Solvent extraction of rare earth metals by mixture of di-2-ethylhexylphosphoric acid and tri-n-butyl phosphate

Nitric acid and cerium (3) extraction by isomolar mixtures of di-2-ethylhexylphosphoric acid (HDEHP) and tri-n-butyl phosphate (TBP) with sum concentration of 1.0 mol/l in decane from solutions with different nitric acid and lithium nitrate concentration is investigated. It is shown that nitric acid extraction is described by adolitivity equation. This testifies to the fact that nitric acid does not form mixed complexes and weak interaction between extractants does not lead to any sufficient change of their concentrations. Effective constant values of nitric acid extraction by HDEHP and TBP solutions are presented. During cerium (3) extraction by HDEHP and TBP mixture a synergetic effect is observed the value of which is decreased with the increase of nitric acid and salting out agent (lithium nitrate) concentration. Synergetic effect maximum corresponds to the molar ratio of extractant concentrations TBP:HDEHP=(3:2)-(4:1)