In May, an oil pipeline in Santa Barbara County burst, pouring some 21,000 gallons of oil into the Pacific Ocean. Despite clean-up crews' efforts to contain it, the oil slick stretched along the coast for miles, serving as a glaring reminder that spill mitigation strategies are still lacking. But responders may soon have a new tool to aid in clean-up efforts: Researchers report today in Science Advances that a plant-based, eco-friendly molecule could be used to clean up the inevitable spills of the future.
Right now, booms are most often used to reign in oil, or dispersants are deployed that take advantage of wave action to break up slicks. But in the calm, ice-dotted seas of the Arctic, where oil exploration is at the top of the United States’ agenda, these strategies won’t work. Controlled burning of spills on the ocean’s surface is one way to quickly remove oil from the water, minimizing the effects of the rogue oil on the environment. In order to burn oil, slicks have to be relatively thick, but they tend to spread out in thin layers across the ocean’s surface. The high surface tension of water—the same property that allows bugs to walk on water—pulls the oil slick outward. Silicone-based products called chemical herders can be sprayed around the edges of the slick to lower the surface tension of the water, causing the oil slick to contract.
Phytol-based herders aren’t a universal remedy for oil spills, but in certain scenarios they could become the go-to mitigation strategy.
The trouble is, after the oil is burned away, today’s silicone-based chemical herders remain in the water and their full effects on ocean habitats, and the animals that live there, are still unknown. That fact prompted a team of researchers from the City College of New York and Tulane University to create an eco-friendly herder from a substance already abundant in the ocean: phytol, an organic compound released from Chlorophyll.
The phytol-based molecules are amphiphiles, molecules with a water-loving head and water-repelling tail. That structure allows the molecules to align themselves in a single layer across the surface of the water, ensuring a sufficient drop in surface tension.
To find out how the eco-friendly chemical compared to silicone herders, the team created tiny oil spills in trays of water at varying temperatures and salinities in the lab. And the new herders worked just as well as the silicone-based molecules, according to the authors. When they deployed the phytol herders, the tiny slicks contracted, thickening by as much as 500 percent in five degree Celsius water, and 2,500 percent in water at 35 degrees Celsius.
Another advantage of the phytol herders: Unlike traditional silicone herders, they are broken down by water in just one month. "Once [the herder] does the job, then it goes away," says George John, a professor of chemistry at the City College of New York, and principle author on the study.
Phytol-based herders aren’t a universal remedy for oil spills, but in certain scenarios they could become the go-to mitigation strategy, John says. "It’s a new tool in the toolbox."
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