A facile combustion process for the preparation of magnetic MnFe2O4 nanorods and their adsorption mechanism of methyl blue

Magnetic MnFe2O4 nanorods were fabricated via the alcohol-solution combustion and calcination process. The morphology, microstructure, and composition of the as-prepared MnFe2O4 nanorods were characterized by x-ray diffraction, energy dispersive spectroscopy, and transmission electron microscopy and using a vibrating sample magnetometer. In addition, the magnetic MnFe2O4 nanorods were employed to remove methyl blue (MB) from aqueous solutions; the experimental results showed that the pseudo-second-order kinetic model was fitted well for the adsorption of MB onto MnFe2O4 nanorods in the initial MB concentration range of 100–400 mg l−1, while the isotherm data of MB onto MnFe2O4 nanorods could conform to the Langmuir model owing to the value of the square deviation (R2 > 0.99), and the maximum adsorption capacity of MB was 102.2 mg g−1, which suggested that the adsorption mechanism of MB onto MnFe2O4 nanorods at room temperature was the monolayer and multilayer adsorption. The effects of the solution pH and the recycle on the MB adsorption were evaluated. The adsorption capacity of MB onto MnFe2O4 nanorods could keep a high level at pH greater than 5. More than 78% of the removal efficiency of MB onto MnFe2O4 nanorods could be maintained after 10 cycles.