Recovery of platinum,palladium, rhodium,iridium, and gold after lead fusion and perchloric acid parting

A method is described for the wet analysis of the lead-noble metals button which is parted with perchloric acid after heating at 160–180°C, thus resulting in the complete dissolution of platinum, palladium, rhodium, and gold, indium remains totally unattacked. Quantitative group precipitation of the precious metals from the diluted lead perchlorate filtrate solution is possible with 2-mercaptobenzothiazole as precipitant. The noble metals precipitated are isolated by filtration and are easily determined. The proposed procedure is rapid, precise, and applicable to a wide variety of platiniferous materials.     

Extractive spectrophotometric determination of platinum, rhodium and iridium

Platinum, iridium and rhodium in mixtures are determined sequentially, with rubeanic acid, tin(II) chloride and tin(II) iodide respectively. The working ranges (in microg) are: Pt 7-100, Rh 7-70, Ir 7-30.     

The rapid isolation and determination of iridium after simultaneous liquid-liquid extraction and determination of platinum,palladium, rhodium and gold

The proposed method provides a rapid isolation of iridium form the other noble metals, as well as from Ni, Cu, Fe, Cr, Co and Na. The scheme comprises an initial removal of ruthenium and osmium by volatilization of their tetroxides followed by the simultaneous extraction of platinum, palladium, rhodium and gold as their 2-mercaptobenzothiazole—tin(II) chloride complexes into chloroform. Iridium in the raffinate is complexed by the same reagent system, after boiling, and extracted into chloroform. The extracts after evaporation of the solvent are converted to hydrochloric acid solutions and the noble metals are determined by atomic absorption spectrometry. Satisfactory results are obtained for various noble metal solutions, and for a solid platiniferous sample.     

Particle size determination of platinum, palladium and rhodium

Simple and sufficiently accurate equations are suggested for calculating the particle size of most frequently used supported or unsupported platinum metal catalysts from the amount of chemisorbed gas.

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A solvent-extraction scheme for the determination of platinum,palladium, rhodium,iridium and gold in platiniferous materials

The integrated scheme described for the determination of five noble metals, combines solvent extraction procedures with atomic absorption spectrometric finishes. It comprises an initial extraction of gold, a simultaneous extraction of platinum and palladium as iodides, and a subsequent simultaneous extraction and preconcentration of rhodium and indium as their 2-mercaptobenzothiazol? complexes. The same solvent, methyl isobutyl ketone, and the same acidity, 6 M, are used throughout the extractions. As large amounts of platinum and palladium can be extracted quantitatively as readily as small amounts, the proposed scheme is applicable to a wide range of platiniferous materials, particularly to those with extremely high Pt + Pd to Rh + Ir ratios.     

Investigation of the surface properties of platinum,rhodium and iridium electrodes in hydrofluoric acid solutions

The charging curves, the potentiodynamic curves and the isoelectric potential shifts have been measured on Pt, Rh and Ir electrodes in HF and HF + KF solutions in a Teflon cell. From the obtained data, the Γ_H⁺?? curves and the Δσ?? curves of the first kind have been calculated by means of the thermodynamic theory of the hydrogen electrode. The Γ_H⁺ values in 0.14 M HF and 0.3 M HF + 0.12 M KF are much less than in 0.005 M H₂SO₄ and 0.005 M H₂SO₄ + 0.5 M K₂SO₄ solutions. In the presence of F^? anions, the potentials ?_ε=0 and ?_Q=0 are by 25–55 mV more anodic than in the presence of SO^2?₄ anions. In an acidified fluoride solution the values of σ are higher than in an acidified sulfate solution. The analysis of the results obtained leads to the conclusion that on platinum metals the fluoride anions in the ?_r region investigated (from ?_r = 0 to ?_r = 900 mV) are the most weakly adsorbed anions.     

Selective extraction of platinum,iridium, and palladium with macrocyclic endo-receptors from hydrochloric acid solutions

Extraction of Pt, Ir, Pd by the macrocyclic polyethers dibenzo-18-crown-6 (DB18C6) and cis-syncis-dicyclohexyl-18-crown-6 (DCH18C6, isomer A) in organic solvents (chloroform, dichloroethane) from 3–10 M aqueous HCl was studied. It was found that DCH18C6 in dichloroethane excellently extracted Pt, Ir, and Pd in the presence of KSCN. Re-extraction of Pt, Ir, and Pd from the organic phase can be fulfilled by 1 M HNO₃. Thus, the macrocyclic polyethers are effective reagents for isolation of Pt, Ir, and Pd from HCl solutions.     

A new solvent extraction scheme for the separation of platinum,palladium, rhodium and iridium

A new scheme is proposed for the separation of platinum, palladium, rhodium and iridium in hydrochloric acid solutions, by solvent extraction. Platinum and palladium are complexed with 2-mercaptobenzothiazole and potassium iodide and simultaneously extracted into chloroform, thus separating them from rhodium and iridium. Palladium is separated from platinum by extracting its dimethylglyoxime complex into chloroform, while rhodium is separated from iridium by extracting its 2-mercaptobenzothiazole complex into chloroform after reduction with tin(II) chloride.     

Electrothermal atomization-laser induced fluorescence determination of iridium,rhodium, palladium,platinum and gold at the ng/l level in pure water

Trace determination of Au, Rh, Ir, Pd and Pt in pure water solution has been performed by electrothermal atomization-laser induced fluorescence (ETA-LIF). Limits of detection obtained are in the ng/l⁻¹ range, improving previously published absolute limits of detection by one or two orders of magnitude. The day to day reproducibility for iridium is around 8%. Thus, the ETA-LIF technique can be used routinely for the determination of precious metals at ultratrace concentrations.     

Studies on iridium and platinum determination in metallic rhodium by NAA and CPAA

The determination of Ir and Pt in rhodium neutron monitors was investigated via¹⁹²Ir and¹⁹⁹Au after neutron activation, via¹⁹¹Pt and¹⁹⁴Au–¹⁹⁶Au after proton activation. Ir was determined by instrumental NAA. A chemical separation of gold, with a yield measurement method by a radioactive tracer, was developed for platinum determination after neutron or proton irradiation.     

Separations of platinum metals by ion exchange : The separation of palladium from iridium

Palladium and iridium are separated by passing an ammoniacal solution of the chlorides over Amberlite IR-100 resin. Palladium is retained as Pd(NH₃)₄⁺² while iridium, as IrCl₆^-3, passes through the column quantitatively. Palladium is then removed from the column by elution with 1 M hydrochloric acid.     

Simultaneous neutron activation determination of palladium,gold, platinum and iridium in some natural materials

A method for rapid simultaneous neutron activation determination of Pd, Au, Pt and Ir in USGS standard rocks, ores and minerals has been developed based on selective extraction of determined elements. Results of determination of noble metals in standard rocks are discussed.     

The rapid separation and determination of iridium after lead collection and perchloric acid parting

A rapid and accurate method is described for the determination of iridium in platiniferous materials.The method is based on the classical fire-assay collection of the noble metals into a lead button and the subsequent complete dissolution of lead with perchloric acid after heating at 160—180°C. Iridium remains totally unattacked by the parting acid whereas Pt, Pd, Rh and Au pass completely into the perchloric acid-lead perchlorate solution. After filtration, the residue is fused with sodium peroxide, Ru and Os are removed by boiling with perchloric acid, and iridium is finally determined photometrically or by atomic-absorption spectrometry. The proposed method shows a universal applicability and provides what is perhaps the simplest isolation procedure for iridium.     

Simultaneous determination of palladium, platinum and rhodium in crude platinum samples by activation analysis and high-resolution gamma spectrometry

Instrumental neutron-activation analysis using a Ge(Li) detector has been investigated for the simultaneous determination of platinum, palladium and rhodium in crude platinum samples contained in lead cupels. This technique proved feasible and appears promising for extension to the determination of most of the noble metals.     

Neutron activation analysis for iridium,palladium and silver in platinum

A sensitive procedure for the simultaneous determination of trace levels of iridium, palladium and silver in a platinum stock, by thermal-neutron activation analysis utilizing gamma-ray spectrometry, was developed. The radiochemical-separation scheme involved an elution of the chloro complexes of iridium and silver, and subsequently palladium, through a strongly-basic anion-exchange resin, followed by further chemical-separation methods. The ion-exchange method served to greatly reduce the hazard from radiations emitted by the bulk of the activities in the matrix. Activities of 13.5-hr¹⁰⁹Pd, 74.2-d¹⁹²Ir and 255-d^110m Ag were monitored by accumulation of pulses from a 3-in diam. NaI(T1) crystal detector. Further discrimination was attained by resolution of decay curves. The procedure provided analyses for a platinum stock of 0.015±0.0021 ppm Ir; 0.028±0.0043 ppm Pd and 2.4±0.27 ppm Ag.     

Graphite furnace atomic absorption spectrometric determination of iridium,rhodium and ruthenium in high-purity platinum after matrix extraction

Ir, Rh and Ru are separated from a large excess of platinum by extraction with isoamyl alcohol-isobutyl methyl ketone mixture. Graphite furnace atomic absorption spectrometry using the method of standard addition is then used to determine the metals with satisfactory precision and accuracy.     

Neutron activation analysis of high purity noble metals (palladium,platinum, rhodium,gold and silver)

Methods of neutron activation analysis of high purity noble metals have been developed based on the selective extraction procedures for matrix activities separation. These procedures are shown to provide purification coefficients from matrix of about 10⁶–10⁸. High-resolution gamma-spectrometry makes possible the determination of 25–30 elements simultaneously in aqueous phases remained after matrix separation. Complex standard for NA analysis of pure materials has been described.