Chlorinated byproducts from the TiO2-mediated photodegradation of trichloroethylene and tetrachloroethylene in water

Results are reported from laboratory experiments on the degradation of aqueous solutions of trichloroethylene and tetrachloroethylene by photolysis at over 290 nm, in the presence of titanium dioxide as catalyst. Various chlorinated degradation products were identified. There were 2 mechanisms involved: a reductive pathway involving conduction band electrons which produced dechlorinated byproducts, and an oxidative pathway resulting in mineralization and formation of trichlorinated byproducts. Some implications of the findings for treatment of polluted groundwater by photolysis are indicated.