The Oleo Sponge has undergone its first real-world test
Over a year ago, InnovOil looked at the Oleo Sponge, an oleophilic foam invented by the Department of Energy’s Argonne National Laboratory in the US. The sponge can adsorb hydrocarbons from contaminated water before being wrung out, thereby retrieving the oil and making the sponge reusable.
In April, the Oleo Sponge received its first real-world test off the coast of Southern California, in the Santa Barbara Channel.
InnovOil got back in touch with Oleo Sponge co-inventor Seth Darling to talk about what has been happening over the last year and the importance of the recent test.
“The closer to a real-world situation in which you can demonstrate Oleo Sponge’s use, the more compelling it is to somebody in the industry that it might be realistic to use it in the real world,” he said.
Oleo Sponge is a porous foam, starting out as polyurethane, which provides a large surface area to help adsorb oil, as well as a cheap and easily accessible starting material.
In order to make the polyurethane adsorb oil, Argonne National Laboratory applied a process it invented nearly a decade ago called Sequential Infiltration Synthesis (SIS).
“This penetrates all the little fibres that make up the polyurethane foam with aluminium oxide, just near the surface, not all the way through the fibres,” Darling explained. “And that provides very effective attachment points, anchors, if you will, for the second step, which is a molecule that we attach to the aluminium oxide that has the property of being superoleophilic.
“We do that SIS step, we dunk it in the solution of that molecule, and then you’re good to go, you’ve turned polyurethane foam into Oleo Sponge.”
This is what gives Oleo Sponge its oleophilic properties. Once the oil is adsorbed, the sponge can be compressed and the oil retrieved, along with a now-empty Oleo Sponge.
“The way we change the chemistry on the surface is extremely robust, so it holds up to very harsh conditions – you basically can’t remove that coating from the sponge once it’s on there. No matter how much you squeeze it, how many times, what chemicals you expose it to, it just stands up to it all,” Darling said.
“We’ve done a lot of testing, and Oleo Sponge holds up well against everything we’ve put it through,” he added.
Oleo Sponge was previously tested in the laboratory at Argonne and at Ohmsett, a large-scale seawater tank used by companies and government agencies to evaluate technologies for oil spill response.
The first open water test took place at the Coal Oil Point Seep Field, a naturally occurring marine petroleum seep, where hydrocarbons naturally emerge from the Earth’s surface. The location remains one of the largest and best studied areas of active marine seepage in the world.
The test involved a set of 2-foot by 2-foot (0.6-metre) Oleo Sponges for this purpose, which were deployed from a small fishing boat.
Not keen on sheen
When the researchers arrived at the seep field, they discovered that there was a large oil sheen, a layer of surface oil roughly one micron thick that perpetually shimmers on top of the water.
“It just so happened that when we were out there the vast majority of the oil on the water was in the form of a sheen, and that gave us a great opportunity to test performance in terms of mitigating oil sheen,” Darling said.
Sheen is a particular problem involved in oil spill clean-up operations, as it is difficult to clean up, which can bring serious repercussions down on the organisations involved in the clean-up.
“The way the regulations are written, if you are an oil and gas operator and you create a spill, as long as there is a visible sheen on the water, that means there’s a spill that you need to clean up. Even though a sheen represents a very small volume of oil, there is still a legal obligation to address it,” Darling said.
“And cleaning up oil sheen is a real challenge practically speaking, because the methods that oil spill responders typically use like skimming or doing an in situ burn will not work on oil sheen – you can’t skim it and you can’t burn it, so your options are extremely limited in terms of how you can clean it up,” he added.
Many clean-up operations turn to gelling agents to deal with sheen, which adds specialised chemicals to the surface of the water to coalesce the oil into a solid mass that can then be skimmed off the surface.
This can be expensive, however, owing to the large amount of consumable gelling agents needed, as well as the removal of large volumes of hazardous waste created in the process.
Oleo Sponge proved to be effective at removing the sheen. “We would position our vessel out in a big field of this oil sheen and then simply drag a pad of Oleo Sponge across the surface,” Darling said. “In the wake of the pad, you would see pristine clean water. Every bit of oil that this sponge touches it grabs, leaving behind clean water. And if you can pick up the sponge, you can see on the face of it that it’s brown from the oil it pulled off the water.”
In previous tests, Oleo Sponge has proved capable of removing oil from under the surface of the water and has extracted droplets of oil that are emulsified inside the water column.
Sending out an SIS
With field tests completed, Argonne National Laboratory is looking at scaling up production of the Oleo Sponge. The process utilises common and readily available materials, meaning that it should be easy to scale it up for commercial production.
“The process cost if done in a continuous fashion would also be extremely low. There’s nothing that’s particularly energy-intensive or other expensive consumables involved, so it’s a relatively low-cost process,” Darling said.
“Argonne is actively looking for partners on the commercial side where we can transfer this technology to them so they can do to a scalable roll-to-roll style manufacturing process to make enough material to get out there and deal with spills in the field,” he added.
Furthermore, Argonne is interested in adapting the SIS technology for other uses.
“It is a platform technology,” Darling said. “You can attach a different type of molecule to target different pollutants. There’s thousands and thousands – probably millions – of molecules that one could attach to the SIS-modified polyurethane sponge, and one can chose different ones to target different pollutants. You can use your imagination as to the type of things one might target, and we’ve been working on that over the past year.
“There’s nothing we’re ready to go public with just yet but we’re excited about these different pathways as well.”