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Give up? Polyethylene (or PE), the most common form of plastic, is everywhere in the modern world: the containers we store things in, the bottles we drink water out of, the plastic bags that we choose over paper ... it's all polyethylene. It's convenient, cheap, light and strong, but it's also stubborn stuff, and can stick around from 500 to 1,000 years, and that's why you see it everywhere.
The problem with plastic
And that's the problem, David Constable from the American Chemical Society, told VOA. "Most is not recycled and its ultimate fate depends on where you are in the world," Constable says. For instance, "there is an enormous swirl of plastic refuse in the Pacific Ocean. There are plastic microbeads distributed throughout the marine environment." A stunning 8 trillion microbeads a day, according to research from Oregon State University. And while the beads themselves aren't dangerous, they soak up toxic waste and contaminants that end up in marine wildlife and fish, and from there they move right up the foodchain to us. The other problem is that it's hard to recycle plastic, much harder than it is to recycle paper or glass or metals such as aluminum. Here's why: Before any plastic can be recycled, it has to go through a complicated and in some cases costly sorting process. That's because there are different kinds of plastics.
A novel chemical process converts post-consumer polyethylene plastic bottles, bags, and films into liquid fuels and waxes.
Take a look at the little triangle and number imprinted somewhere on your plastic bottle, bag or container. That number tells you what kind of plastic it is, and there are seven different numbers. Before any recycling can begin, plastics must be separated by number. Constable calls it a "robust sorting process" requiring "relatively pure plastic." What is pure plastic? According to Constable, it's plastic that is "not contaminated with food wastes, not blends of plastic, etc." In modern food packaging, for example, he explains there are somewhere around 20 layers between the air and the food. "These complex plastic laminates are very difficult to recycle or break down into their component parts." And in many cases, even recycled plastic ends up in landfills because of "chemical contamination."
Break it down
But now the good news: researchers may have found a way to get rid of all this waste cheaply and easily, and break it down into liquid fuel and wax. The new research was reported Friday in Science Advances and is part of a four-year research project by scientists from the University of Shanghai and the University of California, Irvine. One of the project leaders, Zheng Huang, says they took a known process, called catalytic cross alkane metathesis (CAM), that uses carbon and hydrogen-based molecules called alkanes to scramble the hydrocarbons that make up polyethylene and ultimately break it down. "After many cycles of CAM with light alkanes," Zheng says, "PE will be eventually converted to short hydrocarbons suitable for transportation oils."
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Scientists have developed membranes that produce a tiny bit of disinfecting hydrogen peroxide when exposed to light. They could find their way into food packaging as well, the researchers say, helping cut down on foodborne diseases. The research is published in the journal Science Advances.
Nearly 500 health workers died during the 2014 Ebola outbreak in West Africa. Front-line caregivers wear full-body protective suits when they come into contact with patients with virulent diseases, but the process of removing the gear is a prime opportunity for infection if the surface is contaminated. "If there's any live bacteria or virus on the surface, it's still transmissible and could cause infection," said University of California, Davis, researcher Gang Sun.
A health worker sprays a colleague with disinfectant during a training session for Congolese health workers to deal with Ebola virus in Kinshasa, Oct. 21, 2014. The process of removing the full-body protective suit is a prime opportunity for infection if the surface of the gear is contaminated.
Sun and colleagues developed membranes that could line the outside of that protective gear. When exposed to daylight, molecules on the surface of these membranes react with oxygen in the air to produce small amounts of hydrogen peroxide — less than what you'd use to remove laundry stains, but enough to kill germs, according to Sun. "The approach is quite novel," said University of Maryland food scientist Rohan Tikekar, who was not involved with this research. He says others have developed materials that produce disinfecting chemicals, but most only work under high-energy ultraviolet light.
The new membrane also works in the dark, for at least an hour or two, thanks to chemical properties that recharge its germ-killing powers. "That is a really significant improvement," Tikekar added. In addition to coating protective gear for health workers, Sun says adding a layer of this material to fresh-produce packaging could reduce contamination and prolong storage life. Some versions of the material use natural compounds. Sun says one of the next steps is to make it edible.
Daylight Turns Plastic Sheet into Germ-Killing Material
