Crown ether functionalized polysulfone membrane coupling with electric field for Li+selective separation.

• A crown ether functionalized PSf membrane was prepared by in situ graft on CMPSf membrane surface • The selective separation performance of for Li⁺ was improved membrane by coupling with electric field • The PSf-sg-AB12C4 dense membrane shows good selective separation for Li⁺. • The separation factor of the PSf-sg-AB12C4 dense membrane for Mg²⁺ to Li⁺ is up to 32.6. In order to improve the selective separation performance of the membrane for Li⁺ and enhance the separation efficiency, a crown ether functionalized polysulfone membrane was prepared in this paper, and the Li⁺ was separated by electrodialysis process. Chloromethylated polysulfone (CMPSf) was used as the base membrane, 4′-aminobenzo-12-crown-4-ether (AB12C4) was in-situ grafted onto the surface of CMPSf membrane to obtain the PSf-sg-AB12C4 membrane. The chemical structure of the membrane surface was characterized by ATR-FTIR and XPS. The surface and cross-sectional morphologies of the membrane were characterized by FESEM. The PSf-sg-AB12C4 membrane was used for selective separation of Li⁺ by membrane coupling with electric field. The results show that the CMPSf membranes and the PSf-sg-AB12C4 porous membrane have almost no selective separation performance for Li⁺, while the PSf-sg-AB12C4 dense membrane can selectively separate Li⁺. After optimizing the conditions of voltage, ion concentration and solution pH, the separation factor of the PSf-sg-AB12C4 dense membrane for Mg²⁺ to Li⁺ is up to 32.6. In addition, the separation factors of coexisting ions such as Na⁺, K ⁺, Ca²⁺ to Li⁺ are all higher than that of Mg²⁺ to Li⁺, suggesting that the PSf-sg-AB12C4 dense membrane is a promising material for selective separation of Li⁺ from brine. [Display omitted] [ABSTRACT FROM AUTHOR]