选择性
膜
电渗析
复合数
离子交换
图层(电子)
化学
化学工程
薄膜复合膜
聚合物
扩散
无机化学
色谱法
材料科学
离子
复合材料
有机化学
催化作用
反渗透
生物化学
工程类
物理
热力学
作者
Ryan M. DuChanois,Lauren Mazurowski,Hanqing Fan,Rafael Verduzco,Oded Nir,Menachem Elimelech
标识
DOI:10.1021/acs.est.3c00445
摘要
Separation of specific ions from water could enable recovery and reuse of essential metals and nutrients, but established membrane technologies lack the high-precision selectivity needed to facilitate a circular resource economy. In this work, we investigate whether the cation/cation selectivity of a composite cation-exchange membrane (CEM), or a thin polymer selective layer on top of a CEM, may be limited by the mass transfer resistance of the underlying CEM. In our analysis, we utilize a layer-by-layer technique to modify CEMs with a thin polymer selective layer (∼50 nm) that has previously shown high selectivity toward copper over similarly sized metals. While these composite membranes have a CuCl2/MgCl2 selectivity up to 33 times larger than unmodified CEMs in diffusion dialysis, our estimates suggest that eliminating resistance from the underlying CEM could further increase selectivity twofold. In contrast, the CEM base layer has a smaller effect on the selectivity of these composite membranes in electrodialysis, although these effects could become more pronounced for ultrathin or highly conductive selective layers. Our results highlight that base layer resistance prevents selectivity factors from being comparable across diffusion dialysis and electrodialysis, and CEMs with low resistance are necessary for providing highly precise separations with composite CEMs.
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