Sorption of uranium(VI) from aqueous solutions by akaganeite.

Removal of U(VI) ions from aqueous solutions was investigated using synthetic akaganeite-type nanocrystals. Nanocrystals of iron oxyhydroxides were synthesized with two different methods and then compared their adsorption capacities. Akaganeite (beta-FeOOH) was synthesized in the laboratory by precipitation from aqueous solution of Fe(III) chloride and different precipitating agents. The relative importance of test parameters like solution pH, contact time, temperature and concentration of adsorbate on adsorption performance of akaganeite for U(VI) ion were studied. Typical adsorption isotherms (Langmuir, Freundlich, Dubinin-Raduskevich) were determined for the mechanism of sorption process. Also the thermodynamic constants (DeltaH degrees , DeltaS degrees and DeltaG degrees ) were calculated. The product materials were examined by powder X-ray diffraction for crystalline phase identification and scanning electron microscope (SEM).