A Nano‐Heterogeneous Membrane for Efficient Separation of Lithium from High Magnesium/Lithium Ratio Brine,Advanced Functional Materials

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A Nano‐Heterogeneous Membrane for Efficient Separation of Lithium from High Magnesium/Lithium Ratio Brine
Advanced Functional Materials ( IF 18.5 ) Pub Date : 2021-01-27 , DOI: 10.1002/adfm.202009430
Huawen Peng ₁ , Qiang Zhao ₁

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Lithium extraction from salt lake brines is highly demanded to circumvent the lithium supply shortage. However, polymer nanofiltration membranes suffer from low lithium permeability while nanofluidic devices are hindered by complicated preparation and miniaturized scales despite high permeability. Here, the authors report a facile strategy to prepare positively charged nanofiltration membranes for ultrapermeable and selective separation of lithium ions from concentrated magnesium/lithium mixtures. A new electrolyte monomer (diaminoethimidazole bromide, DAIB) containing bidentate amine groups is designed to modify pristine polyamide composite membranes. Structure characterizations and simulations show that the DAIB modification brings about nano‐heterogeneity that not only improves surface hydrophilicity, but also reduces water transport resistance through the ≈100 nm thick separation layer. Water permeance of the modified membrane improves fivefold and is coupled with good stability in 200‐h continuous nanofiltration. It exhibits high lithium flux (0.7 mol m⁻² h⁻¹) for brines (Mg²⁺/Li⁺ ratio 20) at 6 bar operation pressure.

中文翻译：

纳米异质膜可有效分离高镁/锂比盐水中的锂

迫切需要从盐湖盐水中提取锂，以解决锂供应短缺的问题。然而，聚合物纳米过滤膜的锂渗透率低，而尽管渗透率高，但复杂的制备和规模缩小却阻碍了纳米流体装置的发展。在这里，作者报告了一种简便的策略，可制备带正电的纳滤膜，用于从浓镁/锂混合物中选择性分离锂离子，从而实现超渗透和选择性分离。包含二齿胺基团的新型电解质单体（二氨基乙咪唑溴化物，DAIB）被设计用于改性原始聚酰胺复合膜。结构表征和模拟表明，DAIB改性带来了纳米异质性，不仅提高了表面亲水性，而且还会降低水通过约100 nm厚分离层的阻力。改性膜的透水性提高了五倍，并且在200小时连续纳滤中具有良好的稳定性。它显示出高锂通量（0.7 mol m对于在6 bar工作压力下的盐水（Mg ²⁺ / Li ⁺比率20），为^-2 h ^-1）。

更新日期：2021-04-01

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