Molecular Dynamics Simulation of the Impact of Functional Head Groups and Chain Lengths of PFAS Degradation Using Ultrasound Technology

PFASs, or per- and polyfluoroalkyl substances, comprise a diverse group of synthetic chemicals known for their widespread use, persistence, and potential environmental and health risks. The sonolytic treatment of PFASs is one of the technologies with the ability to complete destruction without harmful byproducts. This study aims to provide a theoretical explanation for the sonolytic treatment of PFAS. Combining insights from molecular dynamics simulations with experimental data, the influence of chain length and functional headgroups on the PFAS destruction mechanism was investigated. The findings revealed that the impact on functional head groups and chain length on PFAS degradation via sonolysis treatment is complex and multifaceted. The preliminary degradation step is attributed to be headgroup cleavage, while differences in degradation rates between perfluorocarboxylic acids (PFCAs) and perfluorosulfonic acids (PFSAs) are primarily influenced by adsorption at the air–water interface of micro/nanobubbles created by ultrasound and dictated by compound hydrophobicity characteristics. Moreover, longer-chain PFAS compounds tend to degrade faster than shorter-chain counterparts due to their enhanced hydrophobic characteristics, facilitating adsorption and subsequent mineralization. The sonolytic environment significantly influences PFAS degradation, with aqueous sonolysis proving the most effective compared to dry pyrolysis or thermal combustion, highlighting the importance of considering environmental factors in remediation strategies. These insights provide valuable guidance for designing effective PFAS remediation strategies, emphasizing the need to consider molecular structure and environmental conditions. Further research and technological innovation are essential for developing sustainable approaches to mitigate PFAS pollution’s adverse impacts on human health and the environment.