Ionic Liquids Enabling Efficient Extraction of Pfacs: Cosmo-Rs Screening and Experimental Verification

Liquid-liquid extraction (LLE) using ionic liquids (ILs) -based methods to remove perfluoroalkyl chemicals (PFACs), such as perfluorooctanoic acid (PFOA) and perfluorooctanesulfonic acid (PFOS) from wastewater, is an important strategy. However, the lack of physicochemical and LLE data limits the selection of the most suitable ILs for the extraction of PFACs. In this work, 1763 ILs for PFACs extraction from water were systematically screened using COSMOtherm to estimate the infinite dilution activity coefficient (ln γ ∞ ) of PFOA and PFOS in water and ILs. To evaluate the accuracy of COSMOtherm, 8 ILs with various ln γ ∞ values were selected, and their extraction efficiency ( E ) and distribution coefficient ( D e ) were measured experimentally. The results showed that the predicted ln γ ∞ was inversely proportional to the experimental extraction efficiency of PFOA or PFOS, while the predicted distribution coefficient D p was consistent with the experimental D e , proving that the method can be used to screen ILs with high extraction efficiency. In summary, this work provides an efficient basis for selecting ILs for the extraction of PFACs from wastewater.