Siliceous Materials for Immobilization of Photoheterotrophic Bacteria

Abstract

Preparation of transparent silica as potential carrier for photocatalysts and photosynthetic bacteria is presented. SiO 2 was obtained by sol-gel techniques using tetraethyl orthosilicate as precursor. Glycol and glycerol were used as solvents. The increase of porosity of the studied materials was reached by application of soluble and commercial potato starch as a filler. Calcinations at 825 K for 6 hours removed all organic compounds. The rate of gelation was enhanced applying hydrochloric acid. Different materials were obtained in a series of syntheses with different concentrations of individual components. Transparency of the obtained materials varied between 50 and 97% (in range of λ 350 -800 nm). Surface area varied between 300 and 400 m 2 /g and pore diameter was 5 -18 nm. Samples were studied with SEM, nitrogen sorption at 77 K and UV-Vis spectroscopy. The obtained transparent materials with occluded TiO 2 or CaTiO 3 were tested in photocatalytic splitting of water.