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Consider chicken feathers. That's right, that cheap substitute for down that nobody wants in their pillows.
"More than 1 billion kilograms of chicken feathers are produced in the U.S. alone each year," Narendra Reddy, a materials scientist at the University of Nebraska, Lincoln, said this spring at a meeting of the American Chemical Society in Anaheim, California. "Most of these are disposed of in landfills because there is not much use for them."
That's because, while feathers might are composed largely of the protein keratin (a major component of human hair, skin and fingernails) and could theoretically be processed into animal feed, such uses were banned in the U.S. in 1997, due to concerns about the spread of mad-cow disease from slaughterhouse leftovers in cattle feed.
But animal feed isn't the only way to use feathers. Reddy thinks it's possible to use them to make plastics. If he's right, it would not only solve a difficult waste-disposal problem, but save over 15 million litres of petroleum a year. Better yet, the feather-based plastics would be biodegradable.
Early experiments with feather-based plastics didn't work well, however. "They didn't hold up well when wet," Reddy says in a comment that produces unpleasant thoughts of wet chickens.
But then his team hit on the idea of chemically grafting conventional oil-based polymers onto the feather-plastics, in a heat-based process similar to that used for making disposable soda bottles and drinking cups.
The result seems to work. And while that means 20 to 30% of the product is petroleum based - well, 70 to 80% isn't. And each kilogram of feathers is one kilogram of petroleum that's not needed. Nor should there be health risks, because the heat required - 179°C - should be high enough to kill any unwanted microbes.
"I dream of the day when I can drink from a chicken-feather cup," said Enqui Jin, another member of Reddy's team.
And if it could work for chickens, what about other animal byproducts? At the same meeting, Fehime Vatansever, a materials scientist from Clemson University in South Carolina, reported that she had developed a method of making bioplastics out of meat and bone meal, other slaughterhouse waste products now condemned to landfills to prevent spread of mad-cow disease. According to Vatansever, about three times as much bioplastic can be made from these materials than with chicken feathers.
Bigger gains yet come from used crankcase oil from engines. In another presentation at the same meeting, Su Shiung Lam from the University of Cambridge in England reported that this oil, generally regarded as toxic waste, can be converted with about 90% efficiency into usable fuel, using giant microwave ovens. The microwaves, Lam said, decompose the oil into lighter components, via a chemical process called heat pyrolosis.
This is done, said Lam, by mixing the oil with a material that absorbs microwave radiation to become very hot. This then heats the waste oil, breaking it down, or 'cracking' it, into reusable materials which then vaporise and can be recaptured in distillation-style processes.
The process, he added, also can be designed to minimise the production of toxic chemicals, such as heavy metals or polyaromatic hydrocarbons - all with an energy efficiency of "at least" 70 to 80%.
Another environmental win-win involves used cooking oil. Some of it, of course, gets washed down the sink with the greasy dishes. But the majority of it comes in the form of fryer oil at restaurants and food processing plants. Right now, the oil that is a waste product - a shame because there's enough of it to drive the average car for perhaps a week. A growing biofuel industry, in fact, is looking for ways to collect and reprocess as much as possible.
