Photooxidation of trichloroethylene

Driessen MD, Goodman AL, Miller TM, Zaharias GA, Grassian VH (1998) Gas-phase photooxidation of trichloroethylene on Ti02 and ZnO Influence of trichloroethylene pressure, oxygen pressure, and the photocatalyst surface on the product distribution. J Phys Chem B 102 549-556... 

Larson, S.A., and Falconer, J.L. Characterization of Ti02 Used in Liquid Phase and Gas Phase Photooxidation of Trichloroethylene, in D.F. Ollis, and H. Al-Ekabi (Eds.), Photocatalytic Purification of and Treatment of Water and Air . Elsevier Science Publishers, Amsterdam (1993), p. 473. 

Figure 11. Concentration changes during photooxidation of trichloroethylene (0.8 ppm) with nitrogen oxides...

There has been an emphasis on recovery and recycling of trichloroethylene to reduce emissions of this photoreactive chemical to the atmosphere (CMR 1986 McNeill 1979). Photooxidative destruction has been successfully used in conjunction with air-stripping techniques to volatilize trichloroethylene from water and degrade it to nontoxic products (Bhowmick and Semmens 1994). If possible, recycling should be used instead of disposal. 

Photoredox reactions can be carried out with semiconductors. Irradiation of nitrobenzene in the presence of zinc oxide particles in alcohol produced phenylhydroxylamine in 73% yield.443 Irradiation of 4-cyanophenylazide in ethanol containing titanium dioxide gave 4-cyanoaniline in 98% yield. Photooxidation of cyclohexane in the presence of titanium dioxide gave 85.4% cyclohexanone, 2.6% cy-clohexanol, and 12% carbon dioxide.444 To be of use commercially as part of a route to nylon 6,6, the amount of carbon dioxide must be reduced. This method has also been studied for the detoxification of wastewater containing organic contaminants, such as trichloroethylene.445... 

PROBABLE FATE photolysis, tropospheric photooxidation of volatilized trichloroethylene by hydroxyl radicals to phosgene and dichloroacetyl chloride is very rapid, C-Cl bond can photolyze slowly oxidation not important except for photooxidation, photooxidation half-life in air 1.1-11.3 days hydrolysis not important under environmental conditions, first-order hydrolytic half-life 10.7 months volatilization rapid volatilization is the major transport process, evaporation from water 25°C of 1 ppm solution 50% after 19-24 min, 90% after 63-80 min ... 

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... 

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