A new type of mesh has the ability to hold oil, while letting water pass through. The technique could be deployed on large scale to quickly arrest oil spills in the ocean and reduce the devastation that ensues.
Researchers in the U.S have developed a new type of stainless steel mesh that attracts and traps oil but lets water pass through. Lab tests conducted involving oil-water suspensions, proved highly successful, with the researchers easily collecting oil on top of the mesh, and tipping it into a beaker for disposal. The special oil-repelling coating on the mesh causes the oil to bead up and roll exactly where they need it to go, explained lead researcher and mechanical engineer Bharat Bhushan, from Ohio State University,
“If you scale this up, you could potentially catch an oil spill with a net. We got the idea from how a lotus leave functions – or rather, how it doesn’t function. Thanks to a specialised series of bumps on the surface of the leaves, the lotus plant is able to perfectly repel water, but not heavier, stickier drops of oil.”
Bhushan’s team needed to do the opposite, so they mimicked this bumpy surface texture by spraying drops of silica nanoparticles onto a piece of stainless steel mesh. Explaining how they one-upped nature, Philip Bowen, another member of the team shared,
“Nature reaches a limit of what it can do. To repel synthetic materials like oils, we need to bring in another level of chemistry that nature doesn’t have access to.”
So the team sought the help of surfactants – compounds that are commonly used active ingredients in detergents, soaps, emulsifiers, and foaming agents. The team coated this bumpy surface in an oil-repelling substance made from polymer molecules embedded with surfactants and watched as the mesh perfectly separated oil molecules from water molecules.
The secret in the seemingly simple design lies in figuring out the right combination of bumps and repellents. Over the past decade, they’ve discovered that certain combinations of the bumpy and oil-repelling layers can actually produce nanoparticles that would bind to the oil instead of repelling it, and even the minuscule shape of the nanoparticles had to be taken into account, as they could affect the way the oil was repelled.
So when can this super-mesh be deployed to protect from the oil-spills and their devastating aftereffects? Currently, the team is exploring the possibility of replacing the silica nanoparticles with tiny nanotubes – about a thousand times smaller than a single human hair – made from a compound called molybdenum disulfide. This chemical is known to bind well with oil, which means it could make the mesh capture oil modules more effectively.
The team has realized that the most practical and present-day need for their super-mesh is cleaning up oil spills. Hence they expect their product to be scaled up and deployed within the next 2-5 years.
[Image Credit | Jo McCulty, The Ohio State University, The Washington Post]