Thermal behavior of MnFe2O4 and MnFe2O4/C nanocomposite synthesized by a solvothermal method

A new solvothermal method for MnFe2O4 nanoparticles and MnFe2O4/C nanocomposite synthesis is reported. Manganese ferrite nanoparticles thus sinthesized are not stable at thermal treatment in oxidizing atmosphere, due to Mn(II) oxidation to Mn(III), evidenced at 640 °C by thermal analysis. The FTIR spectroscopy also confirmed the oxidation of Mn(II) to Mn(III). XRD analysis has revealed the complete decomposition of manganese ferrite around 700 °C. The specific surface area of the composite with activated carbon was much higher (253 m2 g−1), in comparison with that of the naked ferrite (65 m2 g−1). Scanning electron microscopy and transmission electron microscopy images evidenced the obtaining of nearly spherical ferrite nanoparticles, with diameters within the range 10 nm − 30 nm, loaded on the surface of activated carbon in case of the composite. The magnetization of the synthesized composite (30 emu g−1) was below the one of naked manganese ferrite (40 emu g−1), but sufficient to insure a facile magnetic separation of the composite from aqueous solution, in case of its use as adsorbent for pollutant removal.