From eliminating the harmful chemicals that are released during the recycling of lithium-ion batteries, to creating barriers that prevent them leaching into the atmosphere, the race is on to tackle PFAS.
It has been two decades since perfluoroalkyl and polyfluoroalkyl substances (PFAS) first gained widespread attention, when studies revealed the contamination of drinking water sources, especially near military bases and industrial sites that used firefighting foam.
Since then, the long-lasting environmental and health risks connected to them have sparked growing concern into their impact on ecosystems and human health. Innovative approaches have been taken in the attempts to minimise their harm.
Researchers find way to destroy PFAS
Lithium-ion batteries are proving to be critical in the transition to clean energy, powering everything from laptops and electric bikes to smartphones and pacemakers. They also play a crucial role in storing excess renewable energy for later use.
However, this growing reliance on them comes with some major environmental challenges, especially when it comes to their disposal. One of the key concerns is the release of harmful PFAS during recycling.
So, when researchers recently identified a new type of PFAS called bis-perfluoroalkyl sulfonimides (bis-FASIs) in lithium-ion batteries, CSIRO scientists Dr Jens Blotevogel and Dr Wenchao Lu, along with Professor Anthony Rappé from Colorado State University, teamed up to determine the optimal conditions to thermally destroy PFAS during battery recycling processes.
“People often call PFAS ‘forever’ chemicals, but a better term would be ‘everywhere’ chemicals – because while they’re in the ambient atmosphere and present in soils and water, we have actually already worked out some methods to break them down,” Blotevogel told create.
Due to strong carbon-fluorine bonds, PFAS are highly resistant to conventional methods of degradation. However, emerging technologies, such as electrochemical oxidation, thermal and non-thermal plasma treatment, and supercritical water oxidation, are showing promise.
“We conducted this research because we wanted to better understand the conditions needed to fully destroy bis-FASIs using thermal treatment, known as pyrometallurgy, which is used to recover metals such as cobalt, nickel and copper from these batteries during recycling,” Blotevogel said.
PFAS chemicals are stable and can withstand high temperatures. But the exact temperature needed to destroy PFAS is the biggest unknown in lithium-ion battery recycling.
Using the science of quantum mechanics, based on first principles, the team used a computer to accurately simulate the behaviour of any molecules during incineration, including bis-FASIs.
“Our research showed that at relatively low temperatures, around 200-500°C, PFAS volatilises and moves from the battery into the gas phase, where transformation begins – but it doesn’t yet result in harmless products,” Blotevogel said.
Taking into account that incinerators are generally designed to maintain a gas phase retention time of about two seconds, Blotevogel said they were able to determine that to fully break down PFAS, minimum temperatures of roughly 950°C are required.
“We identified the intermediate compounds formed, the key barriers in the process, and determined the required temperatures and times to fully break down these chemicals,” he said.
The next step is in raising awareness among recycling operators, who may be unaware that their processes are responsible for releasing the PFAS in the first place.
“While most plant operators are aware of valuable resources like lithium, nickel and cobalt in batteries, they often don’t realise that PFAS are also involved,” he said. “We’ve built an innovative model to guide them – now it’s up to the operators to design their plants so that the PFAS are completely destroyed.”
Read more: Emergency floodwater treatment yields PFAS solution
Creating barriers in PFAS-contaminated concrete
Destroying PFAS completely is one way of addressing the environmental damage they cause, but preventative measures are just as critical. Now, an Australian engineering firm that specialises in environmental technology solutions has created a range of products addressing historical PFAS contamination challenges in critical infrastructure sites.
Andrew Kita, Managing Director of AmbioLock Australia, said the products are the subject of international patents and patent applications that broadly cover the immobilisation and encapsulation of PFAS compounds within engineered substrates, including concrete structures.
“This breakthrough technology is a world first in environmental safety and remediation,” Kita told create.
Designed to allow a number of things, including the safe ongoing use of PFAS contaminated concrete infrastructure, AmbioSeal is silicate-based and works by penetrating and sealing the pores in concrete to prevent contaminated fluids moving through the concrete or leaching out.
“It makes a concrete denser, harder and significantly less permeable to fluids,” Kita said. “It’s resistant to UV rays and heavy vehicle traffic. Additionally, it has a high thermal tolerance, making it perfectly suited to treating fire training grounds. It is also highly effective – we are achieving up to a 99.2 per cent reduction in PFAS leaching from a single treatment.”
In addition to locking in harmful PFAS, a second product called AmbioLock allows concrete and other building materials contaminated with PFAS to be safely recycled and reused onsite, instead of being sent to landfills or incinerators for expensive treatment.
“There are so many uses – we enable beneficial onsite reuse through our AmbioLock product, which immobilises and encapsulates PFAS contamination within new cement-based materials.”
Over on EA OnDemand, Engineers Australia members can learn about biological leachate remediation, which offers a solution for end-to-end landfill leachate treatment.
