Characterization of a Novel Crown Ether System for Lithium Isotope Separation

6Li and 7Li, with excellent nuclear properties, are important raw materials in the development of the nuclear industry. In the current work, a mercury-free extraction and lithium isotopic separation system with benzo-15-crown-5 (B15C5) ether as the extractant, ionic liquid as the co-extractant, and anisole as the diluent was constructed. In addition, a novel method for extracting lithium ions with B15C5 and multistage cross-flow separation of lithium isotopes by the organic liquid film were introduced. After 20 stages of cross-flow extraction, the abundance of 6Li increased from 7.498 to 9.654% and the abundance of 7Li increased from 92.502 to 93.561%. It was demonstrated that the B15C5 system not only can enrich 6Li but also can serve to enrich 7Li. The reason for the enrichment of lithium isotopes by this method was explored. Moreover, this study predicted the number of theoretical cross-flow stages of the abundance of 6Li and 7Li which can be used as a nuclear material.