New Heterocyclic Dithioether Ligands for Highly Selective Separation and Recovery of Pd(II) from Acidic Leach Liquors of Spent Automobile Catalyst

The solvent extraction behavior of Pd(II) from a hydrochloric acid solution with heterocyclic dithioether ligands, namely, 1,2-bis((5-methyl-1,3,4-thiadiazol-2-yl)thio)ethane (BMDTE) and 1,2-bis((5-(methylthio)-1,3,4-thiadiazol-2-yl)thio)ethane (BMTDTE) were investigated, for the first time, as potential extractants by using chloroform as diluent. Various experimental parameters such as effects of the concentration of hydrochloric acid, extractant concentration, hydrogen ion, chloride ion, and diluents on the extraction of Pd(II) was also investigated in detail. By comparing the extraction time, BMDTE exhibits a more rapid and quantitative extraction of Pd(II) even within 5 min than BMTDTE (30 min). The loading experiments indicated that the maximum loading capacity of BMDTE and BMTDTE for Pd(II) was determined to be 124 and 118 ppm, respectively. The stoichiometry of the extracted species during extraction was confirmed by 1H NMR and Job’s method analysis. Both of the two extractants exhibit high extract...