High frequency ultrasound for destruction of per- and poly- fluoroalkyl substances

Abstract

Per- and poly-fluorinated substances (PFAS) are man-made chemicals, used for more than 50 years in plastics, waterproofing, non-stick pans, surfactants and aqueous firefighting foams. Due to their widespread use, and extreme persistence PFAS are now everywhere in the environment. However, PFAS are toxic, bioaccumulate in animals and plants and can lead to numerous ill-health effects. Many PFAS are now banned or heavily regulated and hence legacy and environmental PFAS require destruction. PFAS contain a hydrophobic fluorinated carbon chain and hydrophilic head group(s) giving them desirable chemical properties which also makes them extremely recalcitrant to typical degradation methods. This work will give an overview of how sonolytic degradation of PFAS is expected to be useful toward total remediation of environmental contaminations. We focus on high frequency ultrasound (1001,000 kHz) and examine parameters such as frequency, liquid height, power density, and reactor configuration. The approach will be discussed in reference to remediation samples of fire fighting foam and landfill leachate concentrate. Considerations of how high frequency ultrasound may be employed in an industrial setting will be discussed.