Solvent extraction of rare earth(3) nitrates with dioctylisoamylphosphine oxide from aqueous solutions

Distribution of lanthanide(3) and yttrium(3) nitrates (Re(3)) between their aqueous solutions and 30% solution of dioctylisoamylphosphine oxide (DOIAPO, S) in kerosene and n-pentadecane at 298.15 K, pH 2 is studied. Production of [Ln(NO3)3S3] composition solvates is ascertained. Equations for describing isotherms of Re(3)DOIAPO nitrate extraction under a broad variation of aqueous and organic phase composition are proposed. Values of phase extraction equilibria constants are determined. It is ascertained that extraction constant values grow under transition from lanthanum(3) to europium(3), and then are reduced under transition from gadolinium(3) to lutetium(3). Extraction constant value for yttrium is between extraction constant values for thulium(3) and ytterbium(3). 14 refs., 2 figs., 3 tabs