Theoretical and experimental study of new deep eutectic solvents for extraction of perfluorinated iodoalkanes

There is a lack of attention and reporting in aspects of the neutral/nonionic perfluoroalkyl substances (PFASs) and corresponding treatment mechanisms. Herein, new function-oriented deep eutectic solvents (DESs) with pyridine moiety were designed for perfluorinated iodoalkanes extraction from the oil phase. The effect of hydrogen bond acceptor (HBA) functional groups on the effectiveness of targets retrieval was investigated. Moreover, different structural, quantum-chemical, solvatochromic, and statistical thermodynamics parameters were conducted, calculated, and correlated to the distribution coefficients of the studied DESs. Results showed that functional groups of HBAs significantly affected the extraction effectiveness of eutectic mixtures. The pyridine ring-based DESs with the CO group possessed the highest extraction efficiencies among the studied groups. To some extent, the extraction performances of the DES were substantially affected by the electrostatic potential extrema of the donor halogen atom and pyridine analogues. For targets with relatively short alkyl chain length, the topological indices had a positive relationship with the treatment efficacy of the DESs, and the quantum-chemical parameters of these solvents had a strong negative relationship with them. For targets with long alkyl chain length, the solvatochromic parameters of DES had a great influence on the distribution coefficients and also on the selectivity of these solvents. Furthermore, the halogen and hydrogen bonds presented cooperativity, clarifying via quantum-chemistry calculations. The synergism mechanism between them is beneficial to the extraction of perfluorinated iodoalkanes. Besides shedding light on the structure–property-performance relationships of the DESs, these findings also provided novel insights into the directional design and selection of DESs.