A PRODUCT STUDY OF THE OH RADICAL-INITIATED OXIDATION OF PERCHLOROETHYLENE AND TRICHLOROETHYLENE

Gas-phase reactions of perchloroethylene (PER) and trichloroethylene (TCE) initiated with hydroxyl radical (OH) were studied by using a photochemical reaction chamber, in order to clarify their degradation products, particularly carbon tetrachloride (CCl4) in connection with stratospheric ozone depletion by chlorine. As degradation products of PER, phosgene (COCl2), trichloroacetylchloride (TCAC) and CCl4 as well as CO and CO2 were identified, while dichloroacetylchloride (DCAC) and chloroform (CHCl3) were observed for TCE. Formation of CCl4 was confirmed, but its yield was estimated to be lower than 0.1% of the PER degraded. It was inferred that chlorine atom produced through the PER-OH and TCE-OH reactions was involved in the degradation of PER and TCE, leading to formation of TCAC and DCAC in that order and that CCl4 and CHCl3 was probably produced through photodecomposition of TCAC and DCAC, respectively.