三氯乙烯 - 用途和安全等

Overview

  • CAS No. 79-01-6
  • EC No. 201-167-4
  • UN number 1710
  • Chemical formula C2HCl3
Trichloroethylene/TCE is a colorless liquid with an odor similar to chloroform.

use

Trichlorethylene is an effective solvent for many organic materials.

It is mainly used for cleaning. Trichlorethylene is an active ingredient in a variety of printing inks, varnishes and industrial paint formulations. Other uses include

  • Dyeing and finishing operations
  • Adhesive formula
  • Rubber industry
  • adhesive
  • Varnishes and paint strippers

When trichlorethylene was first widely produced in the 1920s, its main use was to extract vegetable oils from plant materials such as soybeans, coconuts and palms. Other uses in the food industry include decaffeinated coffee and the preparation of flavor extracts from hops and spices. TCE is used as a freezing point depressant in carbon tetrachloride fire extinguishers.

anaesthetization

Trichlorethylene is an excellent analgesic in concentrations of 0.35% to 0.5%. Trichlorethylene has been used to treat trigeminal neuralgia since 1916.

From the 1940s to the 1980s, trichlorethylene was almost always used as a volatile anesthetic along with nitrous oxide, both in Europe and North America. Marketed in the UK as Trilene by Imperial Chemical Industries, it is dyed blue to avoid confusion with the similar-smelling chloroform. Trilene is stabilized with 0.01% thymol.

TCE replaced the early anesthetics chloroform and ether in the 1940s because it was less toxic than chloroform and relatively less flammable, but in the 1960s TCE itself was replaced in developed countries with the introduction of halothane, which Making induction and recovery times much faster and much easier to manage. Trilene is also used as an inhaled analgesic, primarily during labor and delivery, usually by the patient. Trichlorethylene was introduced for obstetric anesthesia in 1943 and was used until the 1980s. Its use as an anesthetic was banned in the United States in 1977, but its use in the United Kingdom continued until the late 1980s.

It is used along with Halothane in tri-service field anesthesia devices used by the British Armed Forces in field conditions. However, as of 2000, trichlorethylene was still used as an anesthetic in Africa.

Trichlorethylene has been used in the production of another anesthetic, halothane.

cleaning solvent

It is also used as a dry cleaning solvent, although it has been largely replaced by perchlorethylene, except for spot cleaning, where it is still used under the trade name Picrin.

Perhaps the greatest use of TCE is as a degreaser for metal parts. Since the 1920s, it has been widely used in degreasing and cleaning due to its low cost, low flammability, low toxicity, and high efficiency as a solvent. In the 1950s, demand for TCE as a degreasing agent began to decline and was replaced by the less toxic 1,1,1-trichloroethane. However, as 1,1,1-trichloroethane production has been phased out in much of the world under the terms of the Montreal Protocol, the use of trichlorethylene as a degreasing agent has rebounded.

Trichlorethylene is used to remove oil and lanolin from wool before weaving.

TCE has also been used in the United States to clean kerosene-fueled rocket engines. During static ignition, RP-1 fuel can leave hydrocarbon deposits and vapors in the engine. These deposits must be flushed from the engine to avoid the possibility of explosions during engine operation and future ignition. TCE is used to flush the engine's fuel system before and after each test fire. The flushing procedure involves pumping TCE into the engine's fuel system and allowing the solvent to escape, lasting anywhere from a few seconds to 30-35 minutes, depending on the engine. For some engines, the engine's gas generator and liquid oxygen (LOX) hood are also flushed with TCE before test firing. The F-1 rocket engine had its liquid oxygen dome, gas generator and thrust chamber fuel jacket flushed with TCE during launch preparation.

refrigerant

TCE is also used in the manufacture of a range of fluorocarbon refrigerants, such as 1,1,1,2-tetrafluoroethane. Due to its high heat transfer capacity and cryogenic specifications, TCE is also used in industrial refrigeration applications.

safety and regulations

Trichlorethylene may cause eye and skin irritation. Exposure to high concentrations can cause dizziness, headache, drowsiness, confusion, nausea, unconsciousness, liver damage, and even death. Trichlorethylene is a known carcinogen.
Workers may be harmed by exposure to trichlorethylene. Exposure depends on dose, duration and work performed.

If sufficient amounts of trichlorethylene are leaked into the environment, trichlorethylene will exist as a dense non-aqueous phase liquid (DNAPL).

Two British public chemists reported in 1949 two separate instances of well contamination caused by industrial emissions of trichlorethylene. Based on existing federal and state investigations, 9% to 34% of U.S. drinking water supplies may contain some TCE contamination, although the EPA reports that most supplies meet maximum contamination levels.

Generally speaking, areas with concentrated industry and population have the highest levels of trichlorethylene in the atmosphere. Rural and remote areas tend to have the lowest atmospheric levels.

Average TCE concentrations measured in the air across the United States typically range from 0.01 ppb to 0.3 ppb, but averages as high as 3.4 ppb have been reported.

Trichlorethylene levels in food have been below a few parts per billion; however, levels as high as 140 ppb have been detected in some food samples. TCE levels were found to be higher than background levels in houses undergoing renovations.

Current regulations in the U.S. and EU

In 2023, the U.S. Environmental Protection Agency determined that trichlorethylene poses an unreasonable risk of harm to human health under 52 of 54 conditions of use, including manufacturing, processing, mixing, recycling, vapor degreasing, and as a lubricant and adhesive. , sealants, cleaning process products and sprays. Both inhalation and dermal exposure are hazardous and are closely associated with immunosuppressive effects of acute exposure and autoimmune effects of chronic exposure. Effective June 1, 2023, two US states (Minnesota and New York) have taken action based on the EPA's findings to ban the use of trichlorethylene in all circumstances except research and development. According to the U.S. EPA, in October 2023, it “proposed a ban on the manufacturing, processing, and commercial distribution of TCE for all uses and imposed longer compliance time frames and workplace controls on certain products.” Processing and industry before the ban took effect and commercial use” to protect everyone, including bystanders, from the harmful health effects of trichlorethylene.

Bacteria that degrade TCE

On the in-situ remediation of trichlorethylene in soil and groundwater. Naturally occurring bacteria have been identified with the ability to degrade TCE. Dehalococcus sp. degrades trichlorethylene via reductive dechlorination under anaerobic conditions.

European nitrosifying bacteria can degrade a variety of halogenated compounds, including trichlorethylene. It has been reported that toluene dioxygenase is involved in TCE degradation by Pseudomonas putida.

In some cases, Flavobacterium autotrophica can convert up to 51% of TCE into CO and CO2.

TCE has been used as a recreational drug

Common ways to take trichlorethylene recreationally include inhaling it with a rag and drinking alcohol. Most TCE abusers are young people and workers who use the chemical in their workplaces. The main reasons for abuse are TCE's euphoric and mild hallucinogenic effects.

Where is trichlorethylene found?

Natural and processed foods may contain trichlorethylene due to direct absorption from the environment, contamination of water used in food processing, and contamination from solvents used to clean food processing equipment.

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