A steel mesh that lets water through but collects and holds oil - courtesy of a coating of nanoparticles - could clean up oil spills quickly and inexpensively, U.S. researchers suggest.
Engineers at Ohio State University have created a steel mesh that allows water to pass through but blocks oil from passing, thanks to a bit of nanotechnology inspired by nature.
The researchers took their inspiration from the leaves of the lotus plant, which can repel water but not oil. They've turned that capability on its head with a polymer coating that has molecules of surfactant, the material that gives soaps and detergents their cleaning power, embedded in it.
It was applied over a layer of nanoparticles of silica applied to the steel mesh.
In lab tests, a mixture of water and oil was poured onto a sample of the mesh; the water flowed through to land in a beaker underneath, while the oil remained on top of the mesh, rolling easily into another beaker as the mesh was tilted.
All of the materials used to create the mesh - the silica, polymer, surfactant and the stainless steel of the mesh itself - are nontoxic as well as fairly inexpensive, notes OSU postdoctoral researcher Philip Brown.
If scaled up from the small sample of mesh created in their labs, it could be made for less than $1 a square foot - making it an ideal economical way to deal with oil spills, the researchers say.
"If you scale this up, you could potentially catch an oil spill with a net," says mechanical engineering Professor Bharat Bhushan.
So how does the mesh work?
Certain combinations of material layers can yield nanoparticles that will bind to oil instead of repelling it, Bushan says.
He has spent 10 years creating and patenting nano-scale structural coatings that copy the texture of the lotus leaf, improving the effects and tuning them to different applications.
Many surfaces in nature have provided inspiration to scientists and engineers, he points out.
"We've studied so many natural surfaces, from leaves to butterfly wings and shark skin, to understand how nature solves certain problems," Bhushan says. "Now we want to go beyond what nature does, in order to solve new problems."
There is a limit to what nature can do, Brown says, and research must help find new solutions.
"To repel synthetic materials like oils, we need to bring in another level of chemistry that nature doesn't have access to," he says.
A description of the mesh creation has been published in the journal Nature Scientific Reports.
