Sonochemical degradation of per- and polyfluoroalkyl substances (PFAS): mechanisms, efficacy, and future directions

Abstract

Per- and polyfluoroalkyl substances (PFAS) are a class of persistent organic pollutants characterized by their exceptional chemical stability, environmental mobility, and adverse health effects. Their widespread presence in water resources and resistance to conventional treatment methods necessitate the development of effective destructive technologies. Sonochemical degradation, an advanced oxidation process (AOP) driven by acoustic cavitation, has emerged as a promising technology for the complete mineralization of PFAS. While previous reviews have provided foundational overviews, this work critically synthesizes the latest mechanistic insights, quantitative kinetic models, and emerging byproduct considerations (e.g. volatile organic fluorine (VOF) compounds) that distinguish the current state-of-the-art from earlier understanding. We systematically examine the effects of frequency, power density, solution chemistry (pH, temperature, matrix components), and PFAS molecular structure on degradation rates, with a new emphasis on Langmuir–Hinshelwood and Michaelis–Menten kinetic frameworks. The review uniquely integrates data from complex environmental matrices (groundwater, soils, AFFF source zones, ion exchange regeneration brines) and evaluates the energy efficiency of synergistic systems (sono-persulfate, sono-electrochemical, sono-piezocatalytic) using standardized electrical energy per order (EE/O) metrics. This review identifies critical knowledge gaps, including the fate of VOF byproducts, the scalability of hybrid reactors, and the treatment of short-chain PFAS. By addressing these areas, the work provides a forward-looking perspective on the research and engineering required to advance sonochemistry to field-scale remediation.