Characterization of nano-iron oxyhydroxides and their application in UO2 2+ removal from aqueous solutions

The nano-iron oxyhydroxides (alpha- and gamma-FeOOH) were synthesized by using three ferrous and ferric salts (FeSO4, FeCl2, Fe(NO3)(3)) as iron precursors under alkaline conditions. Morphologies of nano-iron oxyhydroxides were characterized by employing X-ray powder diffraction (XRD) and specific surface area (SSA) analysis respectively. The occurrence of needle-like shape of nano-goethite and rod-like shape of nano-lepidocrocite were attributed to hydrolysis of Fe3+ cations and/or oxidization of Fe2+ at alkaline conditions in terms of XRD analysis. The N-2-BET SSA and BJH (Barrett-Joyner-Halenda) pore size analysis showed that internal SSA of nano-lepidocrocite is higher than that of nano-goethite, although they have similar N-2-BET SSAs. The distribution of average pore size of nano-iron oxyhydroxides are higher than that of predominant pore size due to formation of the heterogeneous nanoparticles under the experimental conditions. These nanoparticles possess the high sorption capacity and the strong affinity for contaminants. Application of nano-iron oxyhydroxides in environmental engineering plays an important role to remove a variety of contaminants, such as heavy-metal ions and organic pollutants.