Trichlorethylene

Removal of Refractory Organics. Ozone reacts slowly or insignificantly with certain micropoUutants in some source waters such as carbon tetrachloride, trichlorethylene (TCE), and perchlorethylene (PCE), as well as in chlorinated waters, ie, ttihalomethanes, THMs (eg, chloroform and bromoform), and haloacetic acids (HAAs) (eg, trichloroacetic acid). Some removal of these compounds occurs in the ozone contactor as a result of volatilization (115). Air-stripping in a packed column is effective for removing some THMs, but not CHBr. THMs can be adsorbed on granular activated carbon (GAG) but the adsorption efficiency is low. 

At least two catalytic processes have been used to purify halogenated streams. Both utilize fluidized beds of probably noimoble metal catalyst particles. One has been estimated to oxidize >9000 t/yr of chlorinated wastes from a vinyl chloride monomer plant (45). Several companies have commercialized catalysts which are reported to resist deactivation from a wider range of halogens. These newer catalysts may allow the required operating temperatures to be reduced, and stiU convert over 95% of the halocarbon, such as trichlorethylene, from an exhaust stream. Conversions of C-1 chlorocarbons utilizing an Englehardt HDC catalyst are shown in Figure 8. For this system, as the number of chlorine atoms increases, the temperatures required for destmction decreases. 

Vinyl chloride Gelatine Trichlorethylene Caproyl peroxide Demineralised water... 

The trichlorethylene is a solvent transfer agent used to control molecular weight. 

Other additives that may be incorporated include sodium hydrogen phosphates as buffering agents to stabilise that pH of the reaction medium, lauryl mercaptan or trichlorethylene as chain transfer agents to control molecular weight, a lubricant such as stearic acid and small amounts of an emulsifier such as sodium lauryl sulphate. 

In one process the resulting solution is continuously withdrawn and cooled rapidly to below 75°C to prevent hydrolysis and then further cooled before being neutralised with ammonia. After phase separation, the oil phase is then treated with trichlorethylene to extract the caprolactam, which is then steam distilled. Pure caprolactam has a boiling point of 120°C at 10 mmHg pressure. In the above process 5.1 tons of ammonium sulphate are produced as a by-product per ton of caprolactam. 

Used at temperatures up to 140°C, polysulfone has good resistance to aqueous solutions of acids and alkalis it is satisfactory with aliphatic solvents but is swollen by aromatics and stress cracked by several organic solvents, including acetone, ethyl acetate, trichlorethylene and carbon tetrachloride. 

Damp conditions contribute to gas-checking of some synthetic stoving lacquers, quite apart from the effects of foul oven gases, or the presence of detrimental solvent vapours, e.g. from a trichlorethylene degreasing plant. 

Ocular Effects. No studies were located regarding ocular effects in humans following oral exposure to trichlorethylene. 

Trichlorethylene has been nominated for listing in the National Toxicology Program (NTP) 9th Report on Carcinogens. Evaluation of this substance by the NTP review committees is ongoing (NTP 1997)... 

Astrand I, Ovrum P. 1976. Exposure to trichlorethylene. I. Uptake and distribution in man. Scan J Work Environ Health 4 199-211. 

Carbon disulphide Disulphur dichloride Benzene, including benzol Carbon tetrachloride Trichlorethylene... 

An optical-fiber CL sensor is reported for trichlorethylene assay [87], The sensor consists of a glass fiber bundle and a transducer consisting of three components (i) a gas-permeable membrane to separate trichlorethylene from water, (ii) H2S04-NaN03 mixture as oxidizing agent, and (iii) a luminol solution. The assay of trichloroethylene can be done in the 0.05-0.6- J,g/mL concentration range with a detection limit of 0.03 J.g/mL. 

Topical application of a single 2 mL dose of undiluted -hexane had no effect on survival or body weight in exposed guinea pigs observed for 35 days after exposure (Wahlberg and Boman 1979). Deaths and/or effects on body weight were seen with similar doses of other common industrial solvents tested in this study (carbon tetrachloride, dimethylformamide, ethylene glycol monobutylether, 1,1,1-trichloroethane, and trichlorethylene). 

Solvent degreasing Vapors perchloroethylene, trichlorethylene, vapor decomposition (e.g., phosgene)... 

Kimbrough RD, et al Trichlorethylene An update, y Toxicol Environ Health 15 369-383, 1985... 

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