Analytical Sciences

Solvent Extraction of Several Trivalent Metal Ions with4-Isopropyltropolone into Chloroform

Junji NORO

Research Department, NISSAN ARC,LTD., Natsushima-cho, Yokosuka-shi, Kanagawa 237

The solvent extraction of lanthanum(III),praseodymium(III), neodymium(III), samarium(III), europium(III),gadolinium(III), thulium(III), ytterbium(III), lutetium(III),scandium(III), and indium(III) (M(III)) in 0.1 mol dm^-3 sodiumnitrate solutions with 4-isopropyltropolone (Hipt) into chloroform wasstudied. From the dependence of extraction on the concentration of4-isopropyltropolonate anions in the aqueous phase and also on theconcentration of metal ions, it was concluded that scandium(III) andindium(III) were always extracted in the mononuclear form,M(ipt)₃. But dinuclear lanthanoid(III) chelate complexes,M₂(ipt)₆.nHipt where n=0 or 1, werealso extracted with mononuclear ones even when the metal concentration inthe organic phase was higher than about 10^-6 moldm^-3. The degree of dinuclear species formation was greater inthe following order: lutetium(III) tosamarium(III) > neodymium(III) > praseodymium(III) > lanthanum(III) > scandium(III)- indium(III). On the other hand, the stability of the self-adductdinuclear chelate complexes in the organic phase was higher in the order:lanthanum(III) togadolinium(III) > thulium(III) > ytterbium(III) > lutetium(III). (Keywords: Solvent extraction, lanthanoids, scandium, indium,4-isopropyltropolone, polynuclear chelate complex)

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