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 phot ochemical reaction chamber, in order to clarify their degradation prod ucts, particularly carbon tetrachloride (CCl4) in connection with stra tospheric 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 ch loroform (CHCl3) were observed for TCE. Formation of CCl4 was confirme d, but its yield was estimated to be lower than 0.1% of the PER degrad ed. It was inferred that chlorine atom produced through the PER-OH and TCE-OH reactions was involved in the degradation of PER and TCE, lead ing to formation of TCAC and DCAC in that order and that CCl4 and CHCl 3 was probably produced through photodecomposition of TCAC and DCAC, r espectively.