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首页> 外文学位 >Determinations of critical limits in ion transport in membrane electrodialysis and their current vs. voltage characteristics for ion concentration control in pulp and paper mill waste stream.
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Determinations of critical limits in ion transport in membrane electrodialysis and their current vs. voltage characteristics for ion concentration control in pulp and paper mill waste stream.

机译：确定膜电渗析中离子传输的临界极限及其电流与电压特性，以控制纸浆和造纸厂废水中的离子浓度。

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Membrane electrodialysis (MED) has been used in several processes that require electrical potential as a vehicle to accomplish separation of mixed ionic components.; MED can be used as a second stage treatment to effectively control ion concentrations in the process stream. This can be accomplished by understanding the distributions of ion concentration and/or electrical potential in the membrane-electrolyte system, which can be related to the concept of limiting current density that plays an important role in enhancing the separation efficiency.; Experimentally, the measurement of current vs. voltage characteristics of dilute electrolytic solutions (KCl, NaCl, and LiCl) were carried out in a laboratory scale MED unit. The observed experimental results show that there is a critical change in the apparent conductance for all these systems. These critical phenomena suggest that in the low electrical field the separation efficiency is limited by the rate of ion exchange within the membrane. The ion exchange limit inside the membrane is due to the fact that the capability of ion transport in the membrane is not infinite. There will be ion accumulation inside the membrane near the surface where the number of ions entering the membrane is over its capacity to transport ions. Both the order of the critical point and the magnitude of the apparent conductance at the critical point indicate that the ion exchange limit is related to ion size, which is consistent with the results from the theoretical parametric analysis. This work provides a new understanding of ion transport in ion exchange membrane and electrolyte solution during estimation of separation efficiency of the MED process, such as the optimum usage of ion exchange membrane, energy consumption, and process stream recycling condition. (Abstract shortened by UMI.)
机译：膜电渗析（MED）已用于多种需要电势的过程中，以作为媒介来完成混合离子组分的分离。 MED可以用作第二阶段处理，以有效控制工艺流中的离子浓度。这可以通过理解膜电解质系统中离子浓度和/或电势的分布来实现，这与限制电流密度的概念有关，该电流密度对提高分离效率起着重要作用。实验上，在实验室规模的MED装置中测量稀电解液（KCl，NaCl和LiCl）的电流-电压特性。观察到的实验结果表明，所有这些系统的表观电导都发生了重大变化。这些关键现象表明，在低电场中，分离效率受到膜内离子交换速率的限制。膜内部的离子交换极限是由于膜中离子传输的能力不是无限的事实所致。在进入膜的离子数量超过其传输离子的能力的表面附近的膜内部将存在离子累积。临界点的顺序和临界点的表观电导的大小都表明离子交换极限与离子尺寸有关，这与理论参数分析的结果一致。这项工作为估算MED工艺分离效率期间离子交换膜和电解质溶液中离子的迁移提供了新的认识，例如离子交换膜的最佳使用，能耗和工艺流循环条件。 （摘要由UMI缩短。）

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