Using Fe-Mn binary oxide three-dimensional nanostructure to remove arsenic from aqueous systems

Fe-Mn binary oxide flower-like three-dimensional nanostructure synthesized from a hydrothermal procedure was used to remove arsenic (As) from aqueous solution. The samples were characterized with X-ray diffraction (XRD), scanning electron microscopy (SEM) and Fourier-transform infrared spectrometry (FTIR). SEM images revealed that the Fe-Mn binary oxide was dispersed as flower-like spheres with a diameter of 500 - 800 nm and the width of the petals was 20 - 30 nm. Sorption of the As to the Fe-Mn binary oxide reached equilibrium in less than 180 s, which is much faster than pure MnO2 and amorphous iron manganese binary oxide. The adsorption isotherm agreed well with the Freundlich adsorption model with adsorption capacities of 26.5 mg/g, when the equilibrium concentration was 34.5 mg/L. The effect of temperature revealed that the adsorption of As was exothermic, and the adsorption decreased with increasing temperature from 20 degrees C to 70 degrees C. The removal percentage of As by Fe-Mn binary oxide reached 100% from aqueous solution at pH 4.0 - 6.0. The Fe-Mn binary oxide nano-flowers are a potential highly efficient nanomaterial for removal of As from water.