Fionn & Co.
A company Fionn founded in 2020 to take the magnetic-liquid method he developed for removing microplastics out of the lab and into the world.
Where things stand
Fionn founded Fionn & Co. in 2020. He is no longer involved in the company and has no role in its work, so nothing on this page should be read as speaking for it.
What’s kept here is the part that belongs to the research itself: how the microplastics problem is shaped, and how the extraction method works. Fionn’s current work is at the Green Journey Coalition.
In the Press
European Patent Office feature
European Patent Office · 2023 · Fionn Ferreira on removing microplastics from water
The Problem
What are microplastics,
and why do they matter?
Since mass plastic production began in the 1950s, humanity has made over nine billion tonnes of the stuff — most of which still exists in some form today. Plastic doesn’t biodegrade; it just breaks into smaller and smaller pieces, small enough to evade most existing water treatment and detection infrastructure. That gap — between the scale of the problem and the state of the tools for it — is what the work below was aimed at.
A matter of scale
> 25 mm
Macroplastics
Roughly a bottle cap, or larger
5 mm – 1 µm
Microplastics
From a grain of sand down to a human hair
< 1 µm
Nanoplastics
Smaller than a red blood cell — invisible under a standard microscope
Where they come from
Microplastics are usually split into two categories: primary particles, manufactured small from the start, and secondary particles, formed when larger plastic items break down. Five sources account for most of what ends up in the environment.
Synthetic textiles
A single laundry load can shed hundreds of thousands of microfibres from polyester, nylon, and acrylic clothing — thought to be the largest source of primary microplastics reaching the ocean.
Tyre wear
Every time a car brakes, corners, or accelerates it sheds particles of synthetic rubber. Tyre wear is estimated to be the single largest source of microplastics released into the environment overall.
Personal care products
Exfoliating microbeads in scrubs, toothpaste, and cosmetics have been phased out in some countries, but remain legal and common elsewhere.
Industrial pellets
Raw plastic "nurdles" spilled during manufacturing, shipping, and handling — an under-reported source of pollution concentrated near ports and production sites.
Breakdown of larger debris
UV light, waves, and abrasion slowly fragment bottles, bags, and packaging into ever-smaller pieces. This "secondary" pathway accounts for most of the microplastic mass already in the environment.
The full journey
From source, to environment, to the food chain, to the human body — every stage of this journey is a point where a removal or detection method can intervene.
Stage 1
Source
Textiles, tyres, cosmetics, industrial pellets, and the slow breakdown of larger plastic debris.
Stage 2
Environment
Carried into oceans, soil, drinking water, and the air — settling almost everywhere on Earth.
Stage 3
Food chain
Taken up into seafood, salt, and produce — the food and water people consume every day.
Stage 4
Human body
Detected in blood, lungs, and placental tissue — and, per a 2024 study, in arterial plaque.
The Science
How the method removes
microplastics from water.
It started with a simple discovery Fionn made at 16: a magnetic liquid that binds to microplastic particles suspended in water. That result won the 2019 Google Science Fair, and it was the reason the company was founded a year later.
The principle is straightforward: a non-toxic magnetic liquid is mixed into contaminated water, where it attaches to microplastic particles rather than to the water itself. Because the liquid is magnetic, all it takes to pull the plastic back out again is a magnet.
Step 1
Contaminated sample
Water carrying microplastic fragments and fibres — from a waterway, a wastewater outflow, or a lab test rig.
Step 2
Add the magnetic liquid
A proprietary, non-toxic magnetic liquid is mixed into the sample.
Step 3
Liquid binds to plastic
The magnetic liquid preferentially binds to microplastic particles rather than the surrounding water. The exact chemistry is part of our IP.
Step 4
Magnetic extraction
Because the liquid is magnetic, a magnet draws the plastic-laden clusters straight out of the water.
Step 5
Clean water, recovered plastic
What's left behind is cleaner water — and a concentrated, magnet-collected sample of plastic ready to be counted, identified, or disposed of.
In prototype testing, the method achieved 95%+ extraction of microplastics from water across a range of common polymer types. Fionn continues to work on microplastic detection and removal — independently of the company — through the Green Journey Coalition.
Founder
Fionn Ferreira
Founder, 2020 — no longer involved
Fionn grew up in Ballydehob, West Cork, the son of two boatbuilders — kayaking the Atlantic coastline and watching the tide bring in more plastic every year. At 16, he discovered that a magnetic liquid could bind to microplastic particles and pull them out of water with a magnet, winning the 2019 Google Science Fair Global Grand Prize against 2,000+ projects from 80+ countries.
Since then he’s taken the microplastics crisis to the World Economic Forum in Davos and the House of Lords in London, been named to Forbes 30 Under 30 and a National Geographic Explorer, and worked as a TV presenter, fluent in five languages. He continues to work on microplastic detection and removal, and on getting more young people into science.