It’s an attractive idea. Magnets could be used to pull oil from spills out of the water, with the help of iron oxide nanoparticles.
The stickiness of oil makes it difficult to remove from marine plants and animals once it is leaked by tankers and offshore rigs, so finding a way to quickly remove spills is essential for protecting ocean environments.
Now Yi Du at the University of Wollongong and his team have found a way to do this, using tiny particles of iron oxide that bind tightly to droplets of oil.
When added to small water tanks polluted with oil, these 25-nanometre-wide particles turn the oil into a magnetic liquid that can be drawn towards a simple bar magnet.
Du envisages sprinkling these particles over oil spills in the ocean, with them sticking to both lighter oils floating on the surface and heavier ones that have sunk. “Then, ships with small magnets could move around the spill, and all the oil would be sucked towards the magnets and collected,” he says.
The particles are non-toxic, and any excess could be hoovered up with magnets and reused, Du says. “Iron oxide nanoparticles are already commonly used in medical imaging, so we know they’re safe,” he says.
The idea is promising, but how practical it will be in real ocean oil spills is uncertain, says Orlin Velev of North Carolina State University in Raleigh. “A key issue is making sure the droplets can be collected efficiently and completely,” he says.
The team is now planning to test the magnetic nanoparticles in larger tank experiments, before seeking permission to trial them in open water.