| Article ID | Journal | Published Year | Pages | File Type |
|---|---|---|---|---|
| 639899 | Separation and Purification Technology | 2016 | 9 Pages |
•Three lanthanoid ions were efficiently extracted in ionic liquids [C1Cnim+][Tf2N−].•Three neutral ligands TODGA, CMPO and phosphorous-containing calix[4]arene were used.•Very different composition of the extracted species was established.•The system TODGA-calix[4]arene offers synergistic enhancement.
Liquid-liquid extraction of trivalent lanthanoids (Ce, Eu and Lu) from aqueous solutions into ionic liquids (ILs) of the imidazolium family [C1Cnim+][Tf2N−] (n = 4, 6, 8 and 10) has been investigated using N,N,N′,N′-tetraoctyldiglycilamide (TODGA) and octyl(phenyl)-N,N-diisobutylcarbaoylmethyl phosphine oxide (CMPO) as extractants alone and their mixtures. In addition, the extraction behavior of 5,11,17,23-tetra-tert-butyl-25,26,27,28-tetrakis-(dimethylphosphinoylmethoxy)calix[4]arene (C4) was studied in order to understand the role of macrocyclic effect in the combined neutral/neutral solvent systems toward 4f-ions. The slope analysis of the extraction data was deduced to compare the results of solution extraction chemistry. The synergism is observed only for TODGA/C4/[C1Cnim+][Tf2N−] (n = 4, 10) selections, but not for the cases when CMPO was combined with TODGA or calix[4]arene in almost all cases. The study revealed that log D values decrease as a function of n, i.e. with a trend following that of the hydrophobicity of ILs’ cations: n = 4 > n = 6 > n = 8 > n = 10. The selectivity of Eu/Ce pair i.e. light/middle intra-group separation is critically depicted.
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