Effect of temperature and counterion on adsorption of imidazolium ionic liquids at air-water interface
Effect of temperature and counterion on adsorption of imidazolium ionic liquids at air-water interface
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DOI：
10.1016/j.colsurfa.2010.08.057
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发表时间：
2010-11-05
影响因子：
5.2
通讯作者：
Aratono, M.
中科院分区：
文献类型：
--
作者：
Matsubara, H.;Onohara, A.;Aratono, M.
采用表面张力法研究了1-烷基-3-甲基咪唑阳离子与不同阴离子的离子液体在空气-水界面上的吸附行为。从表面张力数据的热力学分析，提出了吸附膜结构的物理模型：HMIM+和BF 4-离子占据相同的水平，由于在HMIMBF 4系统中的离子配对，而Br-离子主要分布在顶部表面以下的扩散双电层中的DeMIMBr系统。在前一种情况下，当表面密度接近饱和时，与吸附相关的熵变随着浓度的增加而增加，因为水合水在HMIM+和BF 4-的离子配对期间被释放。此外，吸附膜的结构几乎与纯离子液体表面相同;这可能是因为阴离子和阳离子都高度集中在吸附膜中。(C)2010 Elsevier B. V.保留所有权利。
The adsorption behavior of ionic liquids based on the 1-alkyl-3-methylimidazolium cation with different anions to the air-water interface was investigated through surface tension measurements. From the thermodynamic analysis of the surface tension data, a physical model for the structure of the adsorbed film is proposed: the HMIM+ and BF4- ions occupy the same level of the surface due to ion-pairing in the HMIMBF4 system, whereas the Br- ions are mainly distributed in the diffuse electrical double layer below the top surface in the DeMIMBr system. In the former case, the entropy change associated with adsorption increases with increasing concentration when the surface density is close to saturation because the hydrated water is released during the ion-pairing of HMIM+ and BF4-. Furthermore, the structure of the adsorbed film is almost the same as a neat ionic liquid surface; this is probably because both the anions and the cations are highly concentrated in the adsorbed film. (C) 2010 Elsevier B.V. All rights reserved.