How nanotechnology is fighting microplastic pollution

Microplastics and nanoplastics have emerged as pressing global concerns, capturing significant scientific attention and driving advancements in nanotechnology that is aimed at addressing their pervasive presence in the environment.

These minute particles infiltrate our air, water, and soil, and even make their way into the bodies of animals and humans.

Originating from everyday consumer products and the breakdown of larger plastic materials, they represent an unseen environmental foe with potentially far-reaching impacts on ecosystems and human health.

The hidden dangers of nanoplastics

Microplastics, defined as fragments smaller than 5 mm in diameter, are already recognized as a major issue.

However, nanoplastics, which are nearly a thousand times smaller, pose an even more insidious threat.

These particles can bypass biological barriers and infiltrate the vital organs of living creatures. Alarmingly, recent research has even detected nanoplastics in the human brain.

Study senior author Henrique Eisi Toma is a professor in the Institute of Chemistry at the University of São Paulo (IQ-USP).

“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 Professor Toma.

Nanotechnology solutions for plastic pollution

Researchers at USP, with support from FAPESP, have developed a novel solution using nanotechnology.

The team, led by Professor Toma, created a low-cost method employing magnetic nanoparticles functionalized with polydopamine (PDA), a polymer derived from dopamine which is a neurotransmitter present in the human body.

These nanoparticles bind to micro- and nanoplastic waste, allowing for their removal through the application of a magnetic field.

“Polydopamine is a substance that mimics the adhesive properties of mussels, which cling very tenaciously to many surfaces,” noted Toma.

“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.”

Striving for plastic degradation

The research team aims for more than just the removal of these particles; they are also exploring methods for sustainable degradation.

By immobilizing lipase, an enzyme capable of breaking down polyethylene terephthalate (PET), the team decomposes PET and other plastics into their basic components, such as terephthalic acid and ethylene glycol, which can be reused in the production of new plastics.

“Our goal isn’t just to remove plastic from water but also to contribute to its recycling in a sustainable manner,” Toma emphasized.

PET is a significant pollutant due to its prevalence in plastic bottles and other common items.

The degradation process developed by Toma’s team breaks PET down into monomeric forms, enabling the reuse of these components in new manufacturing processes.

“Our study focused on PET, but other researchers can include other specific enzymes to process different plastics, such as polyamide or nylon, for example,” he noted.

Challenges and complexities

Addressing the micro- and nanoplastics problem is far from straightforward.

While bioplastics offer a potential solution as they come from renewable sources, they too can fragment into micro- and nanoplastics before fully degrading.

“Being biocompatible, they’re even more insidious because they can interact more directly with our organisms and trigger biological reactions,” Toma explained.

An additional concern raised by Professor Toma is the contamination of bottled mineral water. While mineral water is often valued for its taste and mineral content, it can contain higher levels of micro- and nanoplastics than treated tap water.

“Treated potable water undergoes processes such as filtration, coagulation and flotation to eliminate most residues, whereas mineral water, which is better in some ways – it’s lighter, contains more salts and tastes better, for example – isn’t processed in any of these ways because that would destroy its properties,” said Toma.

“If the environment from which it’s collected is contaminated by bioplastics, these particles will reach the consumer.”

Advancing solutions with nanotechnology

The scale of this environmental challenge demands continuous innovation and policy intervention.

The nanotechnology developed by Toma and his colleagues represents a significant advancement, showcasing how science can address complex environmental issues.

Professor Toma calls for persistent research efforts and urges public administrators to recognize and tackle the problem, stressing the need for collective action to safeguard the planet.

The study is published in the journal Micron.

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