Abstract This work presents a new approach to correcting for concentration polarization (CP) in pressure-driven membrane measurements. In the existing test cells (both cross-flow and stirred-batch) there are distributions of extent of CP over membrane surface. This complicates the interpretation of experimental data. A novel design of test cell with equally-accessible membrane surface has been developed based on the classical configuration of rotating disk combined with the possibility of applying trans-membrane hydrostatic pressure differences of up to 20 bar. Due to the equal accessibility, corrections for CP can easily be made even in multi-ionic systems, which would be much more difficult with other membrane test cells. Since the membrane has to be sealed at the edge the geometry somewhat deviates from the ideal case of infinite disk. The impact of these deviations has been quantified via CFD simulations. A major part of the membrane surface is shown to be equally accessible while there are some expectable deviations close to the sealed membrane edge. This zone could be “screened” in the experiments. The approach could also be validated experimentally via studying the dependence of observed rejection on the rotation speed and demonstrating that intrinsic rejection was practically independent of it. Finally, to demonstrate the cell utility, we performed and interpreted a number of experiments using commercial NF270 membrane and various feed solutions (single salts and electrolyte mixtures). We conclude that this cell can be employed for systematic transport characterization of membranes and the obtained information can be used as input in the CFD modelling of membrane modules.

中文翻译：

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用于压力驱动测量的旋转盘状膜单元具有同等可接近的膜表面：数值模拟和实验验证

摘要 这项工作提出了一种在压力驱动的膜测量中校正浓差极化 (CP) 的新方法。在现有的测试单元（错流和搅拌分批）中，CP 的范围分布在膜表面上。这使实验数据的解释复杂化。基于旋转盘的经典配置以及应用高达 20 bar 的跨膜静水压差的可能性，开发了一种具有同等可接近膜表面的测试单元的新颖设计。由于具有相同的可访问性，即使在多离子系统中也可以很容易地对 CP 进行校正，而这对于其他膜测试电池来说要困难得多。由于膜必须在边缘密封，几何形状与无限圆盘的理想情况有些不同。这些偏差的影响已通过 CFD 模拟进行量化。膜表面的主要部分显示为同样可接近，而靠近密封膜边缘有一些可预期的偏差。该区域可以在实验中“筛选”。该方法还可以通过研究观察到的排斥对旋转速度的依赖性并证明内在排斥实际上与其无关来进行实验验证。最后，为了证明电池效用，我们使用商用 NF270 膜和各种进料溶液（单盐和电解质混合物）进行了许多实验并进行了解释。我们得出结论，该单元可用于膜的系统传输表征，获得的信息可用作膜组件 CFD 建模的输入。