Successfully developed stainless steel mesh for water to flow through and keep the oil in place

A research team at Ohio State University (The Ohio State University - OSU), USA, has built success that promises to make a big change in cleaning up the environment in the future. Thanks to an almost invisible layer of oil pushing on the surface, this filter allows water to flow through and keep the oil in place.

Successfully developed stainless steel mesh

In the experiments, the researchers poured the mixture of water and oil onto the filter. The water has flowed through and fallen into a glass cup below. Meanwhile, oil is filtered on the surface and can easily be poured into another glass by tilting the filter.

Image of a stainless steel mesh with oil-repellent coating.Oil (red) is retained on the mesh, while water can flow through.

The surface coating of the sieve is one of nature's nano-inspired technologies being developed by OSU and has been published in two papers published in Scientific Reports. This product promises to have many applications in oil spill cleanup as well as monitoring underground oil fields.

'If you enlarge the grid, you can handle an oil spill with just one net,' said Bharat Bhushan, a key member of the research team.

Inspired by lotus leaves with natural grainy surfaces that prevent them from sticking to water but oil, scientists have thought of creating a coating that can perform the opposite task. To do that, the team first sprayed a fine layer of silica nanoparticles (SiO ₂ ) onto a stainless steel mesh to create a random, grainy surface like that of a lotus leaf. Then, a polymer layer with surfactant molecules is coated on the surface. As a result, the net after coating has the characteristics of pushing oil but allowing water to pass through.

One of the important issues for a new material is the production cost. The good news is that according to Dr. Brown, another research team member, silica, surfactant, polymer and stainless steel are all non-toxic and relatively cheap materials, so calculating it takes less than 1 USD / 1 square foot (1 sf = 0.093m ² , about 10 USD for 1 m2) for a big net.

In terms of transparency, the team said that because the coating is only a few hundred nanometers thick, it is almost impossible to detect by normal senses. If you touch it, you will not feel the difference in the roughness of the covered mesh compared to the regular mesh. However, because the coating only has a transparency of 70%, the filter net after being coated will have a lower brightness for the uncoated.

An interesting information is to explain the choice of silica among materials to form a net, the team revealed that because silica is a component in glass, they wanted to try this technology. can it be used to create glass coatings that resist fingerprinting. Unfortunately, with a transparency of 70% as mentioned above, the coating can only be used in automotive glass, or mirrors, but it cannot be used to cover the screen of smartphones. However, because research is still ongoing, this may change in the future.

Professor Bhushan (in the middle) and his colleagues are proving the technology they develop

'Our goal is to reach 90% or more,' said Professor Bhushan. 'In all our overlays, different combinations of components in layers give different properties. The key is to choose the appropriate [cover] layers. '

It is known that this work has been started for more than 10 years before Bhushan began building and patenting nanostructured coatings that mimic the surface structure of the lotus leaf. Since then, he and his team have conducted studies to amplify the effects and adjust it to suit different situations.

'We have studied many surfaces naturally, from leaves to butterfly wings or shark skin to find out how to naturally solve certain problems . Now, we want to go. far beyond what nature does, to solve new problems , 'Professor Bhushan said when talking about his research.