Comparative Study on Palladium(II) Extraction Using Thioamide-Modified Acyclic and Cyclic Extractants

For extraction from a single Pd(II) solution, 1,1′-bis[(dimethylthiocarbamoyl)oxy]-2,2′-thiobis[4-t-butylbenzene] (1) in a CHCl3 diluent was found to exhibit a higher extractability for Pd(II) ions (E% = 99.9%) in Cl– media (0.1 M) over 30 min as well as a higher extraction efficiency compared to 2,2′-thiobis[4-t-butylphenol] (2) as a starting material of 1 and macrocyclic compounds such as tetrakis[(dimethylthiocarbamoyl)oxy]thiacalix[4]arene (3) and p-tert-butylthiacalix[4]arene (4). Also, various parameters, such as the shaking time, diluents used, concentrations of Pd(II) and 1, effects of HCl, and effects of H+ and Cl– ions, were studied. Extractant 1 could also be used for the selective extraction of Pd(II) ions (E% > 99%) from the leach liquors of automotive catalysts that also contained the ions of Rh, Pd, Pt, Zr, Ce, Ba, Al, La, and Y in Cl– media and was found to be a more efficient extractant than 2 for Pd(II) recovery. In addition, the Pd(II) ions could be stripped from 1 using 0.1 M thiourea ...