Electronanofiltration Membranes with a Bilayer Charged Structure Enable High Li+/Mg2+ Selectivity,ACS Applied Materials & Interfaces

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Electronanofiltration Membranes with a Bilayer Charged Structure Enable High Li+/Mg2+ Selectivity
ACS Applied Materials & Interfaces ( IF 8.3 ) Pub Date : 2024-01-25 , DOI: 10.1021/acsami.3c16092
Jia-Shuai Chen _{1,

2} , Jing Wang _{1,

2} , Ji-Hong Zhang _{1,

2} , Zhi-Yuan Guo _{1,

2} , Pan-Pan Zhang _{1,

2} , Xiao-Fu Guo _{1,

2} , Jie Liu _{1,

2} , Zhi-Yong Ji _{1,

2}

Affiliation

Achieving separation of lithium and magnesium with similar radii is crucial for the current lithium extraction technology from salt lakes, which usually possess a high lithium-to-magnesium ratio. Herein, we proposed the facile sequential interfacial polymerization (SIP) approach to construct electronanofiltration membranes (ENFMs) with a bilayer charged structure consisting of a high positively charged surface and a negatively charged sublayer. The trimesoyl chloride (TMC) concentration was adjusted to enhance the −COOH content and negative charge of the polyamide sublayer to promote Li⁺ migration, and then the quaternized polyethylenimine was introduced to the membrane surface by the SIP process to increase the positive charge density on the surface of the ENFMs, which would block the migration of Mg²⁺ and enhance the Li⁺/Mg²⁺ selectivity of the ENFMs. The optimal quaternary-modified ENFMs achieved outstanding selectivity for Li⁺/Mg²⁺ (49.85) and high Li⁺ flux (4.10 × 10^–8 mol cm^–2 s^–1) at a current density of 10 mA cm^–2. Moreover, in simulated brines with low lithium concentration and high Mg²⁺/Li⁺ ratio, the optimal ENFMs also displayed elevated Li⁺/Mg²⁺ selectivity (>45), highlighting the substantial promise of the membranes for practical applications.

中文翻译：

具有双层带电结构的电纳滤膜可实现高 Li+/Mg2+ 选择性

实现半径相似的锂和镁的分离对于当前从盐湖中提取锂的技术至关重要，盐湖通常具有较高的锂镁比。在此，我们提出了简便的顺序界面聚合（SIP）方法来构建具有双层带电结构的电子纳滤膜（ENFM），该双层带电结构由高带正电的表面和带负电的子层组成。调节均苯三甲酰氯（TMC）浓度，提高聚酰胺底层的-COOH含量和负电荷，促进Li ⁺迁移，然后通过SIP工艺将季铵化聚乙烯亚胺引入到膜表面，增加聚酰胺底层的正电荷密度。 ENFMs的表面，这会阻止Mg ²⁺的迁移并增强ENFMs的Li ⁺ /Mg ²⁺选择性。最佳的四元改性ENFM在10 mA cm ^–2的电流密度下实现了对Li ⁺ /Mg ²⁺的出色选择性（49.85）和高Li ⁺通量（4.10 × 10 ^–8 mol cm ^–2 s ^–1 ）。此外，在低锂浓度和高Mg ²⁺ /Li ⁺比的模拟盐水中，最佳ENFM还表现出较高的Li ⁺ /Mg ²⁺选择性（>45），凸显了该膜在实际应用中的巨大前景。

更新日期：2024-01-25

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