Sorption and desorption of Th(IV) on nanoparticles of anatase studied by batch and spectroscopy methods

The removal of Th(IV) from aqueous solution by using nanoparticles of anatase is studied under ambient conditions. The sorption of Th(IV) on TiO2 increases markedly at pH 1.5–4 and then maintains level with increasing pH values. The presence of HA/FA enhances the sorption of Th(IV) on TiO2 at low pH values. The Langmuir, Freundlich, Redlich-Peterson and Dubini-Radushkevich models are used to simulate the sorption isotherms, respectively. The results suggest that the sorption of Th(IV) on TiO2 occurs mainly by surface complexation. The adsorbed Th(IV) is very difficult to be desorbed from the solid surface. The results of XRD and Raman analysis indicate that the matrix of TiO2 does not undergo any structural change after the sorption of Th(IV) ions. The Ti-O-H stretching occurred in the IR spectral region of 1000–1300 cm−1 for the hydrated TiO2 samples is responsible for sorption of metal binding, and provides indirect evidence for the surface complexation mechanism.