Synthesis, characterization, and application of titanate nanotubes for Th(IV) adsorption

Titanate nanotubes (TNTs) have been synthesized by a hydrothermal method using rutile TiO2 powder as titanium source. The determination of the structure and morphology was characterized by XRD, FTIR, SEM and TEM. The results indicate that the TNTs successfully synthesized under hydrothermal conditions of 150 deg C. The adsorption of Th(IV) on TNTs was studied as a function of contact time, pH values, ionic strength, initial Th(IV) concentration and temperature under ambient conditions by using batch technique. The results indicate that adsorption of Th(IV) on TNTs is strongly dependent on pH values, but weakly dependent on ionic strength; Adsorption kinetics was better described by the pseudo-second-order model. The adsorption isotherms are simulated by Langmuir and Freundlich models well. ΔG deg, ΔH deg and ΔS deg free energy were calculated from experimental data, The results indicate that the adsorption of Th(IV) on TNTs is an endothermic and a spontaneous process, and increases with increasing temperature. The adsorption of Th(IV) on TNTs is mainly dominated by chemical sorption or surface complexation. (author)