An army of tiny magnetic coils could dissolve microplastics from water, and possibly help us clean up waterways and oceans.
Microplastics are used in all sorts of cosmetics and household products, and they have spread into the ocean. Once there, they they can damage the environment. For instance, they can be听ingested by marine life.
Some people have suggested ways of getting plastic out of the ocean, including a team for the Netherlands that wants to use a string of sausage-shaped floats to trap substantial pieces of plastic that float. But microplastic is so small that it is much more difficult to tackle.
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Now lab tests have demonstrated a way to dissolve microplastic and turn it into carbon dioxide and water. This would release greenhouse gas, so it is far from perfect. But it would help avoid some of the damage plastic does to the environment.
The method involves putting microscopic metal coils into water along with a chemical called peroxymonosulfate. A chemical reaction between the two creates compounds called radicals, which then break down the plastic.
The fact that the coils are magnetic doesn鈥檛 help the reaction work. However, it means they can be easily removed from the water 鈥� just wave over a larger magnet. 鈥淭hey can be used multiple times without significantly losing their reactability,鈥� says Xiaoguang Duan at the University of Adelaide in Australia, who led the work.
In their tests, Duan and his team put 80 ml of water containing microplastics from cosmetic products in a pressurised container along with the coils and peroxymonosulfate. Then they heated the water to 120 degrees Celsius. After 8 hours, the mass of microplastics had decreased by half.
Cleaning up
Duan says he ultimately hopes to use his process to clean the outflows from water treatment plants. This would stop microplastics from getting into the ocean. Before that, he says he will test it on larger volumes of water and on different types of microplastic.
鈥淚t鈥檚 interesting that people are now looking at remediation potential, but it鈥檚 still very academic,鈥� says Caroline Gauchotte-Lindsay of the University of Glasgow. 鈥淚t鈥檚 a nice approach, but I think it鈥檚 a long way away.鈥� She worries that the technology would be expensive, has only been tested under lab conditions, and requires heating the water to get maximum efficiency.
Matter
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