Nanocomposites based on silicon dioxide of different nature with functional titanium dioxide nanoparticles

Abstract

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.