Inspired by water plants, researchers at the Karlsruhe Institute of Technology and Bonn University are developing new material that can clean up oil spills quickly and in an environmentally friendly manner.
Some water ferns are able to absorb large volumes of oil quickly, because their leaves are strongly water-repellent, and also highly oil-absorbing. The researchers found that this behaviour is due to the hairy microstructure of these plants' leaves, and are using that microstructure as a model to further develop new Nanofur material for cleaning up oil spills.
Conventional methods to clean up oil spills have various drawbacks. Burning the oil, or using chemicals to accelerate oil decomposition, cause secondary environmental pollution. Trying to soak up the oil using sawdust or plant fibres tend to be ineffective, since they also absorb large amounts of water.
However, some aquatic ferns are able to simultaneously repel water, but absorb oil. These include some species of ferns that reproduce quickly, and are considered weed in Europe.
According to researcher Claudia Zeiger, this is the first time researchers have studied these ferns' ability to absorb oil, and they found them to have considerable potential as low-cost, rapid, and environmentally friendly oil absorbers.
"The plants might be used in lakes to absorb accidental oil spills," Zeiger says.
The plants are allowed to absorb the oil and reach maximum absorption after less than 30 seconds, after which they can be skimmed off together with the absorbed oil. The researchers focused on a species of water plant called salvinia, which has trichomes on the leaf surface – hairy extensions of 0.3 to 2.5 mm in length.
Comparison of different salvinia species revealed that leaves with the longest hairs did not absorb the largest amounts of oil -- rather, the oil-absorbing capacity is determined by the shape of the hair ends.
The largest quantity of oil was absorbed by leaves of the water fern salvinia molesta, whose hair ends are shaped like an eggbeater.
With this knowledge, the researchers were able to make improvements on their 'Nanofur', which is made of plastic, but which mimics the water-repellent and oil-absorbing effect of salvinia to separate oil and water.