Nanocomposites Based on Silicon Dioxide of Different Nature with Functional Titanium Dioxide Nanoparticles
Nanocomposites TiO2/SiO2 with photocatalytic and adsorptive properties were prepared by codispersing of η-modification and anatase (commercial Hombifine N) and SiO2 (opal, granules, ultrafine) in ethanol (or ethanol–water mixture in the presence of chlorophylls or porphyrins) with ultrasonic treatments of the mixture (method 1) and an aqueous solution of KOH with a microwave treatment (method 2), as well as the introduction of SiO2 in the reaction mixture during the synthesis of TiO2 by brief hydrolysis of sulfate titanyl (method 3). It was found that the state of titania in the sample (X-ray amorphous or nanocrystalline) and its deposition on SiO2 nanocomposites depend on the method and the conditions of obtaining. It was established that the photocatalytic activity of nanocomposite TiO2/SiO2 (granules) (method 1) photosensitized by coproporphyrin I in the visible range and the photocatalytic activity of nanocomposite TiO2/SiO2 (opal) (method 3) in the near UV range exceed activity of the commercial sample of TiSiO4 by more than 20-fold and ~7-fold, respectively. It was shown that the nanocomposite TiO2/SiO2 (opal) significantly reduces the concentration of cations (in particular, Be, Ni, Bi) in the model water systems.