In 2010, a blowout at the Deepwater Horizon rig let loose a torrent of oil deep in the Gulf of Mexico. Rather than floating to the surface, much of the oil hovered deep underwater, rendering useless many of the traditional ways of coping with spills.
Now, almost seven years later, scientists have developed a reusable sponge that can absorb oil from water both on the surface and below. It’s not clear how the sponge will behave at Deepwater Horizon depths, but its performance on the surface and just below is promising. Plus, its creators say it could be ready for widespread use in five years.
The researchers, based at the Argonne National Laboratory in Illinois, started with run-of-the-mill polyurethane foam and applied technique known as sequential infiltration synthesis, which allowed them to coat the nooks and crannies of the foam with aluminum oxide. The aluminum oxide served as a base coat on which the scientists deposited oil-loving, or oleophilic, compounds.
Initial tests of the specially treated polyurethane foam showed that the sponge could absorb 30 times its weight in oil. But another type of foam the researchers were investigating, polyimide, is a more stable compound that allowed them to run the first step of the treatment process—sequential infiltration synthesis—at higher temperatures, which produces better results.
The higher temperatures made a big difference—the polyimide sponges were able to soak up 90 times their weight in oil, three times more than the polyurethane foam.
Foams in hand, the Argonne team headed east to test their creations. Here’s Megan Guess, writing for Ars Technica:
The sponge was tested extensively in a New Jersey saltwater research tank, where it was able to collect both diesel and crude oil from the tank, whether the oil was above or below the water’s surface.
Seth Darling, the sponge’s co-inventor and a scientist with Argonne’s Center for Nanoscale Materials, said in a press release that “The material is extremely sturdy. We’ve run dozens to hundreds of tests, wringing it out each time, and we have yet to see it break down at all.”
In large spills, this reusability could be a boon for response crews. Rather than having to procure large amounts of the stuff, they can pull it out of the water, wring it out, and dunk it back in. Darling even says that the recovered oil can be reused.
If the sponges can be made cheaply enough, their use may not be limited to larger spills. Rather, they might be routinely dragged behind ships in harbors to absorb diesel and other fuels that spill into the water in smaller quantities.