Recovery of dissolved uranium in seawater (IV)

In order to prepare a effective adsorbent for the recovery of dissolved uranium from seawater, hydrous titanium(IV) oxide was prepared by the hydrolysis of titanium tetraisopropoxide in aqueous alkaline solution. Effects of hydrolysis temperature on the adsorptive characterics of adsorbent were investigated in terms of the surface properties of adsorbent, and the mechanism of adsorption. The results were as follows. 1. The amount of uranium adsorbed was increased as the hydrolysis and adsorption temperatures increase. 2. The adsorptive abilities of adsorbent had a higher dependency with mean pore radius rather than with hydroxyl groups, solid acidity, and aqueous solid acidity of the sample. 3. As the preparation temperature increases, the degree of crystallinity of the sample was increased, and the crystal structure was mainly anatase. 4. The heats of adsorption of the samples were found to be -1.0∼-2.5Kcal /mol (endothermic). 5. The adsorption isotherms could be expressed by the equation of Freundlich isotherm, and 1/n is in the range of 0.06∼0.21. 6. The mechanism of adsorption of uranium on hydrous titanium(IV) oxide was elucidated as intraparticle diffusion controlling (pore volume diffusion), and effective pore volume diffusivities were in the range of 1.62∼6.23X10-6 cm2/s. (Author)