Analytical Sciences

Polymerization and Adduct Formation of Some Lanthanide(III) Decanoates in the Extraction of Lanthanides(III) with Decanoic Acid Using 1-Octanol and Benzene as a Solvent

Hiromichi YAMADA, Michio MIYASHITA, Yukinari SEKIGUCHI, Masashi KOJIMA and Hiroko WADA

Department of Applied Chemistry, Nagoya Institute of Technology, Gokiso, Showa, Nagoya 466-8555, Japan

The solvent extraction of lanthanum(III), cerium(III), neodymium(III), samarium(III), gadolinium(III), dysprosium(III), erbium(III) and ytterbium(III) with decanoic acid in 1-octanol and benzene was carried out at 25ûÃ and at an aqueous ionic strength of 0.1 mol dm -3 (NaNO3). In extraction systems using 1-octanol as a solvent, all of the lanthanides were found to be extracted as two kinds of monomeric decanoates; in those using benzene, the monomeric, dimeric and tetrameric lanthanide(III) decanoates were proven to be responsible for the extraction, except for gadolinium(III), whose extracted species were the monomeric and dimeric species. The dimerization, tetramerization and adduct formation con-stants of lanthanide(III) decanoates in the organic phase were estimated. A so-called "gadolinium break" was observed for the polymerization constants of lanthanide(III) decanoates. (Keywords: Polymerization of lanthanide(III) decanoates, solvent extraction of lanthanides(III), solvent effects, solvation of extracted species)

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