Heavy metals [chromium (VI) and lead (II)] removal from water using mesoporous magnetite (Fe3O4) nanospheres.

Magnetite nanospheres with hollow interiors were synthesized using a simple, one-pot, and template free solvothermal method with ferric chloride as the iron precursor. The composition, surface properties and morphology were studied using X-ray powder diffraction (XRD), energy dispersive X-ray fluorescence (EDXRF), Fourier transform infrared spectroscopy (FTIR), surface area analysis, point of zero charge (pHpzc), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and magnetic moment determination. These mesoporous nanospheres have a SBET=11.3m(2)/g and a high saturation magnetization of 77.5emu/g. These magnetite nanospheres successfully remediated Cr(6+) and Pb(2+) from water. The optimum pHs for Cr(6+) and Pb(2+) adsorption were 4.0 and 5.0, respectively. Adsorption was carried out at 25, 35 and 45°C. The sorption data were fitted using Freundlich, Langmuir, Redlich-Peterson, Sips, Koble-Corrigan, Radke and Prausnitz and Toth adsorption models. The pseudo-second order model better fitted the kinetics data. The Langmuir adsorption capacities of magnetic nanospheres were ∼9 and ∼19mg/g for Cr(6+) and Pb(2)(+), respectively. Magnetic collection of these magnetite nanospheres can be used to isolate and regenerate the used adsorbent.