A fundamental study of the transport properties of aqueous superacid solutions.
A fundamental study of the transport properties of aqueous superacid solutions.
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超强酸水溶液传输特性的基础研究。
DOI：
10.1021/jp909572q
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发表时间：
2010
期刊：
影响因子：
--
通讯作者：
Fontanella,JohnJ
中科院分区：
文献类型：
--
作者：
Suarez,SophiaN;Jayakody,JayRP;Greenbaum,SteveG;ZawodzinskiJr,Thomas;Fontanella,JohnJ
对酸性水溶液的输运性质进行了广泛的研究。所研究的酸是三氟甲磺酸(CF3SO3H)、双(三氟甲磺酰基)亚胺[(CF3SO2)2NH]和对甲苯磺酸(CH3C6H4SO3H)，其中前两种被认为是超强酸。核磁共振测量自扩散系数(D)、自旋−晶格驰豫时间(T1)和化学位移，以及离子电导率(σ)、粘度(η)和密度测量，在2−112水到酸分子的浓度范围内进行。结果表明，三种酸的σ峰均在12−20的水-酸分子浓度范围内较宽。这与阴离子DS中的最小值相吻合，并归因于局部分子有序性、溶液介电常数的降低和离子相互作用的增加。σ中最大值的位置与观察到的水合磺化全氟聚合物(如Nafion)的位置有关，当水酸分子比约为15−20时，Nafion具有最大的离子传输能力。在这三种酸中，双(三氟甲磺酰亚胺)被发现对水化程度的依赖性最小。离子电导率极大值和阴离子自扩散极小值之间的反相关关系的出现支持了该区域的过量质子迁移率，并可能提供关于水介质中氢键强度以及高酸浓度在格洛特斯质子传输机制中的作用的额外信息。
An extensive investigation of the transport properties of aqueous acid solutions was undertaken. The acids studied were trifluoromethanesulfonic (CF3SO3H), bis(trifluoromethanesulfonyl)imide [(CF3SO2)2NH], andpara-toluenesulfonic (CH3C6H4SO3H), of which the first two are considered superacids. NMR measurements of self-diffusion coefficients (D), spin−lattice relaxation times (T1), and chemical shifts, in addition to ionic conductivity (σ), viscosity (η), and density measurements, were performed at 30 °C over the concentration range of 2−112 water to acid molecules. Results showed broad maxima in σ for all three acids in the concentration range of 12−20 water to acid molecules. This coincided with minima in anion Ds and is attributed to a local molecular ordering, reduced solution dielectric permittivity, and increased ionic interactions. The location of the maxima in σ correlates with what is observed for hydrated sulfonated perfluoropolymers such as Nafion, which gives a maximum in ionic transport when the ratio of water to acid molecules is about 15−20. Of the three acids, bis(trifluoromethanesulfonyl)imide was found to be the least dependent on hydration level. The occurrence of the anticorrelation between the ionic conductivity maximum and the anion self-diffusion minimum supports excess proton mobility in this region and may offer additional information on the strength of hydrogen bonding in aqueous media as well as on the role of high acid concentration in the Grotthuss proton transport mechanism.
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DOI：
--
发表时间：
1981
期刊：
Laboratory investigation; a journal of technical methods and pathology
影响因子：
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作者：
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