Soaking up an oil spill

Scientists at the US Department of Energy’s (DOE) Argonne National Laboratory have invented a foam, called Oleo Sponge, that not only absorbs oil from water, but is also reusable and can pull dispersed oil from the entire water column - not just the surface.

The material could help in operations to clean up oil spills such as the 2010 Deepwater Horizon incident where the oil formed a plume and drifted through the ocean under the surface as well as accumulating on the surface.

“The Oleo Sponge offers a set of possibilities that, as far as we know, are unprecedented,” said Seth Darling, a scientist with Argonne’s Center for Nanoscale Materials and a fellow of the University of Chicago’s Institute for Molecular Engineering. “We already have a library of molecules that can grab oil, but the problem is how to get them into a useful structure and bind them there permanently.”

The scientists started out with common polyurethane foam, used in everything from furniture cushions to home insulation. This foam has a large surface area but the scientists needed to give the foam a new surface chemistry to attach the oil-loving molecules.

Previously, Darling and fellow Argonne chemist Jeff Elam had developed a technique called sequential infiltration synthesis, or SIS, which can be used to infuse hard metal oxide atoms within complicated nanostructures.

After some trial and error, they found a way to adapt the technique to grow a thin layer of metal oxide ‘primer’ near the foam’s interior surfaces. This served as a glue for attaching the oil-loving molecules, which are deposited in a second step. The result is a block of foam that easily adsorbs oil from water. The material can also be wrung out to be reused - and the oil itself recovered.

At tests at the National Oil Spill Response Research & Renewable Energy Test Facility in New Jersey, the Oleo Sponge successfully collected diesel and crude oil from both below and on the water surface.

Darling said: “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.”

Oleo Sponge could potentially also be used to clean harbours and ports, where diesel and oil tend to accumulate from ship traffic.