Cerium-doped mesoporous TiO2–montmorillonite composites were studied; the composites were obtained by hydrothermal impregnation (115°C, 0.5 h) of mechanically and thermally activated montmorillonite with a solution containing titanium/cerium polyhydroxo complexes with a mole fraction of cerium of 1.1–2.4 × 10–2 (Ce4+) and 1.4 × 10–2 (Ce3+). The adsorption capacity and photocatalytic activity of the composites with respect to the model dye Rhodamine B in an aqueous solution under the action of UV and visible radiation were evaluated by spectrophotometry. The concentration of Ce and its oxidation state were found to significantly affect the values of equilibrium adsorption and rate constant of the dye bleaching reaction. The obtained composites were characterized by low-temperature nitrogen adsorption/desorption, scanning electron microscopy, dynamic light scattering, X-ray diffraction analysis, energy-dispersive spectroscopy, X‑ray photoelectron spectroscopy, and diffuse reflectance spectrophotometry. Doping with cerium affects the ratio of the anatase and rutile phases, the size of their nanocrystallites, as well as the surface morphology and textural properties of the composites. In general, a well selected dopant concentration can significantly increase the synergistic effect of the adsorption and photocatalytic properties of this composite.
Butman et al. (Wed,) studied this question.