiO2@meso-SiO2-NH2 adsorbent by acid treatment.

An amino-functionalized magnetic mesoporous microsphere was fabricated by a colloidal chemical method and using cationic surfactants (CTAB) as structure-directing agents. The prepared nanocomposite microspheres were mesoporous and magnetizable, with a diameter of ca. 480 nm, a high surface area of 474 m2/g, a pore size of 2.1 nm, and a saturation magnetization of 36.0 emu/g. As an adsorbent, these multifunctional microspheres showed excellent adsorptive capability toward heavy metal ions (Pb2+, Cu2+, Cd2+) and the adsorption capacity was as high as 289.7 mg/g (1.40 mmol/g) for Pb2+, 196.5 mg/g (3.09 mmol/g) for Cu2+ and 154.2 mg/g (1.37 mmol/g) for Cd2+. The amino-functionalized magnetic mesoporous microsphere can be easily removed from solution by an external magnetic field and regenerated easily by acid treatment. These results suggest that this kind of nanocomposites is a potentially useful material for effectively adsorbing and removing the heavy metal ions in aqueous solution.

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