MIT researchers devise technique to clean up oil spills using magnets

Possibly the only good thing to come out of the Deepwater Horizon disaster is the subsequent increase in research into finding more effective ways to clean up oil spills, including such initiatives as the X PRIZE Foundation’s Wendy Schmidt Oil Cleanup X CHALLENGE. Joining the list is a new method devised by researchers at MIT who propose separating oil and water using magnets. The new technique would allow the oil to be recovered to help offset the costs of the cleanup operation.
Oil isn’t magnetic, but suspending magnetic nanoparticles within the oil turns it into a magnetic liquid known as a ferrofluid. Previous research efforts using ferrofluids typically involved pumping a water-and-ferrofluid mixture through a channel with magnets on the outside directing the flow of the water one way and the flow of the ferrofluid another. However, this technique will work only if the concentration of the ferrofluid is known beforehand and remains constant – neither of which is possible in water contaminated by an oil spill.
For their approach, the MIT researchers made two modifications to the existing method. Instead of placing the magnets on the outside of the stream, they were immersed within it, and instead of being oriented parallel to the flow of the stream, they run perpendicular to it.
Because the magnetic field of the cylindrical permanent magnets used by the MIT team is strongest at its edges, the oil is attracted to the tips of the magnets much more strongly than the sides. And as the bottoms of the cylindrical magnets were embedded under the waterline in the base of a reservoir and the tops of the magnets were positioned above water level, the oil didn’t collect around them. Rather, it shot up the sides of the magnets to form beaded spheres at the top.