New Dual‑Tech Breakthrough Against “Forever Chemicals”

Per‑ and polyfluoroalkyl substances – the infamous “forever chemicals” – have been a nightmare for water utilities worldwide. Their carbon‑fluorine bonds are so strong that conventional treatment barely scratches them, and the compounds linger in rivers, lakes and even drinking water supplies.

Now a team at Helmholtz‑Zentrum Dresden‑Rossendorf (HZDR) thinks it may finally have a lever. By pairing two very different physical tricks – the violent implosion of microscopic vapor bubbles and the gentle but aggressive glow of cold atmospheric plasma – they have demonstrated measurable degradation of PFAS in the lab.

The first method leans on hydrodynamic cavitation. Water spiked with PFAS is forced through a narrow constriction, spawning a swarm of tiny bubbles. As the flow exits the bottleneck, pressure spikes and the bubbles collapse in a flash of heat that can reach several thousand degrees Celsius. "When those bubbles burst, any PFAS that have clung to their surface experience an almost instantaneous furnace," explains Dr. Sebastian Reinecke, head of HZDR’s Water and Environmental Technologies department.

That extreme, localized heat isn’t the only weapon. The implosion also splinters water molecules, producing hydroxyl radicals – highly reactive species that gobble up intermediate breakdown products. In experiments focused on perfluorooctane sulfonate (PFOS), the team observed a steady rise in free fluoride ions, signalling that fluorine atoms were being ripped away from the original molecules. By the end of a one‑hour run, roughly 37 % of the dissolved PFOS had vanished, and the fluoride concentration kept climbing.

“Our goal is to push that degradation past the 80 % mark and mineralise at least half of the bound fluorine,” says Dr. Ysabel Huaccallo‑Aguilar, the post‑doctoral lead on the cavitation study. “If we can break enough carbon‑fluorine bonds, the chemicals essentially become harmless salts.”

The second approach sidesteps heat altogether. Environmental engineer Dr. Amit Kumar generated a cold atmospheric plasma directly at the water surface while simultaneously bubbling a benign gas (often just air) through the PFAS‑laden water. PFAS molecules, being surface‑active, preferentially adsorb to the rising bubbles and are ferried to the plasma‑treated interface. There, energetic electrons and reactive nitrogen/oxygen species slice the molecules apart.

In the plasma tests, both long‑chain and short‑chain PFAS were almost completely destroyed within minutes, and about 35 % of the fluorine was released as fluoride salts. The speed is impressive, but the method is energy‑hungry and creates a suite of transformation products – some gaseous – that the researchers have yet to fully characterize.

“Plasma offers rapid kinetics, but we need to balance that against the power demand and the mystery of the by‑products,” notes Reinecke. Ongoing work at the Helmholtz Centre for Environmental Research (UFZ) is cataloguing those compounds and hunting ways to recycle the released fluoride.

If either technology can be scaled up efficiently, they could become vital tools in Germany’s National Water Strategy and, more broadly, in any region grappling with PFAS‑contaminated effluents. Rather than merely diverting the chemicals to another pond, the aim is to annihilate them at the molecular level before they ever reach a river or a drinking‑water intake.

Both routes are still in the prototype phase, but the early results are enough to spark optimism. A future where industrial wastewater leaves treatment plants free of forever chemicals may finally be within reach.