Solvent extraction of intra-lanthanides using a mixture of TBP and TODGA in ionic liquid

Abstract

In this study, we have investigated the solvent extraction of yttrium(III) and lanthanide(III) ions from nitric acid solutions in an organic phase consisting of a mixture of two electrically neutral extractants, namely tri-n-butyl phosphate(TBP) and N,N,N',N'-tetra(n-octyl)diglycolamide (TODGA). We employed hydrophobic room-temperature ionic liquid 1-methyl-3-butyl-imidazolium bis(trifluoromethanesulfonyl)imide as more environmentally benign diluent as compared to conventional molecular solvents. The results revealed that the addition of TBP as a co-extractant to TODGA dissolved in this ionic liquid not only enhance greatly the metal ion extraction, but also induce high intra-lanthanide ion selectivity. This was attributed to the formation of complex lanthanide species with both organic extracting agents, TBP and TODGA. In addition, when IL is used as diluent, cationic exchange between metal-organic ligand species and IL cations and neutral complex extraction result in more efficient extraction. Moreover, hydrophobic anionic IL entities could be also involved in the extraction mechanism resulting in the lipophilic metal-organic ligand complexes. The synergic solvent combination of TODGA, TBP and ionic liquid offers a possibility of excellent separation among the lanthanide(III) ions.

Chelating Extractants for Metals

“…A mixture of trivalent lanthanides (La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu) can be separated into individual elements contained in nitric acid solution by using a solution of extractants-tri-(n-butyl) phosphate (TBP) and N,N,N′,N′-tetraoctyldiglycolamide (compound 13) in ionic liquid 3, which is more environmentally friendly than conventional molecular solvents [18]. It was found that Ho, Er, Tm, Yb, and Lu are most effectively extracted using the above system.…”

“…It should be noted that in the above-mentioned works [18][19][20][21][22][23][24][25][26][27][28][29][30][31][32][33][34], separation of REEs from impurities of heavy and alkaline earth metals Fe (III), Pb (II), Ti (IV), Cu (II), Mg (II) and others as well as thorium Th (IV) contained in rare earth ores was not investigated.…”

Rhenium(VII) extraction from sulfuric aqueous solutions using ionic liquids as diluent and extractant: insights on the extraction stoichiometry and process parameters

“…Another important point that should not be ignored is the transfer of IL ions from the diluent to the aqueous phase, in this case either [omim] + or [Tf 2 N] − . Recent works 28,31,32 have pointed out that, when using conventional extractants in IL diluents, the cation or the anion of these diluents could undergo ion exchange stoichiometry with the subsequent transfer of IL ions to the aqueous phase. However, according to Eqn (9), the extraction of perrhenate anions is accompanied by the extraction of protons while maintaining the charge neutrality of the aqueous phase, and therefore there would not be a transfer of either [omim] + or [Tf 2 N] − to the aqueous phase.…”

Unraveling the coordination approach of Eu(iii) in cyphos nitrate ionic liquid – a comprehensive luminescence spectroscopy study

“…[1][2][3][4] Nevertheless, the unwanted burden of the loss of ionic components to the aqueous phase in the case of traditional imidazolium based ionic liquids ultimately reduces the meritorious impact of ionic liquids over molecular solvents. [1][2][3][4][5][6][7][8][9][10] To address this issue, long alkyl chain quaternary ammonium such as methyltrioctylammonium ([N 1888 ] + ) or phosphonium such as trihexyl(tetradecyl)phosphonium ([P 66614 ] + ) based ionic liquids have shown their potentiality in the metal ion recovery since they are highly hydrophobic and sustainable (reusability and recyclability) in nature. This essen-tially allows them to restrict the loss of ionic liquid cations to the aqueous stream during the extraction process.…”