A new technique can extract oil from fouled beaches, and is also a more environmentally friendly way of exploiting tar sands, says a team of researchers at Penn State University.
The method uses ionic liquids to separate the oil from sand.
Oil sands represent as much as two-thirds of the world’s estimated oil reserves - but extracting oil from them comes at a high environmental cost. Much of the damage comes from the storage of contaminated wastewater from the separation process in large open-air ponds.
Wastewater from these can seep into groundwater and pollute lakes and rivers.
In contrast, the Penn State separation method uses very little energy and water, and all solvents are recycled and reused. It uses ionic liquids - salt in a liquid state - to facilitate separation.
"Essentially, all of the bitumen is recovered in a very clean form, without any contamination from the ionic liquids," says Paul Painter, professor of polymer science.
"Because the bitumen, solvents and sand/clay mixture separate into three distinct phases, each can be removed separately and the solvent can be reused."
The process can also be used to extract oil and tar from beach sand after oil spills, such as the Deepwater Horizon incident. Unlike other methods of cleanup, says the team, itcompletely removes the hydrocarbons, and the cleaned sand can be returned to the beach instead of being sent to landfill.
In an experiment using sand polluted by the BP oil spill, the team was able to separate out the hydrocarbons in seconds. The small amount of water required to clean the remaining ionic liquids was cleanly recovered.
"It was so clean you could toss it back on the beach. Plus, the only extra energy you need is enough to stir the mixture," says team member Aron Lupinsky.
The researchers have built a functioning bench top model system, and are working towards a patent.