Removal of methylene blue and mechanism on magnetic gamma-Fe2O3/SiO2 nanocomposite from aqueous solution

Magnetic gamma-Fe2O3/SiO2 (M-gamma FS) nanocomposite was prepared using gamma-Fe2O3 as the magnetic carriers. M-gamma FS was characterized by transmission electron microscope (TEM), X-ray diffraction (XRD), and Fourier Transform infrared spectroscopy (FTIR). The characterizations of M-gamma FS exhibit the irregular core-shell structure, and SiO2 has been successfully coated on the surface of gamma-Fe2O3. M-gamma FS has much higher adsorption capacity 116.09 mg/g calculated by coated SiO2 on M-gamma FS than gamma-Fe2O3 and SiO2, and the alkaline conditions are beneficial to the adsorption of MB. Coexisting cations, ionic strength and humic acid can influence the adsorption capacity. Meanwhile, adsorption kinetics data for M-gamma FS show good fit to the pseudo-second-order kinetics model, and the Langmuir equation is more appropriate to describe the adsorption behavior of MB on M-gamma FS. Moreover, after recycling four times, M-gamma FS washed by ethanol can still keep high adsorption capacity for MB adsorption. (C) 2016 Published by Elsevier B.V.