Enhancement in Li + /Mg 2+ separation from salt lake brine with PDA–PEI composite nanofiltration membrane
Enhancement in Li + /Mg 2+ separation from salt lake brine with PDA–PEI composite nanofiltration membrane
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DOI：
10.1002/app.49549
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发表时间：
2020-12
影响因子：
3
通讯作者：
M. Ashraf;Junfeng Wang;Baichun Wu;Penglei Cui;Baohua Xu;Xingchun Li
中科院分区：
文献类型：
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作者：
M. Ashraf;Junfeng Wang;Baichun Wu;Penglei Cui;Baohua Xu;Xingchun Li
利用纳滤膜从高镁锂比盐湖卤水中提取锂是一项极具挑战性的工作。为了提高锂离子的分离效率，采用界面聚合的方法，用聚多巴胺(PDA)和聚乙烯亚胺(PEI)对纳滤膜进行改性。比较了PDA/PEI沉积前后三种纳滤膜的渗透性和盐截留率(Li+和Mg2+)，发现分离效率不仅受空间位阻的影响，还受Donnan排阻机制的影响。对于简单聚合后的NF2 70膜，由于孔径分布小，Zeta电位测量证实其电荷密度较低，在流量为2 1.33 L·m−2·h−1时，Li+渗透率达到95%左右。虽然改性后的DK膜，分离因子SFLi/Mg也增加到60，但孔的缩窄效应显著降低了锂的渗透率和通量。实验结果表明，简单的改性不仅提高了稳定性和亲水性，而且将高的镁锂比从30降到了4.1。
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 SFLi/Mgwas 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.