Atmospheric oxidation of chlorinated ethylenes

Abstract

Limestone Slurry Scrubbing. Stack gas is washed with a recirculating slurry (pH of 5.8-6.4) of limestone and reacted calcium salts in water using a two-stage scrubber system for particulates and SO2 removal. Limestone feed is wet ground prior to addition to the scrubber effluent hold tank. Calcium sulfite and sulfate salts are withdrawn to a disposal area for discard.Lime Slurry Scrubbing. Stack gas is washed with a recirculating slurry (pH of 6.0-8.0) of calcined limestone (lime) and reacted calcium salts in water using a two-stage venturi scrubbing. Lime is purchased from "across the fence" calcination operation, slaked, and added to both circulation streams. Calcium sulfite and sulfate are withdrawn to a disposal area for discard.Magnesia Slurry Scrubbing-Regeneration to H2SO4. Stack gas is washed using a two-stage venturi scrubbing. Water is utilized for removal of particulates, and a recirculating slurry (pH 7.5-8.5) of magnesia (MgO) is utilized for removal of SO2. Makeup magnesia is slaked and added to cover only handling losses since sulfates formed are reduced during regeneration. Slurry from the SO2 scrubber is dewatered, dried, calcined, and recycled, during which concentrated SO2 is evolved to a contact sulfuric acid plant producing 98% acid.Sodium Solution Scrubbing-SO2 Reduction to Sulfur. Stack gas is washed with water in a venturi scrubber for removal of particulates and then washed in a valve tray scrubber with a recirculating solution of sodium salts in water for SO2 removal. Makeup sodium carbonate is added to cover losses due to handling and oxidation of sodium sulfite to sulfate. Sodium sulfate crystals are purged from the system, dried, and sold. Water is evaporated from the scrubbing solution to crystallize and thermally decompose sodium bisulfite, driving off concentrated SO2. The resulting sodium sulfite is recycled to the scrubber, and the SO2 is reacted with methane for reduction to elemental sulfur. Catalytic Oxidation. Stack gas is first cleaned of particulates by a high-temperature electrostatic precipitator. Then the SO2 is catalytically converted to SO3, and available excess heat is recovered. The SO3 reacts with moisture in the stack gas to form H2SO4 mist which is scrubbed in a packed tower using a recirculating acid stream to yield 80% acid. The mist is removed by a Brink mist eliminator, and the clean 254°F gas is exhausted to the stack. Acknowledgment I am indebted to T. Y. Yan of Mobil Research and Development Corp. for his help in constructing the material balance tables and A. M. Chung of Drexel University for his valuable suggestions.

Occurrence, sources, and fate of trichloroacetic acid in swiss waters

“…Hypothetical mechanisms for TCA formation have been suggested using perchloroethene as a starting material [12,13]. 1,1,2-Trichloroethene is not considered a precursor because laboratory studies of the simulated atmospheric degradation have shown neither the formation of TCA nor the formation of the TCA precursor trichloroacetylchloride [14].…”

Ozone Production from Irradiation of Acetylene/Chlorine Mixtures in Air

“…A more detailed discussion of the optical system, interferometer, and spectral data techniques are given elsewhere. 2 In these experiments the path length was 144 m and spectral resolution was 1.0 cm" 1 .…”

Assessment of the Contribution of Chemical Species to The Eye Irritation Potential of Photochemical Smog

“…30 Subsequent measurements of the reaction products of photooxidation in the presence of nitrogen oxide indicated dichloroacetyl chloride was a major product with smaller yields of formic acid and phosgene. 31 Dichloroacetyl chloride is reported to be an eye irritant. 32 No formaldehyde, acrolein, or peroxyacyl nitrates were detected.…”

“…32 No formaldehyde, acrolein, or peroxyacyl nitrates were detected. 31 Laboratory reaction studies with simple mixtures indicate the peroxynitric acid is likely to be a significant product in atmospheric photochemical reactions. 33 - 34 The structure of peroxynitric acid, HO2 NO2 is similar to several other eye irritants so it too may contribute to the intensity of eye irritation observed in ambient atmospheres.…”