A team at Argonne National Laboratory has developed Oleo Sponge – a revolutionary, re-usable material which can adsorb hydrocarbons in the water column
Oil spill response has a range of chemical and material tools at its disposal. However, skimmers and booms can only attempt to contain hydrocarbons as best as possible, or move it towards separators, while surfactants are used for dispersal. Although other molecules can help bond to the oil, aiding recovery, much of the rest must be left to naturally occurring bacteria while other environmental consequences are dealt with on the surface.
Systems for more efficiently collecting spilled oil could improve the effectiveness of clean-up efforts dramatically. Such a possibility may now exist, in the form of a new system developed by the US Department of Energy’s (DoE) Argonne National Laboratory. Researchers here have devised an oleophilic foam, nicknamed Oleo Sponge. The material adsorbs hydrocarbons easily from surrounding water, and will not only collect dispersed oil from the surface, but from the entire water column – something the researchers claim no other product can do. Better still, it is also reusable.
“The Oleo Sponge offers a set of possibilities that, as far as we know, are unprecedented,” said the materials’ co-inventor Seth Darling, a scientist with Argonne’s Center for Nanoscale Materials and a fellow of the University of Chicago’s Institute for Molecular Engineering.
A team comprised of Argonne scientists Jeff Elam, Anil Mane, Joseph Libera and postdoctoral researcher Edward Barry all contributed to the development of the Oleo Sponge. Their preliminary results were collated in their paper – “Advanced oil sorbents using sequential infiltration synthesis” – recently published in the Journal of Materials Chemistry.
Insulation innovation The platform for the innovation was first established in earlier research by Darling and Elam. Previously, the two developed a technique involving sequential infiltration synthesis (SIS), a process related to atomic layer deposition (ALD) – a cyclic, gas phase process for depositing thin films based on controlled surface reactions. The process can be used to infuse hard metal oxide atoms within complicated nanostructures. The Oleo Sponge begins life as polyurethane foam – the same substance used in everything from furniture cushions to home insulation. This porous foam provides ample surface area with which to collect oil, but does not have a suitable enough surface chemistry for bonding in its ordinary form. The application and adaptation of SIS techniques allowed the team to grow an extremely thin layer of metal oxide “primer” near the foam’s interior surfaces, creating a structure suitable enough for another layer of molecules.
The primer provided a base upon which to introduce a second layer, comprised of oleophilic molecules –organometallic precursors (either diethylzinc or trimethylaluminium), according to the published paper. As described by researchers, these molecules “hold onto the metal oxide layer with one end and reach out to grab oil molecules with the other”. The resulting porous material – which resembles a seat cushion, or perhaps a doormat – will therefore adsorb oil from water when submerged.
In their paper, the researchers note that “crude oil sorption on the order of 30 and 90 times the initial foam weight for polyurethane and polyimide respectively, both with highly favourable reusability.” In experiments, some polyimide foams showed sorption capacities as high as 90 g/g. Because it is porous, it can also be wrung out and reused, and the oil itself can be recovered. “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,” Darling said.
Big squeeze Practical tests of the material have been carried out in a large seawater tank at Ohmsett, the National Oil Spill Response Research & Renewable Energy Test Facility. Here the Oleo Sponge collected diesel and crude oil from both below and on the water surface. Indeed, backers of the project include the US Coast Guard and the Bureau of Safety and Environmental Enforcement, both of whom could certainly put the material to good use. These tests also proved that the concept could be scaled up to practical levels. “Both the SIS and the oleophilic grafting can be done in large batches. For instance, our Ohmsett campaign represented a roughly 10,000-times scale-up compared to our bench-scale studies,” Emal explained in an emailed response to InnovOil.
Beyond emergency response, Oleo Sponge could become a valuable tool in more routine cleaning operations – for example, to remove or reduce oil and fuel fouling in harbours and ports caused by ship traffic. Better still, it seems as though it could be done cheaply. “The surface treatment is at the monolayer-level, so it uses very little material, and the chemicals are relatively inexpensive – and, of course, polyurethane foam is very cheap,” Elam continued. “We imagine that commercial trawlers could drag large nets that incorporate our Oleo Sponge through subsurface oil plumes to clean up oil.”
The university appears well aware of the commercial potential of the innovation, from material manufacturers, to environmental clean-up groups, to oil and gas companies – and “everyone in between.” Argonne Technology Development and Commercialization business development executive John Harvey notes that the team is actively looking to commercialise the material. Those interested in licensing or collaborating with the laboratory on further development are encouraged to contact the department via the details listed below.
In the meantime, Elam, Darling and the team are continuing to develop the technology and, they confirmed, are experimenting with other surface treatments which may be suitable for attracting other molecules beyond crude and diesel. Elam said that the group would also “explore other applications for our functionalised foam beyond oil clean-up.” Expanding on the plans, he noted: “The technique offers enormous flexibility, and can be adapted to other types of clean-up besides oil in seawater. You could attach a different molecule to grab any specific substance you need.”
Hopes are high that the material could lead to some promising applications elsewhere, but the oil industry and its partners should pay attention. While the lessons learned from major spills like Exxon Valdez and Deepwater Horizon have helped to improve safety and response, technologies like this could make a real difference to any future incidents – and an avenue operators and environmental regulators cannot afford to leave unexplored.