Synthesis and Characterization of Magnetic Nanosized Fe3O4/MnO2 Composite Particles

Using the prepared Fe3O4 particles of 10 nm-25nm as magnetic core, we synthesized Fe3O4/MnO2 composite particles with MnO2 as the shell by homogeneous precipitation. Their structure and morphology were characterized by X-ray diffraction (XRD), X-Ray photoelectron spectroscopy (XPS), transmission electronic microscopy (TEM), Fourier transform infrared spectra (FTIR), and vibration-sample magnetometer (VSM). We show that with urea as precipitant transparent and uniform MnO2 coating of ca.3 nm thick on Fe3O4, particles can be obtained. The composite particles have better dispersivity than the starting materials, and exhibit super-paramagnetic properties and better chemical adsorption ability with saturated magnetization of 33.5 emu/g. Decoloration experiment of methyl orange solution with Fe3O4/MnO2 composite suggested that the highest decoloration rate was 94.33% when the pH of methyl orange solution was 1.3 and the contact time was 50 minutes. So this kind of Fe3O4/MnO2 composite particle not only has super-paramagnetic property, but also good ability of chemical adsorption. Copyright (C) 2009 Z. Shu and S. Wang.