Separation and Recovery of Palladium (II) and Platinum (IV) from Automotive Catalysts by Solvent Extraction Using Tri-n-butyl Phosphate and Aliquat 336

Pt, Pd, Fe, Ni, and Cr are among the metals found in spent automotive catalysts, which are both environmentally critical and economically beneficial. In this study, solvent extraction methods were utilized to separate and recover palladium (Pd) and platinum (Pt) from wasted car catalyst. The synthetic leach liquor employed in this investigation contains (mg/L): Pd-140, Pt-500, Ni-800, Fe-2000 and Cr-150. The variation of tri-n-butyl phosphate (TBP) in Shellsol D70 from 0.1 to 2 M revealed selective and quantitative Pd extraction even at the lowest extractant concentration. Stripping Pd from loaded organic (LO) phase using 1 M thiourea and 1 M HCl yielded stripping efficiency of 99%. The use of Aliquat 336 at concentrations ranging from 0.05 to 0.5M in the extraction of Pt from Pd free raffinate demonstrated selective extraction of Pt, reaching 99.7% at 0.2M. The use of a McCabe-Thiele plot in 0.2M Aliquat 336 is expected to result in the extraction of more than 99% of Pt in two stages when an A/O phase ratio of 3 is used. The stripping efficiency of Pt from loaded organic (LO) at O/A ratio 6 with 0.5 M thiourea (tu) and HCl was 99.9 percent.