Photocatalytic degradation of dichloroacetyl chloride adsorbed on TiO

Dichloroacetyl chloride (DCAC) attracted our attention as an intermediate product of the photocatalytic degradation of trichloroethylene (TCE). The adsorption and photocatalytic reaction of DCAC on TiO have been investigated by FTIR spectroscopy. The influence of the surface structure of several TiOs on the reaction mechanism was discussed in order to understand the complete degradation mechanism of TCE as well as DCAC. DCAC was transformed into dichloroacetic acid (DCAA) on the relatively hydrophobic TiO surface by the small amount of the water molecules weakly adsorbed on the surface. This DCAA was degraded to phosgene, CO, and CO during UV irradiation. For the hydrophilic TiO, DCAC was mainly transformed into the dichloroacetate anion. UV irradiation allowed this species to produce chloroform in addition to phosgene, CO, and CO. It is suggested that DCAC easily reacts with the Ti-OH group on the hydrophilic TiO and forms the bidentate titanium chelate of dichloroacetate, which efficiently degrades into chloroform. © 2010 Springer Science+Business Media B.V.