'Super-sponge' made from sawdust to clean up oil spills

Scientists have created the ideal nontoxic 'super-sponge' for cleaning oil spills in the icy, turbulent waters of the Arctic, by chemically modifying sawdust to make it exceptionally oil-attracting and buoyant.
Containing oil spills in cold waters is especially tricky, as bobbing ice chunks push oil below the water's surface, making it difficult to collect. The same goes for rough waters, whose tall, clashing waves disperse oil.
The new nontoxic material absorbs up to five times its weight in oil and stays afloat for at least four months.
"Most of today's oil remediation materials are designed for warm water use," said George Bonheyo, from the US Department of Energy's Pacific Northwest National Laboratory (PNNL).

"But as ice retreats in the Arctic Sea, fossil fuel developers are looking north, and we need new oil spill response methods that perform well in extreme conditions," said Bonheyo, who leads the modified sawdust's development from PNNL's Marine Sciences Laboratory.
"The chance of an oil spill in the Arctic is real. We hope materials like our modified sawdust can help if an accident happens," said PNNL microbiologist Robert Jeters, who is also part of the project.

The modified saw dust pulls double duty. Beyond absorbing oil, it also enhances another approach to combatting oil spills - controlled burns.
If changing weather or tides move spilled oil towards a sensitive area fast, oil can be burned before it can cause further harm.

Called in-situ burning, the practice can significantly reduce the amount of oil in water and minimise its adverse environmental effects.
Researchers looked to develop an environmentally friendly and inexpensive material that floats despite rough or freezing waters and can support in-situ burning.
Not wanting to create more pollution if emergency responders can not retrieve oil cleanup material, they considered other natural ingredients like rice hulls and silica.
They ultimately found their winner in a fine dust called wood flour. A woodworking byproduct, wood flour is often used to make wood composites.
To make the dust into a thirsty oil mop, researchers chemically attached components of vegetable oil onto the material's surface.

These attachments make the modified material oil-grabbing and water-shunning. The final product is a light, fluffy, bleached powder.
The team is also trying out adding tiny, oil-eating microbes - fungi and bacteria - to the powder's surface so any left-behind material could naturally break down oil over time.
Applying the modified sawdust is simple: sprinkle a thin layer over oil on the water's surface.
The material immediately starts soaking up oil, creating a concentrated and solid slick that stays afloat thanks to the material's buoyant nature. The oil-soaked material can either be burned or retrieved.