(IPS) LONDON -- Freon and other chlorofluorocarbons (CFCs) -- chemicals which destroy the ozone layer -- could be converted to relatively harmless substances such as salt and ingredients used in toothpaste, say scientists at Yale University in the United States.
Professor Robert Crabtree and graduate student Juan Burdeniuc used sodium oxalate, a chemical found in rhubarb leaves, to break down ozone-depleting chemicals.
When sodium oxalate is heated to the temperature normally used for baking bread, it breaks down the CFCs into salt and sodium fluoride. "We're very happy that it might make a contribution to the quality of life in the next century," says Crabtree.
Results completely unexpected
who is from Buenos Aires in Argentina, which is below a widening hole in the ozone layer, discovered the reaction while working on a much broader project for his doctoral thesis. Crabtree was surprised at the results.
"I would never have chosen it, and I don't think an industrial research team would have chosen it," he comments. Burdeniuc points out that sodium oxalate is safe, readily available and relatively cheap at $40 a pound. Previous methods suggested for breaking down CFCs produced explosive reactions or burned to produce corrosive acid gases.
"No one thought that CFCs would react with such a mild and unassuming material as sodium oxalate," says Crabtree who describes it as like "watching a popgun punch holes in steel."
Freon and CFCs are widely used in automobile air conditioners, and as refrigerants, solvents and cleaning agents. They break down very slowly and build up in stratosphere where reactions take place which destroy ozone. The ozone layer in the stratosphere shields the Earth from ultraviolet radiation.
Thinning of this protective layer has been linked to increased risk for skin cancer and cataracts, the destruction of plant life and global warming.
Production of CFCs for use in most developed countries ended on January 1 under the 1992 Montreal Protocol. Ten years ago, 211,000 tons of CFC-11 and CFC-12 were used worldwide for air conditioning and refrigeration while another 500,000 tons went into aerosols and blowing agents.
By the end of 1995, 139 countries had banned the production of CFCs, but stockpiles can continue to be used and developing countries have until 2010 to comply with the Montreal Protocol. Chemical plants can still produce CFC refrigerants, but only for use in developing countries and for certain uses deemed to be essential.
Western industry has had eight years to develop alternative refrigerants that are ozone friendly and the lubricating oils that can be used with them.
Will not remove CFCs already in the atmosphere, but useful in destroying stockpiles
has also been developed to recover and recycle used refrigerants. The research is overseen by the Air Conditioning and Refrigeration Institute in the U.S. where more than 60,000 centrifugal chillers still are working on CFC-11 and CFC-12.
But a global shortage is expected soon and this is reflected in the amount of smuggled CFC-12, about $1.5 million worth, that has been impounded in Florida ports alone. Some estimates say as much as $35 million worth has got through.
In the United States, new types of refrigerants are now required in new cars and air conditioners, but freon can still be used in older model vehicles. Freon is now becoming a popular black market item with plenty of potential sources; U.S. automobile industry sources estimate that up to 100 million pounds may be stockpiled.
The new process discovered at Yale cannot be used to remove CFCs already in the atmosphere but will be useful in destroying stockpiles, according to Mario Molina of Massachusetts Institute of Technology who, with his colleagues, won the 1995 Nobel Prize for chemistry last year for showing how CFCs destroy ozone.
He still sees the main problem as the CFCs already in the environment and says the main solution is not to produce them.
Some enterprising companies are turning the situation to their advantage, such as OZ Technology Inc. of Post Falls, in Idaho.
The company has fought a year long battle to win approval from the U.S. Environmental Protection Agency (EPA) and in face of fierce opposition from the chemical giant DuPont for its substitute hydrocarbon refrigerant, HC-12a, which it is marketing as an environmentally friendly alternative to DuPont's freon.
Meanwhile the problems of preparing for eventual compliance with the Montreal Protocol remain, especially for developing countries and many East European countries.
Bulgaria became the first Eastern European to formally adopt a CFC emissions abatement strategy in December after receiving World Bank support of $10.5 million. The money will be used to reduce industrial emissions of CFCs, which now total some 74,500 cubic meters a year. Bulgaria aims to reduce these emissions by 86 per cent using the World Bank money.
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