Few environmental challenges are as persistent as per- and polyfluoroalkyl substances (PFAS). These are the so-called “forever chemicals” and they earned their name through pure chemical stubbornness. Built around ultra-strong carbon-fluorine bonds, PFAS compounds resist degradation, accumulating in water, soil, wildlife and, increasingly, human tissue. The result is a long-term pollution problem that has outstripped our ability to deal with it effectively.
PFAS contain extremely strong carbon-fluorine bonds that do not degrade naturally. Because of this, they accumulate in the environment, wildlife and the human body over time.
A new study provides an important piece of the puzzle. Researchers have shown that intense ultraviolet (UV) light can cause a reaction in water that generates hydrogen radicals, which are highly reactive species capable of breaking down PFAS molecules without the need for additional chemicals. The finding doesn’t eliminate the PFAS problem overnight, but it offers something just as valuable: a clearer understanding of HOW these chemicals can be destroyed.
Breaking the unbreakable
The difficulty with PFAS lies in the chemistry. Carbon-fluorine bonds are among the strongest in organic chemistry, making them extremely resistant to both biological degradation and conventional treatment processes. Therefore, most current approaches focus on Cancellations instead of destruction – filtering PFAS from water using activated carbon or membranes, only to face the problem of disposal later.
New research shifts the focus right DEGRADATION. When water is exposed to high-energy UV light—especially at wavelengths below 300 nanometers—it can produce hydrogen radicals. These radicals are highly reactive and, more importantly, able to attack PFAS molecules at their weakest points. Over time, they remove the fluorine atoms, breaking the molecule into smaller, less stable compounds.
Previous work tended to emphasize other reactive species, such as hydrated electrons or hydroxyl radicals, as the main drivers of PFAS degradation. However, by identifying hydrogen radicals as a dominant player, the new study reframes the way chemists and engineers approach treatment system design.
From removal to destruction
The difference between PFAS removal and destruction is more than semantic. As Associate Professor Zongsu Wei, who led the study, has emphasizedfiltration alone does not solve the problem – it simply transfers contaminants from one phase to another. What remains needed is a sustainable and scalable way to completely dismantle PFAS molecules.
The challenge is that even with UV-generated radicals, degradation can be slow. Intermediate compounds can form when PFAS structures break down piecemeal, and not all degradation pathways are fully understood. However, knowing which reactive species are doing the work provides a clear direction for optimization. It suggests that future systems could be designed to maximize hydrogen radical production while minimizing energy input.
In practical terms, this could mean new classes of photochemical reactors designed specifically for PFAS destruction—systems that use tailored UV wavelengths, optimized reactor geometry, and controlled water chemistry to accelerate radical formation. The ultimate goal would be to move from laboratory-scale demonstrations to continuous industrial-scale processes.
Canadian parallels: radical chemistry meets environmental engineering
The emerging focus on target response mechanisms has strong parallels with Canadian research in water treatment and environmental chemistry. Canadian universities and research institutes have been active in developing advanced oxidation and reduction processes, many of which rely on reactive radicals to degrade persistent pollutants.
For example, research groups across Canada have explored the use of UV photolysis, electrochemical systems and plasma-based methods to generate reactive species capable of breaking down objectionable pollutants. These approaches are conceptually consistent with the new findings: rather than relying on bulk removal, they aim to engineer appropriate reactive environment to dismantle pollutants at the molecular level.
There are also crossovers with Canadian work in granular and soft systemsparticularly in how materials respond to external energy inputs such as vibrations or light. At McGill University, studies on reconfigurable metamaterials highlight how structure and energy input can interact to create controllable transformations in matter. While the physics differs from PFAS chemistry, the underlying principle is similar: understanding the internal mechanisms of a system allows engineers to switch between states—in one case, mechanical; in the other, chemical.
Meanwhile, Canadian research in granular blocking and fluidization has demonstrated how materials can transition between solid and liquid states under controlled conditions. In a chemical context, UV activation plays an analogous role, transforming relatively inert water into a reactive medium capable of transforming stable compounds. In both cases, the behavior of the system depends on how the energy is introduced and managed.
Despite the promise, the UV-hydrogen radical route is not without challenges. High-energy UV light is energy intensive to produce, raising questions about cost and sustainability. The design of the reactor must also ensure that light penetrates effectively and that radicals have sufficient opportunity to interact with PFAS molecules before they recombine or disperse.
There is also the issue of scale. PFAS contamination is not limited to laboratory volumes—it exists in groundwater systems, industrial runoff, and municipal supplies. Any viable technology will need to operate reliably on a large scale, often in complex environments with mixed chemicals.
However, the history of environmental engineering suggests that such challenges are not insurmountable. Many now-standard treatment methods, from ozone disinfection to membrane filtration, began as separate, energy-intensive processes before being optimized and widely adopted.
The real importance of the new findings is not in providing an immediate solution, but in refining the roadmap. PFAS have long been described as virtually indestructible, a characterization that has sometimes obscured the fact that they’re not immune to the chemistry—they’re just tough targets. By identifying hydrogen radicals as a key degradation agent, researchers have narrowed the search for effective intervention strategies.
In this sense, the study represents a shift from empirical trial and error to mechanism-driven design. Instead of asking what can work, scientists may now ask what MUST be optimized.
