According to recent studies, ultrasonic treatment may be able to remove
PFAS (permanently toxic alkaloids) from contaminated groundwater.
Per- and poly-fluoroalkyl compounds, sometimes referred to as "forever
chemicals," were developed about a century ago and were formerly widely
employed in the production of cookware, waterproof apparel, and personal
care products. As of right now, experts know that exposure to PFAS can
result in a variety of health problems for people, including cancer and
birth abnormalities. However, it is renownedly difficult to remove these
compounds from the environment since the connections inside them are tough
to break.
Due of these challenges, scientists at The Ohio State University are
investigating the potential effects of ultrasonic degradation—a method that
breaks down compounds by using sound to split apart their constituent
molecules—against various kinds and amounts of these pollutants.
The Journal of Physical Chemistry
A published the study.
They observed that, over the course of three hours, the smaller compounds
of fluorotelomer sulfonates—PFAS compounds often found in firefighting
foams—degraded far more quickly than the bigger ones. These studies were
conducted on lab-made mixes comprising three different sized compounds of
fluorotelomer sulfonates. In contrast, smaller PFAS are actually harder to
treat with many other PFAS treatment techniques.
The Ohio State University professor of civil, environmental, and geodetic
engineering Linda Weavers, a co-author of the study, said, "We showed that
the challenging smaller compounds can be treated, and more effectively than
the larger compounds." "That's what has the potential to make this
technology really valuable."
This work, one of the few to investigate the potential applications of
ultrasonography to remove harmful per- and polyfluoroalkyl substances (PFAS)
from our environment, builds on Weavers's earlier findings that the same
technique might break down medications in municipal tap and
wastewater.
PFAS chemicals are distinct from other hard-to-remove compounds since many
of the destruction methods used in environmental engineering for other
compounds don't work for them, according to Weavers. Therefore, in order to
determine which technologies could be helpful in various applications, we
actually need to be creating a variety of them.
Because ultrasound emits sound at a frequency far lower than that of
medical imaging, it purifies PFAS, in contrast to other conventional
destruction methods that try to break them down by reacting them with
oxidizing chemicals, according to Weavers. Cavitation bubbles are discrete
vapor pockets that are produced when the solution is compressed and pulled
apart by the low-pitched pressure pulse of ultrasound.
According to Weavers, "the bubbles heat up as they collapse because they
gain so much momentum and energy that it compresses and
over-compresses."
These small bubbles may reach temperatures of up to 10,000 Kelvin, much
like powerful combustion chambers. It is precisely this heat that breaks
down the stable carbon-fluorine bonds that make up PFAS and basically
renders the byproducts harmless. Weavers stated that although this degrading
process can be very expensive and energy-intensive, there may not be many
other choices, thus the public may need to consider making an investment in
it to safeguard groundwater for drinking and other purposes.
Regulating bodies are trying to raise public knowledge regarding PFAS
avoidance while manufacturing sectors are beginning to shift away from using
them.
The National Primary Drinking Water Regulation (NPDWR), which was proposed earlier this year by the US Environmental Protection
Agency, would mandate that public water systems keep an eye out for certain
PFAS, alert the public when these levels are exceeded, and take action to
lower them.
The study adds that because ultrasound is so good at removing PFAS from
solutions, researchers and government organizations ought to think about
incorporating it into the development of future treatment technologies, both
alone and in conjunction with other combined-treatment strategies.
The study did point out that Weavers's work may be the first step toward
developing compact, high-energy water filtration equipment that the general
public may utilize inside of homes, even though it is not yet ready to be
scaled up to support more extensive anti-contamination initiatives.
Weavers explained, "Our research focuses on attempting to understand how
you scale to something bigger and what you need to make it work." Since
these substances are ubiquitous, it is critical to advance scientific
knowledge of their degradation and breakdown mechanisms as we learn more
about them.
William P. Fagan and Shannon R. Thayer, both from Ohio State, are
additional co-authors.
Provided by
The Ohio State University
