Effect of water and oxygen contents on the decomposition of gaseous trichloroethylene in air under electron beam irradiation

An electron beam (EB) treatment of gaseous trichloroethylene (TCE) in air was studied as a purification method of off-gases containing gaseous chloroethylenes. The model air containing TCE at input concentrations of 5-75 ppmv, detected mostly in actual off-gases, was irradiated with 1-MeV EBs in a gas-flow vessel at 10 L/min under the conditions of atmospheric pressure, 298 K, and different H2O Contents. The decomposition of 75 ppmv TCE was also examined in humid air under different O-2 contents of 1 X 10(3)-2.1 X 10(5) ppMV. In the existence of H2O and O-2 contents with greater than or equal to 3 X 10(2) ppmv and greater than or equal to 5 X 10(3) ppmv, respectively, the decomposition ratios of TCE were enhanced and TCE was decomposed into 83.0 +/- 1.5% of dichloroacetyl chloride (DCAC) and 17.5 +/- 0.6% of carbonyl chloride (COCl2) independently of the input TCE concentrations based on the carbon balance. Trichloroethylene of 5-75 ppmv was effectively decomposed by the OH radical through Cl-radical chain oxidation under the above-mentioned air conditions.