Oil spills are messy and harmful to local ecosystems—just ask anyone on the Louisiana coast. So far, there’s no foolproof way to clean them up, and some methods—like burning the oil—can result in even more pollution. Now, researchers have come up with a potential solution: reusable, oil-wicking sponges made of wood that can absorb more than 40 times their weight in oil.
To make the sponges, scientists started with balsa wood, a low-density material often used in model airplanes. The researchers used chemicals to break down the wood’s cell walls and remove the polymers, lignin and hemicellulose, that make it rigid and strong. The resulting highly porous “scaffold” had a density just one-third that of balsa wood. The researchers then topped the scaffold with a coating that repelled water but readily absorbed oil.
The team tested its sponges on a variety of oils—such as motor oil and the industrial solvent dichloromethane—dispersed in water. The sponges wicked up between 16 and 41 times their weight in oil and could be used as a filter to continuously remove oil from a solution (video above). What’s more, the sponges could be reused more than 10 times after they’ve been wrung out, the researchers report this month in ACS Nano.
These sponges are promising for cleaning up a real oil spill in the ocean, say researchers, though they still need to test their technology at scale.