| Abstract
| - This study investigated an application of TiO2 photocatalystsensitized with tris(4,4‘-dicarboxy-2,2‘-bipyridyl)ruthenium(II) complex to CCl4 degradation under visible light irradiation.By injecting electrons from the photoexcited sensitizerto the conduction band, the sensitized TiO2 degraded CCl4under the irradiation of λ > 420 nm. The quantum yieldof CCl4 dechlorination was about 10-3. The dechlorinationrate of CCl4 was reduced in the presence of dissolvedO2 due to its competition for conduction band electrons.The photolysis rate was dependent on pH due to the strongpH dependence of the sensitizer adsorption on TiO2surface with a maximum degradation rate achieved at pH∼3. A two-site Langmurian model successfully describedthe adsorption of the sensitizer on TiO2 particles. Themonolayer coverage was achieved at the added sensitizerconcentration of 10 μM at [TiO2] = 0.5 g/L. However, thephotolysis rate of CCl4 showed a maximum at a sensitizersurface coverage of 0.3 monolayer. Since the photoinducedelectron injection gradually depleted active sensitizermolecules on TiO2, sacrificial electron donors to regeneratethe sensitizer were sought. 2-Propanol as an electrondonor was efficient in the present RuIIL3/TiO2/CCl4 system,which showed no sign of deceleration in the dechlorinationrate up to 6 h of irradiation.
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