The difficulty of cleaning up oil spills could be refined if only the oil were magnetic. How do you make oil magnetic? With water-repellent nanoparticles made of iron, say a team of electrical engineers from MIT.
The first difficulty is isolating the spill so that the magnetic nanoparticles do not escape into the environment, creating a secondary spill.
But once that is done, turning the oil into a so-called ferrofluid is as simple as adding magnetic nanoparticles to the mix of water and oil. Because the magnetic nanoparticles are water repellant, they will stay with the oil and can then be used to separate the oil away from the water.
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Previous experiments with separating magnetic fluid from water ran into trouble if the concentration of magnetic fluid was unknown or changed during the process. The previous techniques typically separated the fluid into two channels, where magnets were placed along one side. When the concentrations weren't near 50:50 however, either one of the channels could become inundated with the wrong type of fluid.
The team at MIT have worked around the separation problem by embedding cylindrical magnets into the stream of the flow like pillars, with half the magnet above the flow. The oil with the iron nanoparticles would crawl up out of the water and collect at the top of the magnets.
The team, led by Shahriar Khushrushahi, a post-doc at MIT, have filed two patents on their work. They say once the magnetic oil is collected, the nanoparticles can be removed and re-used and the oil sent for processing.
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The engineers are confident the entire process could be done on board a ship over several days at sea. Ronald Rosensweig, a former Exxon researcher and a pioneer in the study of ferrofluids, agreed that the adding the magnetic nanoparticles to collected water from a spill to turn the oil magnetic would be "no problem" on board a ship.