Frequency-dependent sonochemical degradation of perfluoroalkyl substances and numerical analysis of cavity dynamics

Ultrasonic breakdown of perfluorooctanoic acid and perfluorooctane sulfonic were evaluated at various ultrasonic frequency (575 kHz, 860 1140 kHz), pH (3–12), bulk water temperature (14.5–30 °C), gases (Helium, Nitrogen, Oxygen, Ozone, Argon). Contrary to the result reported in literature, we observed an increase rate kinetics PFOA PFOS decomposition air environment (i.e., without sparging any gases), higher pH, temperature. The degradation follows order as Helium > Nitrogen Argon Oxygen Ozone. present work concludes that presence known/unknown chemical compounds formed during sonolysis, influence interaction with cavity-water interface. cavity collapse simulation using Gilmore equation showed acoustic pressure increases compression ratio bubble radial velocity collapsible cavity. This study suggests lower compared PFOA, over a range ultrasound frequencies, is due number active cavities collapsing temperatures. radius cavities, maximum velocity, was 3.2 µm, 2 1.7 µm 575 respectively.