When liquids are subjected to ultrasound, bubbles are created and collapsed, a phenomenon called cavitation. PFAS is an environmental toxin that can cause cancer and liver damage and is extremely difficult to degrade.
"The hypothesis is that PFAS-molecules are collected in micro bubbles in the water. By collapsing these cavitation bubbles with high-intensity ultrasound, an extreme pressure arises and the increase in temperature causes degradation and neutralization of the molecular chains", says Örjan Johansson, professor in Engineering Acoustics at Luleå University of Technology.
The challenge is to create an energy-efficient method that can be applied on an industrial scale. For best results, optimization of the flow conditions and the intensity and frequency content of the ultrasound is required, with respect to the substances to be treated..