Pd(II) and Pt(IV) dispersive or non-dispersive extraction from model and real leach solutions with alkoxyimine-1-propylpyridinium derivatives

Abstract

The studies present results of Pt(IV) and Pd(II) conventional liquid–liquid extraction and non-dispersive extraction in pseudo-emulsion hollow fiber strip dispersion (PEHFSD) with alkoxyimine-1-propylpyridinium derivatives. Liquid-liquid extraction was used to extract Pd(II) and Pt(IV) both from the model solutions (single and two-component) and from the real solutions, obtained after the leaching PGM from spent automotive catalysts with aqua regia or HCl/H2O2/H2SO4 mixture. The extraction efficiency of Pt(IV) or Pd(II) from one-component solutions with all extractants used (except 4-[1-(2-ethylhexyloxyimine)methyl]-1-propylpyridinium chloride) was high (>90%). However, phase separation took place after 24 h. Also, the coextraction of the H+ ions into the organic phases was observed. It was found that the coextraction of H+ with PGM from one- and two-component model solutions was slight and did not affect the extraction efficiency of PGM. However, for real solutions, the higher the concentration of H+ ions in the feed solution, the stronger the H+ coextraction effect was noted, and resulted in decrease in the extraction efficiency of metal ions from real leach solutions. 3-[1-(decyloxyimine)ethane]-1-propyl-pyridinium chloride (D3EI-PrCl) was found to be asuitable Pd(II) carrier for the liquid membrane technique PEHFSD for the removal of Pd(II) from the Pd(II)/Pt(IV) mixture. The kinetics of the Pd(II) removal depended on the composition of the feed solution; in the presence of Pt(IV), Pd(II) extraction took 2 h, while almost 100% Pd(II) was removed from one-component model solution in 1 h.