Polyvinyl alcohol-graft-benzo-15-crown-5 ether for lithium isotopes separation by liquid–solid extraction

A film material, polyvinyl alcohol-graft-benzo-15-crown-5 ether (PVA-g-B15C5) for lithium isotope separation by liquid–solid extraction was prepared from polyvinyl alcohol (PVA) and 4′-formoxylbenzo-15-crown-5 ether (FB15C5). The effect of immobilization amount of crown ether on film, the counter anion of lithium salt, extraction solvent and temperature on separation factor were explored in detail. The maximum separation factor 1.060 ± 0.002 was obtained by an isopropanol-LiI/PVA-g-B15C5 film system at 20 °C. The heavy isotope, 7Li was enriched in the film phase owning to a stronger bonding environments from the synergistic effect of B15C5 and hydrophilic PVA as well as the linking groups.