Fabrication and characterization of nanostructured MgO•Fe2O3 composite by mechanical milling as efficient adsorbent of heavy metals

Nanocrystalline magnesium ferrite is synthesized by high-energy ball milling of alpha-Fe2O3 and MgO powders and annealed at 700, 800 and 900 degrees C temperatures. The Prolonged mechanical milling process has reduced the average crystallite size of MgFe2O4 to the nanometer range as confirmed by the X-ray diffraction analysis. Along with MgFe2O4 phases of alpha-Fe2O3 and metallic Fe were highlighted by the Rietveld XRD refinements. The scanning electron microscopy micrographs of as-milled MgO-Fe2O3 showed cauliflower-like nanostructure with narrower size distribution (approximate to 75 nm). Furthermore, nitrogen adsorption BET analysis demonstrated flatter rather than cylindrical shaped pores with an average pore diameter in the range 24.7-66.3 nm and decreased surface area from 13.45 to 2.23m(2)/g, as a function of annealing temperature. This is consistent with the increased crystallite size values obtained from XRD analysis. The magnetic study indicated a ferromagnetic behavior with low coercivity (68.68 Oe), remanence (0.840 emu/g) and saturation magnetization of 6.517 emu/g. The variation of magnetization as a function of temperature signified cations redistribution within the spinel phase MgFe2O4. The as-obtained nanopowders were tested for heavy metal removal from aqueous solutions where the data revealed improved ions removal by low temperature annealed nanoparticles especially for Ni+2 and Cd+2 indicating their potential for contaminants removal. (c) 2018 Published by Elsevier B.V.