Effect of concentration polarization on permselectivity
Effect of concentration polarization on permselectivity
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DOI：
10.1103/physreve.89.012302
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发表时间：
2014-01-06
影响因子：
2.4
通讯作者：
Zaltzman, Boris
中科院分区：
文献类型：
--
作者：
abu-Rjal, Ramadan;Chinaryan, Vahe;Zaltzman, Boris
本文系统地分析了由非理想选择渗透离子交换膜（均相或非均相）和两个二元单价电解质扩散层组成的三层膜系统在浓差极化过程中选择渗透性的变化。对于非均质膜，提出了一个离子传输模型，这是服从分析处理。在这个模型中，假设膜中的固定电荷恒定，且不考虑水的裂解，整个迁移问题被简化为求解一个关于反电荷迁移数的代数方程。它的结论是，对于这两种类型的膜的浓差极化可能会显着影响透过选择性的系统通过诱导的非均匀性的coion扩散通量在膜（coion浓度分布的凸性）和不同的膜-溶液界面浓度的影响。虽然前者是显着的低膜固定电荷密度，对于异质膜，后者可能会受到相当大的影响，在渗透膜段的通量聚焦效应。
In this paper, the variation of permselectivity in the course of concentration polarization is systematically analyzed for a three-layer membrane system consisting of a nonperfectly permselective ion exchange membrane, homogeneous or heterogeneous, flanked by two diffusion layers of a binary univalent electrolyte. For a heterogeneous membrane, an ionic transport model is proposed, which is amenable to analytical treatment. In this model, assuming a constant fixed charge in the membrane and disregarding water splitting, the entire transport problem is reduced to solution of a single algebraic equation for the counterion transport number. It is concluded that for both types of membrane the concentration polarization may significantly affect the permselectivity of the system through the effects of the induced nonuniformity of the coion diffusion flux in the membrane (convexity of the coion concentration profile) and varying membrane-solution interface concentration. While the former is significant for low membrane fixed charge density, for a heterogeneous membrane, the latter might be considerably affected by the flux focusing effect at the permeable membrane segments.