Trichloroethylene

Colorless, non-flammable liquid, one of the most abundant halogenated organic volatile contaminant with chemical formula: CHCl=CCl₂. Abbreviated as TCE.

 

Physical properties:

Boiling Point: 87 ^oC at 760 mmHg
Freezing/Melting Point: -86 ^oC
Specific Gravity/Density:1.5

Solubility (g/100 ml at 20 ^oC): 0.1
Vapor Pressure: 77.3 mbar at 20 ^oC
Vapor Density: 4.5 (air=1)
Autoignition Temperature: 410 ^oC

Explosion Limits: 8-10.5 Vol %

Log P: 2.42

Earlier it was used as anesthetic, but due to its toxicity and potential carcinogenecity its use in the food (e.g. for coffee decaffeination) and pharmaceutical industries has been banned in much of the world. The greatest use of TCE has been as a degreaser for metal parts, which resulted in the contamination of soil and groundwater. As the density of TCE is higher than that of the water, and it is poorly soluble in water, TCE is adsorbed on the soil grains and it is concentrated in the aquifers as a plum called also DNAPL (Dense Non-Aqueous Phase Liquids). TCE is degraded by the soil micobes, therefore the DNAPL contains beside TCE also DCE (dichloroethylene) and VC (vinyl chloride).

As other Voltile Organic Compounds (VOC), TCE causes eye and skin irritation, it is well soluble in the lipids of the organism explaining its neurotoxic effect, transport through the blood-brain barrier and excretion in maternal milk. Breathing large amounts of trichloroethylene may cause impaired heart function, unconsciousness, and death. Breathing it for long periods may cause nerve, kidney, and liver damage. Drinking or breathing high levels of trichloroethylene may cause nervous system effects, liver and lung damage, abnormal heartbeat, coma, and possibly death. Skin contact with trichloroethylene for short periods may cause skin rashes. Some studies of people exposed over long periods to high levels of trichloroethylene in drinking water or in workplace air have found evidence of increased cancer. TCE may be concentrated in inner atmosphere of dwellings above plums. The EPA has set a maximum contaminant level for trichloroethylene in drinking water at 0.005 mg/L or 5 parts of TCE per billion parts water. The Occupational Safety and Health Administration (OSHA) has set an exposure limit of 100 parts of trichloroethylene per million parts of air (100 ppm) for an 8-hour workday, 40-hour workweek.