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Chinese researchers have developed a method of removing oil from polluted water using tiny barbed spikes that mimic the natural design of a cactus. Writing in Nature Communications, the Beijing-based researchers describe how arrays of tiny copper spikes, similar to the cone-shaped spikes of a type of cactus known as Opuntia microdasys, are able to collect micron-sized oil droplets that might otherwise be difficult to remove from water.

The cactus opuntia microdasys. Photo credit: Wikimedia Commons

The copper spikes are extremely thin at their point but get wider as they get closer to the base, creating a pressure difference that pulls droplets of oil toward the artificial skin-like surface. The oil then coalesces at the base of the cone, which can then be removed from the water.

“Each conical needle in the array is a little oil collection device,” said Lei Jiang, lead author of the report.

In tests, the researchers found that the needle arrays were able to remove about 99 percent of oil content from water, suggesting that the design could lead to new methods of cleaning up oil spills.

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