Per- and polyfluorinated substances (PFAS) have earned the nickname of “forever chemicals” as they are extremely resilient and can persist in the environment without degrading. This class of chemicals has been found in our soil, air, and drinking water, making PFAS a significant environmental and human health issue. A variety of researchers are exploring ways to break down these chemicals, including Yang Yang, PhD, assistant professor of civil and environmental engineering at Clarkson University. Yang recently received the National Science Foundation (NSF) CAREER Award for his proposed work to break down PFAS, and will receive funding from NSF to follow through on this project from May 2023 until 2028.
Q: Can you elaborate on the potential dangers of PFAS and why it is important for researchers to develop effective ways of breaking down these substances?
A: PFAS are a family of man-made chemicals widely used since the 1940s. They are designed to be chemically stable and easy to stick with oil or water phases. Unfortunately, once released into the environment, their unique properties make them toxic compounds that are difficult to be removed or destroyed in the natural environment. Some of the PFAS, such as PFOA and PFOS, have already proved to be toxic to humans, animals, and aquatic organisms. With a simple search online, you will find many toxicological reports and ongoing environmental lawsuits. It is also important to point out that PFOA and PFOS have been banned in many industries since 2004, yet we are still able to detect them in water and soil.
It is an endless battle for environmental engineers to develop cost-effective mitigation strategies.
Aside from PFOA and PFOS, there are many other PFAS alternatives with minor structural changes being developed and used, with the toxic effect largely unknown. We have to admit that modern industries need fluorocarbon-containing products. The “toxicity revealed-elimination-alternative replacement” cycle is likely to be an infinite loop. Via this loop, many PFAS will be released into the environment. It is an endless battle for environmental engineers to develop cost-effective mitigation strategies.
Q: Can you explain the process you will be exploring to break down PFAS and why this technique is promising compared to existing methods?
A: It is very challenging to destroy PFAS under ambient conditions. Many ongoing PFAS research efforts are heavily invested in water treatment technologies. In contrast, our focus is the treatment of PFAS in solid phases, such as PFAS-contaminated soil, sediments, and sorbents. Destruction of solid-state PFAS in the absence of solvents is very challenging because none of the prior knowledge in water treatment techniques could be applied. We proposed a novel approach called piezoelectric ball milling. In this process, piezoelectric materials (PZMs) will be milled with solid PFAS in a ball mill. The ball mill contains several steel balls. Once agitated, balls will collide with each other to generate impact energy. Under impact, the piezoelectric materials will generate kV surface potential to destroy PFAS in contact with the PZMs. This process is highly promising in treating PFAS chemicals and PFAS-laden soil. The process can completely convert PFAS to fluoride as one of the end products. More information can be found in our latest article.
Q: Who will be helping you with this project? What fields of science do your team members represent?
A: My graduate students will be the backbone of the project. I also receive analytical support from the Center for Air and Aquatic Resources Engineering and Sciences (CAARES), the shared analytical facility center at Clarkson University.
Q: What do you anticipate will be the biggest challenges you face during this project?
A: The biggest challenge is to reduce the required amount of PZMs to achieve complete destruction of PFAS, which is also a challenge associated with the cost when scaled up.
Q: Are there other anticipated challenges regarding scale up that could prevent this method from being implemented?
A: There are two potential roadblocks in my mind: 1. Can the properties of the treated solid (e.g., solids and sediments) be changed after treatment? Can the treated, PFAS-free solid be returned to the environment? 2. What would be the final layout of the scale-up process? There are many ways to make the collision happen. For example, ball mills can be in the form of a vibration chamber, jars on a planetary disk, and a rotatory drum. The determination of the best configuration requires deeper understanding of mechanochemistry, precise force simulation, and pilot scale validation.
Q: What does it mean to you to be awarded the NSF CAREER project award and how will this funding help expedite your research?
A: I am very grateful to NSF for the CAREER award. This five-year grant gives me the freedom to explore an area that was opened up by my team with lots of uncertainty and exciting possibilities. The award is also a recognition of my past hard work as a PhD student, postdoc, then faculty. It also motivated me to keep up the good work to solve the PFAS problems. PFAS should not be our legacy to the next generations.
Not a single technology can be applicable for treating PFAS with various structures embedded in different matrices.
Q: In your opinion, what else needs to be done to truly resolve this massive PFAS problem and alleviate the burden from future generations?
A: There is no panacea for all PFAS problems. Not a single technology can be applicable for treating PFAS with various structures embedded in different matrices. We need to develop a portfolio of treatment approaches. Academia and industry should work hand-in-hand to test the best treatment practice based on a deep understanding of PFAS contamination scenarios (is contaminant telomer dominant or prevailed by perfluorinated structure? What are the co-existing organics and salts in water/soil matrices? What would be the receiving water/land after treatment?).
Moreover, breaking the cycle of “toxicity revealed-elimination-alternative replacement” needs close collaboration of policymakers, manufacturers, and scientists. I do not think fluorinated organic products should be and could be completely phased out in our lives. However, new alternative PFAS should be under more stringent scrutiny, such as toxicity evaluation and treatability investigation, before emerging on the market. The life cycle of PFAS-containing products should be traced.
Lastly, in addition to PFAS, we are actually facing many challenges brought by other emerging contaminants. But I am optimistic that the treatment paradigm and chemical management framework established for PFAS will be downward compatible with many anthropogenic chemical contaminants.
Yang Yang received his PhD from Tsinghua University in 2014 and his postdoc training at the California Institute of Technology from 2014 to 2018. He joined the Department of Civil and Environmental Engineering at Clarkson University as an assistant professor in 2019.
Yang is specialized in the synthesis and characterization of advanced electrocatalytic materials and their environmental applications. Yang has published 30+ peer-reviewed articles and owns two patents in subject areas of emerging contaminant analysis, wastewater treatment, and flue gas purification.