A sponge for mopping up spilled oil?

According to a paper published recently in a Nature online report, researchers at Rice University and Penn State University have discovered a technology for developing a reusable sponge for mopping up oil spilled in water. The technology involves the addition of small amounts of boron to microscopic carbon tubes called nanotubes, to form spongy blocks that repel water but readily absorb oil.

In laboratory-scale tests the scientists have floated a sponge made from the material on water, to absorb motor oil floating on the water. After removal of the sponge from the water, the oil can be stored in the sponge, burned off, or expelled by squeezing the sponge. The sponge can be re-used repeatedly and has been shown to remain elastic after as many as 10,000 compressions, the researchers say.

Apparently the sponge can absorb more than 100 times its weight in oil.

“They’re super low density, so the available volume is large,” said Daniel Hashim, the lead author of the report. “That’s why the uptake of oil can be so large.”

The researchers found that the use of boron provided the key to connecting nanotubes into lattice-like blocks by inducing the nanotubes to bond at an atomic level to form a complex tangled network.

But can the resulting sponge-like material be scaled up for use in, for example, an offshore oil spill response?

The researchers say that they are investigating ways of making large sheets of the sponge, or welding smaller pieces of sponge together.

Other potential uses for the material include the manufacture of lightweight batteries, the construction of scaffolds for bone-tissue regeneration and perhaps the fabrication of polymers for aircraft and automobile construction, the researchers say.

—Alan Bailey