Formoxylbenzo-15-crown-5 ether functionalized PVA/NWF composite membrane for enhanced 7Li+ enrichment

Abstract Few work focuses on the 7 Li + enrichment materials even though each Li isotope plays an important role in the nuclear industry. In this work, we present an efficient composite membrane for 7 Li + enrichment. The composite membrane was prepared using nonsolvent-induced phase separation (NIPS) method, obtained by casting the polymer polyvinyl alcohol (PVA) grafted formoxylbenzo-15-crown-5 (FB15C5) (PVA- g -FB15C5) in DMSO solution on non-woven fabrics (NWF). The composite membrane exhibited a large amount of sponge-like structure with the average pore diameter of 0.36 µm. The dynamic liquid–solid extraction results clearly indicated that the distribution coefficient ( K d ) increased dramatically from 136 to 175 mL g −1 with an increase of crown ether immobilization amount from 0.76 to 2.13 mmol g −1 , and the equilibrium separation factor (α) also increased significantly from 1.013 ± 0.002 to 1.065 ± 0.002, which is much higher than that obtained using FB15C5 by the liquid–liquid extraction (1.022 ± 0.002) and non-porous PVA- g -FB15C5 film via liquid–solid static extraction (1.046 ± 0.002). More importantly, 7 Li + concentrated on the composite membrane as a result of the enhanced electron density of the crown ether after grafted onto PVA. In a word, the functional composite membrane exhibits an attractive application potential in the development of green and highly efficient membrane chromatography for lithium isotope adsorptive separation.