Bipolar membrane electrodialysis (BMED) is a promising process to prepare LiOH from the salt lake brine. Revealing the effects of the cell configuration and property of bipolar membrane (BM) on the mass transfer and current efficiency of BMED is crucial to promote its industrial application. Herein, two-compartment (C-B) and three-compartment (A-C-B), and three types of BMs (FBM, BP-1, and TWBP1) were systematically studied. Results show that three-compartment is superior to two-compartment, as the latter could restrain electromigration of Li, enable recombination of H and OH, and lead to lower current efficiency. Among three BMs, TWBP1 has highest current efficiency, while BP-1 can prepare LiOH solution with least impurity ions. To reveal the influencing mechanism of the BMs’ properties on the electromigration of Li and co-ions leakage, CVC curves and chronopotentiograms were detailly investigated. Results show that the higher energy consumption of BP-1 may be attributed to its highest specific resistivity, while its better co-ions selectivity is beneficial to prepare acid/base solutions with lesser impurities, indicating that effects of the specific resistivity and selectivity of BMs on BMED process for producing LiOH from salt lake brine is an important “trade-off” relationship needing to be balanced to realize the higher current efficiency and higher quality products.

中文翻译：

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池结构和双极膜对双极膜电渗析盐湖卤水制备LiOH的影响


双极膜电渗析 (BMED) 是一种从盐湖卤水中制备 LiOH 的有前景的工艺。揭示双极膜（BM）的细胞结构和性质对BMED传质和电流效率的影响对于促进其工业应用至关重要。在此，系统地研究了两室（C-B）和三室（A-C-B）以及三种类型的BM（FBM、BP-1和TWBP1）。结果表明，三室优于两室，因为后者可以抑制Li的电迁移，使H和OH复合，并导致电流效率较低。在三种BM中，TWBP1具有最高的电流效率，而BP-1可以制备杂质离子最少的LiOH溶液。为了揭示BM性能对Li和共离子泄漏电迁移的影响机制，对CVC曲线和计时电位图进行了详细研究。结果表明，BP-1较高的能耗可能归因于其最高的比电阻率，而其较好的共离子选择性有利于制备杂质较少的酸/碱溶液，这表明BMs的比电阻率和选择性的影响BMED盐湖卤水生产LiOH工艺是一个重要的“权衡”关系，需要平衡才能实现更高的电流效率和更高质量的产品。