ICMM-CSIC creates a method that captures nanoplastics from water and converts them into materials for decontaminating heavy metals

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A study published in Chemical Engineering Journal demonstrates that iron oxide nanoflowers designed at the Madrid Institute of Materials Science (ICMM), a center of the Spanish National Research Council (CSIC), are capable of capturing particles the size of one millionth of a millimeter (nanoplastics) from PET plastics, one of the most widely used materials in the manufacture of bottles, packaging and clothing. In addition, the research team has managed to adhere these nanoflowers to the captured plastic waste, creating a new magnetic platform capable of adsorbing other contaminating substances such as heavy metals and organic dyes.

Currently, waste treatment plants use macro-scale processes at high cost. With the aim of improving the efficiency of these processes, ICMM researchers developed iron oxide nanoparticles in the form of nanoflowers, which are eco-friendly and reusable.

"Iron oxide is a magnetic material that allows many contaminants to be trapped at once. Furthermore, its flower-like structure allows the particles to have multiple nuclei that cooperate to improve their magnetic properties," explains Álvaro Gallo-Córdova, ICMM-CSIC researcher and one of the main authors of the work together with Rafael Herrera-Aquino and María del Puerto Morales, also from ICMM-CSIC. As a result, the developed nanoparticles already demonstrated in 2024 their ability to extract and degrade microplastics—between 0.001 and 5 millimeters—from water originating from cosmetics.

Now, the new study shows that the iron oxide nanoflowers are capable of capturing nanoplastics, with a size equivalent to one billionth of a meter and, therefore, a thousand times smaller than conventional microplastics. A single gram of these magnetic nanoflowers is capable of capturing up to 10,000 milligrams of nanoplastics, "a figure not seen until now," highlights Gallo-Córdova.

This technique has been used to capture PET nanoplastics (polyethylene terephthalate), one of the most widely used materials in the world, present, for example, in bottles, food packaging and polyester textile fibers. "When they reach the end of their useful life, a large part of PET plastics ends up in the environment, where sunlight and physical wear act like sandpaper that grinds them down and turns them into nanoplastics, a kind of very fine dust that contaminates our soils and water sources," adds the researcher.

Nanoplastics repurposed as decontaminants

The ICMM-CSIC work is not limited to capturing nanoplastics, but goes further and transforms them into magnetic materials capable of extracting other pollutants, such as heavy metals or organic dyes present in water. "After capturing the nanoplastics using our magnetic nanoparticles, we upcycle them into functional materials, transforming a polluting waste into a new raw material within a circular economy approach."

The magnetic nanoflowers use magnets to adhere to the surface of the nanoplastics. This is how magnetic hybrid materials are formed that incorporate the plastic waste into their structure and functionality. Thanks to this integration, the resulting material combines magnetic properties with the ability to adsorb other pollutants, and even to participate in catalytic degradation processes.

In other words, "we use the pollutant itself to help remove other pollutants, closing the loop and giving a second life to a waste that would normally be considered discarded," highlights Gallo-Córdova. According to the researcher, the process used consumes very little energy because magnetic heating acts locally: it generates heat right on the surface of the nanoparticles, without the need to raise the temperature of the entire aqueous medium, which saves energy. Furthermore, the material withstands repeated use over time: after five cycles of use, it retained 88% of its decontaminating capacity and released less than 0.82% of the initial iron content into the water, confirming its stable, reusable and safe properties.

The results of this study open new opportunities to transform plastic nanowaste into decontaminating platforms. "Our work suggests a path toward circular strategies in which plastic waste could be reused in environmental technologies, such as advanced water treatment," concludes the researcher. 

Reference:

Rafael Herrera-Aquino, Fernanda Lyzeth Rivera, Carlos Díaz-Ufano, Lucía Gutiérrez, Sabino Veintemillas-Verdaguer, María del Puerto Morales, Alvaro Gallo-Cordova. Magnetic capture and process-oriented upcycling of PET nanoplastics enabled by mesocrystalline iron oxide nanoflowers. Chemical Engineering Journal. DOI:  10.1016/j.cej.2026.179081