Photocatalytic oxidation of humic substances with TiO2-coated glass micro-spheres

Abstract

The photocatalytic oxidation of humic substances in aqueous solutions and natural waters with TiO 2 attached to buoyant, hollow glass micro-spheres was studied. A maximum oxidation efficiency of 3.6 mg W 1 h 1 was achieved in neutral or alkaline media at a plane surface concentration of the catalyst attached to the micro-spheres of 25 g m 2 . Proceeding by different mechanisms in acidic and alkaline media, the photocatalytic oxidation efficiency did not benefit from an excessive presence of hydroxyl radical promoters, hydrogen peroxide and alkali.

Aqueous Photocatalytic Oxidation of Lignin: The Influence of Mineral Admixtures

“…This could be explained by the UV-light penetration to a certain depth of the TiO 2 layer, which is active in PCO reactions. A similar phenomenon was observed earlier with the photocatalyst attached to the microspheres: the oxidation efficiency increased with increased thickness of the catalyst layer until a certain limit, above which the PCO efficiency did not increase further [27].…”

The influence of ferrous ions on the efficiency of aqueous photocatalytic oxidation of 2‐ethoxy ethanol

“…Titanium dioxide was attached to the surface of the micro-beads by the thermal method [10]: equal volumes of dry microspheres and aqueous suspension of titanium dioxide with a concentration of 1 g L −1 were mixed by stirring and sonication for 30 min. The micro-spheres were then separated from the mixture by filtration with a membrane filter, heated to dryness at 120 • C and calcinated at a temperature of 300 • C for 4 h. This procedure was repeated six times, which was found to be the optimum number of attachment operations [11]. Analogously, TiO 2 was attached to the surface of the glass plates (one side) in approximately equal amounts either by multiple submerging of the plates in the TiO 2 suspension with subsequent drying after each submersion, or by spraying the TiO 2 suspension over the surface of the plates and drying.…”

Visible light-assisted photocatalytic oxidation of organic pollutants using nitrogen-doped titania

“…The result with suspended Degussa P25 with phenol was far more advanced; phenol was practically completely removed in the reference experiments under the described experimental conditions. Humic substances also readily yielded to PCO on the attached Degussa P25 surface under UV-radiation (Portjanskaja et al 2004). The N-doped catalysts thus exhibited poor photocatalytic properties in respect to these compounds.…”