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

Few work focuses on the Li-7(+) 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 Li-7(+) 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) (PVAg-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 gm. 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 (alpha) 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, Li-7(+) 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. (C) 2019 Taiwan Institute of Chemical Engineers. Published by Elsevier B.V. All rights reserved.