Nature and Biodiversity

Meet the teen science star using magnetic liquid to remove microplastics from water

A scientist uses a magnifying glass to look at sea sample taken from the Mediterraneean Sea as part of a scientific study about microplastics damaging marine ecosystems, at the Villefranche Oceanographic Laboratory (LOV), in Villefranche-Sur-Mer on the French Riviera, France, October 19, 2018. Picture taken October 19, 2018. REUTERS/Eric Gaillard - RC18ECF017F0

Ferreira tried his experiment out on 10 different types of plastic Image: REUTERS/Eric Gaillard

Sean Fleming
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Plastic Pollution

This article is part of: World Economic Forum Annual Meeting
  • Irish teenager Fionn Ferreira developed a technique to remove microplastics from water using oil and rust.
  • His idea won at the 2019 Google Science Fair.
  • He now wants to scale his idea to be used in industry.
  • He’s one of 10 young change-makers attending the 2020 World Economic Forum Annual Meeting in Davos.

Kayaking around the craggy shores of West Cork, in a remote corner of Ireland, Fionn Ferreira’s eye was drawn to the amount of plastic pollution being washed in by the Atlantic.

He decided to do something about it. Along the way, he was awarded $50,000 when his idea won the 2019 Google Science Fair. And now he’s one of 10 young change-makers attending the World Economic Forum Annual Meeting in Davos to help foster intergenerational collaboration.

Fionn’s idea was to combine vegetable oil and rust powder and create a ferrofluid – a liquid that acts as a carrier for tiny particles of a magnetic substance. That fluid, he thought, could then be used to capture and extract microplastic particles from water. He was right.

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In more than 1,000 tests, Ferreira’s ferrofluid had an 87% success rate at removing plastic particles of less than 2 mm diameter from water. He even built his own visible light spectrometer so he could accurately measure the density of microplastic in his test solutions.

He used a magnet to extract the plastic from the water – the microplastic had bound itself to the rust powder, meaning that when the rust clung to the magnet the plastic was carried along too.


What is the World Economic Forum doing about plastic pollution?

Stopping the problem at its source

Ferreira tried his experiment out on 10 different types of plastic, including PET, PVA, and fibres from a washing machine, and performed more than 200 separate extractions.

He had expected a reduction in the amount of plastic by at least 85% and in the experiments that turned out to be the case. But he also determined that the use of oil made no significant statistical difference to the success rate, so in future he’ll be creating a ferrofluid without the oil base.

Average % decrease in plastics by plastic type.
Ferreira’s experiments proved successful with a wide range of plastics. Image: Fionn Ferreira

Ferrofluids have been tested as a possible tool for cleaning up oil spills in the ocean, following leaks from pipelines or ships. Early signs are encouraging and pilot projects are under way to see if this is an approach that will work at the size and scale of an ocean oil slick.

While that inspired some of Ferreira’s thinking, he thinks his invention’s future lies away from the ocean, capturing microplastics from wastewater before it reaches the sea. Constructing a ferrofluid-based microplastic-capture system for use in water treatment and sewage facilities could be one route.

Scaling up from the lab

Tackling microplastic pollution isn’t the only string to Ferreira’s bow. When he isn’t studying chemistry at the University of Groningen in the Netherlands, he plays the trumpet at orchestra level. He has given more than 300 planetarium lectures, and even has a planet named after him.

But it’s Ferreira’s experiments into extracting microplastics from water that catapulted him into the limelight.


The benefits of plastic for wrapping sterile medical products, keeping food fresh, and more are evident. But more collective action must be taken to ensure its responsible disposal.

Some studies estimate the ocean is contaminated by as many as 8.3 million pieces of microplastic per cubic metre of water. These tiny particles, no bigger than dust in many cases, can end up in the global food chain.

Small fish, such as anchovies, eat these tiny pieces of plastic, and are in turn eaten by larger fish – not to mention humans. The effects and consequences of this have yet to be fully examined – but it further amplifies the need to identify solutions to the problem of marine plastic pollution.

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