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Revolutionary technology eliminates toxic ‘forever chemicals’ from groundwater

[Sept. 29, 2023: Staff Writer, The Brighter Side of News]

A previously unexplored method has been identified that could hold the key to treating a group of insidious pollutants known as PFAS. (CREDIT: Creative Commons)

In a groundbreaking study from The Ohio State University, a previously unexplored method has been identified that could hold the key to treating a group of insidious pollutants known as PFAS (per- and poly-fluoroalkyl substances), using none other than the science behind ultrasound technology.

PFAS, sometimes dubbed the "forever chemicals", have been part of our lives for nearly a century. Originally hailed as scientific breakthroughs, these chemicals found their way into a vast range of everyday items— from cookware to waterproof clothing, even personal care products. The term "forever" isn't just a fancy moniker. These chemicals, due to their stubborn chemical bonds, have an uncanny persistence in the environment, making them particularly challenging to eliminate.


Compounding the concern, modern-day science has unearthed a darker side to PFAS. Exposure to them has been linked to a plethora of human health concerns, including birth defects and certain types of cancer. But the very property that makes them useful— their resilience— also makes them a formidable challenge to remove from the environment.


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Ultrasound: A Beacon of Hope?

Seeking a solution to this enduring challenge, researchers at The Ohio State University have delved into ultrasonic degradation. This innovative process leverages sound to dismantle substances, essentially tearing apart the molecules constituting them. Linda Weavers, a co-author of the study and a professor of civil, environmental, and geodetic engineering at the University, elaborated on the findings.

“We showed that the challenging smaller compounds can be treated, and more effectively than the larger compounds,” Weavers remarked. “That’s what makes this technology potentially really valuable.”


Their study primarily involved experiments on lab-crafted mixtures holding three different-sized compounds of fluorotelomer sulfonates, a type of PFAS typically associated with firefighting foams. One major revelation was that smaller compounds degraded at a significantly faster rate compared to their larger counterparts— a unique outcome when set against other PFAS treatment techniques.

PFAS is notoriously difficult to clean from the environment, but ultrasound may offer a more effective solution compared to past efforts. (CREDIT: Getty Images)

This research, now available in The Journal of Physical Chemistry A, isn’t the team’s first venture into the world of ultrasound degradation. Earlier investigations by Professor Weavers revealed that the same method could also be harnessed to degrade pharmaceuticals present in municipal tap and wastewater.


Dwelling on the distinctiveness of PFAS compounds, Weavers explained, “PFAS compounds are unique because many of the destruction technologies that we use in environmental engineering for other hard-to-remove compounds don’t work for them.”

Ultrasound degrades “legacy” per- and polyfluoroalkyl substances (PFAS) via thermolysis at the interface of cavitation bubbles. (CREDIT: Journal of Physical Chemistry A)

Understanding the Ultrasound Mechanism

Unlike many traditional techniques that attempt to dismantle PFAS by reacting them with other chemicals, ultrasound purification is distinct. Ultrasound emits sound at a frequency notably lower than what's commonly used for medical imaging. As Weavers clarifies, the process involves a low-pitched pressure wave that alters the solution's structure, creating cavitation bubbles.


“As the bubbles collapse, they gain so much momentum and energy that it compresses and over-compresses, heating up the bubble,” explained Weavers. This heat, akin to that in powerful combustion chambers, can spike up to an astonishing 10,000 Kelvin. Such intense temperatures fracture the stable carbon-fluorine bonds unique to PFAS, rendering the resultant byproducts virtually harmless.

Interestingly, 4:2 and 8:2 FtS had different evolutions of fluoride-to-sulfate ratios, [F–]/[SO42–], over time. (CREDIT: Journal of Physical Chemistry A)

However, while promising, this approach is not without its challenges. The process, as it currently stands, is both energy-intensive and costly. Yet, with limited alternative solutions on the horizon, it could be a vital avenue for safeguarding our groundwater— a crucial resource for drinking and myriad other purposes.


The Road Ahead

Despite industries gradually phasing out their reliance on PFAS, efforts to raise awareness among the public about these chemicals and their hazards are ramping up. The U.S Environmental Protection Agency, earlier this year, introduced the National Primary Drinking Water Regulation (NPDWR). This regulation mandates public water systems to not only monitor the levels of specific PFAS but also inform the public of these figures. Furthermore, they're required to actively reduce these levels if they surpass a stipulated threshold.

Initially, [F–]/[SO42–]4:2 FtS and [F–]/[SO42–]8:2 FtS were respectively higher and lower than theoretical ratios. This difference was attributed to the lower maximum surface excess of 8:2 FtS, hindering its ability to pack and, consequently, defluorinate at the interface. (CREDIT: Journal of Physical Chemistry A)

Given ultrasound’s efficacy in treating PFAS, the study advocates its consideration in shaping future treatment technology strategies and combined-treatment approaches.


While this research remains in its nascent stages and isn’t prepared for large-scale deployment, its potential applications are promising. As the study alludes, we could be on the cusp of seeing compact, high-energy water filtration units designed for residential use.

Ultrasound degrades “legacy” per- and polyfluoroalkyl substances (PFAS) via thermolysis at the interface of cavitation bubbles. (CREDIT: Journal of Physical Chemistry A)

Weavers, with her forward-thinking approach, encapsulates the study’s broader implications: “These compounds are found everywhere, so as we learn more about them, understanding how they can degrade and break down is important for furthering the science.”


In an era where our battle against pollution is increasingly pressing, innovative approaches like this offer a glimmer of hope. With the continued pursuit of knowledge and technological advancements, solutions to some of our most pressing environmental challenges might be closer than we think.

For more science news stories check out our New Innovations section at The Brighter Side of News.


Note: Materials provided above by The Brighter Side of News. Content may be edited for style and length.


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