Abstract
Novel solvent-impregnated resins (SIRs) were prepared by treatment of styrene–divinylbenzene copolymer (LPS-500) with mixtures of the promising polydentante extractant (2-diphenylphosphoryl)-4-ethylphenoxy)methyl)diphenylphosphine oxide (L) and an ionic liquid [C4mim]+[Tf2N]−for the extraction chromatography recovery of Nd(III) from nitric acid solutions. It was shown that introduction of the ionic liquid into the SIR composition results in considerable enhancement of the Nd(III) recovery efficiency compared with resin impregnated only by L in slightly acidic media. The influence of the L: ionic liquid molar ratio in the SIRs composition, their percentages, concentration of metal and HNO3 in the eluent, and acid type on the value of synergistic effect and adsorption efficiency of Nd(III) recovery was studied. The SIR containing 40% of mixture of L and [C4mim]+[Tf2N]− with molar ratio 2:1 turned out to be the most efficient. The selectivity of Nd(III) separation from light and heavy rare-earth elements was studied and the optimal conditions of Nd(III) adsorption recovery and stripping by this SIR were chosen. It was found that in recovery efficiency of Nd(III) developed SIR exceeded the SIR containing Cyanex 923 (a mixture of monodentate trialkylphosphine oxides) and [C4mim]+[Tf2N]−.
Highlights
Applications of rare-earth elements (REEs) in various high technology industries are conditioned by their unique physical properties
The influence of HNO3 concentration on the adsorption recovery of Nd(III) with SIRs impregnated by phosphorylpodand L alone (SIR 10), [C4mim]+[Tf2N]− alone (SIR 11), and their mixture (SIR 4) was studied
SIR 4 extracts Nd(III) much better than SIR 10 and SIR 11 in the range of HNO3 concentrations from 0.001 to 0.1 (Figure 2). This means that introduction of an ionic liquid into the SIR composition results in a synergistic enhancement of the value of Nd(III) Kd when it is extracted by SIR 4 in slightly acidic media, which is likely due to the replacement of NO3- by more hydrophobic Tf2N- in extracted complexes of Nd(III) [50]
Summary
Applications of rare-earth elements (REEs) in various high technology industries are conditioned by their unique physical properties. The values of distribution coefficients in both subgroups smoothly rise with atomic number of element It was established using the method of extraction equilibrium shift that the metal: L ratio in extracted complexes is 1:2 irrespective of the nature of the rare earth element. Increasing attention is focused on using of ionic liquids as promising dilutents both in liquid–liquid extraction [36,37,38], and as components of SIRs [39,40,41,42] In both cases, the using of ionic liquids leads to a significant improvement of REEs recovery efficiency. Novel SIRs containing (2-diphenylphosphoryl)-4-ethylphenoxy)methyl) diphenylphosphine oxide and ionic liquid [C4mim]+[Tf2N]− were obtained and the features of the chromatographic extraction of Nd (III) from nitric acid solutions were studied as well. The comparison of recovery efficiency of Nd(III) by novel SIR and resin based on the mixture of Cyanex 923 (a mixture of monodentate trialkylphosphine oxides) and [C4mim]+[Tf2N]− was performed
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