Similar physicochemical properties render the separation of Li/Mg from salt lake brine difficult for two-dimensional (2D) membranes. Herein, ultraefficient Li/Mg separation was achieved under the influence of an electric field using MXene/carbon nanotube (CNT) membranes developed on tubular ceramic substrates via thermal crosslinking. Crosslinking reactions between CNTs and MXene yielded well–intercalated CNTs between MXene nanosheets, forming antiswelling MXene/CNT membranes (MCMs) (interlayer spacing: 8.04 Å) suitable for Li/Mg separation. At 2.8 V applied voltage, the MCMs exhibited Li flux of 0.0491 mol m h and high Li/Mg selectivity of 54.5, which outperform existing state–of–the–art 2D membranes. Specifically, under a positive electric field, Li with a small hydration diameter and low hydration energy permeated through the membrane nanochannels more easily than Mg, increasing and decreasing Li and Mg flux, respectively. Additionally, Mg retention was enhanced via the complexation of enriched Mg with –OH and –COOH on the membrane surface. The MXene membrane surface was thus reconfigured to be positively charged, inducing effective Mg rejection. This study offers a novel and practical approach for efficiently separating Li/Mg as well as monovalent/multivalent ions.

中文翻译：

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电场辅助下使用 MXene/CNT 膜超高效分离 Li+/Mg2+

相似的物理化学性质使得二维 (2D) 膜难以从盐湖卤水中分离锂/镁。在此，利用通过热交联在管状陶瓷基板上开发的 MXene/碳纳米管（CNT）膜在电场的影响下实现了超高效的 Li/Mg 分离。 CNT 和 MXene 之间的交联反应在 MXene 纳米片之间产生了良好嵌入的 CNT，形成适合 Li/Mg 分离的抗膨胀 MXene/CNT 膜 (MCM)（层间距：8.04 Å）。在 2.8 V 施加电压下，MCM 表现出 0.0491 mol mh 的 Li 通量和 54.5 的高 Li/Mg 选择性，优于现有的最先进的 2D 膜。具体来说，在正电场下，具有小水合直径和低水合能的Li比Mg更容易渗透膜纳米通道，分别增加和减少Li和Mg通量。此外，通过富集的 Mg 与膜表面上的 –OH 和 –COOH 的络合增强了 Mg 的保留。因此，MXene 膜表面被重新配置为带正电荷，从而诱导有效的镁排斥。这项研究为有效分离锂/镁以及单价/多价离子提供了一种新颖实用的方法。