Electromigration separation of lithium isotopes: The effect of electrolytes

The high-abundance lithium isotopes are key materials for the development of the nuclear industry. Lithium amalgamation is currently the only industrial method used to produce lithium isotopes, but it involves serious environmental pollution. Electromigration separation is one of the green and promising alternatives. Here, a “lithium salt aqueous solution │ organic solution │ aqueous solution” electromigration system was fabricated for lithium isotope separation. At a higher or lower voltage, the effects of species and initial pH of catholyte on the separation effects of lithium isotopes during electromigration were studied with different migrate time, and the origin of isotope separation was discussed. It was found that the initial pH values of the catholyte had an effect on the pH values of the anolyte. While the dramatic variation of pH in the electrolyte during electromigration was averse to the migration of Li+ and isotope separation. Furthermore, an extremely high isotope separation coefficient (1.6) was obtained at a very low Li+ migration ratio that is based on the dynamic separation. While the separation coefficient decreases with the increase of Li+ migration ratio rapidly and finally levels off, that is based on the equilibrium separation. This work provides important guidance for understanding the electromigration process and the origin of isotope separation in this system. •Lithium isotopes separation by electromigration with a higher 6Li separation coefficient.•The dramatic variation of pH in the electrolyte was averse to the migration of Li+ and isotope separation.•Isotope separation originates from both equilibrium separation and dynamic separation.