The adsorption and separation of Pd(II) from Pt(IV), Ir(IV) and Rh(III) by silica microparticles functionalized with triethylenetetramine (TETA), 2-(2-aminoethylthio)ethanamine (NSN) and 2-(2-(2-aminoethyl)ethylthio)ethanamine (NSSN) in 1 M hydrochloric acid medium was investigated by continuous column studies. The functionalized sorbent materials were characterized by microanalysis, SEM-EDS and FT-IR. Palladium selectivity of the sorbent materials was achieved by stripping of rhodium, iridium and platinum chlorido species with 0.5 M of NaClO4 in 1 M HCl while [PdCl4]2 was eluted with 3% w/v thiourea. The desorption efficiency of thiourea was confirmed by the SEM-EDS analysis of the materials after Pd(II) elution. Palladium loading capacity of the sorbents were in the order S-NSSN (23.85 mg/g) > S-NSN (12.70 mg/g) > S-TETA (4.97 mg/g). The extraction patterns on the sorbent materials were explained by considering the coordination chemistry of the ligand with [PdCl4]2ˉ and ionic interactions of [PtCl6]2ˉ and [IrCl5(H2O]ˉ. The square planar complexes, [Pd(HNSSNH)Cl2]Cl2 and [Pd(NSNH)Cl2][PdCl4]2, were isolated, analyzed by spectroscopy and single crystal X-ray, whereas evidence of the fraction of Pd(II)-TETA complex was obtained by HPLC studies. This provided proof of the inner sphere coordination mechanism as the mode of interaction of these ligands with [PdCl4]2ˉ. Trace amounts of Brˉ anions in ligands resulted in the inadvertent isolation of bromide coordinated Pd(II) NSN and NSSN complexes. The ion-pair salts of [TETAH4]4+ with [PtCl6]2ˉ, [IrCl6]3ˉ and [RhCl6]3ˉ were also isolated and characterized by microanalysis and IR to further explain the extraction patterns.
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:nmmu/vital:27046 |
| Date | January 2016 |
| Creators | Moyo, Cyprian Bertrand |
| Publisher | Nelson Mandela Metropolitan University, Faculty of Science |
| Source Sets | South African National ETD Portal |
| Language | English |
| Detected Language | English |
| Type | Thesis, Masters, MSc |
| Format | xvi, 125 leaves, pdf |
| Rights | Nelson Mandela Metropolitan University |
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