PHOTOCATALYTIC ACTIVITY OF COMPOSITE MATERIAL OBTAINED BY THE METHOD OF SOL-GEL DEPOSITION OF TIO<sub>2</sub> ON SILICA SUPPORT
On the basis of a preliminary comprehensive analysis of the features of the interaction of TiO<sub>2</sub> particles synthesized by the sol-gel method with silica supports of various genotype, a technology for production of a photocatalytic composite material (PCM) of the TiO<sub>2</sub>-SiO<sub>2</sub> system was proposed and tested. At the first stage, the nonionic surfactant is homogenized in a water-alcohol mixture. With the subsequent addition of an organo-inorganic titanium-containing precursor to the homogenized mixture, the formation of TiO<sub>2</sub> particles occurs due to the hydrolysis and polycondensation reactions. At the second stage, the introduction of a silica support into the reaction mixture during the continued formation of TiO<sub>2</sub> particles ensures the deposition and fixation of the latter on the surface of the silica support. In the third stage, the product is dried in order to evaporate the solvent. At the fourth stage, high-temperature treatment of the resulting mixture completes the process of the composite material production: firing of the resulting product leads to the formation of the most photocatalytically active modification of TiO<sub>2</sub> (anatase) on the surface of particles of a silica support, which is confirmed by the results of X-ray phase analysis. Study of morphological features of the surface of the synthesized PCM by scanning electron microscopy showed a uniform distribution of spherical TiO<sub>2</sub> particles with sizes from several to 150 nm on the surface of the silica support. To confirm the possibility of using of the synthesized PCM in the composition of photocatalytic cleaning and self-cleaning systems, its photocatalytic activity was evaluated by the intensity of decomposition of the organic dye Rhodamine B depending on the type of silica support. Photocatalytic composite material based on diatomite (PCM<sub>diatomite</sub>) exhibited the highest degree of degradation (discoloration) of Rhodamine B (86%) after 26 h of ultraviolet radiation exposure.