Guo Yun, He Jinlong, Zhang Junwei, Sheng Meng, Wang Zhiwei, Elimelech Menachem, Wang Li
State Key Laboratory of Water Pollution Control and Green Resource Recycling, Shanghai Institute of Pollution Control and Ecological Security, School of Environmental Science and Engineering, Tongji University, Shanghai 200092, China.
Failure Mechanics and Engineering Disaster Prevention Key Laboratory of Sichuan Province, MOE Key Laboratory of Deep Earth Science and Engineering, College of Architecture and Environment, Sichuan University, Chengdu 610065, China.
Sci Adv. 2025 Jun 6;11(23):eadu8302. doi: 10.1126/sciadv.adu8302. Epub 2025 Jun 4.
Membrane-based processes, such as reverse osmosis (RO) and nanofiltration (NF), are widely used for water purification and desalination due to their high energy efficiency and exceptional solute-water selectivity. Nevertheless, the fundamental, molecular-level mechanisms governing ion selectivity are still not fully understood. This study explores ion selectivity in polyamide desalination membranes, focusing on the partitioning and diffusion mechanisms of co-ions and counterions. Our experimental and molecular simulation results reveal that electrostatic interactions play a key role in impeding co-ion partitioning while enhancing their diffusion. The results further suggest that ion selectivity is predominantly controlled by the partitioning step, particularly the selective partitioning of co-ions. This finding highlights the importance of focusing on ion partitioning at the water-membrane interface to improve membrane ion-ion selectivity. In addition, our results point out to a trade-off between partitioning and diffusion, requiring careful tuning of these processes. Overall, this study provides the scientific foundation for molecular design of membranes with high ion-ion selectivity.
基于膜的工艺，如反渗透（RO）和纳滤（NF），因其高能效和出色的溶质-水选择性而被广泛用于水净化和海水淡化。然而，控制离子选择性的基本分子水平机制仍未得到充分理解。本研究探索聚酰胺脱盐膜中的离子选择性，重点关注同离子和反离子的分配和扩散机制。我们的实验和分子模拟结果表明，静电相互作用在阻碍同离子分配的同时增强其扩散方面起着关键作用。结果进一步表明，离子选择性主要由分配步骤控制，特别是同离子的选择性分配。这一发现凸显了关注水-膜界面处离子分配以改善膜离子-离子选择性的重要性。此外，我们的结果指出了分配和扩散之间的权衡，需要仔细调整这些过程。总体而言，本研究为具有高离子-离子选择性的膜的分子设计提供了科学依据。
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