Enhancement in Li+/Mg2+ separation from salt lake brine with PDA–PEI composite nanofiltration membrane,Journal of Applied Polymer Science

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Enhancement in Li+/Mg2+ separation from salt lake brine with PDA–PEI composite nanofiltration membrane
Journal of Applied Polymer Science ( IF 2.7 ) Pub Date : 2020-07-04 , DOI: 10.1002/app.49549
Muhammad Awais Ashraf _{1,

2} , Junfeng Wang _{1,

3} , Baichun Wu ₄ , Penglei Cui ₁ , Baohua Xu ₁ , Xingchun Li ₄

Affiliation

Extraction of lithium from high Mg²⁺/Li⁺ ratio salt lake brine with the nanofiltration (NF) membrane is significantly challenging. Interfacial polymerization was utilized for the facile modification of NF membranes with polydopamine (PDA) and polyethylenimine (PEI) to enhance lithium separation efficiency. Comparing permeability and salts rejection (Li⁺ and Mg²⁺) of three NF membranes before and after PDA/PEI deposition, it was observed that separation efficiency was not only dependent on steric hindrance but also affected by Donnan exclusion mechanism. In the case of NF270 membrane after facile polymerization, due to small pore size distribution and low charge density confirmed by zeta potential measurements, Li⁺ permeability was reached about 95% at a flux of 21.33 L·m⁻²·h⁻¹. Although with the DK membrane, separation factor SF_Li/Mg was also increased up to 60 after modification, the pore narrowing effect significantly decreased lithium permeability and flux. Experimental results showed that facile modification not only enhanced stability and hydrophilicity but also reduced the high Mg²⁺/Li⁺ ratio from 30 to 4.1 in single‐stage separation.

中文翻译：

PDA-PEI复合纳滤膜增强盐湖盐水中Li + / Mg2 +的分离

使用纳滤（NF）膜从高Mg ²⁺ / Li ⁺比盐湖盐水中提取锂具有很大的挑战性。界面聚合用于利用聚多巴胺（PDA）和聚乙烯亚胺（PEI）轻松修饰NF膜，以提高锂分离效率。比较PDA / PEI沉积前后三种NF膜的渗透性和盐截留率（Li ⁺和Mg ²⁺），观察到分离效率不仅取决于空间位阻，而且还受Donnan排斥机制的影响。对于容易聚合后的NF270膜，由于孔径分布小和zeta电位测量证实的电荷密度低，Li ⁺通量为21.33 L·m ^-2 ·h ^-1时，渗透率达到了约95％。尽管使用DK膜，改性后分离系数SF _{Li / Mg}也增加到60，但细孔收窄效果显着降低了锂的渗透性和通量。实验结果表明，简单的改性不仅提高了稳定性和亲水性，而且还使单级分离中的高Mg ²⁺ / Li ⁺比例从30降低至4.1。

更新日期：2020-07-04

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