Kinetics effects of the power density and initial concentration on the sonochemical degradation of PFOS and PFOA in concentrated waste

Sonolysis has been suggested as a viable approach for the destruction of per- and polyfluoroalkyl substances (PFAS) in aqueous media. However, the impact of ultrasonic parameters on PFAS degradation must be better understood to transition the technology from the research discovery phase to field application. This study investigated the degradation of perfluorooctanesulfonic acid (PFOS) and perfluorooctanoic acid (PFOA) and the effect the power density (100–200 W/L) and initial concentration (10–82 μM) on the kinetics of sonolytic degradation. Results show that for a given power density, PFAS degradation was controlled by saturation kinetics, as indicated by an increase in the PFAS degradation rate with an increase in the initial concentration, until a maximum value was reached. Furthermore, the saturation conditions were dependent on the power density. Saturation was reached at a lower concentration of 40 μM at 100 W/L compared to >82 μM at 200 W/L. Results of the study demonstrate that the sonolytic degradation efficiency increases with an increase in the power density and that the optimal rate of degradation is achieved at saturation conditions. Sonolysis is a promising technology to effectively treat PFAS concentrated waste.