Palladium(II) extraction by sulfur-containing calix[4,6]arenes from hydrochloric acid solutions

Selective extraction of Pd(II) ions from automotive catalyst residue in Cl− media by O-thiocarbamoyl-functionalized thiacalix[n]arenes

“…Compounds 3 and 4 showed much lower Pd(II) affinity, due to inhibition of deprotonation of the phenolic groups by the HCl media, and were thus unable to form complexes with Pd(II) through the bridging sulfur. These results indicated that compounds 3 and 4 were not suitable for the extraction of Pd(II) in acidic media (Rajiv Torgov et al, 2008Torgov et al, , 2012. In contrast, extractants 1 and 2, which contain thiocarbamoyl moieties, showed very high Pd(II) extraction efficiency.…”

“…Few extractants fail to extract Pd(II) ions at 1.0 M HCl and higher, whereas in 0.0001 M HCl (~pH 4) to 0.1 M HCl (~pH 1) good extraction was observed. For example, the extractants dibenzyl sulfide, octylbenzyl sulfide, acyclic 2,2-thiobis(4-tert-butyl)phenol, p-tert-butylthiacalix[4]arene, and ptert-butylthiacalix[6]arene were found to extract Pd ions at pH 1-4 but show negligible extraction in 1 M HCl media (Rajiv Torgov et al, 2008Torgov et al, , 2012. Sato et al (2011) studied the liquid-liquid extraction of Pd(II) from HCl solutions by dihexyl sulfide and dihexyl sulfoxide.…”

Extraction of Pd(ii) and Pt(ii) from aqueous hydrochloric acid with 1,3-diaminocalix[4]arene: switching of the extraction selectivity by using different extraction modes

“…[21][22][23] Various coordinating groups have been introduced to the upper and/or lower rims of calixarenes to produce multidentate ligands that can be applied to the extraction of PGMs. [24][25][26][27][28][29][30][31][32][33][34] However, similar to other types of extractants, most reports on PGM extraction with calix-based extractants deal with the extraction and selectivity of Pd, and papers on the extraction of other PGMs are scarce. In addition, to the best of our knowledge, there is no report on the selective extraction of other PGMs with calix-based extractants in the presence of Pd.…”

Calix[4]arene‐Based n‐Dialkylamino Extractants for Selective Platinum Group Metal Separation from Automotive Catalysts

“…synthesized “upper” and “lower” rim functionalized calix‐[4]arenes and studied their ability to extract transition metals, gold, and PGMs . Kostin and coworkers used many sulfur‐containing calix[4/6]arenes for the extraction of PGMs from hydrochloric acid solutions . Ohto reviewed the solvent extraction of various metal cations with calixarene derivatives .…”