Tetrachloroethylene, ozonization

U.S. EPA. Preliminary study of selected potential environmental contaminants - Optical brighteners, methyl chloroform, trichloroethylene, tetrachloroethylene, ion exchange resins. Office of Toxic Snbstances, Report 560/2-75-002,1975,286 p. U.S. EPA. Report on the problem of halogenated air pollntants and stratigraphic ozone. Office of Research and Development, Report-600/9-75-008, 1975a, 55 p. 

No data were located regarding the transformation and degradation of hexachlorobutadiene in air. Based on the monitoring data, the tropospheric half-life of hexachlorobutadiene was estimated by one author to be 1.6 years in the northern hemisphere (Class and Ballschmiter 1987). However, analogy to structurally similar compounds such as tetrachloroethylene indicates that the half-life of hexachlorobutadiene may be as short as 60 days, predominantly due to reactions with photochemically produced hydroxyl radicals and ozone (Atkinson 1987 Atkinson and Carter 1984). Oxidation constants of <10 and 6 (m hr) were estimated for reactions with singlet oxygen and peroxy radicals, respectively (Mabey et al. 1982). 

Peyton G R, Huang F Y, Burleson J L, Glaze W H (1982) Destruction of Pollutants in Water with Ozone in Combination with Ultraviolet Radiation. 1. General Principles and Oxidation of Tetrachloroethylene, Environmental Science Technology 16 448-453. 

Volatile organic compounds (VOCs), especially trihalomethanes, are frequently found in drinking water due to the chlorination of humic acids. When UV irradiation is applied to the pre-ozonation of humic acids, the decomposition of VOC precursors increases (Hayashi et al., 1993). The ozonation rates of compounds such as trichloroethylene, tetrachloroethylene, 1,1,1-trichloroethane, 1,2-dichloroethane, and 1,2-dichloropropane were found to be dependent on UV intensity and ozone concentration in the aqueous phase by Kusakabe et al. (1991), who reported a linear relationship between the logarithmic value of [C]/[C0] and [03]f for 1,1,1-trichloroethane, trichloroethylene, and tetrachloroethylene. The other two organochlorines followed the same first-order kinetics with and without UV irradiation (Kusakabe et al., 1991). Thus, the decomposition rate can be expressed as ... 

Bhowmick and Semmens (1994) studied the photooxidation kinetics of five halogenated VOCs, including chloroform (CHL), carbon tetrachloride (CTC), trichloroethylene (TCE), tetrachloroethylene (PCE), and 1,1,2-trichloroethane (TCA) by UV/ozone. In the low to intermediate concentration range of 0.07 to 1.11 mg/L, the reactivities of the organics rank in the following order TCE > PCE > CTC > CHL > TCA. This order indicates that the reaction between ozone and saturated hydrocarbons is much slower than that of ozone with unsaturated compounds such as alkenes. For CHL, TCA, and CTC, an increase in ozone concentration had little effect on the rate constant. By comparison, the rates of oxidation for TCE and PCE increased with added... 

The authors identified the epoxide CH3Cl-COC-CH3Cl that they attributed to the addition of carbonyl oxide (1) to the olefin, which has not been clearly demonstrated [31, 32]. The epoxide formation has also been observed in the case of the ozonization of tetrachloroethylene [33-35] which yielded tri-chloroacetyl chloride (CCl3-CO-Cl) and phosgene (C12C=0) (Scheme 7) and in the case of a highly hindered olefin like compound (Scheme 8). 

Pedit et al. [226] used a kinetic model for the scale-up of ozone/hydrogen peroxide oxidation of some volatile organochlorine compounds such as trichloroethylene and tetrachloroethylene. The kinetic model was applied to simulate the ozone/hydrogen peroxide treatment of these pollutants in a full-scale demonstration plant of the Los Angeles Department of Water and Power. The authors confirmed from the model that the reaction rate of the pollutant with ozone was several orders of magnitude lower than that with the hydroxyl radical. When considering that the natural organic matter acts as a promoter of hydroxyl radicals, the ozone utilization prediction was 81.2%, very close to the actual 88.4% experimentally observed. 

Gehringer P, Proksch E, Szinovatz W, Eschweiler H. Decomposition of tri-chlorethylene and tetrachloroethylene in drinking water by a combined ra-diation/ozone treatment. Water Res 1988 22 645-646. 

Ozone-based AOPs are being used increasingly to treat landfill leachates. " They are also used for ground-water treatment to destroy trichloroethylene (TCE), tetrachloroethylene, and pentachlorophenol. In addition, they are used for groundwater remediation at Superfund sites in the United States to destroy volatile organic compounds and benzidines. Another application of ozone-based AOPs involves their use at U.S. ammunition plants to destroy explosives. ... 

Peyton, G. R., F. Y. Huang, J. L. Burleson, and W. H. Glaze. 1982. Destruction of pollutants in water with ozone in combination with ultraviolet radiation. 1. General principles and oxidation of tetrachloroethylene. Environ. Sci. Technol. 16 448-453. 

The reaction of volatile chlorinated hydrocarbons with OH radicals is temperature dependent and is thus expected to proceed more rapidly in the summer months. The degradation products of this reaction include phosgene, chloroacetylehlorides, formic acid, carbon monoxide, carbon tetrachloride, and hydrochloric acid (Gay et al. 1976 Itoh et al. 1994 Kirchner et al. 1990 Singh et al. 1975). Reaction of tetrachloroethylene with ozone in the atmosphere is too slow to be an effective agent in tetrachloroethylene removal (Atkinson and Carter 1984 Cupitt 1987). 

EPA considers the photochemical reactivity of tetrachloroelhylene leading to the production of ambient ozone to be negligible (EPA 1996a). Therefore, tetrachloroethylene has been added to the list of compounds excluded from the definition of volatile organic compounds for purposes of preparing state implementation plans to attain the national ambient air quality standards for ozone. 

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