In recent years, awareness of microplastics has increased dramatically, prompting scientists and researchers to investigate ways to eliminate them.
Microplastics are everywhere, including the depths of the ocean, where they accumulate largely unnoticed. Besides polluting marine, polar, and freshwater ecosystems, nanoplastics are also spreading into and contaminating the soil. Both plants and aquatic systems, essential components of human diets, are affected.
Categorized as ’emerging contaminants,’ microplastics are pollutants that have been recognized only as such since the 1990s. It has been only recently that we began to differentiate between microplastics, which are of the size of 1 mm – 1 µm, and nanoplastics, which are even smaller than 1 µm in size.
Nanoparticles are so tiny that they cannot be seen with the naked eye; they are actually smaller than the diameter of an average human hair. This minuscule size grants them an exceptionally high capacity to permeate biological membranes.
These nanoplastics are not just made deliberately—usually for use in cheap filling material and found in cosmetics, toothpaste, and skin care products—but they are also the result of plastic debris breaking down into tiny particles. Against the backdrop of the volume of plastic debris in the environment, projected to reach 12 billion tonnes by 2050, this is a cause for concern.
Not to mention, plastics’ molecular structure makes them highly persistent, which makes them an attractive ingredient for various products. However, this also means that plastic waste remains in the environment for a long time. Plastic does not decompose; rather, it disintegrates.
This disintegration occurs in several ways, including fragmentation, cellular processes, ultraviolet radiation, and the force of water. Consequently, plastic has continued to persist and break down into smaller pieces for decades. For instance, a small piece of polyethylene can disintegrate into approximately 1,500 microparticles or 150,000 nanoplastic particles over time.
The smaller the particles, the bigger the problem. This is because nanoparticles can easily penetrate our body’s cells. Estimates suggest that we consume up to 5 grams of microplastics every week. Meanwhile, a study led by a graduate student in chemistry at Columbia University used stimulated Raman scattering microscopy to discover that 90% of the particles in popular US water brands are nanoplastics, predominantly composed of polyethylene terephthalate (PET) and polyamide.
Moreover, these nanoplastic particles have properties like flexibility and resistance to temperature and corrosion, making them more hazardous to the environment than previously thought.
As we have reported previously, their small size also makes it easier for them to be ingested by wildlife and enter the food chain. This environmental movement of nanoplastics through the food chain creates substantial toxicity in living beings.
In plants, these tiny particles can penetrate their cell wall to become embedded within the tissue, which can mean negative consequences for food safety and ecological function.
In humans, nanoplastics are linked to cardiovascular and respiratory diseases. A study reported discovering polyethylene in carotid artery plaque in 150 patients. Moreover, patients who had microplastics and nanoplastics in their atheroma (plaque) were found to be at higher risk of having a composite of myocardial infarction, stroke, or death from any cause.
The negative effects of nanoplastics further involve inflammation, immunotoxicity, inhibition of growth, oxidative damage, and changes in behavioral ability. In fact, microplastics are detected even in the human placenta. This shows just how pervasive this man-made pollution is and just how detrimental it is to our health.
Given their both short-term and long-term effects on living beings, nanoplastic particles have become a huge concern. The tiny size of nanoplastics, however, means common elimination methods like oxidation or filtration are not suitable for tackling them.
A Novel Solution to Remove Nanoplastics from Water
Most recently, scientists from the University of Missouri were able to accomplish the removal of nanoplastics from water with more than 98% efficiency.
The study published in ACS Applied Engineering Materials this month aims to develop a cost-effective solution to get rid of these tiny particles so that we can have clean water, which remains a challenge. To achieve this result, researchers from Mizzou University created a liquid-based solution that can remove the vast majority of these microscopic plastic particles from water. According to study lead Piyuni Ishtaweera, an alumna who conducted this study while getting her doctorate in nano and materials chemistry at Mizzou:
“Nanoplastics can disrupt aquatic ecosystems and enter the food chain, posing risks to both wildlife and humans.”
She’s now working in the US Food and Drug Administration (FDA) in St. Louis. She added:
“In layman’s terms, we’re developing better ways to remove contaminants such as nanoplastics from water.”
This new method involves using water-repelling solvents, which are made from natural, safe, and non-toxic ingredients. Additionally, their ability to repel water, which helps prevent any further contamination of water sources, makes them a “highly sustainable solution.”
This works by allowing the solvent to sit on the surface of the water, just like oil. However, once the solvent is mixed with water and left to re-separate, it floats back to the surface and carries nanoplastics within its molecular structure.
The team of researchers tested their innovative method for five varying measurements of nanoplastics based on polystyrene, a polymer used to make different consumer products, including Styrofoam cups, which account for 25-35% of all landfill waste. The world produces over 14 million tons of Styrofoam annually, with Americans alone throwing away around 25 billion Styrofoam cups each year.
The results of the Mizzou study outperformed previous studies, which were primarily focused on a single size of plastic particles.
Now, to remove the solvent laden with nanoplastics, the researchers used a pipette in the lab, which left behind plastic-free, clean water. This was done at a small scale, but in the future, the idea is to scale up the whole process so that the method can be applied to large bodies of water, starting with lakes and eventually moving on to oceans. The new method is effective not just in freshwater but also in saltwater.
According to the study’s corresponding author, Gary Baker, who’s an associate professor in the Department of Chemistry at Mizzou:
“Our strategy uses a small amount of designer solvent to absorb plastic particles from a large volume of water.”
However, the capacity of the solvents isn’t well understood yet, noted Baker, who added that in their future research, they will aim to determine exactly this — the maximum capacity of the solvent. Moreover, they will explore ways to recycle the solvents so that they can be used again and again “multiple times if necessary.”
Overall, this innovative solution offers a practical solution to a critical issue while paving the way for further research and development in advanced water purification technologies.
“From a scientific perspective, creating effective removal methods fosters innovation in filtration technologies, provides insights into nanomaterial behavior, and supports the development of informed environmental policies.”
– Ishtaweera
Other Innovative Approaches to Nanoplastic Pollution
Nanoplastics have been drawing a lot of attention for the past several years and for good reasons. As we detailed above, their propensity to spread across the environment and pose a threat to all organisms needs to be made a priority. This is especially important as these nanoparticles escape conventional procedures to remove macro- and micro-plastic particles, hence continuing to increase in water and influence society.
Over the years, several methods have been experimented with to offer effective solutions to remove particular nanoparticles. These include photocatalysis, membrane separation with a reactor, and microorganism-based degradation, in addition to traditional procedures like gravity settling, flocculation, and centrifugation.
Filtration with coagulation has actually been found to offer greater than 99% efficiency at removing nanoplastics from drinking water. But, of course, limitations persist in terms of the solution’s scalability, residual management, and limited efficacy for different types of nanoplastics.
So, let’s examine some approaches introduced over the years to address this issue that threatens human life.
One such method has been using a chromium-based metal-organic framework to remove polystyrene nanoplastics (PSNPs). For this, Cr-MOF was synthesized via a hydrothermal method using chromium nitrate and terephthalic acid, which offered researchers a 96% removal efficiency.
A few years ago, researchers at FAU used magnets to remove various sizes and types of plastic particles. In the demonstration, researchers used SPIONs, non-toxic nanoparticles designed to bond with plastic surfaces to form agglomerates. These were then collected using magnets, thanks to being specially coated with iron oxide. These SPIONs were about 30 nm in diameter and acted like glue. More importantly, the surface functionalities of SPIONs could be adjusted to connect to specific kinds of plastics.
Researchers from the Korea Institute of Science and Technology (KIST) meanwhile used ‘Prussian blue’ to achieve this task. Interestingly, the same substance is used to dye jeans a deep blue color. So, by developing a solid flocculant, the study was able to collect nanoplastics effectively under visible light irradiation. This method was able to remove 99% of microplastics and clean up radioactive cesium without requiring any additional equipment but just flocculants alone.
A few months ago, researchers at the University of Waterloo also introduced a novel way. They used epoxy to remove harmful nanoplastics with 94% efficiency. This waste polymer, which can’t be reprocessed and tends to find its way into water system networks, was converted into activated carbon by the team and then used to treat the contaminated water.
Tizazu Mekonnen, a professor at Waterloo Chemical Engineering who led the research, said:
“To end the plastic waste crisis and reduce the environmental impact of plastics production, we need to implement a circular economy approach that considers every stage of the plastic journey.”
She also aims to apply the procedure to other types of plastics and contaminants and scale it up in municipal wastewater treatment facilities.
Even artificial intelligence (AI), which is transforming industries, is being utilized by researchers to tackle the problem of nanoparticles. A team of researchers from the University of Waterloo created an AI tool called PlasticNet that utilizes deep learning and spectroscopy to identify the unique “fingerprints” of these particles.
PlasticNet has been shown to be a successful tool in a local wastewater treatment plant, where it has demonstrated enhanced microplastic detection and removal.
Given the toxicity of these nanoparticles, accurate identification of their types is essential. After all, not all plastics are the same; they can be polyethylene, Teflon, polystyrene, polyvinyl chloride, and more.
International standards recommend electron microscopy (EM) for identification. EM produces nanoparticle images, allowing identification based on size. However, automatic image analysis becomes problematic when particles are present as aggregates or have complex shapes.
So, an improved method has been created to help the nanomaterial industry as well as environmental and health protection agencies. By incorporating an AI machine learning function, POLLEN Metrology’s software tool is now able to “accurately identify 1000s of NP images in a few seconds in an automatic, non-subjective way.” The Smart3 software suite is expected to help speed up the identification of potentially harmful nanoparticles.
Besides all the research, even organizations are trying to find ways and developing technologies to tackle the issue of nanoplastics.
For instance, Polymateria is a company that is making innovative biodegradable plastics so that there will be no microplastics and nanoplastics from the start.
PureCycle Technologies has taken a similar approach to indirectly reducing nanoplastic pollution. The company, which ended Q2 of 2024 with $10.9 million in unrestricted cash, is focused on recycling plastics by creating high-purity recycled polypropylene.
Its game-changing polypropylene recycling technology consists of seven process stages, including melting and filtering (Polymer Extruder and Polymer Filter), extraction (Polymer/Solvent Mixer and Extraction Column), mixing and settling (Polymer Mixer and Large Particle Settler), filtering (Candle Filters), purification (Columns), separation (Polypropylene/Solvent and Product Decanter), and Extruding & Pelletizing (Polymer Extruder and Polymer Pelletizer).
There are also efforts like Ocean CleanUp that remove plastic from oceans and are investigating methods to capture small plastic particles from large bodies of water. Meanwhile, Anfiro is developing advanced filtration membranes to remove a wide range of contaminants, including microplastics and nanoplastics.
Wasser3.0 is another project-turned-company that uses a whirlpool and specially designed hybrid silica gel to remove nanoparticles. This compound, Wasser 3.0 PE-X, works as a clumping agent to draw together microplastics into lumps, which rise to the surface and get skimmed off using a sieve.
There are many more such companies and projects that are working on creating better, cost-effective, and more advanced solutions to get rid of nanoparticles and completely remove them from our ecosystem with a focus on making them scalable.
Conclusion
With landfills and ocean beaches littered with plastic items, nanoplastics (smaller than 0.001 mm) have become ubiquitous and, as a result, a danger to plants, birds, oceanic life forms, and humans. Exposure to nanoparticles has been found to have negative effects on living beings, becoming a concern for the environment and creating a pressing need to solve this emerging enemy of human health.
As a result, researchers and organizations have been exploring various non-traditional ways to get rid of these tiny particles, which are known for their persistence. However, all these experiments are limited to labs for now, and we have yet to find a scalable solution.
However, these new methods are a significant step in the right direction, addressing the pervasive issue of nanoplastic pollution. Also, given the attention the issue is getting and the progress we are seeing, we can expect to get a solution in the near future that can be applied at scale and effectively to provide us with clean water and healthier ecosystems.