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Salt permeation mechanisms in charge-patterned mosaic membranes†
Molecular Systems Design & Engineering ( IF 3.2 ) Pub Date : 2018-11-13 00:00:00 , DOI: 10.1039/c8me00061a
Mark J. Summe 1, 2, 3, 4 , Sushree Jagriti Sahoo 5, 6, 7, 8 , Jonathan K. Whitmer 1, 2, 3, 4 , William A. Phillip 1, 2, 3, 4
Affiliation  

Charge-patterned mosaic membranes contain channels of both positive and negative charge, creating a preference for the transport of whole salts to neutral solutes. In filtration processes, this unique property results in the enrichment of the salt concentration in the solution that permeates through the charge-patterned mosaic membrane. While this concept has been known since the pioneering work of Söllner, the lack of robust, repeatable manufacturing processes for generating chemically-patterned mosaic membranes has obscured the fundamental origins of this novel transport mechanism. Here, we utilize inkjet printing techniques to precisely pattern the pore wall chemistry of track-etched membranes and characterize them using diffusion cell experiments. Critically, the template-assisted inkjet printing method offers the advantage of a direct comparison between the well-understood case of single-charge membranes and charge-patterned membranes that were manufactured using the same ink formulations and printing methodology. Concomitantly, a model that adapts the constraint of Donnan equilibrium to account for the local variations in the electrical potential that arise near charge-patterned surfaces is developed to elucidate the pivotal role of patterning in determining the properties of the mosaic membranes. Experimentally, we observe that the salt permeability increases with concentration for the single-charge membranes, and decreases with concentration for the charge-patterned membrane. Strong quantitative agreement between the model and experiments implies that the local distribution of ions within the double layer, and its effects on ion partitioning, results in the emergence of distinct transport properties when charged elements are patterned on a substrate.

中文翻译:

电荷型镶嵌膜中的盐渗透机制

带有电荷图案的镶嵌膜包含正电荷和负电荷的通道,因此优先考虑将全部盐运输到中性溶质。在过滤过程中,这种独特的特性导致溶液中盐浓度的增加,该盐浓度会渗透通过带电荷图案的镶嵌膜。尽管自从Söllner的开创性工作以来就已经知道了这一概念,但是由于缺乏用于生成化学图案化的镶嵌膜的坚固,可重复的制造工艺,已经掩盖了这种新型运输机制的基本起源。在这里,我们利用喷墨印刷技术来精确地图案化径迹蚀刻膜的孔壁化学结构,并使用扩散池实验对其进行表征。至关重要的是 模板辅助喷墨打印方法的优点是,可以很好地将单电荷膜和采用相同油墨配方和印刷方法制造的带电荷图案的膜直接进行比较。因此,开发了一种模型,该模型适用于Donnan平衡的约束条件,以说明在带电荷图案的表面附近出现的局部电势变化,从而阐明了图案在确定镶嵌膜特性方面的关键作用。在实验中,我们观察到盐的渗透性随单电荷膜的浓度而增加,而随电荷形成膜的浓度而降低。
更新日期:2018-11-13
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