Extraction Of Palladium Research Articles

Palladium(II) extraction from hydrochloric acid solutions with 2,6-bis[(methylsulfanyl)methyl]cyclohexan-1-one

Palladium(II) extraction from hydrochloric acid solutions with 2,6-bis[(methylsulfanyl)methyl]cyclohexan-1-one, obtained from natural methanethiol, was studied using chloroform as a diluent. Palladium(II) is recovered rapidly and with high efficiency by the extractant from solutions of 0.1–10 mol/L HCl and can be separated with high selectivity from Pt(IV), Cu(II), Ni(II), Zn(II) and Fe(III). A coordination mechanism of the palladium(II) extraction from 1 M HCl solutions was established. The extraction agent is coordinated to the Pd(II) ion through donor sulfur atoms in an extracted compound of the [PdCl2L] type. Stripping of Pd(II) is effectively carried out with a 1 M NH4OH solution or an acidic (0.1 mol/L HCl) thiourea solution.

Diphosphonic ionic liquids as anion-exchangers for palladium(II) and platinum(IV): Synthesis, complexation and selective extraction from hydrochloric solutions

The demand for platinum group metals (PGMs) continues to grow. To reduce the negative environmental impact, it is necessary to switch to secondary sources of PGMs and to improve the separation and purification processes of these metals. In this work, new phosphonium-based ionic liquids (diphosphonium salts) were synthesized as extractants for the selective recovery of palladium(II) and platinum(IV) from hydrochloric acid solutions. Substances synthesized contain a doubly-charged cation, which significantly affects the selectivity of extraction compared to singly charged phosphonium extractants. It was found that diphosphonium salts have a high extraction efficiency of metallic ions that form stable doubly-charged chloride anionic complexes. Thus, solutions of synthesized ionic liquids in 3-nitrobenzotrifluoride can selectively extract palladium(II) and platinum(IV) in the presence of all d‐metal ions studied, which are contained in PGMs secondary sources. The extraction efficiency under optimal conditions is 99.6 % and 98.5 % for palladium(II) and platinum(IV), respectively. The extraction mechanism has been investigated by X-ray diffraction, DFT calculations and 31P, 111Cd NMR spectroscopy. Extraction proceeds through the anion-exchange mechanism, however, in the case of the studied compounds, the significant role of bromide as a counterion of ligands was shown. It was found that bromide is likely included in the extracted ion pair, displacing chloride ions from anionic metal complexes during extraction.

TERPENE BASED AMINO OXIMES ON SOLID SUPPORTS AS SELECTIVE EXTRACTANTS OF PRECIOUS METALS

Chelators based on terpene bis(α-amine oximes) applied onto low-polar sorbents (coal, Sibunit, Polysorb) are effective selective extractants for the extraction of palladium and gold from acidic aqueous solutions containing the mixtures of precious metals and 3d-elements. The use of sorbents impregnated with the new chelators allows extraction in the liquid-solid mode without using any organic solvent.

Effective Transport Recovery of Palladium(II) from Hydrochloric Acid Solutions Using Polymer Inclusion Membrane with Tetrabutylammonium Bromide.

This article reports on the extraction of palladium(II) from hydrochloric acid (HCl) solutions using polymer inclusion membranes (PIMs) containing tetrabutylammonium bromide (TBAB) as the ion carrier. The membranes were based on cellulose triacetate (CTA) as the polymer support. The main aim of this study is to determine the possibility of TBAB's application as the effective ion carrier/extractant of Pd(II) from hydrochloric acid solutions. At first, the effect of the hydrochloric acid concentration in the aqueous phase on palladium(II) extraction was investigated. Next, cellulose triacetate membranes with TBAB as the carrier were prepared and applied for the recovery of Pd(II) from HCl solutions. As a result of the investigations, the optimal composition of the receiving phase was determined to be 0.5 M thiourea in 0.1 M hydrochloric acid. The effect of the acid concentration in the source phase was investigated. The results show a linear decrease in the permeability coefficient and initial flux of palladium(II) with an increase in the hydrochloric acid concentration in the source phase. The separation of Pd(II) from Pt(IV) from the hydrochloric acid solution was also studied. The transport rate of Pd(II) was higher than Pt(IV). The separation coefficient SPd/Pt was 1.3. The results show that transport through PIMs with TBAB can be used as an effective method to recover Pd(II) from hydrochloric acid, especially at a low concentration of this acid.

NEW TECHNOLOGIES FOR PROCESSING TAILINGS OF A COPPER PROCESSING PLANT FOR THE EXTRACTION OF PLATINOIDS

The most important task of the mining and metallurgical industry in the world is the development of technology for the processing of industrial waste from metallurgical industries. In the world, balance ores of precious metals are practically available. This issue develops the processing of man-made waste, refractory ores, off-balance and low-grade dumps. The article considers studies of the material and rational compositions of the tailings of a copper concentrating plant in the conditions of JSC Almalyk MMC, determines the optimal method for tailings enrichment with an increase in the content of precious metals in the concentrate, and enhances an unconventional new scheme for processing platinum group concentrates with the extraction of platinum, palladium, silver and high recovery gold. Based on the learned subjects and analysis of studies results, the authors concluded that the centrifugal concentration of platinoids from the composition of the tailings was achieved due to accurate determinations of the particle size in the tailings with the selection of intense gravity modes. Combined hydrometallurgical methods for purifying platinoids and gold from impurities using combinations of chemical solvents have been developed. As a result, the developed technologies have achieved the possibility of complex extraction of platinum group metals from the tailings of concentrating plants of copper production with high degrees, through extraction of all precious metals.

NEW TECHNOLOGIES FOR PROCESSING TAILINGS OF A COPPER PROCESSING PLANT FOR THE EXTRACTION OF PLATINOIDS

The most important task of the mining and metallurgical industry in the world is the development of technology for the processing of industrial waste from metallurgical industries. In the world, balance ores of precious metals are practically available. This issue develops the processing of man-made waste, refractory ores, off-balance and low-grade dumps. The article considers studies of the material and rational compositions of the tailings of a copper concentrating plant in the conditions of JSC Almalyk MMC, determines the optimal method for tailings enrichment with an increase in the content of precious metals in the concentrate, and enhances an unconventional new scheme for processing platinum group concentrates with the extraction of platinum, palladium, silver and high recovery gold. Based on the learned subjects and analysis of studies results, the authors concluded that the centrifugal concentration of platinoids from the composition of the tailings was achieved due to accurate determinations of the particle size in the tailings with the selection of intense gravity modes. Combined hydrometallurgical methods for purifying platinoids and gold from impurities using combinations of chemical solvents have been developed. As a result, the developed technologies have achieved the possibility of complex extraction of platinum group metals from the tailings of concentrating plants of copper production with high degrees, through extraction of all precious metals.

Retraction Note: Application of Polypropylene Amine Dendrimers (POPAM)-Grafted MWCNTs Hybrid Materials as a New Sorbent for Solid-Phase Extraction and Trace Determination of Gold(III) and Palladium(II) in Food and Environmental Samples

Retraction Note: Application of Polypropylene Amine Dendrimers (POPAM)-Grafted MWCNTs Hybrid Materials as a New Sorbent for Solid-Phase Extraction and Trace Determination of Gold(III) and Palladium(II) in Food and Environmental Samples

Extraction of Palladium from Spent Nuclear Fuel Reprocessing Solutions

New solvent systems for selective separation of palladium from nuclear wastes represent a prospective way to reduce the total waste volume and induce this metal’s extraction. For this purpose, the potential of modern green solvent room-temperature ionic liquid was assessed with diamide-type extractants based on N-heterocycles and S-donating thiodiglicolic acid. The N-donating heterocyclic extractants demonstrate structure-dependent high selectivity toward palladium in the presence of various impurity metals (such as Zr, Cs, Sr, Mo, Ce, Fe, and Cr) from spent nuclear fuel. Palladium is extracted into the organic phase quite selectively with a separation factor greater than a thousand for all extractants. Ionic liquid media are capable of selective palladium separation from platinum group metals and synergetically increase the selectivity of the extractants.

Development of highly efficient bimetallic metal organic frameworks for the extraction of Pd(ii) from aqueous solutions

The application of these innovative bimetallic MOFs, open up new avenues for the creation of robust MOFs especially designed for effective extraction of precious palladium.

An Aryl-ether-linked Covalent Organic Framework Modified with Thioamide Groups for Selective Extraction of Palladium from Strong Acid Solutions.

Efficient adsorption of palladium ions from acid nuclear waste solution is crucial for ensuring the safety of vitrification process for radioactive waste. However, the limited stability and selectivity of most current adsorbents hinder their practical applications under strong acid and intense radiation conditions. Herein, to address these limitations, we designed and synthesized an aryl-ether-linked covalent organic framework (COF-316-DM) grafted dimethylthiocarbamoyl groups on the pore walls. This unique structure endows COF-316-DM with high stability and exceptional palladium capture capacity. The robust polyarylether linkage enables COF-316-DM to withstand irradiation doses of 200 or 400 kGy of β/γ ray. Furthermore, COF-316-DM demonstrates fast adsorption kinetics, high adsorption capacity (147 mg g-1 ), and excellent reusability in 4 M nitric acid. Moreover, COF-316-DM exhibits remarkable selectivity for palladium ions in the presence of 17 interference ions, simulating high level liquid waste scenario. The superior adsorption performance can be attributed to the strong binding affinity between the thioamide groups and Pd2+ ions, as confirmed by the comprehensive analysis of FT-IR and XPS spectra. Our findings highlight the potential of COFs with robust linkers and tailored functional groups for efficient and selective capture of metal ions, even in harsh environmental conditions.

Selective capture of palladium from acid wastewater by thiazole-modified activated carbon: Performance and mechanism

As a kind of scarce metal, palladium is widely used in many chemical industries. It essential to recover palladium from secondary resources, especially acidic media, owing to high content of palladium in secondary wastes and widespread extraction of palladium via strong acids. Chemically modified carbon materials not only have the advantage of activated carbon but also achieve the precise removal of specific pollutants, which is a kind of adsorption material with broad application prospects. In this direction, we report a solid carbon material named AT-C, which is obtained by one-step synthesis of 2-aminothiazoles grafted to the carbon surface by amidation. The present adsorbent delivers a high palladium adsorption capacity of 178.9 mg g−1, and desirable thermal and chemical stability. The uniform presence of abundant sulfur atoms and CO in the porous network enables AT-C to achieve selective absorption and rapid adsorption kinetics of Pd2+ in the complex water mixture containing many competing ions in the acidic pH range. For the strongly acidic leachates of catalysts, AT-C exhibits outstanding stability in cyclic experiments. Meanwhile, the fixed-bed column test indicates that 1076 bed volumes of the feeding streams can be effectively treated. In addition, AT-C exhibits superior adsorption selectivity, and the recovery efficiency of Pd2+ in actual industrial wastewater is 96.6%. This work realizes an efficient, rapid, and selective removal of palladium under acidic conditions, and provides a reference for complex industrial water treatment and resource recovery of precious metals.

In-syringe low-density solvent dispersive liquid–liquid microextraction of Pd(II) from acidic solutions resulting from hydrometallurgical treatments and quantification by ICP-OES

An in-syringe low-density solvent dispersive liquid–liquid microextraction (IS-LDS-DLLME) is presented for the extraction of palladium from a highly acidic medium before its quantification by inductively coupled plasma optical emission spectroscopy. The extraction solvent was 1-undecanol, and benzil mono-(2-pyridyl) hydrazone was employed as a ligand. Here, no dispersive solvent is needed as the vortex disperses 1-undecanol in the aqueous sample solution. The experimental variables pH, concentration of the ligand, type and quantity of the extraction solvent, vortex time, and addition of NaCl were optimized. The described approach has detection and quantification limits of 0.13 and 0.43 μg L-1, respectively, an enrichment factor of 91, a linear analytical range from 0.4 to 250 μg L-1, and a precision of 1.7–2.0 % (25.0 μg L-1). The approach was used to analyze electronic waste samples and certified reference material.

Palladium Extraction Following Metal-Catalyzed Reactions: Recent Advances and Applications in the Pharmaceutical Industry

Palladium Extraction Following Metal-Catalyzed Reactions: Recent Advances and Applications in the Pharmaceutical Industry

Separation of Spent Nuclear Fuel: Minor Actinide and Palladium Extraction by Heterocyclic Diamides

Separation of Spent Nuclear Fuel: Minor Actinide and Palladium Extraction by Heterocyclic Diamides

Recovery of Precious Metals: A Promising Process Using Supercritical Carbon Dioxide and CO2-Soluble Complexing Polymers for Palladium Extraction from Supported Catalysts.

Precious metals such as palladium (Pd) have many applications, ranging from automotive catalysts to fine chemistry. Platinum group metals are, thus, in massive demand for industrial applications, even though they are relatively rare and belong to the list of critical materials for many countries. The result is an explosion of their price. The recovery of Pd from spent catalysts and, more generally, the development of a circular economy process around Pd, becomes essential for both economic and environmental reasons. To this aim, we propose a sustainable process based on the use of supercritical CO2 (i.e., a green solvent) operated in mild conditions of pressure and temperature (p = 25 MPa, T = 313 K). Note that the range of CO2 pressures commonly used for extraction is going from 15 to 100 MPa, while temperatures typically vary from 308 to 423 K. A pressure of 25 MPa and a temperature of 313 K can, therefore, be viewed as mild conditions. CO2-soluble copolymers bearing complexing groups, such as pyridine, triphenylphosphine, or acetylacetate, were added to the supercritical fluid to extract the Pd from the catalyst. Two supported catalysts were tested: a pristine aluminosilicate-supported catalyst (Cat D) and a spent alumina supported-catalyst (Cat A). An extraction conversion of up to more than 70% was achieved in the presence of the pyridine-containing copolymer. The recovery of the Pd from the polymer was possible after extraction, and the technological and economical assessment of the process was considered.

The Leaching of Palladium from Polymetallic Oxide Ores using Alkaline Ferricyanide Solutions

ABSTRACT The present study investigated a novel method of alkaline ferricyanide leaching to extract palladium (Pd) from a Western Australian disseminated platinum-group metal (PGM) oxide ore that bears Ni and Cu. While cyanide has been used to leach Pd, it is well known for its toxicity and large consumption in the presence of base metals. A more benign alternative, in the form of alkaline ferricyanide, is evaluated in this research to serve the combined role of lixiviant and oxidant. Various leaching parameters, such as ferricyanide concentration (1–30 g/L), dissolved oxygen level (up to 25 ppm), pH (10–12), and temperature (20–80°C), were investigated to evaluate Pd extraction. The Pd extraction was found to be the most sensitive to leach temperature with Pd extraction doubling when the temperature was raised from 20°C to 80°C. The highest Pd extraction of 76.1% was achieved at 10 g/L ferricyanide, pH 11, DO 15 ppm, 80°C, and 10% solids. The alkaline ferricyanide leaching system showed high selectivity for Pd over other metals (Pt, Co, Ni, Cu). The co-extractions of base metals (Co, Cu, and Ni) were all below 2%, and that of Pt was below 10% over the range of temperatures investigated. Although conventional cyanidation at a low cyanide consumption (1 kg/t) showed slightly better performance in Pd extraction, the ferricyanide leaching significantly improved the settleability and filterability of the leaching slurry considering the finely ground nature and high-clay content of the lateritic oxide ores. In contrast, the cyanidation leaching slurry was found to filter or settle poorly.

Improved Palladium Extraction from Spent Catalyst Using Ultrasound-Assisted Leaching and Sulfuric Acid–Sodium Chloride System

This paper presents a process for efficiently recovering palladium (Pd) from spent Pd/Al2O3 catalysts used for hydrogenation reactions, using ultrasound-assisted leaching (UAL). A system composed of H2SO4 and NaCl was investigated under ultrasound-enhanced conditions and compared to regular leaching methods to demonstrate the superiority of UAL. Single-factor experiments were conducted to determine the optimal conditions for leaching, which included an ultrasound power of 200 W, a liquid–solid ratio of 5:1, a leaching time of 1 h, a leaching temperature of 60 °C, H2SO4 concentration of 60%, and 0.1 mol of NaCl. The leaching rate under these conditions was found to be 99%. Additionally, kinetic analysis of the UAL process showed that the apparent activation energy of the Pd leaching reaction was 28.7 kJ/mol, and it was found that Pd leaching from spent catalysts was controlled by diffusion. The tailings were analyzed by SEM, revealing that during ultrasonic leaching, the specific surface area of the spent catalyst increased, the mass transfer rate of the solution was accelerated, the passivation film on the surface of the spent catalyst was peeled off, and a new reaction interface was formed. This improved the leaching rate of Pd and provided a new approach to efficiently leach precious metals such as Pd from spent catalysts.

Dipinodiazafluorenes as Reagents for the Selective Extraction of Palladium, Gold, and Ruthenium

Dipinodiazafluorenes as Reagents for the Selective Extraction of Palladium, Gold, and Ruthenium

Complexation and Separation of Palladium with Tridentate 2,6-Bis-triazolyl-pyridine Ligands: Synthesis, Solvent Extraction, Spectroscopy, Crystallography, and DFT Calculations.

Selective extraction of palladium from high-level liquid waste (HLLW) is desirable for the sustainable development of nuclear energy and resource recovery. In this work, three tridentate 2,6-bis-triazolyl-pyridine ligands (L-I, L-II, and L-III) bearing different alkyl side chains were synthesized and systematically studied for the complexation and extraction of palladium. Altering the alkyl side chains of the ligands led to pronounced differences in extraction performance. Among the three ligands, L-II decorated with two n-octyl groups exhibited the highest Pd(II) extraction efficiency at acidity levels of 1-5 M HNO3 and outstanding selectivity over 13 coexisting competing metal ions. Results from UV-vis titration experiments and theoretical calculations suggested that the differentiated extraction abilities of the ligands could be because of their different hydrophilicity rather than electron-donating effects. Slope analyses and electrospray ionization-high resolution mass spectrometry (ESI-HRMS) experiments revealed the formation of both L/Pd 1:1 and 2:1 species during the extraction process. These stoichiometries were further confirmed by job plots and NMR titration experiments. The ligands were found to aggregate slightly, especially at higher concentrations, which could result from multiple intermolecular hydrogen bonds as illustrated by X-ray crystallography. The configurations of PdL and PdL2 were further elucidated by analysis of single crystal structure and density-functional theory (DFT) calculations, respectively, where the first coordination sphere of Pd(II) was surrounded by four nitrogen or oxygen atoms in a quadrangular manner. This study provides an alternative method to separate palladium from HLLW and brings a new understanding of the coordination and complexation behaviors of Pd(II) with tridentate nitrogen ligands.

Extraction properties of 4-[(hexylsulfanyl)methyl]3,5-dimethyl-1-phenyl-1<i>H</i>-pyrazole in the palladium(II) recovery from nitric acid solutions

Palladium(II) extraction from nitric acid solutions with a complex-forming reagent, 4-[(hexylsulfanyl)methyl]-3,5-dimethyl-1-phenyl-1 H -pyrazole, was studied using chloroform as a diluent. The reagent extracts Pd(II) with high efficiency from 0.5-5 M. HNO3 solutions. It has been established that palladium(II) is extracted from 2 M. HNO3 solutions by a coordination mechanism with the formation of the extracted compound [Pd(NO3)2μ-L] n ( n > 2). Palladium(II) is quantitatively stripped with a nitric acid solution of thiourea. The reagent is promising for the concentration of Pd(II) from nitric acid solutions and its highly selective separation from Fe(III), lanthanides(III), Al(III), Cu(II), and Ni(II).