Zhang Xiaofan, Gao Ming, Liu Tingting, Wang Huili, Wang Xuedong
School of Environmental Science and Engineering, Suzhou University of Science and Technology Suzhou 215009 China
Jiangsu Provincial Key Laboratory of Environmental Science and Engineering, Suzhou University of Science and Technology Suzhou 215009 China.
RSC Adv. 2022 May 5;12(22):13660-13672. doi: 10.1039/d2ra01371a.
Herein, we fabricated three imidazolium-based polymeric ionic liquids (PILs) with different anions (P[VEIM]BF, P[VEIM]PF 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 m g) than carbon-based nanomaterials. They formed hydrogen bonds with free-water molecules in the lattice of PILs, including C-H⋯O-H, Br⋯H-O-H⋯Br, O-H⋯Br, C-H⋯F-P, P-F⋯H-O-H⋯F-P, C-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 C-H⋯HO and C-H⋯HO 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 / against time implied that the shortest time was required for P[VEIM]PF to reach an adsorption equilibrium. Overall, the strong hydrophobicity, small SSA and electrostatic-repulsion force for P[VEIM]PF are all not conducive to its efficient adsorption. Beyond our anticipation, P[VEIM]PF 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]PF and bifenthrin. These findings promote our deep understanding of PILs-triggered differential efficiency through a H-bonding induced effect.
在此，我们制备了三种带有不同阴离子（P[VEIM]BF、P[VEIM]PF和P[VEIM]Br）的咪唑基聚合离子液体（PILs），并通过氢键诱导效应分析了它们对联苯菊酯的差异萃取效率。三种PILs均呈现出不规则的块状结构，表面粗糙，比表面积（SSA，11.2 - 18.7 m²/g）低于碳基纳米材料。它们在PILs晶格中与游离水分子形成氢键，包括C-H⋯O-H、Br⋯H-O-H⋯Br、O-H⋯Br、C-H⋯F-P、P-F⋯H-O-H⋯F-P、C-H⋯F-B和B-F⋯H-O-H⋯F-B。萃取后，O-H伸缩振动峰显著增强，而C-H键略有变化，同时B-F和P-F振动减弱。理论上，萃取后C-H⋯HO和C-H⋯HO键中的C-H振动应比萃取前更强烈。这些相反的光谱变化表明，萃取后PILs中阳离子与游离水分子之间的氢键断裂，导致联苯菊酯与晶格中的H-O-H之间形成氢键。作为游离水结合和释放过程的时间指标，/对时间的曲线斜率最高意味着P[VEIM]PF达到吸附平衡所需的时间最短。总体而言，P[VEIM]PF的强疏水性、小比表面积和静电排斥力均不利于其高效吸附。出乎我们意料的是，在三种PILs中，P[VEIM]PF对联苯菊酯的萃取回收率最高，可达92.4%。因此，这些数据使我们推测上述高效率源于P[VEIM]PF与联苯菊酯之间最强的氢键效应。这些发现促进了我们对通过氢键诱导效应引发的PILs差异效率的深入理解。
