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 °C to 70 °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.