Extraction and separation of lithium isotopes by using organic liquid film extraction system of crown ether-ionic liquid

Abstract

The organic liquid film extraction system, a novel extraction system, was investigated for the extraction and separation of lithium isotopes using ionic liquid as the co-extractant and Dibenzo-15-crown 5-Ether (DB15C5) as the extractant. Multiple subjects were studied during the investigation, including the effects of extraction time; gas flow rate; temperature; counter anions of lithium salt; the length of the cationic carbon chain of ionic liquid on extraction, and separation of lithium isotopes. The maximum separation factor α was 1.037 ± 0.002 and the abundance of 6Li increased from 7.61 % to 7.86 %. Based on the slope analysis method, the formation of 1:1 complex [Li (DB15C5)]+ in the extraction phase was determined. The exchange of lithium isotope is spontaneous reaction at low temperatures (ΔH<0, ΔS<0). Also, the back-extraction times of lithium ions from extraction phase to aqueous phase were studied.