Low-cost method removes micro- and nanoplastics from water

Researchers at the University of S?o Paulo (USP) in Brazil have developed a novel nanotechnology-based solution for the removal of micro- and nanoplastics from water. Their research is published in the journal Micron.

"Nanoparticles aren't visible to the naked eye or detectable using conventional microscopes, so they're very hard to identify and remove from water treatment systems," said Henrique Eisi Toma, a professor at the Institute of Chemistry (IQ-USP) and last author of the Micron article.

The procedure developed at USP uses magnetic nanoparticles functionalized with polydopamine, a polymer derived from dopamine, a neurotransmitter present in the human organism. These nanoparticles can bind to micro- and nanoplastic waste, and the combined particles can then be removed from water via application of a magnetic field.

"Polydopamine is a substance that mimics the adhesive properties of mussels, which cling very tenaciously to many surfaces. It adheres firmly to fragments of plastic in water and enables the magnetic nanoparticles to capture them. This undesirable material can then be removed from the water with a magnet," Toma said.

In the study led by Toma, magnetic nanoparticles of iron (II, III) oxide, or black iron oxide (Fe3O4), were synthesized by co-precipitation and later coated with polydopamine (PDA) by partially oxidizing dopamine in a mildly alkaline solution to form Fe3O4@PDA. Lipase was immobilized on this substrate. Hyperspectral Raman microscopy was used to monitor sequestration and degradation of the plastic in real time.

Image source: Henrique Eisi Toma.