Investigation of uranyl adsorption on mesoporous titanium-based sorbents

Mesoporous titanosilicate sol-gel materials with different silicon to titanium ratios were prepared by hydrothermal synthesis through the micellar template approach. The prepared samples have been characterized via infrared spectroscopy, nitrogen sorption, powder X-ray diffraction, and acid-base titration. The uptake of uranyl ion (UO₂²⁺) by the samples was determined at pH = 5.10. The uranyl loading capacity of the pure mesoporous titania was determined to be the largest. This capacity is much higher than that of the corresponding microporous material. The increase of capacity is correlated to the large surface area induced by the surfactant template synthetic method for mesoporous materials, increased concentrations of TiO^- surface functional ligands, and large pore openings of the mesoporous materials allowing for access to the inner pore surfaces. The adsorption kinetics of our mesoporous sorbents are much faster than those of the corresponding microporous materials. The adsorption equilibria can be reached in less than 15 min.