Analytical Sciences

Synergistic Ion-pair Extraction and Separation of Trivalent Lanthanoid Ions with 4-Isopropyltropolone and 1,10-Phenanthroline into o-Dichlorobenzene

Takuya YAMASHITA, Yoshio NISHIYAMA, Kotaro MORITA, Hirohisa NAGATANI, and Hisanori IMURA

Division of Material Chemistry, Graduate School of Natural Science and Technology, Kanazawa University, Kakuma, Kanazawa 920-1192, Japan

The synergistic extraction of trivalent lanthanoid (Ln(III)) ions with 4-isopropyltropolone (Hipt) and 1,10-phenanthroline (phen) in o-dichrolobenzene (DCB) was investigated. The synergistic effect in DCB is more significant than that in toluene, and the polynuclear complexes found in toluene are not formed in DCB. Based on the 3-dimensional equilibrium analysis, the extracted species for La(III), Eu(III), and Lu(III) are found to be ion-pairs, such as Ln(ipt)₂phen·ClO₄ and Ln(ipt)₂(phen)·ClO₄ in the presence of NaClO₄ as a salt, and the extraction constants of the respective species were determined. The simultaneous extraction of different lanthanoids in the present extraction system was demonstrated. The separation factors between lighter lanthanoids were larger than those with 2-ethylhexyl phosphonic acid mono-2-ethylhexyl ester, an excellent extractant for the separation of lanthanoid ions, in decane.

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