Hydrogen bonds-triggered differential extraction efficiencies for bifenthrin by three polymeric ionic liquids with varying anions based on FT-IR spectroscopy.
RSC Adv 2022;
12:13660-13672. [PMID:
35530395 PMCID:
PMC9069304 DOI:
10.1039/d2ra01371a]
[Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2022] [Accepted: 04/27/2022] [Indexed: 11/21/2022] Open
Abstract
Herein, we fabricated three imidazolium-based polymeric ionic liquids (PILs) with different anions (P[VEIM]BF4, P[VEIM]PF6 and P[VEIM]Br), and analyzed their differential extraction efficiencies for bifenthrin through H-bonding induced effects. Three PILs all presented an irregular block structure with rough surface and lower specific-surface area (SSA, 11.2-18.7 m2 g-1) than carbon-based nanomaterials. They formed hydrogen bonds with free-water molecules in the lattice of PILs, including C2,4,5-H⋯O-H, Br⋯H-O-H⋯Br, O-H⋯Br, C2,4,5-H⋯F-P, P-F⋯H-O-H⋯F-P, C2,4,5-H⋯F-B and B-F⋯H-O-H⋯F-B. After extraction, the O-H stretching-vibration peak was prominently intensified, whereas the C-H bond varied slightly concomitant with reduced B-F and P-F vibration. Theoretically, the C-H vibration should become more intense in the C4,5-H⋯H2O and C2-H⋯H2O bonds after extraction in contrast to before extraction. These contrary spectral changes demonstrated that the hydrogen bonds between cations in the PILs and free-water molecules were broken after extraction, yielding the H-bonding occurrence between bifenthrin and H-O-H in the lattice. As a time indicator for the free-water binding and releasing process, the highest slope for the plot of I t /I 0 against time implied that the shortest time was required for P[VEIM]PF6 to reach an adsorption equilibrium. Overall, the strong hydrophobicity, small SSA and electrostatic-repulsion force for P[VEIM]PF6 are all not conducive to its efficient adsorption. Beyond our anticipation, P[VEIM]PF6 provided the highest extraction recovery for bifenthrin up to 92.4% among three PILs. Therefore, these data lead us to posit that the above high efficiency results from the strongest H-bonding effect between P[VEIM]PF6 and bifenthrin. These findings promote our deep understanding of PILs-triggered differential efficiency through a H-bonding induced effect.
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