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Oranges Are Going Green


Orange peel can be used as biofuel, a mercury absorbent  and of course, a nice addition to a beverage. VVZann/Dariusz Majgier/CSA-Archive/Getty Images  2015 HowStuffWorks
Orange peel can be used as biofuel, a mercury absorbent and of course, a nice addition to a beverage. VVZann/Dariusz Majgier/CSA-Archive/Getty Images 2015 HowStuffWorks

Do you have a stinky closet, scummy glassware or a swarm of aphids wrecking your garden? If so, it's probably time to jump on the orange peel bandwagon and employ oft-discarded bits for these and many other natural uses.

Even scientists are taking orange peel-palooza to a new level. If everything goes according to plan, all that orange enthusiasm could impact the world on a much larger scale than ridding your garbage disposal of that unpleasant aroma ... although that is a nice bonus.

You probably already know that oranges are rich in vitamin C, but little did (most of us) know that a chemical called limonene is squirreled away in the depths of their peels.

A known medicinal superstar, limonene is regularly used in creams and ointments, and is shown to have cancer-fighting and preventing properties, at least with lab animals. This simple hydrocarbon may be very similar in nature to the chemicals we pull from fossil fuels. Naturally, scientists are eager to figure out how to chemically manipulate limonene to ease some of society's dependence on crude oil.

One of the most far-reaching potential uses for limonene is within the polymer industry, which is vital to the creation of many products, including plastics, polyester and carpet. University of York researchers have even developed a promising microwave-based technology that turns the chemicals inherent in orange peels into biodegradable plastic. Multiple research projects also are trying to perfect orange peel biofuel to power our gas-guzzling vehicles.

From a public health perspective, however, one semi-accidental discovery is ready to literally make waves. Originally hoping to develop plastic from recycled waste, Flinders University researchers in Australia discovered that their chosen combination of limonene from orange peels and sulfur (commonly discarded as industrial waste) is more than happy to bind with troublesome mercury. “This material contains strings of sulfur atoms that bridge limonene units,” explains lead researcher Justin Chalkers, Ph.D. via email. “The sulfur in the polymer forms a bond to mercury, trapping it on the surface.”

The researchers, fully aware of what a monstrous headache mercury contamination has become worldwide, realized the potential for this sponge-of-sorts, and set to work.

“Mercury pollution is a serious threat to human health,” Dr. Chalkers explains. “By having contaminated water flow over the surface of our polymer, the mercury will bind to the polymer and be removed from the water,” he says, adding that the polymer, filled to the brim with the sequestered mercury, would then be sent to permanent waste storage. In other words, they're taking one of the pervading problems of the 21st century and literally sucking it right out of the ocean.

This is pretty exciting stuff, folks. Salmon, sharks, swordfish and other large sea-dwellers that are typically contaminated over their long lifespans would be bursting with excitement, were they capable of showing human emotion. Since it always takes time for innovation to gain all the necessary approvals, however, it'll be a while before the concoction really sets sail. “Our goal is to enable cost-effective removal of mercury from the environment,” Dr. Chalkers says. 


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