Ion-selective membranes (ISM) with sub-nanosized pore channels hold significant potential for applications in saline wastewater treatment and resource recovery. Herein, novel synergistic ion channels featuring bi-periodic structures were constructed through the coordination of functional Cyclen (quaternary_1,4,7,10-tetraazacyclododecane, Q_Cyclen) and Cu²⁺-m-Phenylenediamine (Cu²⁺-MPD) to develop supramolecular membranes for lithium extraction. The exterior quaternary ammonium-rich sites exhibit a significant Donnan exclusion effect, resulting in tremendous mono/divalent (Li⁺/Mg²⁺) ion selectivity; while the interior regular-confined channels of Cyclen yield a fast vehicular pathway, facilitating water molecules and Li⁺ ion-selective transport. The optimized membrane exhibited an increased water permeance of 19.2 L·m^-2·h^-1·bar^-1 and simultaneously promoted Li⁺/Mg²⁺ selectivity (achieving a selectivity of 18.5 under a Mg²⁺/Li⁺ mass ratio of 30), surpassing the trade-off limit of conventional nanofiltration membranes. Due to the acquired excellent Li⁺/Mg²⁺ selectivity, lithium extraction from simulated salt-lake brines was successfully achieved through a two-stage nanofiltration process, reducing the Mg²⁺/Li⁺ mass ratio from 40 to 1.1. This work validates the applicability of macrocyclic with intrinsic sub-nanosized channels and desired multifunctionality for developing high-performance ISM for efficient lithium separation and beyond.

中文翻译：

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具有季铵盐循环的超分子配位纳滤膜，用于从高镁/锂比盐水中高效提取锂


具有亚纳米孔径通道的离子选择性膜 （ISM） 在盐废水处理和资源回收方面具有巨大的应用潜力。在此，通过功能性 Cyclen （quaternary_1,4,7,10-四氮杂环十二烷，Q_Cyclen） 和 Cu²⁺-m-苯二胺 （Cu²⁺-MPD） 的配位构建了具有双周期结构的新型协同离子通道，以开发用于锂提取的超分子膜。外部季铵盐富铵位点表现出显著的 Donnan 排斥效应，导致巨大的单/二价 （Li⁺/Mg²⁺） 离子选择性;而 Cyclen 的内部规则受限通道产生快速的车辆通路，促进水分子和 Li⁺ 离子选择性运输。优化后的膜表现出 19.2 L·^m-2·^h-1·^bar-1 的透水率，同时提高了 Li⁺/Mg²⁺ 的选择性（在 Mg²⁺/Li⁺ 质量比为 30 的情况下达到 18.5 的选择性），超过了传统纳滤膜的权衡极限。由于获得了优异的 Li⁺/Mg²⁺ 选择性，通过两阶段纳滤工艺成功地实现了从模拟盐湖卤水中提取锂，将 Mg²⁺/Li⁺ 质量比从 40 降低到 1.1。这项工作验证了具有内禀亚纳米通道的大环和所需的多功能性的适用性，以开发用于高效锂分离及其他领域的高性能 ISM。