Synthesis of Fe3O4 nanoparticles with tunable sizes for the removal of Cr(VI) from aqueous solution

In this study, size-tunable magnetite (Fe3O4) nanocrystal spheres were promptly synthesized by a facile one-pot solvothermal process with the presence of triethanolamine as an additive. The as-synthesized Fe3O4 nanoparticles were characterized by X-ray diffraction, transmission electron microscopy, scanning electron microscopy, Fourier-transform infrared spectroscopy, and vibrating sample magnetometer. The results showed that the synthesized nanoparticles were in the size range of 30-350nm, had well-defined Fe3O4 crystal phase, and had favorable saturation magnetization. The effects of various important parameters, such as initial Cr(VI) concentration, temperature, and pH, on the adsorption properties of the as-obtained Fe3O4 particles for the removal of Cr(VI) in aqueous solution were deeply analyzed and studied. The results confirmed that the adsorption efficiency was highly pH dependent, decreased with the increasing of initial concentration of Cr(VI), and increased with increasing temperature. The adsorption data were well fitted with the Langmuir isotherm. The maximum adsorption capacity calculated from the Langmuir isotherm was 56.625mgg(-1) at temperature of 35 degrees C and pH of 2.0.