New Nanotechnology Mesh Filters Oil but lets Water Through

This scientific breakthrough could make oil spill cleanup much easier and cheaper.

Oil spills are one of the catastrophic environmental disasters. The damage to nature is often devastating and the clean up is very difficult and expensive. A new

Researchers at Ohio State University developed a nano-coated mesh could clean oil spills for less than $1 per square foot. Water is passing through the mesh but oil doesn’t, thanks to a nearly invisible oil-repelling coating on its surface.

The mesh coating is among a several of nature-inspired nanotechnologies under development at Ohio State.

“If you scale this up, you could potentially catch an oil spill with a net,” said Bharat Bhushan, Ohio Eminent Scholar and Howard D. Winbigler Professor of mechanical engineering at Ohio State.

The work was partly inspired by lotus leaves, whose bumpy surfaces naturally repel water but not oil. To create a coating that did the opposite, Bhushan and postdoctoral researcher Philip Brown chose to cover a bumpy surface with a polymer embedded with molecules of surfactant; the stuff that gives cleaning power to soap and detergent.

They sprayed a fine dusting of silica nanoparticles onto the stainless steel mesh to create a randomly bumpy surface and layered the polymer and surfactant on top.

The silica, surfactant, polymer, and stainless steel are all non-toxic and relatively inexpensive, said Brown. He estimated that a larger mesh net could be created for less than a dollar per square foot.

Because the coating is only a few hundred nanometers (billionths of a meter) thick, it is mostly undetectable. To the touch, the coated mesh doesn’t feel any bumpier than uncoated mesh. The coated mesh is a little less shiny, though, because the coating is only 70 percent transparent.

The researchers chose silica in part because it is an ingredient in glass, and they wanted to explore this technology’s potential for creating smudge-free glass coatings. At 70 percent transparency, the coating could work for certain automotive glass applications, such as mirrors, but not most windows or smartphone surfaces.

“Our goal is to reach a transparency in the 90-percent range,” Bhushan said. “In all our coatings, different combinations of ingredients in the layers yield different properties. The trick is to select the right layers.”

He explained that certain combinations of layers yield nanoparticles that bind to oil instead of repelling it. Such particles could be used to detect oil underground or aid removal in the case of oil spills.

“We’ve studied so many natural surfaces, from leaves to butterfly wings and shark skin, to understand how nature solves certain problems,” Bhushan said. “Now we want to go beyond what nature does, in order to solve new problems.”

“Nature reaches a limit of what it can do,” agreed Brown. “To repel synthetic materials like oils, we need to bring in another level of chemistry that nature doesn’t have access to.”

The research has been published in two papers in the journal Nature Scientific Reports here and here.