Preparation of amino-functionalized Fe 3 O 4 @mSiO 2 core-shell magnetic nanoparticles and their application for aqueous Fe 3+ removal.

Fe ₃ O ₄ nanoparticle with magnetic properties and nanoscale features has provoked wide research interest and great potential application. Herein, a modified Stober and template-removing method was adopted to prepare magnetic mesoporous silica nanoparticles (MSNs), comprising a Fe ₃ O ₄ core and a mesoporous silica shell. The shell was functionalized by amino-groups with tunable removal efficiency for aqueous heavy metals ions. Structural and magnetic properties were characterized by XRD, SEM, FT-IR, vibrating sample magnetometer (VSM) and BET (Brunauer-Emmertt-Teller) techniques. Also, the adsorbing efficiency for heavy metal ions was measured by UV-vis spectrometry. Results revealed that the pure magnetite is cubic with a side length of 40 - 70nm, while the silica-coated magnetite is spherical with a diameter of 220-260nm. The mesoporous silica shell has an average pore size of 2.6nm and a high surface area of 675m ² ·g ^-1 , which lead to a large adsorption capacity for Fe ³⁺ (up to 20.66mg of Fe per g of adsorbent). Moreover, rapid magnetic separation and regeneration of as-prepared adsorbent were achieved conveniently. The distinctive structure and the heavy metal ions removal property of magnetic nanocomposites reflect their prospective application in water treatment.
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