Wang Wenguang, Wang Chao, Huang Renyao, Hong Guanghui, Zhang Yanqiu, Zhang Xigui, Shao Lu
MIIT Key Laboratory of Critical Materials Technology for New Energy Conversion and Storage, State Key Laboratory of Urban Water Resource and Environment, School of Chemistry and Chemical Engineering, Harbin Institute of Technology, Harbin 150001, China; School of Materials Science and Engineering, China University of Petroleum (East China), Qingdao 266580, China.
MIIT Key Laboratory of Critical Materials Technology for New Energy Conversion and Storage, State Key Laboratory of Urban Water Resource and Environment, School of Chemistry and Chemical Engineering, Harbin Institute of Technology, Harbin 150001, China.
Water Res. 2025 Jan 1;268(Pt B):122729. doi: 10.1016/j.watres.2024.122729. Epub 2024 Oct 31.
Monovalent cation exchange membranes (MCEMs) have progressively played an important role in the field of ion separation. However, according to transition state theory (TST), synchronously tuning the enthalpy barrier (△H) and entropy barrier (△S) for cation transport to improve ion separation performance is challenging. Here, the enamine reaction between the -NH- and -CHO groups is applied to regulate the subsequent Schiff-base reaction between the -CHO and -NH groups, which reduces the positive charges of the selective layer but increases the steric hindrance. The increased -T△S (△S term) for cation transport plays an important role in improving Li/Mg separation performance. The optimal positively-charged glutaraldehyde@piperazine/polyethyleneimine assembled membrane (M-Glu@PIP/PEI) has a perm-selectivity (Li/Mg) of 31.83 with a Li flux of 1.87 mol·m·h, surpassing the Li/Mg separation performance of state-of-the-art monovalent ion selective membranes (MISMs). Most importantly, the selective electrodialysis (S-ED) process with M-Glu@PIP/PEI can be directly applied to treat simulated salt-lake brines (SLBs), and its superior Li/Mg separation performance and operational stability enables 74.44 % of the lithium resources with a Li purity of 34.02 % to be recovered. This study presents new insights into the design of high-performance MCEMs for energy-efficient resource recovery.
单价阳离子交换膜（MCEMs）在离子分离领域逐渐发挥着重要作用。然而，根据过渡态理论（TST），同步调节阳离子传输的焓垒（△H）和熵垒（△S）以提高离子分离性能具有挑战性。在此，利用-NH-和-CHO基团之间的烯胺反应来调节随后-CHO和-NH基团之间的席夫碱反应，这降低了选择性层的正电荷，但增加了空间位阻。阳离子传输中增加的-T△S（△S项）在提高Li/Mg分离性能方面发挥着重要作用。最优的带正电荷的戊二醛@哌嗪/聚乙烯亚胺组装膜（M-Glu@PIP/PEI）的渗透选择性（Li/Mg）为31.83，Li通量为1.87 mol·m⁻²·h⁻¹，超过了最先进的单价离子选择性膜（MISMs）的Li/Mg分离性能。最重要的是，采用M-Glu@PIP/PEI的选择性电渗析（S-ED）工艺可直接用于处理模拟盐湖卤水（SLBs），其优异的Li/Mg分离性能和运行稳定性使得锂纯度为34.02%的74.44%的锂资源得以回收。这项研究为设计用于节能资源回收的高性能MCEMs提供了新的见解。
