With fingers crossed that the Gulf oil spill is finally quenched, responders still must deal with the remainder of the estimated 5 million barrels of oil released into the Gulf since late April when the spill began.
A material in development could help recover spilled oil by solidifying it into a solid gel floating on the ocean's surface. Oil in a solid state could be scooped away like fat congealed on the top of a pot of soup. The gel could then be melted and the oil separated from the material, which could be reused.
The material will not be ready to help with the oil spill caused by the Deepwater Horizon disaster, its developers said. So far, it has only been tested in the laboratory. Larger scale experiments are needed to examine its safety, effectiveness and cost in a full-scale oil spill.
A team led by George John of the City College of New York and Srinivasa Raghavan of the University of Maryland developed the compound — a soap-like molecule consisting of an oil-loving chain of atoms linked to a type of sugar molecule.
When John's team sprays a solution containing the molecule onto a mixture of diesel fuel and seawater, it creates a strong gel within minutes that completely incorporates the oil.
"The gelling is happening instantaneously," John said.
When they hit water, the molecules create a sponge-like network of fibers that strongly attract oil and repel water. The oil is drawn into the fiber network, swelling the "sponge." The resulting oil-swollen gel is strong enough to be scooped up with a slotted spoon.
The team, who presented the findings in the journal Angewandte Chemie, International Edition, plans to test crude oil next.
This is not the first material made that can solidify oil, John said, but others have drawbacks, including requiring more material to effectively capture the oil.
Another problem with other solidifiers, according to chemist Ed Overton of Louisiana State University in Baton Rouge, who has been extensively involved in the Gulf spill, is that they can sometimes sink, carrying the oil with them into oxygen-free depths where degradation is very slow.
This should not be a problem for his team's approach, John said, because the molecules are smaller than traditional solidifiers. The gels have shown no signs of sinking in laboratory experiments, he said.
"We should always be open to new ways to mitigate an oil spill. And in certain situations, these solidifiers can be quite useful," Overton said. "But large-scale use must be very carefully evaluated for unintended consequences."
Indeed, another approach to mitigating the spill, the use of dispersants to break the oil into smaller droplets, proved controversial over concerns that the dispersants themselves may be toxic to sea life.
The new material is made of non-toxic components used in food, John said. Also, because the material becomes part of the gel, it would be recovered when the gel is scooped up.
This would also allow the material to be reused, John said, which should help reduce cost. Heating the gel melts the sponge-like network, releasing the oil, which can then be distilled away and used, while the material remains behind. "We recovered the oil and we recovered the molecule," he said.
For now, the material is expensive because it is only made in small quantities. It is not difficult to synthesize, however, so it should be possible to make more cheaply, John said.
Larger scale experiments are still necessary to determine how the material would behave outside the laboratory in a real spill situation, he said.