Researchers at the Institute of Materials Science of Madrid (ICMM), part of Spain's CSIC, have developed flower-shaped iron oxide nanoparticles that can capture nanoplastics from water and then convert them into tools for removing other pollutants. The work, published in the Chemical Engineering Journal, marks a step toward a circular economy for plastic waste.
Nanoplastics are fragments a thousand times smaller than microplastics, measuring about a billionth of a metre. They originate from the breakdown of PET—the material used in bottles, packaging, and polyester clothing—through sunlight and physical wear. Once released into the environment, they contaminate soils and water sources across Europe and beyond.
The key to the new technique lies in the shape of the nanoparticles. "Iron oxide is a magnetic material that makes it possible to trap many pollutants at once. On top of that, its nanoflower structure means that the particles have several nuclei that work together to enhance their magnetic properties," explains Álvaro Gallo-Córdova, a researcher at ICMM-CSIC and one of the lead authors, alongside Rafael Herrera-Aquino and María del Puerto Morales.
From cosmetics microplastics to PET nanoplastics
This is not the first application of these particles. In 2024, the same team used them to extract and break down microplastics—between 0.001 and 5 millimetres in size—that come from cosmetics. The new work scales the approach down to nanoplastics, which are far more difficult to remove due to their tiny size.
"When they reach the end of their useful life, a large share of PET plastics ends up in the environment, where sunlight and physical wear act like sandpaper, grinding them down into nanoplastics, a kind of ultra-fine dust that contaminates our soils and water sources," adds Gallo-Córdova.
According to the team, just one gram of these magnetic nanoflowers can capture up to 10,000 milligrams of nanoplastics—a capacity they describe as unprecedented.
Turning waste into a cleaning agent
The process does not stop at capture. Once the nanoplastic is trapped, the researchers transform it into a magnetic material that can extract heavy metals or organic dyes from water. It can also be used in catalytic degradation processes.
"After capturing the nanoplastics with our magnetic nanoparticles, we turn them into functional materials, transforming a polluting waste into a new raw material within a circular-economy approach," says Gallo-Córdova. In effect, the plastic waste itself becomes a tool to clean up other pollution.
The method is energy-efficient because magnetic heating acts locally on the nanoparticle surface, avoiding the need to heat the entire water volume. The nanoflowers also proved durable: after five cycles, they retained 88% of their decontamination capacity and released less than 0.82% of their initial iron content, confirming their stability and reusability.
The ICMM-CSIC team now plans to apply the technology to advanced water treatment, a field of growing importance as European rivers and aquifers face increasing contamination from microplastics and nanoplastics. Similar concerns have driven other innovations, such as magnetic micro-robots for medical applications, showing the versatility of magnetic nanoparticles.
While the research is still at an early stage, the potential for scaling up is significant. If the nanoflowers can be produced in large quantities, they could be deployed in wastewater treatment plants across the continent, helping to address the pervasive issue of plastic pollution in European waterways.
