Bionic Textile Removes Oil From Water

2023 Author : Hannah Pearcy | [email protected] . Last modified: 2023-05-24 11:12

Researchers from the Universities of Bonn and Aachen and Heimbach-GmbH have developed a new method to remove oil contamination in water: textiles with special surface properties passively skim off the oil and transport it into a floating container. Scientists used surfaces from the plant kingdom as a model. The study has now been published in the journal "Philosophical Transactions A".

Transfer superhydrophobia to textiles

The swimming fern Salvinia is of great interest to scientists due to the special properties of its leaves. Because they are extremely afraid of water: when immersed, they wrap themselves in an air jacket and thus remain completely dry. Researchers call this behavior "superhydrophobic", which can be translated as "extremely water-repellent".

However, the Salvinia surface loves oil - in a sense, this is a downside of superhydrophobia. "The leaflets can therefore transport an oil film on their surface," explains Prof. Wilhelm Barthlott, emeritus of the University of Bonn. "And we were also able to transfer this property to technically producible surfaces, such as textiles."

The following video shows how a Salvinia leaf sucks oil from the water surface:

Functional textiles as "fat spoons"

Such superhydrophobic substances can then be used, for example, to remove oil films from water surfaces efficiently and without the use of chemicals . Unlike other materials that have been used for this purpose, they do not absorb the oil. "Instead, it drifts along the surface of the textile, driven solely by its adhesive forces," explains Barthlott.

“In the laboratory, for example, we hung such tapes over the edge of a container floating on the water. In a short time they had almost completely removed the oil from the surface of the water and transported it to the tank.”The drive is provided by gravity; the bottom of the tank must therefore be below the surface of the water with the oil film. "The oil is then completely skimmed off - like with an automatic fat spoon for the broth."

This makes superhydrophobic textiles interesting for environmental technology too . They promise a new solution to the pressing environmental problem of increasing oil pollution on water.

Reusable oil

The new process works without the use of chemicals. The oil is also simply sucked up by conventional binders and can then usually only be burned later. It is different with the superhydrophobia method: "The oil skimmed into the floating container is so clean that it can be reused , " explains Prof. Barthlott.

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Use for smaller soiling

Oil films floating on the water prevent gas exchange through the surface. On the other hand, they are dangerous for many plants and animals when in contact. Since oil films spread quickly over large surfaces, they can endanger entire ecosystems.

However, the process is not intended for large-scale oil spills like after a tanker accident. But even minor contamination - for example from motor oil from cars or ships, heating oil or leaks - is an urgent problem. "Even in stagnant or slow-flowing water, even small quantities pose a danger to the ecosystem," emphasizes the biologist. There he sees the main potential of the new method.