Wang Qingji, Wang Yilin, Wang Dan, Yang Xueying, Tang Ying, Feng Mingna, Wang Mingxia, Li Xuemin, Yan Feng
CNPC Research Institute of Safety and Environmental Technology, Beijing 102206, P. R. China.
State Key Laboratory of Petroleum Pollution Control, Beijing 102206, China.
Langmuir. 2025 Sep 9;41(35):23772-23787. doi: 10.1021/acs.langmuir.5c03056. Epub 2025 Aug 25.
Nanofiltration (NF) stands as a pivotal method for lithium resource recovery. Nonetheless, traditional NF membranes predominantly rely on size exclusion and the Donnan effect, necessitating elevated operating pressures and encountering substantial hurdles in terms of ion selectivity for lithium ions. Inspired by the host-guest recognition of crown ethers toward alkali metal ions, we prepared a crown ether-functionalized loose NF membrane (CE-LNF) via interfacial polymerization of diamino-dibenzo-14-crown-4 (DAB14C4) and trimesoyl chloride on a chloromethylated polysulfone substrate. The preparation conditions of the CE-LNF membranes were systematically optimized. Results revealed that the polyamide (PA) layer structure could be precisely tuned by changing the solvent and concentration of DAB14C4. The diffusion dialysis process with low energy consumption was applied in the Mg/Li separation experiment. Interestingly, the CE-LNF membrane achieved a unique "Li repulsion-Mg permeation" result owing to the efficient host-guest recognition of Li by DAB14C4 on the PA layer. During the diffusion process, the transmembrane flux of Mg (0.5 mol·m·h) surpassed that of Li (0.01 mol·m·h) by 50-fold, leading to a significant reduction in the Mg/Li ratio in the feed (from 19.5:1 to 5.2:1) and generating a Mg-enriched permeate. This work proposes a novel strategy for Mg/Li separation, where CE-LNF-based continuous diffusion dialysis serves as an energy-efficient, nonpressure-driven pretreatment for high Mg/Li ratio brines. The process not only produces high-purity Mg solutions but also facilitates subsequent Li recovery via secondary CE-LNF diffusion or conventional extraction methods.
纳滤（NF）是锂资源回收的关键方法。然而，传统的纳滤膜主要依靠尺寸排阻和唐南效应，需要较高的操作压力，并且在锂离子的离子选择性方面面临巨大障碍。受冠醚对碱金属离子的主客体识别启发，我们通过在氯甲基化聚砜基底上使二氨基二苯并 - 14 - 冠 - 4（DAB14C4）与均苯三甲酰氯进行界面聚合，制备了一种冠醚功能化的疏松纳滤膜（CE - LNF）。系统地优化了CE - LNF膜的制备条件。结果表明，通过改变DAB14C4的溶剂和浓度，可以精确调节聚酰胺（PA）层结构。在镁/锂分离实验中应用了低能耗的扩散渗析过程。有趣的是，由于PA层上的DAB14C4对锂的高效主客体识别，CE - LNF膜实现了独特的“锂排斥 - 镁渗透”结果。在扩散过程中，镁的跨膜通量（0.5 mol·m⁻²·h⁻¹）比锂的跨膜通量（0.01 mol·m⁻²·h⁻¹）高50倍，导致进料中的镁/锂比显著降低（从19.5:1降至5.2:1），并产生富含镁的渗透液。这项工作提出了一种镁/锂分离的新策略，其中基于CE - LNF的连续扩散渗析作为一种节能、无压力驱动的预处理方法用于高镁/锂比盐水。该过程不仅能产生高纯度的镁溶液，还能通过二次CE - LNF扩散或传统萃取方法促进后续的锂回收。
