ChloroflourocarbonsChloroflourocarbons were discovered in the 1920’s by Thomas Midgley, anorganic chemist at General Motors Corporation. He was looking for inert, non-toxic, non-flammable compounds with low boiling points that could be used asrefrigerants. He found what he was looking for in the form of two compounds:dichlorodifluoromethane (CFC-12) and trichloromonoflouromethane (CFC-11). Inboth compounds, different amounts of chlorine and fluorine are combined withmethane, which is a combination of carbon and hydrogen. These two CFCs wereeventually manufactured by E.I. du Pont de Nemours and company, and, under thetrade name “freon,” constituted 15% of the market for refrigerator gases.
CFCs were the perfect answer for cooling refrigerators and airconditioners. They were easily turned into liquid at room temperature withapplication of just a small amount of pressure, and they could easily then beturned back into gas. CFCs were completely inert and not poisonous to humans.
They became ideal solvents for industrial solutions and hospital sterilants.
Another use found for them was to blow liquid plastic into various kinds offoams.
In the 1930’s, household insecticides were bulky and hard to use, so CFCswere created because they could be kept in liquid form and in an only slightlypressurized can. Thus, in 1947, the spray can was born, selling millions ofcans each year. Insecticides were only the first application for CFC spray cans.
They soon employed a number of products from deodorant to hair spray. In 1954,188 million cans were sold in the U.S. alone, and four years later, the numberjumped to 500 million. CFC filled cans were so popular that, by 1968, 2.3billion spray cans were sold in America.
The hopes of a seemingly perfect refrigerant were diminished in the late1960’s when scientists studied the decomposition of CFCs in the atmosphere.
What they found was startling. Chlorine atoms are released as the CFCsdecompose, thus destroying the Ozone (O3) atoms in the high stratosphere. Itbecame clear that human usage of CF2Cl2 and CFCl3, and similar chemicals werecausing a negative impact on the chemistry of the high altitude air.
When CFCs and other ozone-degrading chemicals are emitted, they mix withthe atmosphere and eventually rise to the stratosphere. CFCs themselves do notactually effect the ozone, but their decay products do. After they photolyzed,the chlorine eventually ends up as “reservoir species” – they do not themselvesreact with ozone- such as Hydrogen Chloride, HCL, or Chlorine Nitrate, ClONO2.
These than further decompose into ozone hurting substances. The simplest is asfollows: (How do CFCs Destroy the Ozone) Cl + O3 —–> ClO + O2 ClO + O——> Cl + O2 O3 + O ——-> 2 O2The depletion of the ozone layer leads to higher levels of ultravioletradiation reaching Earth’s surface. Therefore, this can lead to a greaternumber of cases of skin cancer, cataracts, and impaired immune systems, and isexpected to reduce crop yields, diminish the productivity of the oceans, andpossibly contribute to the decline of amphibious populations that is occurringin the world. Besides CFCs, carbon tetrachloride methyl bromide, methylchloroform, and halons also destroy the ozone.
In 1985, the degradation of the ozone layer was confirmed when a large holein the layer over Antarctica was reported. The hole’s existence is due toindustrial chemicals which were manufactured there. During September/October of1985, up to 60 percent of the ozone had been destroyed. Since then, smaller yetsignificant stratospheric decreases have been seen over more populated regionsof the Earth.
Worldwide monitoring has shown that stratospheric ozone has beendecreasing for more than 20 years. The average loss across the globe totaledabout five percent since the mid-1960’s with cumulative losses of about tenpercent in the winter and spring. A five percent loss occurs in the summer andautumn over North America, Europe, and Australia.
The world has been forced to address this issue. Thus, the major powersof the world created a global treaty, the Vienna Convention for the Protectionof the Ozone Layer. The agreement was put into affect in 1988 and thesubsequent Montreal Protocol on Substances that Deplete the Ozone layer wentinto effect in 1989. To date, 140 countries are acknowledging the MontrealTreaty. The countries decided on a timetable for countries to reduce and to endtheir production and consumption of eight major halocarbons. The timetable wasaccelerated in 1990 and 1992. Various amendments were adopted in response toscientific evidence that stratospheric ozone is depleting at a much faster ratethan was predicted.
On the home front, the U.S. Environmental Protection Agency (EPA), underauthority of the U.S. Clean Air Act, have issued regulations for the phase outof production and importation of ozone depleting chemicals. The EPA establishedvarious policies such as refrigerant recycling in both cars and stationary units,a ban on nonessential products, labeling requirements, and a requirement torevise federal procurement specifications.
One of the largest single uses of CFCs is as a refrigerant (CFC-12) usedin automobile air conditioners. Since a big source of this CFC-12 is leakingautomobile air conditioners, many new environmental rules have an impact on theauto service and repair industry. (1)Anyone repairing or servicing motorvehicle air conditioners must recover and/or recycle CFCs on-site or recoverCFCs and send them off-site for recycling. (2)Everyone dealing with A/C mustbe certified to use CFC recovery and recycling equipment. The shop must own EPA-approved recovery and recycling equipment. (3)Retailers can only sell cans ofautomotive refrigerant (less than 20 pounds) to certified technicians. Thisdiscourages do-it-yourselfers from topping off their own A/C.
The fines for violating any of these rules can run as much as $25,000per violation.
If someone wants to keep working on A/C, they will have to make aninvestment in equipment. Is it worth it? Recovery-only units cost about $500 andrecovery/recycling units run from $1,800 to $5,000. People working on airconditioning units must pass an EPA-approved CFC recycling course. CFC-12 usedin motor vehicles was phased out of production at the end of 1995. No more willbe made.
CFCs, when first developed, were thought to be a miracle compound. Theymade excellent refrigerants, pesticides, deodorants, packaging foam, and hadmany other uses. Unfortunately, a hole in the stratosphere was found overAntarctica in 1985, and CFCs were to blame. Since 1989, numerous laws andrestrictions have been made to stop production of CFCs and allow the ozone inthe stratosphere to replenish itself. Fortunately, the laws and restrictionshave been effective and the ozone layer is slowly but surely filling in. Thefuture of the ozone layer looks good indeed.
BibliographyAtmospheric Civic Homepage on-line http://www.epa.gov/Ozone/defns.html#cfcDolan, Edward. Our Poisoned Sky. Cobblehill books, New York: 1991EPA’s Stratospheric Ozone Protection Program World Wide Web Site on-linehttp://www.epa.gov/docs/ozone/index.html, March 8, 1997.
Gay, Kathylyn. Ozone. Impact, New York: 1989.
Hoff, Mary and Mary Rodgers. Our endangered Planet Atmosphere. Lener PublicationCompany, Minneapolis: 1995.
Preston, James. Air Conditioning and Refrigeration Technician’s EPACertification Guide, Quality Books, New York: 1994.
Roan, Sharon. Ozone Crisis. Wiley science editions, New York: 1989.
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Chloroflourocarbons: Discovery, Uses and Negative Impact. (2019, Jan 12). Retrieved from https://graduateway.com/chloroflourocarbons-discovery-uses-and-negative-impact/