Effect of anion-exchange membrane surface properties on mechanisms of overlimiting mass transfer
Effect of anion-exchange membrane surface properties on mechanisms of overlimiting mass transfer
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DOI：
10.1021/jp062433f
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发表时间：
2006-07-13
影响因子：
3.3
通讯作者：
Pourcelly, Gerald
中科院分区：
文献类型：
--
作者：
Belova, Elena I.;Lopatkova, Galina Yu.;Pourcelly, Gerald
研究了离子交换膜系统中提供过限电流传递的四种效应。其中两个与水的分裂有关：附加载流子（H+和OH-离子）的出现和提高效应。另外两种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。三个阴离子交换膜，其表面形态和表面层内离子交换点的性质不同，进行了检查。用伏安法、时电位法和ph法研究了NaCl溶液中离子在这些膜上的转移。排除水分裂和重力对流的影响，表明低盐浓度下窄膜细胞超传质的主要机制是电对流。讨论了水裂解抑制电对流的原因。电位振荡随电流和时间增长的发展情况与鲁宾斯坦和扎尔兹曼理论描述的情况进行了比较。
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.