Research from the University of Michigan presents a groundbreaking method for eliminating per- and polyfluoroalkyl substances (PFAS), commonly referred to as “forever chemicals.” By harnessing the unique properties of plasma interactions with water, scientists have discovered a technique that could significantly improve water decontamination processes.
The team conducted experiments where plasma, when in contact with water, formed intricate self-organizing patterns. These formations, which resemble stars and gears, increase the surface area for interaction, potentially enhancing the efficiency of water treatment systems. This research highlights the importance of understanding plasma physics to optimize water purification methods.
A key finding of the study, published in Plasma Sources Science and Technology, is that the plasma creates electrical forces that distort the water’s surface, generating surface waves. These waves’ size and shape can be manipulated by adjusting the heating rate of the gas and the electrical properties of the water. This manipulation could enable technicians to maximize the plasma’s contact area, allowing for the treatment of larger volumes of contaminated water.
PFAS compounds have been widely used in various products for their resistance to heat and stains, making them integral to items like fire-fighting foams and non-stick cookware. Unfortunately, their strong carbon-fluorine bonds render them nearly indestructible once released into the environment. As a result, PFAS seep into groundwater and surface water, posing significant health risks, including increased cancer risk and endocrine disruption.
The research indicates that cold plasma effectively destroys PFAS when injected into contaminated water. This non-thermal plasma, generated using fast high-voltage pulses, does not heat the water but instead produces ions, solvated electrons, and ultraviolet light. These elements work together to break the carbon-fluorine bonds that characterize PFAS, ultimately mineralizing the contaminants into harmless byproducts.
According to John Foster, a professor of nuclear engineering and radiological sciences at the university and senior author of the study, “Laboratory demonstrations show cold plasma can get rid of a lot of contaminants in water, removing them almost completely. It opens up a new opportunity to treat these legacy chemicals.” However, the energy-intensive nature of plasma injection poses challenges for large-scale implementation in industrial settings.
The research team also explored the fascinating behavior of plasma as it interacts with water. Instead of dissipating like ripples from a drop of rain, the plasma patterns become increasingly complex, enhancing the interaction area. Zimu Yang, a doctoral graduate at U-M and first author of the study, noted that these patterns are governed by non-equilibrium thermodynamics, allowing for self-organization that increases the treatment potential.
To capture the rapid interactions between plasma and water, researchers developed a high-speed camera system that could document events occurring in just 10 microseconds. This setup allowed them to visually confirm that the plasma is the driving force behind water surface deformations. By synchronizing the camera with the plasma jet’s pulses, they could observe the formation of surface waves, which are influenced by the plasma’s characteristics and can be adjusted for improved efficiency.
The implications of this research could lead to the integration of plasma technology into existing water treatment plants, significantly enhancing their capacity to remove harmful contaminants such as PFAS. By advancing our understanding of plasma interactions, scientists are paving the way for more effective strategies to address one of the most pressing environmental challenges of our time.
As efforts to combat water pollution continue, this innovative approach from the University of Michigan stands as a promising development in the field of environmental science. The potential to treat larger volumes of contaminated water efficiently could play a crucial role in safeguarding public health and the environment for future generations.
