Extraction Of Palladium Research Articles

Solvent extraction and separation of palladium from platinum group elements: Synthesis and characterization of 2-mercaptopyridine N-oxide-palladium (II) complex

Platinum group elements (PGEs) are known for their similar chemical properties, which complicates their isolation and separation from mineral ores and recycled products such as autocatalysts. Therefore, this study investigated the separation of PGEs (except Os) in a synthetic autocatalyst mixture using 2-mercaptopyridine N-oxide sodium salt (NaPT) as an extractant. Solvent extraction was performed with an aqueous mixture containing Pt, Pd, Rh, Ir and Ru and NaPT in the presence of toluene, which produced a pink organic layer. An ICP analysis indicated a complete absence of Pd in the orange aqueous layer. The extractions were repeated with different [HCl] and [PT−] and the analytical results confirmed the complete extraction of Pd from the mixture. The formation of a Pd(PT)2 complex in the pink product was confirmed with IR, 1H and 13C NMR. Pd(OAc)2 reacted with NaPT in DMF to form pink crystals, which were suitable for crystallography. The pink crystals were also characterized with IR, 1H and 13C and found to be identical to the product isolated after solvent extraction. The crystal structure indicated the isolation of the square planar Pd(PT)2·DMF complex, which crystalized in the monoclinic P21/n space group with four molecules per unit cell. The two PT− ligands in the complex bonded with the sulfur atoms (and also the oxygen atoms) cis with respect to each other, with the S–Pd–S and O–Pd–O bond angles at 96.27(5) and 91.08(14)° respectively. The two Pd–S bonds distances were 2.2443(13) and 2.2416(15) Å. The selective and complete isolation of Pd from a mixture of PGE using NaPT can be extremely useful in the recovery of Pd from autoctalaysts and other mixed PGE waste materials.

EXTRACTION OF Pd(II), Ni(II), Co(II), Cu(II), Fe(III) AND Zn(II) IONS WITH 1,2,3-BENZOTRIAZOLE IN SYSTEMS BASED ON ANIONIC SURFACTANTS

The phase state and extraction capacities of aqueous systems based on sulfonol, sodium dodecylsulfate or alkylbenzenesulfonic acid as anionic surfactants and hydrochloric (or sulfuric) acid against the influence of 1,2,3-benzotriazole as an organic complexing reagent were studied. Introduc-tion of 1,2,3-benzotriazole into the systems resulted in its exfoliation in two liquid phases. Optimal concentration parameters of the extraction process in the systems under investigation were found: the total volume of the system (10 ml) contained sulfonol or sodium dodecyl sulfate (0.6 g), alkylbenzenesulphonic acid (0.5 g), and 1,2,3-benzotriazole (0.35 g). The aliquation state was maintained in the following concentration interval of HCl (H2SO4), mol L-1, for the systems with: (a) sodium dodecylsulfate: 0.5-6 (0.5-4), (b) sulfonol: 0.1-4 (0.05-3), (c) alkylbenzenesulfonic acid: 0-4 (0-3). Distribution of 0.01 mol L-1 of Pd(II), Ni(II), Cu(II), Co(II), Zn(II) and Fe(III) ions in the above systems was studied at the optimal components ratios. In the systems containing sodium dodecylsulfate, no quantitative extraction of metal ions was observed. In the systems with sulfonol and alkylbenzenesulfonic acid, practically complete (99.9%) extraction of palladium appeared to be possible in the entire range of acid concentrations; with minimal acid content, over 95% of copper and nickel were extracted. The extraction of palladium ions in the presence of interfering ions was studied. Quantitative recovery of palladium ions was found to not be obstructed by 500-fold molar excess of copper, 300-fold excess of cobalt and 70-fold excess of nickel.

PGM ore processing: LIX reagents for palladium extraction & platinum stripping from Alamine 336 using NaOH-NaCl

Solvent extraction can be operated as a batch process or in counter-current mode. The preference for an extractant changes depending on the mode of operation. The extraction kinetics and isotherms are studied for the extraction of palladium using various LIX reagents. It was found that LIX 64N is preferable for counter current extraction, while LIX 984 is suitable for batch extraction of palladium. Further, platinum was stripped from Alamine 336 with a solution of NaOH-NaCl. This reagent is capable of stripping 0.75 g/l of platinum from Alamine 336 in a single contact at A/O of 1. Unlike the thio-reagents studied earlier, this novel stripping reagent is environment friendly. The two studies have been applied for recovering palladium and platinum from ore samples. Palladium and platinum were separated with a purity of >98%.

Neodymium and Palladium Extraction with Phosphorylated Thiacalix[4]- and Calix[4]arenes from Nitric Acid Media

A comparison was made between the separate extraction and coextraction of neodymium and palladium from nitric acid solutions with bifunctional phosphorylated thiacalix[4]arene (TCPO) and monofunctional extractants that modeled it—phosphorylated calixarene (CPO), thiacalixarene (TCA), and their mixtures—for evaluating the mutual influence of S- and PO-donor sites of the extractants. A decrease in DNd was detected only for TCPO: it was less that 0.1 as against 1.6 for CPO. 31P{1H} and 13C{1H} NMR spectroscopy studies showed that the decrease in the neodymium extraction with TCPO is similar to the inhibition of the catalytic activity of enzymes (TCPO analogs) in the presence of effectors (analogs of rare-earth elements) in phosphorylation—dephosphorylation processes. Their coordination to the allosteric CH2P(O)R2 site leads to high chemical shift (4 ppm) of the signal of the 13CH2 spacer and to the formation of TCPO hydrolysis products (n-methylthiacalix[4]arene and, probably, dibutylhydroxophosphinate). The results of the extraction with TCA–CPO mixtures are of interest for a simplified process (PUREX) and a process being developed (CARBEX) as applied to the corecovery of neodymium and palladium from nitric acid solutions and their separation from carbonate solutions after neodymium stripping.

An accurate and sensitive analytical strategy for the determination of palladium in aqueous samples: slotted quartz tube flame atomic absorption spectrometry with switchable liquid-liquid microextraction after preconcentration using a Schiff base ligand.

This study presents a green analytical method for palladium determination by slotted quartz tube flame atomic absorption spectrometry (SQT-FAAS) following switchable liquid-liquid microextraction (SLLME). Efficient extraction of palladium was facilitated by complexation with a Schiff base ligand, synthesized specifically for this study. A three-stage thorough optimization procedure was carried out to boost the absorbance output of palladium. Complex formation was the first stage, and parameters evaluated included buffer solution pH and amount, concentration of ligand, and mixing period. The amount of switchable solvent and concentration and amount of sodium hydroxide and acid amount were optimized in the second stage. Optimization of sample and fuel flow rates and SQT parameters completed the third stage of optimization, and all optimum parameters were used to determine analytical performance of the method. The method had a broad linear dynamic range, and the calibration plots showed good linearity with R2 values greater than 0.9991. The limits of detection and quantification of the SLLME-SQT-FAAS method were 15 and 50μg/L, respectively. The precision of the method, expressed as percent relative standard deviation, was below 9.0% for all measurements. Spiked recovery results performed for a palladium electroplating bath solution gave poor results when quantified against aqueous calibration standards. Matrix matching was therefore used to improve recovery results which ranged between 97 and 105% for four different spike concentrations.

Extractive Recovery and Separation of Palladium(II) from Model Hydrochloric Solution from Refining Shop with Di-n-Heptyl Sulfide and Penconazole

Extractive method for recovery of palladium(II) from a model palladium-rich hydrochloric solution from a refining shop was suggested. It was found that palladium(II) is fully extracted with di-n-heptyl sulfide and penconazole from 3 M hydrochloric solutions with high salt background, with the optimal phase contact duration being 20 and 5 min, respectively. As reagent dilutions served toluene and chloroform. Palladium(II) was back-extracted with a 15% aqueous ammonia and a saturated aqueous solution of sodium rhodanide. The optimal conditions of palladium(II) extraction and its separation from the accompanying platinum(IV) and copper(II).

Exchange Capacity of Polysiloxane Ion Exchangers Modified with Dithiooxamide Groups with Respect to Silver(I), Platinum(IV), and Palladium(II)

A polysiloxane with attached groups of rubeanic acid is proposed for the extraction of silver(I), platinum(IV) and palladium(II) from dilute aqueous systems. The sorbent is synthesized for the first time via modern sol–gel technology and has a high degree of surface modification; the concentration of the attached dithiooxamide groups is 0.90 mmol/g. Isotherms of the sorption of silver(I), platinum(IV), and palladium(II) from individual solutions are constructed. The curves are mathematically processed with the Langmuir, Freundlich, Redlich–Peterson, Langmuir–Freundlich, and Toth equations, so exchange capacity values are determined for the modified polysiloxane. The sorbent has good capacitive characteristics and can be used to accumulate large amounts of noble metal ions.

Ion-Exchange Sorption of Palladium(II) from Hydrochloric Acid Solutions in the Presence of Silver(I)

The sorptive extraction of palladium(II) chloride complexes in the presence of silver(I) chloride complexes from 2 and 4 M aqueous solutions of HCl with a series of Purolite anionites with different functional groups is studied. An anion exchange mechanism of sorption is identified from Raman spectroscopy data. Kinetic properties that are inherent to the investigated ionites and allow the elution of palladium(II) and silver(I) after their extraction in a dynamic mode are revealed.

Palladium(II) Extraction from Hydrochloric Acid Solutions with 4-[(Hexylsulfanyl)methyl]-3,5-Dimethyl-1H-Pyrazole

Palladium(II) extraction from hydrochloric acid solutions with a novel weakly basic complexing reagent, 4-[(hexylsulfanyl)methyl]-3,5-dimethyl-1H-pyrazole, dissolved in chloroform was studied. Palladium(II) was found to be highly efficiently extracted from 0.1–3 mol/L HCl solutions. A coordination mechanism of palladium(II) extraction with a protonated form of the reagent via fast interphase transfer of ion associates was proposed. The composition of the extracted compound, [PdCl2μ-L]n (n > 2), was found, and the way of coordination of the reagent to metal ions through N(2) nitrogen atom and thioether sulfur atom was determined. The reagent can be recommended for concentrating palladium(II) and selectively separating it from platinum(IV), copper(II), nickel(II), and iron(III).

Palladium adsorption and preconcentration onto thiol- and amine-functionalized mesoporous silicas with respect to analytical applications

Abstract Amine- and thiol-functionalized mesoporous SBA-15 silicas were synthesized, characterized and then applied to solid phase extraction of palladium from digested environmental samples (soil and road dust) with subsequent determination by slurry sampling graphite furnace atomic absorption spectrometry (GFAAS). The SBA-15 material was synthesized by the template method and fully characterized by a broad range of instrumental techniques. Functionalized samples were able to adsorb Pd(II) ions quickly and quantitatively from a wide range of concentrations and pH values. The adsorption uptakes were as high as 190 mg g−1 and 68 mg g−1, for thiol- and amine-modified silicas, respectively. GFAAS was used for fast and simple determination of palladium preconcentrated on the silica matrix. The proposed combination of Pd(II) preconcentration and Pd-loaded sorbent slurry sampling GFAAS technique application allowed reaching an Pd(II) enrichment factor of 25 and LOD of 4.8 ng g−1.

Optimization of process parameters using response surface methodology for Pd(II) extraction with quaternary ammonium salt from chloride medium: kinetic and thermodynamics study

In this study, liquid–liquid extraction with Aliquat 336 in the presence of cyclohexane as a mobile carrier was investigated to purify Pd(II) from industrial wastewater. Kinetic and thermodynamics analysis showed that Pd(II) extraction was of first-order reaction: the reaction was endothermic reaction which was governed by the diffusion region. The influence of temperature on isotherm model was also investigated. With an increase in reaction temperature, all three isotherms Langmuir, Freundlich and Temkin isotherm become inaccurate. Results show that the Langmuir isotherm model was preferred for the study of the Pd(II) ion experimental isotherm. Response surface methodology was employed to study the five independent variables which have an effect on the percentage of extraction of palladium(II) ions as a dependent variable. Optimum extraction conditions for the five independent variables were as follows: Aliquat 336 concentration (0.6 M), pH of feed solution (2.0), stirring speed (600 rpm), reaction time (10 min.) and reaction temperature (318 K).

Extraction of palladium from alumina-supported catalyst in supercritical CO2 using functional fluorinated polymers

The use of functional CO2-philic polymers in supercritical carbon dioxide (scCO2) for a greener method of extracting Pd from spent catalysts has been investigated. Three fluorinated polymers bearing complexing units (a thiol-terminated poly(1,1,2,2-tetrahydroperfluorodecyl acrylate) homopolymer PFDA-SH, a poly(1,1,2,2-tetrahydroperfluorodecyl acrylate-co-diphenylphosphinostyrene) gradient copolymer P(FDA-co-DPPS), and a thiol-terminated gradient copolymer P(FDA-co-DPPS)-SH) were synthesized and successfully used to extract palladium from commercial Pd/Al2O3 supported catalysts (beads and pellets with 0.5 wt.% and 5 wt.% Pd loading, respectively). These non-destructive extractions were carried out in scCO2 under mild conditions (40 °C and 25 MPa). Inductively coupled plasma atomic emission spectroscopy (ICP-AES) analysis on the Pd/Al2O3 catalysts before and after extraction confirmed the removal of palladium from the catalytic supports. Up to 40% of palladium was extracted from the commercial supported catalysts with full recovery of the original alumina support.

Extraction of Palladium(II) and Platinum(IV) from Hydrochloric Acid Solutions with Trioctylammonium Nitrate Ionic Liquid without Dilution

The fundamental properties and extraction capability of an ionic liquid (IL), trioctylammonium nitrate ([HTOA][NO3]), for PdII and PtIV, are investigated. At room temperature, [HTOA][NO3] is a solid (melting point: 30.7 °C), but it becomes a liquid (melting point: 16.7 °C) when saturated with water. Water-saturated [HTOA][NO3] exhibits a viscosity of 267.1 mPa·s and an aqueous solubility of 2.821 × 10−4 mol·dm−3 at 25 °C, and can be used as an extraction solvent without dilution. [HTOA][NO3] exhibits an extremely high extraction capability for PdII and PtIV in dilute hydrochloric acid (0.1–2 mol·dm−3 HCl); the distribution ratio reaches 3 × 104 for both the metals. From electrospray ionization mass spectrometry analysis, the species extracted in the IL phase are [PdCl3]− and [PdCl2(NO3)]− for PdII and [PtCl6]2− and [PtCl5]− for PtIV. A majority of the other transition metals are considerably less or marginally extracted into [HTOA][NO3] from a 0.1 mol·dm−3 hydrochloric acid solution. The extraction capacity of [HTOA][NO3] is greater than that of other hydrophobic ILs such as [HTOA]Cl and bis(trifluoromethanesulfonyl)imide-based ILs. The metals extracted into the IL phase are quantitatively back-extracted using an aqueous solution containing thiourea and nitric acid. By controlling the thiourea concentration and shaking time, PdII and PtIV are mutually separated to some extent in the back extraction process. The IL phase used for the back extraction can be reused for the forward extraction of these metals after scrubbing it with an aqueous nitric acid solution.

SORPTION-ATOMIC-ABSORPTION DETERMINATION OF PALLADIUM (II) IN AQUEOUS SOLUTIONS USING DITHIOOXAMIDATED POLYSILOXANE

Polysiloxane modified with groups of rubeanic acid (dithiooxamidated polysiloxane (DTOAP)) is proposed for extraction of palladium (II) from the solution against the background of the accompanying components. Sorbent was synthesized for the first time at the Institute of Organic Synthesis (Ural Branch of the Russian Academy of Sciences) using «sol-gel» technique. Sorption of palladium (II) was carried out under competitive conditions with 9 possible accompanying metals ions present. Palladium (II) is quantitatively and selectively recovered under static conditions with DTOAP from a solution containing transition metal ions, including platinum (IV). It takes 30 minutes for complete extraction of palladium (II). Reversible character of palladium (II) sorption is shown. Quantitative desorption of metal ion from the sorbent surface is possible using a 1% solution of thiourea in 1 M hydrochloric acid. Sorption under dynamic conditions provides separation of palladium (II) from platinum (IV) and concomitant ions of base metals. DTOAP provides quantitative extraction of palladium (II) in an amount up to 0.2 mmol/g. The developed method of the atomic-absorption determination of palladium (II) with a preliminary concentration on a modified polysiloxane was tested in analysis of model and industrial solutions with a high saline background.

Application of magnetic nanoparticles coated with sodium dodecyl sulfate and modified with 2-(5-bromo-2-pyridylazo)-5-diethyl aminophenol as a novel adsorbent for dispersive-magnetic solid-phase extraction and determination of palladium in soil samples.

A rapid, sensitive, precise, and accurate dispersive-magnetic solid-phase extraction technique combined with flame atomic absorption spectrometry was established for pre-concentration and separation of Pd (II) in soil samples. In the developed system, 5-amine-1,10-phenanthroline was used as synergistic complexant; sodium dodecyl sulfate and 2-(5-bromo-2-pyridylazo)-5-diethyl aminophenol ligand coated on magnetic nanoparticles were synthesized by a chemical precipitation method, and then employed as the efficient magnetic adsorbent with good magnetic properties and dispersibility. Various operational parameters affecting the extraction efficiency has been studied and optimized in details. Under the optimum experimental conditions, the detection limit of the mentioned method for palladium ions was 0.12μg/L, while the relative standard deviation was 1.8%. Finally, the developed method was applied for the analysis of palladium ions in three kinds of soil samples and quantitative recoveries were achieved over the range of 96.7-104.0%. It can be a powerful alternative applied to the determination of traces of Pd ions from various real samples in further researches.

Rapid Determination of Trace Palladium in Active Pharmaceutical Ingredients by Magnetic Solid-Phase Extraction and Flame Atomic Absorption Spectrometry

Clutaraldehyde cross-linked magnetic chitosan nanoparticles were synthesized and used as an adsorbent for the dispersive solid-phase extraction of palladium in active pharmaceutical ingredients (APIs) prior to analysis by a flame atomic absorption spectrophotometer. FT-IR, X-ray diffraction, and TEM were used to characterize the adsorbent. Various parameters of experimental performance, such as adsorbent amount, pH, adsorption time, desorption solutions, coexisting ions, and adsorbent reusability, were investigated and optimized. Under the optimized conditions, good linearity was achieved in the 5.0–500 μg/L concentration range, with correlation coefficients of 0.9989. The limit of detection is 2.8 μg/L and the recoveries of spiked samples ranged from 91.7 to 97.6%. It was confirmed that the GMCNs nanocomposite was a promising adsorbing material for extraction and preconcentration of Pd in APIs.

Extraction and separation of palladium(II), platinum(IV), gold(III) and rhodium(III) using piperidine-based extractants

Extraction of palladium(II) from hydrochloric acid media with novel piperidine-based extractants N-decylpiperidine (P-C10), N-dodecylpiperidine (P-C12), N-tetradecylpiperidine (P-C14) and N-hexadecylpiperidine (P-C16) has been investigated. Over 90% of palladium(II) from 0.1M HCl solution can be effectively extracted with P-C12, P-C14 and P-C16 in toluene and the extraction equilibrium is achieved after 10min. Increase in HCl concentration has a negative effect on the effectiveness of palladium(II) extraction. From among the examined stripping solutions the most effective are 0.5M aqueous solution of ammonia and 0.1M thiourea in 1M HCl. The percentage of palladium(II) stripped from loaded organic phase (P-C12) reached nearly 100%. Also the selectivity of palladium(II) extraction over rhodium(III), platinum(IV) and gold(III) with the synthesized N-dodecylpiperidine (P-C12) has been investigated. The selectivity of extraction of palladium(II) over rhodium(III) from 0.1 and 3M HCl with P-C12 was the best. Separation of palladium(II) from platinum(IV) or gold(III) is not so effective and it depends upon the acidity of aqueous solution. N-dodecylpiperidine also shows the extraction ability towards examined noble metal ions in the following order Au(III)>Pd(II)~Pt(IV)>>Rh(III) from 0.1M HCl and Au(III)>Pt(IV)>Pd(II)>>Rh(III) from 3M HCl. Palladium(II), platinum(IV) and gold(III) can be successfully separated through stripping from the loaded organic phase.

Extraction of Palladium(II) from Hydrochloric Acid Solutions by Solvent Extraction with Mixtures Containing Either Cyanex 301 or LIX 63

Cyanex 301 and 5,8-diethyl-7-hydroxyldodecane-6-oxime (LIX 63) can selectively extract Pd(II) over Pt(IV) from concentrated hydrochloric acid solutions. Therefore, solvent extraction experiments have been performed by extractant mixtures containing either Cyanex 301 or LIX 63, and the extraction behavior of Pd(II) was compared. Among the mixtures of Cyanex 301, the highest synergistic enhancement coefficient was achieved by mixing Cyanex 301 and trioctylphosphine oxide (TOPO). However, it was very difficult to strip the Pd(II) from the loaded mixture phase. Among the mixtures of LIX 63, the mixture of LIX 63 and alamine 336/TOPO enhanced the extraction of Pd(II). Although the synergistic coefficient by Cyanex 301 + TOPO was higher than that by LIX 63 + Alamine 336, the Pd(II) in the loaded mixture phase of LIX 63 and alamine 336 was easily stripped by thiourea.

Generation of palladium silicide in the PdAu-SiO2 nanocomposites during heating in hydrogen

Heating PdAu nanoparticles deposited on silica in hydrogen results in palladium silicide(s) formation. The degree of palladium extraction by silicon species (ex-silica) is conversely correlated with the gold content in the PdAu alloys. In addition, the phase changes are less extensive than analogous transformations in a previously investigated PdCu-silica composite. Very high temperatures (>550 °C) are required to initiate the transformation of PdAu-SiO2 into respective bulk metal silicide(s), whereas for the PdCu-SiO2 (and Pd-SiO2) similar changes have already been observed at ≤450 °C. Based on existing literature data, it is considered that the reason for this difference is a relative availability of palladium-rich material at the Pd-IB alloy-silica phase boundary. In the case of PdAu, the segregation of gold at the surface is very pronounced, making this alloy more resistant against Pd extraction required for the silicide formation.

Solid Phase Extraction and Spectrophotometric Determination of Palladium with 1-(2-benzothiazolylazo)-2-hydroxy-3-naphthoic Acid

A selective, sensitive, and fast procedure to determine palladium depended on the sensitive reaction of palladium(II) with 1-(2-benzothiazolylazo)-2-hydroxy-3-naphthoic acid (BTAHN) coupled with solid phase extraction (CPE) of the BTAHN - Pd(II) chelate with a reversed phase polymer-based C18 cartridge was developed. In 5.0 M hydrochloric acid solution and cetyl trimethyl ammonium bromide (CTAB) medium, BTAHN reacts with palladium(II) to form a deep violet complex with a mole ratio 2:1 {BTAHN to Pd(II)}. The complex was enriched by CPE with a reversed phase polymer-based C18 cartridge. An enrichment factor of 500 was achieved by elution of the complex form the cartridge with least volume of isopentyl alcohol. Beer’s law was obeyed in the concentration range of 0.02 - 0.85 μg mL–1. The molar absorptivity of the complex was 2.61 × 105 L mol–1 cm–1 at 669 nm. The detection and quantification limits were calculated and found to be 6.3 and 19.65 ng in the original samples, respectively. For 0.4 μg mL–1 level, the relative standard deviation for eleven replicate samples was 1.06%. This procedure was successfully applied to determine palladium in environmental samples with good results.