Removal of polyfluoroalkyl substances (PFAS) from water using hydrophobic natural deep eutectic solvents (NADES): A proof of concept study

In the present study natural deep eutectic solvents (NADES) were investigated as green and sustainable approach for the extraction of Polyfluoroalkyl Substances (PFAS) from aqueous solutions. NADES, derived from natural products, offer environmentally friendly, low-cost, and biodegradable properties. A hydrophobic NADES, menthol-acetic acid, was shown to be able to extract perfluoroheptanoic acid (PFHpA) from water. The extraction efficiency was about 90 % and was not affected by the PFHpA concentration (0.23–350 mg/L) and by the initial pH of the aqueous solution at the tested conditions. After extraction the pH of the aqueous solution dropped to 2.2, due to a partial dissolution of the acetic acid from the NADES. The mechanism of interaction between the PFHpA and the NADES was unraveled using Density Functional Theory (DFT) calculations. These findings highlight the potential of NADES as a green and sustainable solution for PFAS remediation.