Measurement of the dielectric relaxation property of water-ion loose complex in aqueous solutions of salt at low concentrations.
Measurement of the dielectric relaxation property of water-ion loose complex in aqueous solutions of salt at low concentrations.
复制标题
低浓度盐水溶液中水-离子松散络合物介电弛豫特性的测量。
DOI：
10.1021/jp802757q
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发表时间：
2008
期刊：
影响因子：
--
通讯作者：
Makoto Suzuki
中科院分区：
文献类型：
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作者：
T. Miyazaki;George Mogami;T. Wazawa;T. Kodama;Makoto Suzuki
电解质及其解离离子被认为在其周围形成正或负水化层。在这项研究中，我们已经开发了一种方法来确定的体积和介电弛豫性能（弛豫频率fc，分散强度δ）的水水合离子在盐溶液中。该方法包括四个步骤：（1）利用高分辨率微波介电谱技术，对样品盐溶液和水的介电谱进行了测量。(2)然后根据Hanai混合物理论从样品盐溶液和参考水的每对介电谱计算具有给定体积分数varphi的水层的溶质（离子）的介电谱。(3)每个光谱的溶质与水层在一个给定的varphi分解成几个德拜弛豫函数和散装水成分。(4)体积分数varphi从0.5起操作性地降低，并且在每个varphi下重复步骤（2）和（3），直到本体水组分消失。然后确定溶液中水合溶质（离子）的体积分数。该方法适用于NaF和NaCl溶液。结果表明，在3-26 GHz频率范围内，不同的光谱强度与0.2 M以下的盐浓度几乎成正比。成功地确定了每种盐溶液的水化数Nh和水化层的介电弛豫特性：NaCl的（fc 1，delta 1，Nh）=（18.7，44.9，27.9）; NaF的（fc 1，delta 1，fc2，delta 2，Nh）=（26.0，6.70，5.64，19.2）。
Electrolytes and their dissociated ions are thought to form positive or negative hydration layers around them. In this study, we have developed a method to determine the volume and the dielectric relaxation property (relaxation frequency f c, dispersion intensity delta) of the water hydrating ions in salt solutions. The method consists of four steps: (1) By use of a high-resolution microwave dielectric spectroscopy technique, the dielectric spectra of sample salt solution and bulk water are measured in pair. (2) The dielectric spectrum of solutes (ions) with water layers for a given volume fraction varphi is then calculated from each pair of dielectric spectra of a sample salt solution and reference water according to the Hanai mixture theory. (3) Each spectrum of solutes with water layers at a given varphi is decomposed into a few Debye relaxation functions and the bulk water component. (4) The volume fraction varphi is operationally decreased from 0.5, and steps (2) and (3) are repeated at each varphi until the bulk water component vanished. Then the volume fraction of the hydrated solutes (ions) in solution is determined. The method was applied to NaF and NaCl solutions. As a result the different spectral intensity was nearly proportional to the salt concentration below 0.2 M in the frequency range of 3-26 GHz. The hydration number N h and the dielectric relaxation property of the hydration layer for each salt solution was successfully determined as ( f c1, delta 1, N h)= (18.7, 44.9, 27.9) for NaCl and ( f c1, delta 1, f c2, delta 2, N h) = (26.0, 6.70, 5.64, 19.2) for NaF.