The role of β-diketones in the extraction of cobalt (II) and nickel (II) ions

β-diketones were used for Co(II) and Ni(II) separation from nitrate solutions by liquid-liquid extraction method. Pentane-2,4-dione (1), 3-methyl-pentane-2,4-dione (2) and 3-ethyl-pentane-2,4-dione (3), all in dichloromethane solution were extractants in this process. Potentiometric studies were used to determinate dissociation constants of investigated ligands. Stability constants of the created complexes were found by spectrophotometric methods and the increased in the order of 2 < 1 < 3. Extraction was carried out from three types of aqueous phase: one-component Co(II) or Ni(II), and two-component Co(II)-Ni(II). It was proved that pentane-2,4-dione (1) is the most effective extractant. (paper)