Belova Elena I, Lopatkova Galina Yu, Pismenskaya Natalia D, Nikonenko Victor V, Larchet Christian, Pourcelly Gerald
Physical Chemistry Department, Kuban State University, 149 Stavropolskaya str., 350040 Krasnodar, Russia.
J Phys Chem B. 2006 Jul 13;110(27):13458-69. doi: 10.1021/jp062433f.
Four effects providing overlimiting current transfer in ion-exchange membrane systems are examined. Two of them are related to water splitting: the appearance of additional current carriers (H+ and OH- ions) and exaltation effect. Two others are due to coupled convection partially destroying the diffusion boundary layer: gravitational convection and electroconvection. Three anion-exchange membranes, which differ in surface morphology and the nature of ion-exchange sites within a surface layer, are examined. The ion transfer across these membranes in NaCl solutions is studied by voltammetry, chronopotentiometry, and pH-metry. By excluding the effects of water splitting and gravitational convection, it is shown that the main mechanism of overlimiting mass transfer in narrow membrane cells at low salt concentrations is electroconvection. The reasons explaining why water splitting suppresses electroconvection are discussed. The scenario of development of potential oscillations with growing current and time is compared with that described theoretically by Rubinstein and Zaltzman.
研究了离子交换膜系统中提供过极限电流传输的四种效应。其中两种效应与水分解有关：额外电流载体（H⁺和OH⁻离子）的出现和增强效应。另外两种效应是由于耦合对流部分破坏了扩散边界层：重力对流和电对流。研究了三种阴离子交换膜，它们在表面形态和表面层内离子交换位点的性质上有所不同。通过伏安法、计时电位法和pH测量法研究了NaCl溶液中离子在这些膜上的传输。通过排除水分解和重力对流的影响，结果表明，在低盐浓度下窄膜电池中过极限传质的主要机制是电对流。讨论了水分解抑制电对流的原因。将随着电流和时间增加而产生的电位振荡的发展情况与鲁宾斯坦和扎尔特兹曼理论描述的情况进行了比较。
