Choi Jae-Hwan, Lee Hong-Joo, Moon Seung-Hyeon
Department of Environmental Science and Engineering, Kwangju Institute of Science and Technology (K-JIST), 1 Oryong-dong, Puk-gu, Kwangju, 500-712, Korea
J Colloid Interface Sci. 2001 Jun 1;238(1):188-195. doi: 10.1006/jcis.2001.7510.
The effect of electrolyte solutions on the characteristics of the current-voltage (I-V) curve in a cation-exchange membrane (CMX membrane, Tokuyama Soda, Inc.) was studied based on the concentration polarization and electroconvection theory. The study includes the limiting current density (LCD), plateau length, and the ratio of resistance of region III to region I of the I-V curve (R(3rd)/R(1st)). Different electrolyte solutions, HCl, LiCl, NaCl, KCl, CaCl(2), MgCl(2), and AlCl(3), were used in this study. The LCD values of the electrolytes were correlated with the diffusion coefficient of the cation (D(+)) and valence of the cation and anion (z(+), z(-)). Except for the HCl solution, the LCD values of the electrolytes increased linearly with D(+)(1-z(+)/z(-)), implying that the current in this region was governed by the concentration polarization phenomena. The deviation of the HCl solution from the linearity is due to a particular transport mechanism of the proton called the Grotthuss-type transport. The differences in the plateau length and the resistance ratio, R(3rd)/R(1st), with the electrolytes were explained by the Péclet number (Pe) representing a transport pattern in the electroconvection theory. The Péclet number is proportional to the Stokes radius of an ion. An electrolyte with a large Stokes radius has a shorter plateau length and a lower ratio of R(3rd)/R(1st) than those of an electrolyte with a small Stokes radius. Water-splitting measurements for the different electrolyte solutions in the CMX membrane revealed that the contribution of water splitting to the overlimting current was insignificant regardless of the electrolytes used in this study. However, when metal hydroxides, such as Al(OH)(3), formed on the surface of the membrane, significant water splitting was observed. Copyright 2001 Academic Press.
基于浓差极化和电对流理论，研究了电解质溶液对阳离子交换膜（CMX膜，德山曹达株式会社）中电流-电压（I-V）曲线特性的影响。该研究包括极限电流密度（LCD）、平台长度以及I-V曲线中区域III与区域I的电阻比（R(3rd)/R(1st)）。本研究使用了不同的电解质溶液，即HCl、LiCl、NaCl、KCl、CaCl₂、MgCl₂和AlCl₃。电解质的LCD值与阳离子的扩散系数（D(+)）以及阳离子和阴离子的价态（z(+)，z(-)）相关。除HCl溶液外，电解质的LCD值随D(+)(1 - z(+)/z(-))呈线性增加，这意味着该区域的电流受浓差极化现象控制。HCl溶液偏离线性是由于质子的一种特殊传输机制，即Grotthuss型传输。用代表电对流理论中传输模式的佩克莱数（Pe）解释了不同电解质在平台长度和电阻比R(3rd)/R(1st)上的差异。佩克莱数与离子的斯托克斯半径成正比。斯托克斯半径大的电解质比斯托克斯半径小的电解质具有更短的平台长度和更低的R(3rd)/R(1st)比值。对CMX膜中不同电解质溶液进行的水分解测量表明，无论本研究中使用何种电解质，水分解对过极限电流的贡献都微不足道。然而，当膜表面形成金属氢氧化物，如Al(OH)₃时，会观察到明显的水分解现象。版权所有2001年学术出版社。
