TRANSFORMATION AND DECOMPOSITION OF 1,1,1-TRICHLOROETHANE ON TITANIUM-DIOXIDE IN THE DARK AND UNDER PHOTOILLUMINATION

1,1,1-Trichloroethane (CH3CCl3) in dry air was decomposed to carbon dioxide (CO2), chlorine (Cl2) and hydrogen chloride (HCI) at 313-353 K through a heterogeneous photochemical reaction on titanium dioxide (TiO2). The reaction proceeded on TiO2 mainly through the following two steps: (1) thermal catalytic elimination of HCl to produce 1,1-dichloroetbene (CH2CCl2), and (2) photochemical decomposition of CH2CCl2 to CO2 and other products. Photo-oxidation of chloride took place on TiO2, which could keep the catalytic activity of TiO2, since inhibitors like HCl could be removed from the surface. A potential influence of the heterogeneous reaction on estimation of the tropospheric lifetime of CH3CCl3 and/or tropospheric OH budget, is suggested.