Nano-objects are the latest craze in scientific research, and it’s no wonder given the number of applications they could be useful for, such as drug delivery systems, lasers, data storage and photovoltaics. And now, scientists are exploiting nanoparticles in order to help clean up the environment.
Researchers from Ohio State University have coated a piece of stainless steel mesh with microscopic particles that repel oil but not water. The resulting material allows only water from water-oil mixtures to pass through, leaving the oil to gather on top so that it can easily be collected and removed. This promising new design could have a range of potential uses if it can be scaled up, such as mopping up oil spills or even detecting oil underground. The results have been published in Nature.
Nature often has the answer to many of man’s problems. Lotus leaves, for example, are very good at repelling water, but not oil, thanks to the bumpy microarchitecture on the surface of their leaves. Scientists therefore decided to use these as inspiration to develop a material that does the opposite. They came up with the idea of coating a similarly uneven surface with molecules that had surfactants stuck to them, which are commonly used as detergents.
To produce this rough surface, the team sprayed a stainless steel mesh with silica nanoparticles, and then added layers of the surfactant-tagged molecules on top. According to the researchers, these materials were chosen because they are both affordable and non-toxic. Although they have only made small squares of the material so far, the team believes they could produce larger meshes at the low cost of $1 per square foot.
During their investigation, the researchers also discovered that just by adjusting the combination of layers, they could produce nanoparticles that attract oil as opposed to repelling it, which would be useful for tracking underground oil deposits.
“We’ve studied so many natural surfaces, from leaves to butterfly wings and shark skin, to understand how nature solves certain problems,” study author Bharat Bhushan said in a news release. “Now we want to go beyond what nature does, in order to solve new problems.”
Colleague and co-author Philip Brown agrees with Bhushan: “Nature reaches a limit of what it can do,” he says. “To repel synthetic materials like oils, we need to bring in another level of chemistry that nature doesn’t have access to.”