Self-catalytic behavior in gas-phase photocatalytic oxidation of trichloroethylene using TiO2

The effects of reaction intermediates/products on gas-phase photocatalytic oxidation reaction of TCE with TiO2 were studied. A detailed investigation revealed that the chlorine molecules resulting from the photocatalytic oxidation reaction of trichloroethylene (TCE) and the intermediate, dichloroacetyl chloride (DCAC), are responsible for the very fast photocatalytic oxidation reaction of TCE. In the reactor containing chlorine molecules during the photocatalytic oxidation reaction of TCE with TiO2 the homogeneous photochemical oxidation reaction occurred simultaneously, resulting in an increase of the oxidation rate. The photocatalytic oxidation reaction of TCE with TiO2 progressed very fast, presumably also because the chlorine molecules adsorbed on TiO2 accelerated the net heterogeneous photocatalytic oxidation reaction of TCE.