engleski

Photocatalytic Oxidation of Toluene on Modified TiO₂ Nanoparticles

Surface modification of TiO2 nanoparticles with sodium silicate significantly influences their photocatalytic properties towards oxidation of volatile organic compounds (VOC) in the gas phase. Raman spectroscopic studies showed that surface silicates form isolated nanoislands on the TiO2 particles. Addition of silicates significantly increased the intensity of surface water and hydroxyl group in infrared spectra. The efficiency of photocatalytic oxidation of air pollutants strongly depends on the relative humidity. During the reactions, water forms hy-droxyl radicals which are very important as they act as a primary oxidant. They disappear and have to be renewed in order to keep an acceptable catalytic activity. The photocatalytic destruction of toluene over differently modified TiO2 catalysts was investigated using an annular reactor. A model for the oxidation of VOCs in this reactor was used to obtain the kinetic constants. Small quantities of silicates (around 5%) promote the photocatalytic activity towards toluene oxidation due to their hydrophilic properties. During the oxidation, small quantities of benzoic acid are formed which are responsible for the deactivation of the TiO2. Surface modifi-cation with sodium silicate also leads to an increased stability of the catalyst.

photocatalytic oxidation; TiO2 nanoparticles; toluene

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