Chitosan-graft-benzo-15-crown-5-ether/PVA Blend Membrane with Sponge-Like Pores for Lithium Isotope Adsorptive Separation

Crown ether exhibits a high separation coefficient for lithium isotope separation owing to its precise size selectivity to cations. A crown ether-based solid–liquid extraction method for the lithium isotope separation with a high extraction efficiency is regarded as a valid alternative to the classic liquid–liquid method. A chitosan-graft-benzo-15-crown-5-ether (CTS-g-B15C5)/polyvinyl alcohol (PVA) porous blend membrane for lithium isotope adsorptive separation was fabricated by immersion–precipitation–phase inversion. Results indicated that the finger-like structure of the blend membrane was replaced gradually by a sponge-like structure with the increase of the CTS-g-B15C5 concentration from 20 to 50 wt %. Meanwhile, the porosity and mechanical strength of the blend membrane slightly decreased from 76.9% and 2.68 MPa to 72.5% and 2.02 MPa, respectively, whereas the average pore size increased from 0.33 to 0.73 μm. The obtained CTS-g-B15C5/PVA (50/50 wt/wt) blend membrane exhibited a sponge-like asymmetri...