Can a sponge save our oily shore?
Oil spills can be disasterous for coastal wildlife. Thankfully scientists at Argonne National Laboratory have come up with Oleo Sponge. Chris spoke to the inventor Seth Darling, and then to marine ecologist, Danni Green, about the damage of oil spills...
Seth - We’ve been spilling oil in water as long as we’ve been using oil. There are documents, bills back as early as the early 1900s. Some of the big ones have been the Exxon spill in the Gulf of Mexico - that was more than 400,000 tonnes of oil. Folks remember the 2010 Deepwater Horizon spill also in the Gulf of Mexico - that was actually more than 600,000 tonnes of oil, and spill continue to happen to this day. In the past year they’ve happened in the US, in the UK, and Canada. There are even ongoing spills in places like India, Bangladesh, in the US.
But an important point here is that all of these numbers I’ve just told you are really estimates. There is no good way to know exactly how big these spills are. Also, it’s not the size that matters necessarily, sometimes a comparatively small spill, like the Exxon Valdez spill in the 1980s off the coast of Alaska, can be devastating because they hit a very sensitive habitat.
Chris - When that does happen, what’s the usual way that we seek to mitigate the effects of the spill? How do we clean it up?
Seth - There’s lots of strategies that have been developed over the years to try and deal with oil when it gets in water. One of the ways is you can skim it - that’s where you basically try and scrape the oil off the surface when you see the slick. A more common technique is we just burn it, which does help a little bit with the water pollution problem but, of course, it creates air pollution problems. That’s not an ideal solution, and skimming is not terribly effective because there’s a lot of action in sea waves and, you can imagine, it’s not easy to scrape the oil off the surface.
The truth is that most of the oil is never cleaned up at all. We just let mother nature take care of it. That’s called “bioremediation;” it’s thought of a strategy for cleaning up. It really is just letting mother nature take care of it. You may remember from big spills they’ll fly planes overhead and dump these chemical dispersants on the oil to break it up into little droplets so that it leaves the surface goes down into the water column, and that’s supposed to help with this bioremediation process.
Chris - Of course, none of these solutions are ideal for the very reasons you’ve highlighted. What’s the solution that you’ve developed at Argonne?
Seth - I’ll get to that in one second. I should also mention that all of those techniques I mentioned are for dealing with oil on the surface of the water. None of them address oil in the water column where, of course, it wreaks havoc. You can think back to Deepwater Horizon, these videos of massive plumes of oil under the surface of the water - millions and millions of gallons of oil down there. There is no strategy available today to address oil in the water column. and only iffy strategies of dealing with it on the surface.
So what we tried to work on at Argonne is to develop a sponge that would be able to selectively soak oil out of water, both on the surface and inside the water column, and then be able to recover that oil by just squeezing the sponge like you would your kitchen sponge and reuse that sorbent, that sponge, to go and collect more oil over and over again.
Chris - When you say sponge, do you literally mean like the kind of thing I would have in my bathtub or wash my car with, or is that a metaphor? Is this something which is similar to a sponge but it’s chemically very different?
Seth - I guess both are true. The material that we start with is a foam, a sponge. Our favourite starting material is polyurethane. I’m sitting on polyurethane foam right now; it’s what’s used in furniture cushions, and home insulation, and all kinds of other things. But polyurethane foam or sponges don’t have this property of selectively soaking up oil and not water.
So we start with that material and then we play with the surface chemistry using some technology we’ve invented at Argonne to give it that property, to impart so-called oleophilicity (loving oil), and hydrophobicity (hating water).
Chris - So you add something to the matrix of the sponge so that it actively says I don’t want water molecules but I do want anything that resembles oil molecule, and I’ll take that into the sponge and soak it up?
Seth - Yeah, that's right. It’s really just the surface, the interface of all those pores that are inside the sponge. It’s just that surface layer that really needs to be modified because that’s the only part that the outside world sees. Inside, all the microscopic fibres that make up the sponge, they're still just good old polyurethane.
Chris - How do you deploy this? I’ve got visions of people leaning over the sides of boats with a sponge and dipping it in the oil - obviously not practical. How do you do this and how much oil can you soak up with this?
Seth - There’s various strategies you would use based on the nature of the spill and the environment that it’s in. For surface cleanup it could be something like what you described where you would have pads of this sponge, which would be deployed from vessels or towed behind them and so on, and then brought back on board to compress the oil before being redeployed again.
The really interesting challenge that we're pursuing though, as I mentioned earlier, is cleaning up oil out of the water column itself - submerged clouds of oil droplets. In this case, our vision is to use fishing trawlers, which are already brought to bear when there is a marine oil spill. They bring in fishing trawler to tow booms and other things to try and corral oil spills. Our vision is to let them do what they do best, which is trawl but instead of fishing for fish, you would have nets that were integrated with this oleo sponge to fish for oil.
Chris - Could it also do other pollutants? Could you do the same trick and soak up other stuff other than just oil with this?
Seth - Absolutely. There’s an enormous potential opportunity here. The way in which we manipulate the surface chemistry, there is a huge library of other molecules that we could attach to this sponge to target other pollutants or contaminates that end up in water. You can imagine heavy metals: mercury, lead and so on, or any other vast array of things.
Chris - Thank you Seth
Danni, have you come across any of the impacts of oiling on the marine ecosystem?
Danni - Yes. When I was in the Falkland Islands looking for microplastics, I went to the Falklands conservation. They had a facility set up to help seabirds that have been oiled. I got to actually hand feed some recovering penguins, which was actually a very nice experience because you get a little fish,inject it with some warm saline water so it feels like it’s alive and warm. You hold it up and they just come and take it out of your hand. Unfortunately, as Seth said, it’s quite often the smaller oil spills that create more of a problem because it’s the frequency. It’s these really small oil spills from small boats that can have an affect on individual birds that we’re not even aware of exactly how big the impact is.
Chris - One of the things that was highlighted about the Gulf of Mexico, the Deepwater Horizon disaster, is that the oil in the water column was hitting tuna. Because there are tuna that come to breed in certain areas and it then begins to go into their bodies and you concentrate lots of other toxins and it damages their reproductive fitness because you’ve got animals that may not have where they were hit with oil, but where they want to breed or migrate to gets hit, and so there’s a double whammy.
Danni - Yes, exactly. What he was saying about the water column. That’s not as visible and not as obvious to the human eye, so there could be huge damage that’s being done that we’re not even aware of. And especially damage to habitats too where it’s washing up on the coast and smothering shorelines and killing sessile animals as well.