Solvent extraction of palladium (II) and platinum (IV) from aqueous chloride media with N,N-dioctylglycine

Abstract

Solvent extraction of palladium(II) and platinum(IV) from acidic aqueous chloride media with N,N-dioctylglycine in toulene was investigated. The experimental results of the distribution equilibria suggested that palladium(II) is extracted as a 1 : 2 metal : reagent chelate according to the reaction: PdCL 2 4−+ H 2R 2 ⇋PdR 2+2H ++4Cl− The data indicated that platinum(IV) was extracted as a 1 : 4 : 2 metal : chloride ion : reagent complex according to the solvating reaction: PtCL 2 6−+ H 2R 2 ⇋Pt·2HR·Cl 4+2Cl− The equilibrium constants for these extraction reactions were evaluated as K e = 2.2 × 10 2 (mol/dm 3) 5 for palladium(II) and K e = 6.3 × 10 2 (mol/dm 3). Infrared spectra of the free reagent and the glycino complexes of these metals were studied to obtain some information on the interaction between metal ions and the reagent molecules.