New Tech Removes 99% of Nanoplastics from Water

The water is clear. To the naked eye, it looks pure, refreshing, and safe. But under the lens of an electron microscope, a different reality emerges—one of a chaotic, invisible storm. Billions of tiny synthetic particles, smaller than a bacterium and far more persistent, are swirling in the very fluid that sustains life. These are nanoplastics, the ghostly descendants of our convenience culture, and for years, they have been an unsolvable puzzle for water treatment engineers. They slip through standard filters like sand through a tennis racket. They bypass our body's defenses, lodging in our livers, our hearts, and, as we are now discovering with terrifying clarity, our brains.

For decades, the scientific community has been locked in an arms race against this invisible enemy, with most "solutions" offering only incremental gains. But in a quiet laboratory at the University of Missouri (Mizzou), a team of chemists has just rewritten the rules of engagement. They haven't just built a better filter; they have reimagined the fundamental chemistry of water purification.

Their weapon? A "designer solvent" made from ingredients you might find in a medicine cabinet or a spice rack—menthol and thymol. This new technology, based on Hydrophobic Deep Eutectic Solvents (HDES), has achieved what was previously thought impossible: the removal of over 98%—and in some cases, nearly 100%—of nanoplastics from water in a single pass.

This is not just a story about clean water. It is a story about the convergence of green chemistry, advanced engineering, and a desperate race to save human biology from a plastic apocalypse. This is the comprehensive chronicle of how a liquid that behaves like oil but acts like a magnet is poised to change the world, and why it arrived just in time to face a public health crisis of unprecedented scale.

Part I: The Invisible Enemy

The Nanoplastic Definition

To understand the magnitude of the solution, one must first grasp the insidious nature of the problem. When we talk about plastic pollution, we often visualize floating islands of garbage in the Pacific or a turtle entangled in a six-pack ring. These are "macroplastics." As they break down under the assault of UV radiation, waves, and friction, they become "microplastics" (particles smaller than 5 millimeters).

But the degradation doesn't stop there. The particles continue to fracture, becoming exponentially more numerous and infinitely harder to catch. When a particle fractures into the nanoscale—typically defined as smaller than 1 micrometer (1,000 nanometers), though definitions vary—it undergoes a terrifying transformation. It stops behaving like a piece of debris and starts behaving like a dissolved chemical.

Nanoplastics are so small that they are governed by Brownian motion—the erratic random movement of microscopic particles in a fluid—rather than gravity. They do not sink. They do not float in a way that allows for easy skimming. They form stable suspensions that can persist in water columns for centuries.

The Biological Invasion

The true horror of nanoplastics lies not in their presence in the environment, but in their ability to penetrate biological barriers. In 2024 and 2025, a series of bombshell studies fundamentally shifted our understanding of plastic toxicity.

The Brain Breach:

Research published in Nature Medicine in early 2025 sent shockwaves through the medical community. Analyzing post-mortem tissue samples, scientists found that nanoplastics accumulate in the human brain at concentrations 7 to 30 times higher than in the liver or kidneys. Even more disturbing, the brains of individuals with dementia contained significantly higher loads of these particles than those without.

How do they get there? The Blood-Brain Barrier (BBB) is the body's fortress, a tightly knit layer of cells designed to keep toxins, bacteria, and viruses out of the central nervous system. For decades, it was assumed to be impermeable to plastics. However, recent molecular dynamics simulations have revealed a "Trojan Horse" mechanism. Nanoplastics, particularly those made of polyethylene and polypropylene, are lipophilic (fat-loving). The cell membranes of the BBB are also lipid-rich. When a nanoplastic particle encounters the BBB, it doesn't just bounce off; it can dissolve into the hydrophobic interior of the cell membrane, effectively "hiding" within the wall itself, before exiting on the other side as dispersed polymer chains or re-aggregating in the brain tissue.

The Cellular Sabotage:

Once inside the cell, nanoplastics are not inert. They are agents of chaos.

Mitochondrial Dysfunction: Mitochondria are the power plants of our cells. Nanoplastics have been observed entering these organelles and physically disrupting their membranes. This leads to a leak of mitochondrial DNA into the cytoplasm and a catastrophic drop in ATP (energy) production. The cell, starving for energy, begins to fail.
The Oxidative Storm: The presence of these foreign bodies triggers the production of Reactive Oxygen Species (ROS). These are chemically aggressive molecules that tear apart DNA, proteins, and lipids. This state of "oxidative stress" is a known precursor to cancer, chronic inflammation, and accelerated aging.
The Inflammatory Trigger: Recent studies have identified that nanoplastics can activate the NLRP3 inflammasome, a protein complex that triggers the release of inflammatory cytokines. This suggests that nanoplastics may be a silent driver of the chronic inflammation epidemic linked to autoimmune diseases, heart disease, and metabolic disorders.

Part II: The Mizzou Breakthrough

The Eureka Moment

Against this backdrop of biological urgency, the work of Gary Baker, an associate professor at the University of Missouri, and his doctoral student, Piyuni Ishtaweera, stands as a beacon of hope. Their approach was born from a simple observation: Like dissolves like.

Most plastics are hydrophobic. They hate water. This is why oil and water don't mix, and why plastic bottles float. In a water column, a nanoplastic particle is essentially "unhappy." It is constantly repelling the water molecules around it. Baker and Ishtaweera realized that if they could introduce a substance that the plastic loved—a hydrophobic safe haven—the plastic particles would voluntarily leave the water to enter this new phase.

They didn't want to use toxic industrial solvents like hexane or benzene, which would defeat the purpose of water purification. They needed something green, safe, and effective. They turned to Deep Eutectic Solvents (DES).

The Chemistry of "Liquid Magnets"

Deep Eutectic Solvents are a fascinating class of liquids. They are formed by mixing two solids that, when combined at a specific ratio, spontaneously melt into a liquid at room temperature. This happens because the molecules disrupt each other's crystal structures through hydrogen bonding.

The Mizzou team created a Hydrophobic Deep Eutectic Solvent (HDES). They used natural, benign ingredients:

Menthol: The compound that gives mint its cool taste.
Thymol: An antimicrobial compound found in thyme.
Decanoic Acid: A fatty acid found in coconut oil and breast milk.

When mixed in specific ratios (such as menthol and thymol in a 1:1 ratio, or tetrabutylammonium bromide and decanoic acid in a 1:2 ratio), these solids become a water-repelling liquid that floats on top of water, much like olive oil on vinegar.

The Mechanism: Liquid-Liquid Extraction

The process is elegantly simple, a feat of "liquid-liquid extraction."

The Setup: Contaminated water (containing billions of nanoplastics) is placed in a vessel.
The Addition: A small amount of the HDES is added. Because it is hydrophobic, it doesn't dissolve in the water; it forms a separate layer on top or, with mixing, droplets dispersed throughout.
The Migration: When the water is agitated (stirred or shaken), the HDES droplets come into contact with the nanoplastics.
The Capture: The nanoplastics, being hydrophobic themselves, are chemically drawn to the HDES. They "leap" from the water into the solvent droplets. It is a thermodynamic inevitability—the plastic is energetically more stable inside the solvent than in the water.
The Separation: The agitation stops. The HDES, now loaded with plastic, floats back to the surface.
The Removal: The top layer is skimmed off, leaving behind water that is 98.4% to 99.8% free of nanoplastics.

The Results: Unprecedented Efficiency

The team tested their solvent against five different sizes of polystyrene nanoplastics, ranging from 100 nanometers to much larger particles.

Freshwater: The solvent removed >98% of particles.
Saltwater: In a surprising twist, the efficiency actually increased in saltwater, reaching 99.8%. The ions in salt water likely create a "salting-out" effect, pushing the plastics even more aggressively toward the solvent.

This is a quantum leap over conventional methods. Membrane filtration, the current gold standard, struggles with pore sizes. If the pores are small enough to catch nanoplastics, they clog instantly (fouling), requiring massive energy to force water through. If they are too big, the plastics pass right through. The Mizzou method has no pores to clog. It relies on chemical affinity, not physical sieving.

Part III: The Landscape of Competition

While Mizzou's HDES technology is capturing headlines, it is not the only gladiator in the arena. A comprehensive view of the industry reveals a vibrant ecosystem of competing and complementary technologies. The "War on Nanoplastics" is being fought on multiple fronts.

1. The BioCap: Tannins and Wood Dust

Researchers at the University of British Columbia (UBC) have developed a filter dubbed "BioCap." This technology uses wood dust—a waste product of the lumber industry—coated with tannic acid, a natural polyphenol found in plants like oak bark and tea leaves.

How it works: Tannic acid is a molecular "sticky trap." It forms strong interactions with the polymers in microplastics. When water passes through a column of this wood dust, the plastics bind to the tannins.
Performance: UBC reports removal rates between 95.2% and 99.9% depending on the plastic type.
The Advantage: It utilizes forestry waste, making it incredibly cheap and sustainable.
The Limitation: It is a filtration media, meaning it could eventually saturate or clog, unlike a liquid solvent that can be cycled.

2. Activated Carbon from Epoxy Waste

At the University of Waterloo, engineers have turned a problem into a solution. Epoxy resins are notoriously difficult to recycle. The Waterloo team developed a thermal decomposition method to convert old epoxy into activated carbon with a specific pore structure optimized for nanoplastics.

Performance: They achieved a 94% removal efficiency.
The "Circular" Angle: This technology solves two problems at once: it disposes of unrecyclable epoxy waste and creates a water filter.
The Mechanism: Adsorption. The nanoplastics get stuck in the microscopic Swiss-cheese holes of the carbon.

3. Bio-Based Nanofiber Filters

Another promising avenue involves cellulose nanofibers. These are incredibly fine fibers extracted from plants or bacteria. When spun into a dense mat, they create a filter with pores so small that even viruses struggle to pass.

Performance: Recent studies show nearly 100% rejection for particles larger than 10 nanometers.
The Speed Factor: One major breakthrough in this field is high flux—the ability to pass water through quickly despite the small pores, a historic bottleneck for nanofiltration.

4. The Old Guard: Coagulation and MBR

Traditional wastewater treatment plants (WWTPs) rely on coagulation (adding chemicals like alum to make particles clump) and Membrane Bioreactors (MBR).

The Failure: Standard coagulation removes only about 20-50% of pristine nanoplastics. It works better on "weathered" (rough) plastics, but it is unreliable.
The MBR Problem: While MBRs can achieve 99% removal, they are plagued by "fouling." The plastics coat the membranes, destroying their efficiency and driving up energy costs.

Part IV: The Deep Science of "Green Solvents"

To truly appreciate the Mizzou innovation, one must look deeper into the chemistry of Deep Eutectic Solvents (DES). This is not just "mixing stuff." It is a manipulation of thermodynamics.

The Hydrogen Bond Dance

A solid melts when the thermal energy (heat) is enough to break the lattice energy (the force holding the crystal together). In a DES, two solids are mixed. One acts as a Hydrogen Bond Donor (HBD) and the other as a Hydrogen Bond Acceptor (HBA).

When menthol (HBD) meets decanoic acid (HBA), they form a hydrogen bond network that is energetically favorable but structurally disordered. This disorder prevents the molecules from crystallizing. The result is a "eutectic point"—a melting temperature far lower than either component alone. Menthol melts at 42°C. Decanoic acid melts at 31°C. But the mixture is liquid at room temperature.

Hydrophobicity: The Critical Feature

Most DESs researched in the past 20 years were hydrophilic (water-loving). They would dissolve in water, which is useless for extracting pollutants from water. The Mizzou team's brilliance was in selecting components that are fiercely hydrophobic.

The "Tail" Factor: Both decanoic acid and menthol have long alkyl "tails" (chains of carbon and hydrogen). These tails are non-polar. Water is highly polar.
The Exclusion: Water molecules want to bond with other water molecules. They effectively "squeeze out" the non-polar alkyl tails. This forces the solvent to separate from the water.
The Plastic Attraction: Nanoplastics like polystyrene are also non-polar. When they encounter the HDES, they find themselves in a chemical environment that mimics their own structure. Van der Waals forces (weak electric attractions between molecules) take over, locking the plastic into the solvent.

Green Chemistry Principles

This technology adheres to several of the "12 Principles of Green Chemistry":

Less Hazardous Chemical Syntheses: No toxic solvents like chloroform are used.
Design for Energy Efficiency: The process happens at room temperature. No boiling or high-pressure pumping is required.
Use of Renewable Feedstocks: Menthol and thymol are plant-derived.

Part V: The Future of Water – Scaling and Economics

The transition from a beaker in Missouri to a municipal water treatment plant in London or Tokyo is a journey fraught with peril. This is the "Valley of Death" for new technologies.

The Engineering Challenges

1. Viscosity:

Deep Eutectic Solvents can be thick—viscous like syrup. In a lab, you can mix them with a magnetic stirrer. In a plant treating 100 million gallons a day, mixing a viscous fluid with water requires massive energy.

Solution: Engineers are looking at "emulsification" techniques—breaking the solvent into microscopic droplets to increase surface area, then using centrifugal separators to recover it.

2. Solvent Recovery and Loss:

Even though the solvent is hydrophobic, a tiny fraction might dissolve in water (parts per million). If the solvent is expensive, this loss adds up. If the solvent has any toxicity (even low), it becomes a new pollutant.

The Mizzou Advantage: Menthol and thymol are Generally Recognized As Safe (GRAS). If a trace amount remains, it’s akin to a drop of mouthwash in a swimming pool.

3. The Circular Economy of Solvents:

The team is currently working on the next crucial step: recycling the solvent. Once the HDES is full of plastic, what do you do?

Distillation: You could distill the solvent components, leaving the plastic behind.
Precipitation: Changing the temperature or pH might force the plastic to "fall out" of the solvent, allowing the clean solvent to be reused.

The Economic Case

Current advanced filtration (Reverse Osmosis) costs roughly $0.50 to $2.00 per cubic meter of water, driven largely by electricity (pumping water through tight membranes).

The HDES method is a low-pressure system. The primary costs are the solvent and the mixing energy.

The Cost of Inaction: The economic burden of nanoplastics is currently externalized to healthcare systems. As links to Alzheimer’s, fertility issues, and cardiovascular disease solidify, governments may impose "pollution taxes" or strict Maximum Contaminant Levels (MCLs) for nanoplastics. This would instantly make the HDES technology economically viable, even if the upfront solvent cost is higher.

Regulatory Tailwinds

The regulatory landscape is shifting beneath our feet.

The EU: The European Chemicals Agency (ECHA) has already restricted intentionally added microplastics.
The US: The EPA is currently drafting methods for measuring nanoplastics, a precursor to regulation.
Global Treaty: The UN Global Plastics Treaty is under negotiation.

Technologies that can demonstrate >99% removal will become the gold standard for compliance.

Part VI: A New Era of Water Security

We stand at a crossroads. For a century, water treatment was about killing bacteria and removing dirt. We conquered cholera and typhoid. But we are now facing a "chemical cholera"—a contamination not by life, but by the indestructible byproducts of our lifestyle.

The discovery at the University of Missouri is more than a clever chemical trick. It represents a fundamental shift in how we interact with our environment. It acknowledges that we have polluted our world to the molecular level, and it offers a molecular solution.

This technology allows us to envision a future where wastewater treatment plants are not just waste disposal sites, but resource recovery factories. Imagine a plant where water flows in, and three streams flow out: clean water, recovered biological nutrients (fertilizer), and recovered hydrocarbons (plastics) ready for reprocessing.

The HDES technology is the "kidney" of this future factory. It offers a way to detoxify the planet's lifeblood without destroying the environment in the process.

While we are likely years away from seeing "Menthol-Filtered" water coming out of our taps, the path is clear. The proof of concept is irrefutable. The chemistry is sound. And the need is desperate.

In the war against the invisible, we finally have a weapon that works. And it smells like mint.

Part VII: Detailed Technical Analysis of Competitive Technologies

To understand why the Mizzou solution is so revolutionary, we must dissect the alternatives in detail.

1. Membrane Bioreactors (MBR): The Workhorse with a Weakness

MBRs combine biological degradation (bacteria eating waste) with membrane filtration.

Pros: They are established technology. They produce high-quality effluent.
Cons: Biofouling. Bacteria and plastics form a "cake layer" on the membrane. This cake layer reduces the flux (flow rate). To maintain flow, operators must increase pressure (energy cost) and frequently clean the membranes with harsh chemicals (environmental cost). Nanoplastics exacerbate this fouling by blocking the smallest pores.

2. Advanced Oxidation Processes (AOPs): The Nuclear Option

AOPs use ozone, UV light, or Fenton's reagent to generate hydroxyl radicals. These radicals are chemical buzzsaws—they rip apart any organic molecule they touch.

Pros: They can actually degrade the plastic, turning it into CO2 and water (mineralization).
Cons: They are incredibly energy-intensive. Furthermore, if the degradation is incomplete, they can chop a polymer chain into shorter, more toxic oligomers. They also react with everything in the water, not just plastics, wasting energy on non-target compounds.

3. Electrocoagulation:

This method uses electricity to dissolve metal electrodes (like iron or aluminum) into the water. These metal ions neutralize the charge of nanoplastics, causing them to float or sink.

Pros: No chemical additives (other than the electrode). Good for removal of charged particles.
Cons: The electrodes are "sacrificial"—they dissolve and must be replaced. The process produces a metal-rich sludge that is hazardous waste.

4. The Mizzou HDES Advantage:

Non-destructive: It captures the plastic without breaking it into potentially more toxic byproducts.
Selectivity: By tuning the hydrophobicity, the solvent can target plastics while ignoring biological nutrients or salts.
Regenerability: Unlike a filter that goes to a landfill, the solvent is a liquid tool that can theoretically be used thousands of times.

Conclusion: The Turning of the Tide

As we look toward 2030 and beyond, the narrative of plastic pollution is changing. We are moving from "awareness" to "remediation." The discovery of nanoplastics in the human brain was a dark moment for environmental science, a confirmation of our worst fears. But the response from the scientific community has been equally powerful.

The University of Missouri's development of hydrophobic deep eutectic solvents is a testament to the power of human ingenuity. It reminds us that nature itself provides the keys to solving our most unnatural problems. With menthol, thymol, and a deep understanding of molecular interactions, we have found a way to separate the synthetic from the organic, the pollutant from the pure.

The "Plastic Age" has left its mark on the geological record and the human body. But with technologies like this, we may finally have the means to scrub that mark away, leaving future generations with water that is truly, deeply clean.