Oil spills are a very difficult problem. In addition to being catastrophic to the local environment, they are also incredibly difficult to clean up. After a spill occurs, some always stays on the surface while the rest forms heavy droplets and sink downwards, either becoming suspended in the water or falling to the bottom. Getting at these bits of the slick is difficult, and current methods are neither cost effective nor environmentally friendly themselves.
For example, the containment booms and chemical dispersants that BP used after the Deepwater Horizon spill were highly ineffective, as anyone who followed the news of the spill will recall. Because of that disaster, and others besides, numerous solutions have been proposed to deal with spills in the future – ranging from filters, to tiny submarines, and oil-eating bacteria.
But most recently, a group of researchers from the Chinese Academy of Sciences have suggested a nature-inspired solution. Their concept calls for droplet-collecting “skins” modeled after cactus plants. In the desert, these pants collect moisture when condensation covers the tips of their spines and then falls under its own weight to the base and gets absorbed by the plant.
Working from this, the Chinese researchers created their own “cactus skin” – artificial cone-shaped needles made of copper and coated in silicone that. When submerged in water, the half-millimeter spikes draw down oil droplets and collect them at the bottom. According to the researchers, the method is good for 99% of oil-water mixes and works with several types of oil.
Underwater, these structures mimic cacti and can capture micron-sized oil droplets and continuously transport them towards the base of the conical needles. Materials with this structure show obvious advantages in micron-sized oil collection with high continuity and high throughput.
The researchers think the device could also be used in the open air to remove fine droplets released with sprays. This way, they would be able to neutralize a good portion of oil released by malfunctioning rigs before it began polluting our oceans and waterways. On top of that, research at the Academy, specifically in the Institute of Chemistry, has revealed that this same concept might provide a solution to the problem of city pollution.
Between all of this, we could be seeing artificial cactuses in city environments very soon. Just not as potted plants and in the desert! And it does say much about our biomimetic future, where we are becoming increasingly dependent on solutions born of nature to solve our environmental problems.