Five years after Deepwater Horizon spewed millions of barrels of oil into the Gulf of Mexico, researchers are realizing that the dispersant used to “clean up” the spill is even more toxic to some marine life than the oil itself. But a new technique may eventually be able to remediate oil spills without any chemicals–by using specially coated mesh to scoop oil directly out of water.
Researchers at Ohio State University created a prototype of a coating that attracts oil while repelling water. “In an oil cleanup, we envision that you’d take a large mesh or cloth with this coating, and you just swipe the ocean floor where the spill is,” says Bharat Bhushan, a mechanical engineering professor at Ohio State who led the research. “The water will go through, while the oil is collected in the mesh.”
The new coating was inspired in part by lotus leaves, which naturally repel water (but not oil) through tiny bumps on the surface of each leaf. By covering a similarly bumpy surface with nano-sized particles of a nontoxic cleaning agent, the scientists were able to create a material that could repel oil instead.
“We’ve been working in bio-inspired surfaces for about a decade,” says Bhushan. “The lotus leaf is a classic example in nature to look to, and we’ve created all kinds of structures related to that. We study nature to understand how nature does it, but once we understand that, we don’t copy nature–we use smart materials and manufacturing processes to create the surfaces we’re interested in.”
In this case, the coating is a simpler–and far more environmentally friendly–potential alternative for cleaning up oil spills. “One benefit we see of this technology is that any other things that people are using are very labor intensive,” he says. “People are using cloth to absorb oil, or they’re using highly toxic materials to break up oil. That’s been slow–BP has been doing that for five years, and they barely have gotten rid of the problem.”
Once a mesh sprayed with the coating is scooped through an oil spill, the oil could simply be poured off and the mesh could be reused. “It’s not absorbing oil, it’s collecting oil, which could be skimmed off the mesh,” Bhushan says. “It has no environmental impact. We use eco-friendly materials. The nice thing in working in nature-inspired surfaces is you tend to develop things which are eco-friendly.”
The researchers tested a small sample of the material in the lab, and say that it could easily be scaled up by spraying it on larger surfaces. At this point, they don’t plan to develop the material further, but say that someone could license the technology to develop it for use in actual spills.
“We in academia work on things we get paid to research,” says Bhushan. “If someone came to us and said they’d like to partner with us and they’d like us to develop the technology further, we’d be happy to do it. But in most cases, we develop the basic technology and someone else would license it and further develop it.”
In the meantime, Bhushan’s lab is continuing work on a panoply of other lotus-inspired surfaces: Self-cleaning surfaces that could help keep windows, buildings, or cars clean without water; anti-fogging surfaces that could keep glasses clear in winter air; and surfaces that can clean sand off solar panels or keep bacteria off medical equipment.
“One of the nice things is that our technology is extremely flexible,” says Bhushan.