How Magnetism could be used to Clear Oil Spills from the Sea

Increasing the amount of oil drilling and oil shipping will inevitably result in more oil spills. Existing methods of cleaning up oil spills are not adequate to the task. Magnetic nanotechnology could be the solution.

Why existing methods of clearing oil spills are limited

Existing ways of cleaning up oil spills rely on a combination of dispersants and burning off concentrated surface oil. Even with absorptive drums, there is very little oil recovery.

Most of these techniques may cause as much long-term damage to the environment as the short-term damage they mitigate. Gathering surface oil with booms and burning it creates huge clouds of toxic smoke. It also leaves untouched most of the spilled oil, which can’t be concentrated on the surface with booms.

Dispersants disrupt the ability of local organisms to adapt to environmental changes. They make the oil much more toxic to local organisms than it would have been on its own. When applied in a deepwater setting, as in the Deepwater Horizon spill, they also do not get rid of the oil itself. Instead, both the dispersant and the oil linger in the water column for an undetermined period of time.

Only absorptive drums do not cause separate environmental harm. Unfortunately, these drums also have low recovery rates.

A new way to clean up oil spills

An MIT research team led by Shahriar Khushrushahi has developed a new way to clean up oil spills using magnetic nanotechnology. With this technique, the nanotechnology could be retrieved, along with much of the oil. If this or any related techniques could be established on a large scale, it would greatly reduce the cost of cleaning up oil spills.

The new technology uses water-repellent ferrous nanoparticles. When these particles are mixed in with the oil, they attach to the oil and repel the water. The nanoparticles could then be retrieved using magnets, bringing the oil with them. Multiple passes may be necessary to remove all the oil from the water.

All recovered ferrous nanoparticles would be completely reusable. Magnetism doesn’t run down.

The authors expect that the oil-water mixture could be brought on board an oil-recovery boat. This should enable the nanoparticles to be kept isolated from the environment, as well as increasing the recoverability of the nanoparticles. However, there is still a strong chance that some of the ferrofluid could escape into the environment, either with the recovered oil or with the newly-cleaned water.

Previous research on magnetic particles and ferrofluids

This discovery builds on earlier research which developed the world’s first magnetic soap in September 2012. Whereas the Bristol, United Kingdom, technique uses iron salts which are dissolved in water, the MIT technique uses synthetic magnetic nanoparticles roughly 10 nanometers in size.

Even earlier research in the same field goes back as far as patents filed in 1972. Most of these approaches required branching channels with magnets alongside the branch. For this approach to work fully, the concentration of the oil must be known and must remain constant. In most oil spills, the oil concentration is constantly fluctuating and can’t be known with precision.

One of the MIT team’s innovations is to immerse magnets in the stream and orient them perpendicularly to the flow of the stream. This should enable the technique to work even when the concentration of oil is not known. So far, the team has filed two patents on its technique.