Palladium Content Research Articles

Quantifying Platinum and Palladium in Solid Ore Using Laser-Induced Breakdown Spectroscopy Assisted by the Laser-Induced Fluorescence (LIBS-LIF) Technique.

The laser-induced breakdown spectroscopy assisted by laser-induced fluorescence (LIBS-LIF) in a two-step process was used to measure the concentration of platinum (Pt) and palladium (Pd) by surface analysis of a solid ore core from the Lac des Iles mine followed by analysis of the same core that was pulverized and compacted. This work focuses mainly on the measurement of Pt since the case of Pd has been extensively discussed in previous work. The excitation of Pt is performed at 235.71 nm with fluorescence emission observed near 269.84 nm. Calibration was performed with synthetic samples prepared from the same ore as the samples studied and the calibration curve shows good linearity in Pt content over several orders of magnitude. A limit of detection (LOD) of approximately 0.15 parts per million (ppm) over an average of 200 laser shots was demonstrated. In contrast, conventional LIBS provides a LOD of about 21 ppm over an average of 200 laser shots due to low signal-to-noise ratio and spectral interference from other elements and does not meet the requirements for estimating the average Pt concentration in the ore. The Pt concentrations obtained using LIBS-LIF on solid ore are generally in good agreement with those obtained in its pulverized and compacted form, as well as with laboratory measurements made by conventional chemical methods. However, the comparison of the results obtained for Pd using LIBS-LIF with the laboratory showed a less satisfactory agreement, probably due to its more inhomogeneous distribution in the ore.

Enhancing Palladium Recovery Rates in Industrial Residual Solutions through Electrodialysis.

Palladium is a vital commodity in the industry. To guarantee a stable supply in the future, it is imperative to adopt more effective recycling practices. In this proof-of-concept study, we explore the potential of electrodialysis to enhance the palladium concentration in a residual solution of palladium recycling, thus promoting higher recovery rates. Experiments were conducted using an industrial hydrochloric acid solution containing around 1000 mg/L of palladium, with a pH below 1. Two sets of membranes, Selemion AMVN/CMVN and Fujifilm Type 12 AEM/CEM, were tested at two current levels. The Fujifilm membranes, which are designed for low permeability of water, show promising results, recovering around 40% of palladium within a two-hour timeframe. The Selemion membranes were inefficient due to excessive water transport. All membranes accumulated palladium in their structures. Anion-exchange membranes showed higher palladium accumulation at lower currents, while cation-exchange membranes exhibited increased palladium accumulation at higher currents. Owing to the low concentration of palladium and the presence of abundant competing ions, the current efficiency remained below 2%. Our findings indicate a strong potential for augmenting the palladium stage in industrial draw solutions through electrodialysis, emphasizing the importance of membrane properties and process parameters to ensure a viable process. Beyond the prominent criteria of high permselectivity and low resistance, minimizing the permeability of water within IEMs remains a key challenge to mitigating the efficiency loss associated with uncontrolled mixing of the electrolyte solution.

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.

Amine Functionalization Leads to Enhanced Performance for Nickel- and Cobalt-Ferrite-Supported Palladium Catalysts in Nitrobenzene Hydrogenation.

Easy preparation, good yield and easy recovery are the key challenges in the development of industrial catalysts. To meet all these three criteria, we have prepared intelligent, magnetizable NiFe2O4- and CoFe2O4-supported palladium catalysts that can be easily and completely recovered from the reaction medium by magnetic separation. The fast and facile preparation was achieved by a solvothermal method followed by sonochemical-assisted decomposition of the palladium nanoparticles onto the surface of the magnetic nanoparticles. The metal-support interaction was enhanced by amine functionalization of the supports using monoethanolamine. The performance and stability of the non-functionalized and amine-functionalized NiFe2O4- and CoFe2O4-supported palladium catalysts were compared in the industrially important nitrobenzene hydrogenation reaction. All catalysts showed high catalytic activity during aniline synthesis; complete nitrobenzene conversion and high aniline yield (above 97 n/n%) and selectivity (above 98 n/n%) were achieved. However, during reuse tests, the activity of the non-functionalized catalysts decreased, as the palladium was leached from the surface of the support. On the other hand, in the case of their amine-functionalized counterparts, there was no decrease in activity, and a non-significant decrease in palladium content could be measured. Based on these results, it can be concluded that amine functionalization of transition metal ferrites may result in more effective catalysts due to the enhanced metal-carrier interaction between the support and the precious metal.

ASSESSMENT OF TRACE AND RARE EARTH ELEMENT DISTRIBUTION AND SPECIATION IN BAUXITE DEPOSITS ACROSS EKITI AND ONDO STATES, NIGERIA

The growing significance of rare earth elements (REEs) in advanced electronic technologies and the nuclear industry, coupled with concerns about geopolitical dynamics and supply market vulnerabilities, has reignited global interest in securing domestic and economically viable sources of REEs through dedicated research and developmental pursuits. Bauxite, a naturally occurring mineral primarily composed of aluminum, has been identified to harbor an abundance of sought-after rare earth minerals, thereby rendering it a promising unconventional reservoir of REEs contingent upon geological and mineralogical characteristics. Nigeria, endowed with substantial bauxite deposits prominently situated in Ondo and Ekiti states, stands to offer an intriguing avenue for exploration. In this study, the utilization of inductively coupled plasma mass spectrometry (ICP-MS) facilitated the quantification of trace elements within samples obtained from six distinct production sites spanning Ondo and Ekiti states in Nigeria. The aim was to elucidate correlations between multi-elemental REE compositions and geographical origins. Employing both single quadrupole (SQ) and multi-collection sector field (MS) modes, concentrations of Pb, Cd, As, Zn, Mn, Al, Ca, Ni, K, Na, Mg, Cu, Fe, Ti, P, Cr, and Si were rigorously determined. Remarkably, ICP-MS analysis consistently revealed a palladium (Pd) concentration of 228.05 ppb across all sampled materials, factoring in a dilution factor of 175x. Consequently, the actual concentration of the digested solution was established at 39.91 ppm mg/L. The outcomes of this investigation hold potential significance in categorizing Nigerian bauxite deposits as viable REE sources, as well as in engineering tailored techniques to efficiently recover these elements. Such findings harbor promising economic prospects for the nation, positioning the solid mineral sector as a pivotal driver of Nigeria's burgeoning economy.

Photocatalytic Semi-Hydrogenation of Alkynes: A Game of Kinetics, Selectivity and Critical Timing.

The semi-hydrogenation reaction of alkynes is important in the fine chemicals and pharmaceutical industries, and it is thus important to find catalytic processes that will drive the reaction efficiently and at a low cost. The real challenge is to drive the alkyne-to-alkene reaction while avoiding over-hydrogenation to the saturated alkane moiety. The problem is more difficult when dealing with aromatic substitution at the alkyne center. Simple photocatalysts based on Palladium tend to proceed to the alkane, and stopping at the alkene with good selectivity requires very precise timing with basically no timing tolerance. We report here that the goal of high conversion with high selectivity could be achieved with TiO2-supported copper (Cu@TiO2), although with slower kinetics than for Pd@TiO2. A novel bimetallic catalyst, namely, CuPd@TiO2 (0.8% Cu and 0.05% Pd), with methanol as the hydrogen source could improve the kinetics by 50% with respect to Cu@TiO2, while achieving selectivities over 95% and with exceptional timing tolerance. Further, the low Palladium content minimizes its use, as Palladium is regarded as an element at risk of depletion.

Nanocatalyst for carbon monoxide oxidation based on palladium(II), copper(II) salts, and carbon fiber material

The phase composition, textural, and activity of catalysts for the carbon monoxide low-temperature oxidation based on two series of non-woven carbon fiber material samples CFM-I and CFM-II, and K2PdCl4, Cu(NO3)2, KBr basic components were studied in this work. Catalysts and CFMs were studied by XRD, nitrogen and water vapor adsorption/desorption, and atomic absorption spectrophotometry methods. It has been found that the basic components K2PdCl4 and Cu(NO3)2 deposited on a microporous carbon surface undergo changes and form an X-ray amorphous Pd0 phase and a paratacamite—Cu2(OH)3Cl nanocrystalline phase. The catalysts were tested at carbon monoxide initial concentrations of 300 mg/m3 with an effective contact time of the catalyst with the gas–air mixture from 0.12 to 0.50 s. Catalysts provide air purification from CO to concentrations below MPCCO (20 mg/m3) and can be used in respiratory devices. The maximum catalytic activity is observed when the content of palladium in the catalyst is 1.70⋅10−4 mol/g and the content of copper (ІІ) is 4.68⋅10−4 mol/g.

Photocatalysts Based on Graphite-like Carbon Nitride with a Low Content of Rhodium and Palladium for Hydrogen Production under Visible Light.

In this study, we proposed photocatalysts based on graphite-like carbon nitride with a low content (0.01-0.5 wt.%) of noble metals (Pd, Rh) for hydrogen evolution under visible light irradiation. As precursors of rhodium and palladium, labile aqua and nitrato complexes [Rh2(H2O)8(μ-OH)2](NO3)4∙4H2O and (Et4N)2[Pd(NO3)4], respectively, were proposed. To obtain metallic particles, reduction was carried out in H2 at 400 °C. The synthesized photocatalysts were studied using X-ray diffraction, X-ray photoelectron spectroscopy, UV-Vis diffuse reflectance spectroscopy and high-resolution transmission electron microscopy. The activity of the photocatalysts was tested in the hydrogen evolution from aqueous and aqueous alkaline solutions of TEOA under visible light with a wavelength of 428 nm. It was shown that the activity for the 0.01-0.5% Rh/g-C3N4 series is higher than in the case of the 0.01-0.5% Pd/g-C3N4 photocatalysts. The 0.5% Rh/g-C3N4 sample showed the highest activity per gram of catalyst, equal to 3.9 mmol gcat-1 h-1, whereas the most efficient use of the metal particles was found over the 0.1% Rh/g-C3N4 photocatalyst, with the activity of 2.4 mol per gram of Rh per hour. The data obtained are of interest and can serve for further research in the field of photocatalytic hydrogen evolution using noble metals as cocatalysts.

Synthesis and Structural Characterization of Branched Bimetallic AuPd Nanoparticles with a Highly Tunable Optical Response.

Bimetallic nanostructures composed of gold (Au) and palladium (Pd) have garnered increased interest for their applications in heterogeneous catalysis. This study reports a simple strategy for manufacturing Au@Pd bimetallic branched nanoparticles (NPs), which offer a tunable optical response, using polyallylamine-stabilized branched AuNPs as template cores for Pd overgrowth. The palladium content can be altered by manipulating the concentration of PdCl42- and ascorbic acid (AA) that are injected, which permit an overgrowth of the Pd shell up to ca. 2 nm thick. The homogeneous distribution of Pd at the surfaces of Au NPs can be carried out regardless of their size or branching degree, which allows for an adjustment of the plasmon response in the near-infrared (NIR) spectral range. As a proof of concept, the nanoenzymatic activity of pure gold and gold-palladium NPs was compared, exploring their peroxidase-like activity in the oxidation of 3,3',5,5'-tetramethylbenzidine (TMB). The bimetallic AuPd NPs demonstrate an increase in the catalytic properties attributed to the presence of palladium at the surface of gold.

Valuation of bimetallic Pd/Ni nanoparticles catalyst for the applications in direct methanol fuel cells

AbstractThe electrospinning method has been successfully employed to prepare various percentages of less expensive nickel/palladium (NP) nanofiber catalysts as an alternative to platinum in direct methanol fuel cells (DMFC). The chemical structure, morphological characteristics, and electrochemical (EC) properties have been investigated using a variety of analysis techniques. According to the scanning electron microscope (SEM), all prepared samples with different Pd concentrations exhibit good nanofiber form and a distinct nanoparticle look. Transmission electron microscopy (TEM) reveals an amorphous carbon nanofiber structure with imbedded crystalline spheres of nickel and palladium. The carbonized polyvinyl alcohol nanofibers (PVANFs) have a steady and even distribution of nickel and palladium with an accurate nickel and palladium content, according to the energy dispersive X‐ray mapping results. The lack of hydroxide or oxide phases in the X‐ray diffraction (XRD) pattern proves that Ni–Pd nanoparticles are present in the metallic phase. For the electrooxidation of methanol, urea, and an isopropanol‐methanol mixture, the electrocatalytic features of the fabricated samples have been examined. EC results show that methanol has the best electrocatalytic properties. Hence, NP nanofiber catalysts could be a promising candidate to replace platinum in DMFC.

Development of Highly Efficient Hydroisodeparaffinization Catalysts Based on Micro-Mesoporous SAPO-31: New Approaches in the Synthesis of SAPO-31 and the Preparation of Bifunctional Catalysts

A method is proposed for the synthesis of micro-mesoporous SAPO-31 with a high external surface area and large mesopore volume using tetraethoxysilane as a source of silicon. The synthesis of SAPO-31 is based on the principles underlying the Stöber process approach, which allows control of the pore diameter and volume and, hence, the external surface area of the product material. The use of the proposed methods for depositing the hydro-dehydrogenating component on the synthesized micro-mesoporous SAPO-31 made it possible to obtain highly efficient bifunctional hydroisodeparaffinization catalysts with the platinum or palladium content not higher than 0.2 wt.%. As a result, the process temperature can be decreased by 50–60 °C in comparison with the known analogs. Therewith, for example, in the test reaction of n-decane hydroisodeparaffinization at a temperature of 300 °C and feed rate of 1.5 h−1, the conversion above 90%, and the 97–98% yield of liquid products, the 95% selectivity to isomeric products were achieved.

Microstructural and Mechanical Characterization of Interfacial Phenomena Occurring in Brazing Ti-6AL-4V Alloy Using TiZrCuPd Amorphous Ribbons

The brazing technology with the proper choose of the filler metals should provide a solution for the major disadvantage of titanium alloys related to the problems of joining. This work concerns brazing of the Ti-6Al-4 V substrates with the originally amorphous TiCuZrPd ribbon. The TiCuZrPd filler enables proceeding of the brazing process below the melting temperature of the alloy, at about 880 °C. As the high quality of the filler/substrate interconnection remains substantial for the industrial application, the evolution of the mechanical and structural properties was studied while the induction and resistance heating were used to obtain Ti/Ti joints. The microstructure studies showed that at the interfaces obtained by both methods, the brazed zone was characterized by the uniform microstructure without defects such as separation of intermetallic phases or Kirkendall voids. In both cases, the interface consisted of three zones: upper diffusion zone, filler material zone and lower diffusion zone. It was also observed that regardless of the heating method used, the width of the reaction zone of the joints was similar, about 47 µm. On the other hand the ratio of the widths of the different zones was altered in dependence on the heating method used. The results showed that the brazing by induction heating increased the shear strength of the tested joints by two to three times, depending on the content of palladium in the filler metal. The highest value of shear resistance of approx. 650 MPa was noted for the joints obtained by induction heating at 850 °C.

Palladium-modified TiO2 Photocatalysts: Synthesis, Characterization, and Environmental Application

Sol-gel method was used to prepare palladium-modified TiO2 powder photocatalysts (Pd atomic percentage range of 0–1.00). The materials were characterized by X-ray diffraction, N2 physisorption, UV–Vis diffuse reflectance spectroscopy and transmission electron microscopy. Photocatalytic activity was tested for phenol degradation, with UV and visible lamps. The optimum palladium content was determined (0.10% atomic Pd), showing phenol degradation of 100% under UV irradiation (2 h) and 68% under visible irradiation (5 h). The presence of PdO particles was revealed on this material. Furthermore, the immobilization of this material on glass slides was studied by dip-coating method to overcome the limitations of the slurry mode. This film presented photocatalytic activity under UV and visible irradiation (5 h), reaching 80% and 23% of phenol degradation, respectively. This film is a promising alternative to degradation of pollutant using solar irradiation effectively.

Analytical Method Development and Validation for the Estimation of Palladium Content in Tapentadol Hydrochloride by Atomic Absorption Spectrometer

A validated method for determining the palladium concentration in tapentadol hydrchloride was devised using an atomic absorption spectrophotometer (AAS) with a 0.7 nm slit width and a high speed deuterium lamp (D2). The integration time was set at 5.0 seconds with a wavelength of 247.6 nm. The system performance characteristics were used to evaluate the system performance. The limits of quantifi cation and detection were determined to be 0.30 and 0.10 mg/l, respectively. The percentage recovery for LoQ level, 50, 100 and 150% levels of spiked concentrations of palladium in tapentadol hydrochloride were found to be 100.09, 100.13, 100.11 and 99.78%, respectively. This article discusses the status of trace elements and heavy metals in bulk pharmaceuticals, as well as AAS method which is convenient and simple that may be used for quality control and standardization of bulk drugs and other related items at the industrial level

Low-concentration palladium recovery from diluted aqua regia-based wastewater using lyophilized algal cells

Ion-exchange resins and activated carbons are used in waste refinement in the electronics industry to recover low concentrations of palladium (Pd) dissolved in diluted aqua regia (HCl:HNO3 = 3:1, v/v). However, these techniques are inefficient and have higher costs than benefits. Here, we showed that the lyophilized cells of the microalga Galdieria sulphuraria recovered Pd from 4 M acid-diluted aqua regia with < 135 mg L–1 Pd and 6 M acid solution containing < 50 mg L–1 Pd with greater efficiency than ion-exchange resins and activated carbons. X-ray absorption fine structure, photoemission spectroscopy, and electron microscopy revealed that Pd was adsorbed in the periphery of lyophilized cells by forming an inner-sphere complex with sulfur. Among other metals, G. sulphuraria could recover 97% of Pd from 5 M acid-containing aqua regia-based wastewater generated during the production of printed circuit boards.

Effect of water content and storage conditions on the activity of PdCuFe-containing fibrous carbon catalyst for low-temperature CO oxidation

Effect of water content and storage conditions on the activity of carbon fiber supported palladium-copper-iron containing catalyst was studied. Physical-chemical properties of catalytic system were examined by means of XRD, XPS, SEM and GCh. The optimal water content in the catalyst, which ensures the most effective air purification both at low (0,03 vol.%) and high (0,5 vol.%) CO concentrations in the air and high humidity (70 %) of gas mixture, was determined.Activity loss of the catalytic system after storage under air conditions (1 month) was attributed to the accumulation of the excess amount of water in the catalyst and reorganization of its the active phase – decrease in the palladium content in the near-surface layer and segregation of the Сu2Cl(OH)3 atacamite phase. Catalyst drying in air at 110 оС leads to its complete reactivation. Hermetically sealed freshly as-prepared and dried at 50 оС after experiment samples retain the initial catalytic activity during long-term (more than a year) storage.

ANODIC PROCESSES OF URANIUM ALLOYS CONTAINING PALLADIUM AND NEODYMIUM IN 3LiCl–2KCl-UCl&lt;sub&gt;3&lt;/sub&gt; MELTS

At the reprocessing module of the pilot demonstration power complex site of the Siberian Chemical Combine, a combined technological scheme for the reprocessing of mixed nitride uranium-plutonium spent fuel consisting of pyrochemical operations, hydrometallurgical refining of uranium, plutonium and neptunium is implemented step by step. According to this scheme, the target pyrochemical reprocessing products, purified from the main mass of fission products with actinoid content not less than 99.9%, are sent for hydrometallurgical reprocessing. For pyrochemical reprocessing it is necessary to develop a technology of electrorefining of metallised spent nuclear fuel. To carry out electrolytic refining it is necessary to define processes and regimes of anodic dissolution of alloys simulating product of this head operation “metallization”. In the present work the results of investigations of processes of anodic dissolution of U–Pd and U–Pd–Nd model alloys with different concentrations of palladium and neodymium in melts based on 3LiCl–2KCl–UCl3 (10.1 wt % UCl3) at 550°C using different methods are presented. Uranium alloys containing palladium and neodymium were prepared by direct alloying of uranium metal and palladium metal powders of PdAP-1 grade, and neodymium metal (99.99%) in high-purity argon medium (99.998%). Electrochemical measurements were performed using an Autolab 302N potentiostat/halvanostat equipped with a Booster 20A high-current module. The anodic polarisation curves consist of only one oxidation wave which was attributed to the dissolution of uranium metal. Increasing the palladium content in the alloy from 1.5 to 10.0 wt %, does not affect the shape of the polarisation curves. The increase of neodymium content in the alloy from 1.0 to 10.0 wt % also does not affect the shape of polarization curves. Electrorefining parameters of uranium alloys containing palladium and neodymium were determined. The limiting current density of uranium evolution from uranium alloys containing palladium and neodymium in the electrolyte 3LiCl–2KCl–UCl3 (10.1 wt % UCl3) at 550°C was 0.4 A/cm2. It was shown that palladium does not diffuse into the melt as a result of anodic dissolution and neodymium accumulates in the electrolyte only when the alloy is refined with 10.0 wt % neodymium, which is much higher than the future real concentrations of electrotreated uranium alloy components in the technological chain of spent nuclear fuel processing.

Route Optimization of the Non-covalent Modulator of Hemoglobin PF-07059013 for the Treatment of Sickle Cell Disease, Part I: From Discovery Synthesis to First Kilogram-Scale Manufacture

The scalable route to PF-07059013 (3), a non-covalent modulator of hemoglobin for the treatment of sickle cell disease, is discussed. Optimization of the discovery route is presented, examining bond connections, late-stage Buchwald–Hartwig C–O coupling, and palladium content reduction strategies. The first process chemistry route to deliver 11 kg of the final API is also discussed.

Improvement of the performance of dye-sensitized solar cells employing NickelPalladium alloy-reduced graphene oxide counter electrode: Influence of palladium content

In this work, NickelPalladium-reduced graphene oxide (NiPd-rGO) films have been prepared via liquid phase deposition technique and used as free-platinum (Pt) counter electrode for dye-sensitized solar cell (DSSC). The effect of Pd content in term of various Ni:Pd ratios on the properties such as structure, optical transmission, surface morphology and elemental compositions have been studied. The morphology of NiPd-rGO sample is in the form of crumpled vertical folds in layers and white strips. The influence of Pd content on photovoltaic parameters of the device has also been investigated. The performance parameters were significantly influenced by the Pd content. The device using NiPd-rGO counter electrode prepared at Ni:Pd ratio of 20:2 demonstrated the highest PCE of 3.09%. This is due to the device owns the highest charge recombination resistance (Rrec) and shortest carrier transport time (τ). The efficiency has been improved at the optimum content of Pd. The finding from this work implies that NiPd-rGO is able to substitute Pt as counter electrode in DSSC due to its efficiency is comparable to that of the device employing Pt counter electrode.

Comparative investigation of methane combustion over palladium-based catalysts supported on mesoporous MgAl2O4 and Al2O3

A series of mesoporous Pd/Al2O3 and Pd/MgAl2O4 catalysts with different palladium contents (0.5, 1 and 4 wt%) were prepared by the impregnation method and used for methane combustion. Among the catalysts studied, 1Pd/MgAl2O4 (1 wt% Pd) was found to be highly effective for the catalysis of CH4 combustion below 450 °C, with a low apparent activation energy of ∼50.1 kJ/mol, and had good thermal stability. The characterization results showed that the excellent catalytic performance of Pd/MgAl2O4 can be ascribed to the strong interaction between the MgAl2O4 spinel and PdO species, favoring the dispersion and stability of the species. In addition, the effects of Pd particle size on CH4 combustion were also investigated. It was found that the catalytic activity of Pd/MgAl2O4, with a strong metal-support interaction, showed a volcano-shaped dependence on the size of Pd particles.