Influence of the Exclusion-Enrichment Effect on Ion Transport in Two-Dimensional Molybdenum Disulfide Membranes
Influence of the Exclusion-Enrichment Effect on Ion Transport in Two-Dimensional Molybdenum Disulfide Membranes
复制标题
排阻富集效应对二维二硫化钼膜中离子传输的影响
DOI：
10.1021/acsami.1c03832
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发表时间：
2021
影响因子：
9.5
通讯作者：
Crittenden, John
中科院分区：
文献类型：
--
作者：
Tong, Xin;Liu, Su;Zhao, Yangying;Chen, Yongsheng;Crittenden, John
二维（2D）纳米片膜已被广泛研究用于水和废水处理。然而，2D纳米片膜内部的质量传输远未被完全理解，并且这些膜的合适应用还有待确定。在这项研究中，我们调查离子传输内的二维二硫化钼（MoS 2）膜结合实验结果与数值模拟。具体地，我们分析了双电层（EDL）的扩展对离子在MoS 2膜中扩散的影响，并引入了一个称为排斥-富集系数（β）的参数来量化共离子与EDL之间的静电相互作用对离子扩散的影响。利用本研究中建立的模型，计算了不同实验条件（料液浓度和施加的液压）下的β值。结果表明，β值小于1时，共离子在膜内的扩散受到阻碍。此外，潜在的机制进行了探索，通过理论上估计的径向离子浓度和跨膜纳米通道的电位分布。此外，我们还发现对流质量输运可以通过增大β来减弱排斥-富集效应。基于本研究的结果，讨论了二维纳米片膜的潜在应用和可行的膜设计策略。
Two-dimensional (2D) nanosheet membranes have been widely studied for water and wastewater treatment. However, mass transport inside 2D nanosheet membranes is far from being fully understood, and suitable applications of these membranes are yet to be identified. In this study, we investigate ion transport inside a 2D molybdenum disulfide (MoS2) membrane by combining experimental results with numerical modeling. Specifically, we analyze the influence of the electrical double layer (EDL) extension on ion diffusion in the MoS2membrane, and a parameter called the exclusion-enrichment coefficient (β) is introduced to quantify how the electrostatic interaction between the coions and the EDL can affect the ion diffusion. Using the model developed in this study, the β values under different experimental conditions (feed solution concentration and applied hydraulic pressure) are calculated. The results show that coion diffusion inside the membrane can be retarded since β is smaller than one. Furthermore, the underlying mechanism is explored by theoretically estimating the radial ion concentration and electrical potential distributions across the membrane nanochannel. In addition, we find that convective mass transport can weaken the exclusion-enrichment effect by increasing β. Based on the results in this study, the potential applications and feasible membrane design strategies of 2D nanosheet membranes are discussed.