Sorption behaviors of uranium (VI) ions on alpha-FeOOH

The objective of this study was the examination of the ability of a synthetic goethite nanocrystal to remove hexavalent uranium from aqueous solutions under various conditions. Goethite (alpha-FeOOH), which has a strong affinity for adsorption of the uranyl (UO22+) ion, was synthesized in the laboratory and used as adsorbent. Batch studies have been carried by observing the effects of pH, temperature, concentration of the adsorbate, contact time. etc. Various sorption isotherm models like, Langmuir. Freundlich and Dubinin-Radushkevich have been carried out for the adsorbent. The sorption on the goethite has been found endothermic and feasible in nature. Various thermodynamic parameters, such as Gibb's free energy, entropy and enthalpy of sorption process, have been calculated. Furthermore, the Lagergren first-order, pseudo-second-order and the intraparticle diffusion models were used to describe the kinetic data. The experimental data fitted well the pseudo-second-order kinetics. The product material was characterized by powder X-ray diffraction for crystalline phase identification, scanning electron microscope (SEM) and multi point Brunauer, Emmett and Teller (BET). (C) 2010 Elsevier B.V. All rights reserved.