DIFFUSION COEFFICIENTS OF FERRICYANIDE AND FERROCYANIDE IONS IN AQUEOUS MEDIA, USING TWIN-ELECTRODE THIN-LAYER ELECTROCHEMISTRY
DIFFUSION COEFFICIENTS OF FERRICYANIDE AND FERROCYANIDE IONS IN AQUEOUS MEDIA, USING TWIN-ELECTRODE THIN-LAYER ELECTROCHEMISTRY
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DOI：
10.1021/ac50160a042
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发表时间：
1970-01-01
影响因子：
7.4
通讯作者：
MCDUFFIE, B
中科院分区：
文献类型：
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作者：
KONOPKA, SJ;MCDUFFIE, B
采用微米型薄层电池，采用双电极薄层电化学方法测定了铁和亚铁氰化物在KCI水溶液中的扩散系数D0和Dr。LOOM KCI在25℃下的D0和DR值分别为0.726（±0.011）xq -5和0.667（±0.014）x10 -5 cmVsec，覆盖了总电活性物种的浓度范围为0.61 ~ 6.36 mM。在0.10 M KCI培养基中，在实验不确定度内发现相同的值。本文提出了测定可溶性、稳定氧化还原对的D值的绝对方法的可靠性标准，并与其他工作者获得的D值进行了比较。已经设计了各种方法来确定溶液中物种的扩散系数（D值），例如使用校准膜片电池（1-3），放射化学示踪剂（4,5），电导率(6)和光学方法(7)。对于支持电解质过量的电活性物质，通常使用电化学方法。这些方法，大部分是需要用已知nd值的物质进行校准的相对方法，包括在铂电极上的cottrell型（8-13）、计时电位法（12、14、15）和旋转盘（16）测量，以及在滴汞电极上的极谱测量（11、17）。这些电化学方法的结果彼此之间可能相差10-20%（13,77）。Macero和Rulfs（13）将这些差异主要归因于有效电极面积的不确定性以及使用合适参考离子的必要性。薄层稳态方法具有数学简单和相对不受时间依赖的特点
The diffusion coefficients, D0 and Dr, of the species ferri-and ferrocyanide, respectively, in aqueous KCI media were determined by twin-electrode thin-layer electrochemistry using a micrometer-type thin-layer cell. The values obtained for D0 and DR at 25 C in LOOM KCI were 0.726 (±0.011) Xiq-5 and 0.667 (±0.014) X 10-5 cmVsec, respectively, covering a concentration range from 0.61 to 6.36 mM in total electroactive species. Identical values within experimental uncertainty were found in 0.10 M KCI medium. Criteria for the reliability of this absolute method for measuring the D values of a soluble, stable redox pair are presented, and com-parisons of D values with those obtained by other workers are made.Various methods have been devised for determining the diffusion coefficients (D values) of species in solution, such as the use of the calibrated diaphragm cell (1-3), radiochemical tracers (4, 5), electrical conductance (6), and optical methods (7). For electroactive species in an excess of supporting electrolyte, electrochemical methods often have been used. Such methods, for the most part relative methods requiring calibration with a substance of knownD value, have in-cluded Cottrell-type (8-13), chronopotentiometric (12, 14, 15), and rotating disk (16) measurements at platinum electrodes, and polarographic measurements at the dropping mercury electrode (11, 17). Results by these electrochemical methods may differ from one another by 10-20%(13, 77). Macero and Rulfs (13) have attributed these differences largely to uncertainties in the effective electrode area and to the necessity for using a suitable reference ion. Thin-layer steady-state methods are characterized by mathe-matical simplicity and relative freedom from time-dependent