Elucidating the dynamics behavior of PFASs at the water and hydrophobic low-melting mixture solvents interphase

Abstract

In this work, we studied the interphase dynamics of hydrophobic low-melting mixture solvents (LoMMSs) for the advanced remediation of per- and polyfluoroalkyl substances (PFASs) in wastewater systems by using classical molecular dynamics (MD) simulations. We showed the interaction between widely prevalent PFAS-specifically perfluorooctanoic acid (PFOA) and perfluorooctanesulfonic acid (PFOS) and an innovative LoMMS composed of cineole (CIN) and linoleic acid (LNA) at equimolar ratios. Our investigations reveal that the interphase diffusion of PFASs through the LoMMS is a multi-stage process involving diffusion, interface sorption, and subsequent migration into the bulk aqueous phase. The simulations underscore a robust affinity between the PFASs molecules and the LoMMS, with the displacement of PFASs from the water interface marked by the formation of complex hydrogen-bonded networks. This intricate interplay results in a significant reorganization of water molecules, leading to potential clustering at the interface and compression of the fluid phase. These findings not only substantiate the efficacy of LoMMSs in PFASs extraction but also highlight the need to account for competitive interactions at the water interface, which could impede the absorption kinetics. By providing a detailed molecular-level narrative of the interphase capture phenomena, this study paves the way for designing efficient, low-toxicity LoMMS-based systems for the targeted removal of PFASs from contaminated water sources.