Enhanced formation of ozone by the addition of chloropicrin (trichloronitromethane) to propene/NO/air/photoirradiation systems

The photolysis of chloropicrin in air at 1 atm was performed in a 6-m(3) ph otochemical reaction chamber with a combination of Xe are lamps and Pyrex f ilters as a light source. Phosgene was obtained as one of the main products with a yield of unity. No nitrosyl chloride was observed, which supports t he C-N scission mechanism for the photolysis. Photochemical ozone formation was enhanced when chloropicrin was added to the propene/NO/air/photoirradi ation system after the ozone concentration maximum had been reached. The oz one-formation factor for chloropicrin under the conditions employed was, ho wever, estimated to be 0.25 mole of ozone formed per mole of the decomposed chloropicrin. This implies that the Cl atom, itself, contributes to the de struction of ozone rather than to the formation of ozone under the experime ntal conditions. NO2 released from chloropicrin is the source of enhanced o zone. If the amount of chloropicrin as a soil fumigant increases, it can ca use an increase of the ozone concentration in suburban and/or rural areas.