Synthesis and characterisation of p-diethylaminomethylthiacalix[4]arene for selective recovery of platinum from automotive catalyst residue

The ability of chloroform solutions of p-diethylaminomethylthiacalix[4]arene 1 to extract platinum from HCl media was tested. As an ion-pair extractant, compound 1 had the highest platinum extraction ability among all the thiacalix[n]arene derivatives tested in this study. Compound 1 was a highly specific extractant for Pt(IV) ions from single-metal solutions and platinum-group metal solutions from automotive catalyst residue. Various conditions such as contact time, pH, concentration of 1, effect of chloride ions, effect of acidity and Pt(IV) concentration were studied. The distribution ratio of platinum ions (D) was calculated. The platinum complex stoichiometry ratio was obtained using slope analysis. The 1-Pt(IV) complex was characterised using X-ray photoelectron spectroscopy, FT-IR and H-1 NMR. Finally, the Pt (IV) extraction percentage of compound 1 was compared with that of previously reported thiacalix[n]arene-based extractants.