A composite material based on titanium dioxide and diatomite, possessing high photocatalytic activity, was obtained using solutions with high concentrations of titanium polyhydroxocomplexes under mild hydrothermal conditions at a temperature of 115°C and a pressure of 170 kPa for 0.5, 1, and 5 h. The starting diatomite was pre-processed mechanically by grinding it in a mortar and milling in a planetary mill with zirconium grinding media for 3 min (rotor speed 1500 rpm). The materials were characterized by X-ray diffraction analysis, IR spectroscopy, scanning electron microscopy, energy-dispersive microanalysis, low-temperature nitrogen adsorption-desorption, and static light scattering. The different types of mechanical processing of the starting diatomite had a significant effect on primary crystallization in the autoclave, which changed the surface morphology and the phase ratio of TiO2–anatase and rutile in the composite while varying the hydrothermal treatment time. The composites are characterized by higher textural parameters of the mesoporous structure and significantly higher positive values of the ζ potential compared to those of the starting diatomite. The photocatalytic properties of the composites were studied using the model dye of the cationic type rhodamine B (RhB) as an example. For composites with the highest photoactivity, the degree of RhB decomposition under UV radiation (250 W, 365 nm) was ~95% after 1 h of irradiation for an RhB solution with a concentration of 20 mg L–1 at a photocatalyst load of 1 g L–1.
Ovchinnikov et al. (Sun,) studied this question.