The water sorption behavior of representative pyridinium-based ionic liquid (IL), 1-hexylpyridinium hexafluorophosphate ([C₆Py][PF₆]), was studied over the whole range of the water activity a using a continuous gravimetric method. The analysis of the water sorption isotherm using the combination of a two-mode sorption (i.e. Henry-clustering) allowed to better understand [C₆Py][PF₆]-water interactions. At low and intermediate activity (a ≤ 0.8), the water molecules revealed a very low affinity to [C₆Py][PF₆] and, consequently, the water uptake was rather low. On the contrary, at high water activity (a > 0.8), the water uptake increased exponentially and the water clustering easily occurred. The constant of the Henry-clustering equation as well as the water clustering mechanism in [C₆Py][PF₆] were discussed and compared to those of imidazolium-based ILs: 1-hexyl-3-methylimidazolium hexafluorophosphate [C₆C₁im][PF₆] (water-immiscible IL) and 1-butyl-3-methylimidazolium tetrafluoroborate [C₄C₁im][BF₄] (water-miscible IL). It is shown that the sorption of water molecules by pyridinium-based ILs is controlled not only by the anion's nature, but also by the cation's nature. Moreover, the Zimm-Lundberg theory was used to determine the water mean cluster size (MCS) in [C₆Py][PF₆], [C₆C₁im][PF₆] and [C₄C₁im][BF₄]. The MCS results confirmed the strong capacity of water molecules to be aggregated in [C₆Py][PF₆]. In order to have a deeper insight into the water molecular state, infrared spectroscopy measurements were carried out as a function of the relative humidity value and the obtained results were correlated with the results of water sorption isotherms. It is found that at high water activity (a > 0.8), sorbed water molecules are strongly linked with ILs by hydrogen bonds and, therefore, are easily aggregated.

（IL）代表吡啶鎓类离子液体的水的吸附行为，1-己基吡啶鎓六氟磷酸盐（[C ₆ PY] [PF ₆ ]），进行了研究过的水活度的整个范围一个使用连续重量法。使用两种模式的吸附（即亨利聚类）相结合的水吸附等温线分析可以更好地理解[C ₆ Py] [PF ₆ ]-水的相互作用。在低和中等活性（一 ≤0.8）中，水分子显露[C非常低的亲和力₆ PY] [PF ₆ ]，因此，水吸收是相当低的。相反，在高水分活度下（a > 0.8），吸水量呈指数增长，并且容易发生水团聚。讨论了[C ₆ Py] [PF ₆ ]中Henry-clustering方程的常数以及水团聚机理，并将其与基于咪唑鎓的IL的六氟磷酸1-己基-3-甲基咪唑鎓[C ₆ C ₁ ]进行了比较。im] [PF ₆ ]（与水不混溶的IL）和1-丁基-3-甲基咪唑四氟硼酸盐[C ₄ C ₁ im] [BF ₄]（与水混溶的IL）。结果表明，基于吡啶鎓的离子液体对水分子的吸附不仅受阴离子的性质控制，而且还受阳离子的性质控制。此外，使用Zimm-Lundberg理论确定了[C ₆ Py] [PF ₆ ]，[C ₆ C ₁ im] [PF ₆ ]和[C ₄ C ₁ im] [ BF ₄ ]。MCS结果证实了水分子在[C ₆ Py] [PF _6中聚集的强大能力]。为了更深入地了解水分子状态，根据相对湿度值进行了红外光谱测量，并将获得的结果与吸水等温线的结果相关联。发现在高水活度（a  > 0.8）时，吸附的水分子通过氢键与ILs牢固连接，因此容易聚集。