Extraction Mechanism of Rare Earths with Bifuncional Ionic Liquids (Bif-ILs) [A336][CA-12]/[A336][CA-100] in Nitrate Medium

In this study, solvent extraction of rare earths with bifuncional ionic liquids (Bif-ILs) [A336][CA-12]/[A336][CA-100] was systematically investigated in nitate medium. The extraction abilities for rare earths were compared with those of organic carboxylic acids CA-12/CA-100 and neutral organophosphorus extractants TBP/P350, and they are in the descending order: [A336][CA-12]/[A336][CA-100]>CA-12/CA-100>P350>TBP. The slope analysis method was used to determine the extraction stoichiometry. The study of extraction mechanisms of rare earths by Bif-ILs [A336][CA-12]/[A336][CA-100] showed that the mechanism is in accord with complexing mechanism. By studying the effect of extraction equilibration time and temperature on the extraction efficiencies, we found that the extraction process of rare earths by Bif-ILs [A336][CA-12]/[A336][CA-100] is a fast equilibrium and an exothermic reaction. The recycling and stripping experiments indicated Bif-ILs [A336][CA-12]/[A336][CA-100] with high stability and easy stripping characteristics are suitable for extracting rare earths.