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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. [ABSTRACT FROM AUTHOR]

Platinum group metals (PGMs), including palladium, play a pivotal role in various industries due to their unique properties. Palladium is frequently employed in technologies aimed at environmental preservation, such as catalytic converters that reduce harmful emissions from vehicles, and in the production of clean energy, notably in the hydrogen evolution process. Regrettably, the production of this vital metal for our environment is predominantly centered in two countries—Russia and South Africa. This centralization has led to palladium being classified as a critical raw material, emphasizing the importance of establishing a secure and sustainable supply chain, as well as employing the most efficient methods for processing materials containing palladium. This review explores techniques for palladium production from primary sources and innovative recycling methods, providing insights into current technologies and emerging approaches. Furthermore, it investigates the economic aspects of palladium production, including price fluctuations influenced by emission regulations and electric vehicle sales, and establishes connections between palladium prices, imports from major producers, as well as copper and nickel prices, considering their often co-occurrence in ores. [ABSTRACT FROM AUTHOR]

The interactions between metals and oxide supports, so-called metal-support interactions (MSI), are of great importance in heterogeneous catalysis. Pd-based automotive exhaust control catalysts, especially Pd-based three-way catalysts (TWCs), have received considerable research attention owing to its prominent oxidation activity of HCs/CO, as well as excellent thermal stability. For Pd-based TWCs, the dispersion, chemical state and thermal stability of Pd species, which are crucial to the catalytic performance, are closely associated with interactions between metal nanoparticles and their supporting matrix. Progress on the research about MSI and utilization of MSI in advanced Pd-based three-way catalysts are reviewed here. Along with the development of advanced synthesis approaches and engine control technology, the study on MSI would play a notable role in further development of catalysts for automobile exhaust control. [Display omitted]. [ABSTRACT FROM AUTHOR]

Selective adsorption of palladium from metallurgical wastewater containing Pt (IV), Rh (III), Ca2+, Cu2+, Fe3+, Ni2+, Pb2+, V3+, and Ti4+ has tremendous economic and environmental benefits. In this paper, a novel thiadiazole-based chloromethyl polystyrene-modified adsorbent, viz. 2, 5-bis-polystyrene-1,3,4-thiadiazole (PS-DMTD), was synthesized using chloromethyl polystyrene as the backbone. The experimental results show that PS-DMTD can selectively separate Pd (II) from metallurgical wastewater in a one-step adsorption process. The calculated saturation adsorption capacity of PS-DMTD for Pd (II) was 176.3 mg/g at 25 °C. The separation factors of βPd (II)/Mn+ (Mn+: Pt (IV), Rh (III), Ca2+, Cu2+, Fe3+, Ni2+, Pb2+, V3+, and Ti4+) were all higher than 1 × 104. FT-IR, XPS, and single-crystal X-ray diffraction showed that the adsorption of Pd (II) to PS-DMTD was primarily through a coordination mechanism. Density functional theory (DFT) calculations revealed that the other base metal ions could not coordinate with the PS-DMTD. Pt (IV) could not be adsorbed to PS-DMTD due to its strong chlorophilicity. Furthermore, Rh (III) existed as a polyhydrate, which inhibited Rh (III) diffusion toward the positively charged absorption sites on the PS-DMTD. These results highlight that PS-DMTD has broad application prospects in the recovery of Pd (II) from metallurgical wastewater. [ABSTRACT FROM AUTHOR]

Platinum (Pt) and palladium (Pd) are commonly integrated into automotive catalytic converters to convert harmful emissions into relatively safer substances. Their scarcity has resulted in the rapid development of an industry focused on their recovery. Polyamide 6 (PA6), a microplastic pollutant, is a common industrial material. Proper recycling of PA6 can mitigate the environmental impact caused by its microplastic pollution. This work revealed the capability of PA6 in recovering Pt and Pd from solution. Experimental data demonstrated that PA6 recovered about 90% of Pt and 70% of Pd. Importantly, PA6, without any functionalization or modification, adsorbed Pt and Pd without adsorbing present competing metals, exhibiting notably greater recovery selectivity towards Pt and Pd than materials discussed in other works. Furthermore, approximately 81% of Pt and 83% of Pd could be desorbed from PA6 as noted by the desorption studies. After obtaining fitted results using empirical equations and surface group identification, chelation and electrostatic interaction were discerned to be the key pathways for Pt and Pd recovery. This study represents a novel investigation into PA6's adsorption selectivity for Pt and Pd, through which experimental results confirm PA6's potential as a practical, environmentally-friendly alternative for Pt and Pd recovery, distinguishing it from its conventional counterparts. [Display omitted] • The potential of PA6 for recovering Pt and Pd from solution is revealed. • PA6 exhibited a more fabulous recovery selectivity towards Pt and Pd than other studies' materials. • 0.5 M thiourea with 0.1 M HCl solution desorbed 81% Pt and 83% Pd from PA6. • Possible pathways for Pt/Pd recovery are chelation and electrostatic interaction. [ABSTRACT FROM AUTHOR]

Palladium (Pd) is most widely used in the production of automotive catalytic converters that serve to reduce toxic emissions from motor vehicles. The aim of this study was to analyze the solid–liquid partitioning and dynamic variation of Pd in rainfall runoff. The results showed that the partition coefficients (K) of Pd ranged from 0.05 to 8.55. Transport via suspended particulate matter as the main carrier was the main form of Pd migration in rainfall runoff. Pd phase distribution exhibited complex dynamic variations. The variation in Pd could be roughly divided into three categories, namely the W, M and N types, and the semi-U type was also observed. Rainfall characteristics and microenvironmental factors had a profound effect on Pd phase distribution in the first flush runoff. Under the influence of multifactor coupling, the impact of water quality parameters such as pH, Eh and Cl− on Pd partitioning was significantly weakened. [ABSTRACT FROM AUTHOR]

The present study investigated the resource circulation of precious metals (Pt and Pd) from exhausted catalytic-converters using a green integrative approach of bio-solvo-chemical techniques. Herein, the used biogenic cyanide as a lixiviant medium was produced via the oxidative decarboxylation of glycine during the late exponential growth phase of Chromobacterium violaceum. The advantage of microbial activity was utilized in two-fold: (i) in situ production of the bio-cyanide lixiviant and (ii) bio-destruction of residual cyanide from the Pt/Pd-depleted bleed solution. More than 95% of Pt and Pd were efficiently dissolved in bio-cyanide solution by autoclaving under the optimized condition of temperature, 150 °C; pO2, 14 bar; and time, 120 min. Furthermore, the solvo-chemical extraction of the Pt/Pd-cyanide complex was performed using a green ionic-liquid solvent (Cyphos IL101). The parametric studies revealed that >96% Pt and Pd were extracted under the optimal conditions of ionic-liquid concentration, 0.15 mol L-1; extraction pH, 10.4; and temperature, 20 °C. The extraction thermodynamics yielded negative values of enthalpy changes (i.e., ΔH°(Pt), -39.8 kJ mol-1 and ΔH°(Pd), -34.9 kJ mol-1), which indicated the exothermic characteristics of outer-sphere coordination between the ionic-liquid and Pt/Pd(CN)42- compounds. Subsequently, an excellent selectivity on Pd and Pt stripping from the loaded organic phase was achieved by sequential contact with 2.0 mol L-1 NH4SCN and 1.5 mol L-1 S(CH2CH2OH)2 solutions. The tested recyclability of cyanide-bearing raffinate, regeneration and reusability of the ionic-liquid, and bio-degradation of cyanide-bleed solution drive the process towards zero-discharge of toxic substances. Significantly low-emission exploitation of precious metals (reduced from 10.8 × 106 to only 1.63 t CO2-e) from the waste materials with a sustainable process index value of 0.0145 cap per kg reveals that the process is suitable for sustainable development. [ABSTRACT FROM AUTHOR]

The spent automobile catalysts (SAC) is the major secondary source of palladium and the production of SAC is increasing rapidly over years. The price of palladium keeps rising over the years, which demonstrates its preciousness and urgent industrial demand. Recovering palladium from the spent automobile catalysts benefits a lot from economic and environmental protection aspects. This review aims to provide some new considerations of recovering palladium from the spent automotive catalysts by summarizing and discussing both hydrometallurgical and pyrometallurgical methods. The processes of pretreatment, leaching/extraction, and separation/recovery of palladium from the spent catalysts are introduced, and related reaction mechanisms and process flows are given, especially detailed for hydrometallurgical methods. Hydrometallurgical methods such as chloride leaching with oxidants possess a high selectivity of palladium and low consumption of energy, and are cost-effective and flexible for different volume feeds compared with pyrometallurgical methods. The recovery ratios of palladium and other platinum-group metals should be the focus of competition since their prices have been rapidly increased over the years, and hence more efficient extractants with high selectivity of palladium even in the complexed leachate should be proposed in the future. [ABSTRACT FROM AUTHOR]

We have developed a flexible approach enabling the access to highly functionalized pyrroles under palladium or copper catalysis in the presence of BF3 ⋅ Et2O. This catalytic methodology utilizes commercially available amines as reaction partners, and features ample scope, scalable and friendly operations with the generation of only water as byproduct. The generality of this protocol is demonstrated by the successful preparation of a range of di‐, tri‐, tetra‐ and pentasubstituted pyrroles. This methodology is amenable for the synthesis and derivatization of bioactive compounds. [ABSTRACT FROM AUTHOR]

Palladium (Pd), due to its unique catalytic properties, is an industrially important heavy metal especially in the form of nanoparticles. It has a wide range of applications from automobile catalytic converters to the pharmaceutical production of morphine. Bacteria have been used to biologically produce Pd nanoparticles as a new environmentally friendly alternative to the currently used energy-intensive and toxic physicochemical methods. Heavy metals, including Pd, are toxic to bacterial cells and cause general and oxidative stress that hinders the use of bacteria to produce Pd nanoparticles efficiently. In this study, we show in detail the Pd stress-related effects on E. coli. Pd stress effects were measured as changes in the transcriptome through RNA-Seq after 10 min of exposure to 100 μM sodium tetrachloropalladate (II). We found that 709 out of 3,898 genes were differentially expressed, with 58% of them being up-regulated and 42% of them being down-regulated. Pd was found to induce several common heavy metal stress-related effects but interestingly, Pd causes unique effects too. Our data suggests that Pd disrupts the homeostasis of Fe, Zn, and Cu cellular pools. In addition, the expression of inorganic ion transporters in E. coli was found to be massively modulated due to Pd intoxication, with 17 out of 31 systems being affected. Moreover, the expression of several carbohydrate, amino acid, and nucleotide transport and metabolism genes was vastly changed. These results bring us one step closer to the generation of genetically engineered E. coli strains with enhanced capabilities for Pd nanoparticles synthesis. [ABSTRACT FROM AUTHOR]

[Display omitted] • Innovative double-layer adsorptive membrane consists of a PDA layer and a PDMC layer. • Palladium was adsorbed via the dual mechanism of ion exchange and chelation. • The designed membrane has superior selectivity to Pd(II) in coexisting metal cations. • The membrane can be an alternative to adsorbents for palladium selective separation. Palladium (Pd) recovery from secondary resources is urgently needed to meet the rising demands for precious metals for sustainable development and environmental protection. To achieve the goal of simple, efficient, and selective recovery of precious metal Pd, we reported an innovative strategy that utilized a double-layer adsorptive membrane based on polydopamine (PDA) modification and polymethacryloxyethyltrimethyl ammonium chloride (PDMC) grafting. The adsorption results suggested that the adsorptive membrane exhibited an excellent adsorption capacity of 61.5 mg g−1 towards Pd(II) at pH 2.0 and the adsorption capacity remained stable after six cycles. Moreover, the adsorption processes of Pd(II) were fitted to pseudo second-order kinetic models and the Langmuir isotherm models. Density functional theory (DFT) simulation, and FTIR, XPS analysis indicated the adsorption mechanisms were ion exchange from the PDMC layer and chelation and ion exchange from the PDA layer. In the presence of other metal ions (Ni(II), Cu(II), Zn(II), Ca(II), Mg(II), K(I) and Na(I)), the separation factor of adsorptive membrane for Pd(II) was in the range of 50–529. The remarkable selectivity was due to the mechanism of the combination of electrostatic attraction and coordination interaction to Pd(II) while the electrostatic repulsion to other metal cations. Furthermore, membrane filtration results suggested that Pd(II) was effectively adsorbed and rejected and the leakage risk could be reduced by dual adsorption from the double-layer membrane. This study not only offers an innovative strategy to precisely and effectively recover Pd(II) and other platinum group metals, but also provides valuable insights for the future implementation of adsorptive membranes in recycling low-concentration wastewater in an efficient and friendly way. [ABSTRACT FROM AUTHOR]

Palladium (Pd) is widely used in automotive catalytic converters to reduce toxic gas emissions. The input of Pd in the rainfall-runoff is an important contributing factor to the accumulation of Pd in receiving water bodies. In this study, the Meishe River in Haikou, Hainan Province, China, was used as the research area, and palladium (Pd) was selected as the target pollutant. This study explored the response of Pd in the receiving water body to rainfall-runoff and to analyze the influencing factors. The results showed that the dissolved Pd concentration in the receiving water body had a corresponding relationship with that in rainfall-runoff. The response of suspended Pd in the receiving water body to rainfall-runoff was closely related to the location of the drainage outlet. Compared with that of suspended Pd, the response of dissolved Pd in the receiving water body to that in the rainfall-runoff was more obvious. Seven meters downstream from the outfall was the most sensitive response distance of dissolved Pd in receiving water bodies to rainfall-runoff, and the response time was approximately 0–10 min. The suspended Pd at 3 m downstream from the outfall also had a certain response to the rainfall-runoff, and the response time was approximately 15–25 min. The response time of the suspended Pd in the receiving water body depended largely on the first flush ability of the runoff. There was a moderately positive correlation between the dissolved Pd and Cl− in the receiving water body (r = 0.687; p < 0.05). The effects of pH, Eh, and total suspended solids (TSS) on suspended Pd were reduced in the response process of the receiving water body. The synergistic effect of multiple factors increased the uncertainty of the Pd response. [ABSTRACT FROM AUTHOR]

[Display omitted] • Fabrication of cryogel via rapid UV-irradiation grafting cryopolymerization. • The designed chitosan based-cryogel is flexible and antibacterial in nature. • Better selectivity for Pd(II) ions in the presence of coexisting metal ions. • Maximum adsorption capacity for Pd(II) was 184.93 mg g−1. • The cryogels have a better thermal stability and shelf life. • Promising adsorption performance for Pd(II) in waste electronic materials. Retrieving valuable metals like palladium, gold, and platinum from electronic waste poses significant challenges. In this study, we developed highly macroporous and flexible antibacterial chitosan-based cryogel through rapid cryopolymerization induced by ultraviolet exposure. This designed cryogel exhibited exceptional palladium adsorption capabilities within an acidic environment, demonstrating swift and efficient adsorption. Remarkably, the chitosan-based cryogel showed an impressive palladium adsorption capacity, reaching 184.93 mg g−1 as Langmuir isotherm model, thus highlighting its promising potential for palladium recovery. The adsorption efficiency and concentration examination was conducted using an Inductively Coupled Plasma Optical Emission Spectrometer in the presence of multiple coexisting ions. Various factors and parameters, including pH, contact time, temperature, concentration, and selectivity, were investigated to assess the effectiveness of the biopolymeric cryogel in palladium adsorption. Additionally, the thermal stability of the developed cryogel was explored within the temperature range of 25-100˚C, revealing a commendable palladium adsorption capacity even at 100˚C. This finding underscores the material's potential for application under challenging conditions. The cryogel that was synthesized exhibits an extended shelf-life of up to six months and can be reused without any discernible alteration in its adsorption efficiency. Furthermore, the palladium adsorption capacity was evaluated in a real-world sample, demonstrating commendable adsorption capabilities. Remarkably, the biosorbent displayed a higher selectivity of 91% for palladium, even in the competing ions presence. In summary, biosorbent offers superior adsorption performance and remarkable stability, making it a valuable contribution to polymer chemistry and environmental science. Its potential for recovering precious metals from wastewater is indeed noteworthy. [ABSTRACT FROM AUTHOR]

Nano-sized noble metal particles are an essential component in automotive catalytic converters. However, during customer in-use operation they agglomerate into larger particles and the performance of the catalytic converter is negatively affected. Engine control methods are needed to provide an environment capable of redispersing noble metal catalyst particles while the particle size is still small. In this study, Pd model powder catalysts, supported on three-way catalytic converter washcoat components of ceria-zirconia (Pd/CZO), 4 wt% La 2 O 3 stabilized γ-Al 2 O 3 (Pd/Al) and unstabilized γ-Al 2 O 3 (Pd/A) were exposed to redox cycling at 700 °C for 16 h (to simulate customer in-use operation engine exhaust) either continuously or interrupted with brief air pulses. The two goals of this research were to determine the air pulse length required so that any Pd redispersion gains achieved by air treatment in each 20 min redox cycle will be retained by the end of the 16 h aging, and to determine if these supports enable rapid Pd redispersion on the time scale of a common ∼10 s engine fuel cut. Pd particle size and dispersion measurements were performed with three complimentary techniques of H 2 chemisorption, XRD and electron microscopy since not one technique could be used exclusively. Catalyst activity was determined by CO oxidation with the Water Gas Shift (WGS) reaction and Oxygen Storage Capacity (OSC) measurements to probe the contact between the noble metal and support at a given state of catalyst deterioration, and a CO light-off test to confirm trends observed with Pd metal dispersion. We found that air pulses lasting for 1/6 min applied to interrupt short redox aging spans enabled Pd redispersion only on the Pd/Al catalysts. Strong metal support interaction on the Pd/CZO catalysts by decoration of the Pd surface with support oxide was suspected to slow Pd redispersion by limiting metal mobility. Support oxides that promote the Pd 2+ state may have been required on the Pd catalysts in order to exhibit Pd redispersion. The insight gained from this work could be used to develop engine control and aftertreatment systems that actively intervene and regenerate a catalyst capable of rapid Pd redispersion. [ABSTRACT FROM AUTHOR]

A better understanding of the mechanisms behind adverse health effects caused by airborne fine particles and nanoparticles (NP) is essential to improve risk assessment and identification the most critical particle exposures. While the use of automobile catalytic converters is decreasing the exhausts of harmful gases, concentrations of fine airborne particles and nanoparticles (NPs) from catalytic metals such as Palladium (Pd) are reaching their upper safe level. Here we used a combinatory approach with three in vitro model systems to study the toxicity of Pd particles, to infer their potential effects on human health upon inhalation. The three model systems are 1) a lung system with human lung cells (ALI), 2) an endothelial cell system and 3) a human whole blood loop system. All three model systems were exposed to the exact same type of Pd NPs. The ALI lung cell exposure system showed a clear reduction in cell growth from 24 h onwards and the effect persisted over a longer period of time. In the endothelial cell model, Pd NPs induced apoptosis, but not to the same extent as the most aggressive types of NPs such as TiO 2. Similarly, Pd triggered clear coagulation and contact system activation but not as forcefully as the highly thrombogenic TiO 2 NPs. In summary, we show that our 3-step in vitro model of the human lung and surrounding vessels can be a useful tool for studying pathological events triggered by airborne fine particles and NPs. [Display omitted] • We have combined three in vitro systems into a unique model of the human lung and the surrounding blood and blood vessels. • The three systems are: an ALI system with human lung cells, a vascular endothelial cell model and a whole blood model. • The same Pd NPs werw generated, characterized and evaluated in all three parts of the model with a consistent result. • It was found that Pd NPs triggers a response, but appears to be less activating compared to very harmful NPs such as TiO2. [ABSTRACT FROM AUTHOR]

Estuaries are environmental systems with great resource potential and environmental benefits. This study investigates the role of particulate palladium (Pd) in the Nandu River Estuary in the enrichment of estuarine geochemical processes during spring-neap tides. Particulate Pd was found to show different characteristics during spring-neap tides, with the hydrodynamic condition being one of the key factors causing the difference. In addition, particulate Pd showed a decreasing trend while moving from the mouth to the upstream. The highest value of particulate Pd was 35.32 ng L−1, which occurred at the intersection of the mainstream and the branch during the neap tide, and the lowest value was 0.86 ng·L−1, which occurred in the far mouth area during the spring tide. The concentrations of particulate Pd during the neap and spring tides were 5.53 (1.01–35.32) ng·L−1 and 2.33 (0.86–5.22) ng·L−1, respectively. With the exception of stations 1, 5, 10, 11, and 15, the concentration of particulate Pd during the neap tide was greater than that during the spring tide. The variation in the particulate Pd was inconsistent between the spring tide and the neap tide, and the fluctuation in each study section during the neap tide was greater than that during the spring tide. In addition, since the emissions from catalytic converter are in the form of nanoparticles, they are difficult to be dissolve in natural water, and therefore, the concentration of particulate Pd was obviously greater in the waters near large bridges and main roads. An analysis of the physical and chemical properties of the water showed that Cl− easily combined with dissolved Pd and was one of the important factors that affected the concentration of particulate Pd. In addition, DO and Eh had little effect on the change in the particulate Pd during the tidal cycle, and pH had a significant positive correlation with particulate Pd. [Display omitted] • The particulate Pd in the estuary area was discussed. • Combining tides with pollutant changes. [ABSTRACT FROM AUTHOR]

Palladium (Pd) emitted from vehicles equipped with exhaust catalytic converters has been accumulating at a greater rate relative to other platinum group elements (PGE) in the last 10–20 years. Little is known, however, regarding the various environmental factors and conditions which are likely to modulate the chemical behavior and bioaccessibility of this element post-emission. To meet data needs, soils and a Pd model substance were treated with solutions containing common anions (Cl − , NO 3 − , SO 4 2− und PO 4 3− ) to shed light on the geochemical behavior of emitted Pd under ambient conditions. As part of this, the particle surface chemistry of treated residues (insoluble phase) and solutions (soluble phase) was examined using XPS to assess the chemical transformation of Pd in the presence of inorganic anions. The results show that Pd is the most soluble in the presence of anionic species, followed by rhodium (Rh) and platinum (Pt). Pd in field-collected samples was found to be considerably more soluble than the metallic Pd in the model substance, Pd black, when treated with anionic species. The results also demonstrate that the solubility of Pd black is strongly dependent on solution pH, concentration and the duration of reaction. The outer 3–4 atomic layers of metallic Pd was determined via XPS to be partially oxidized when treated with anion solutions, with the degree being dependent on anion type. The concentration of dissolved O 2 in solution was found to have little impact on the transformation of metallic Pd. Given the ubiquitous nature of the anions examined, we can expect that Pd will become more bioaccessible post-emission. [ABSTRACT FROM AUTHOR]

Nano-sized palladium (nano-Pd) is used in catalytic converters of automobiles, where it can be released into the environment by abrasion. Although these particles may subsequently be transported into surface water bodies, no data estimating their fate and toxicity in aquatic systems exists. This study characterized the particle size development of nano-Pd (advertised size ~12 nm; hydrodynamic size ~70 nm) in media with variable ionic strength (IS). Additionally, the particles' acute toxicity for daphnids and chironomids was assessed. While nano-Pd agglomerated more quickly with increasing IS, it caused only marginal effects in both test species after 96 h of exposure. After 144 h of exposure, however, an EC value of 1.23 mg nano-Pd/L for daphnids was determined indicating effects over the long run. When considering the relatively low environmental concentration of elemental Pd in surface waters (usually ng/L), though, this study suggests only a low aquatic risk in response to nano-Pd. [ABSTRACT FROM AUTHOR]

Extensive use of palladium in many catalysts and catalytic converters causes a high degree of pollution of water and soil resources. Therefore, there is an urgent need to develop rapid and sensitive palladium probes. Herein, a novel "turn-on" near-infrared (NIR) fluorescence and colorimetric probe for Pd has been designed on the basis of the deallylation of the probe, followed by the release of NIR emissive fluorophore through the Tsuji-Trost reaction. The probe can selectively discriminate between the oxidation states of Pd0 and Pd2+. Sensing results demonstrates that the probe has excellent selectivity, sensitivity, fast response time, NIR fluorescence, high biocompatibility, and low detection limit for the Pd detection over a series metal ion. The probe has been successfully applied in visualization of residual Pd content from water, soil, drug and living cell samples by fluorescence observation with the naked eye. [Display omitted] • A novel NIR responsive fluorescent probe TPd for Pd0 is developed. • TPd is used as a fluorescent probe for detection of Pd0 with low the limit of detection as 38.0 nM. • Discrimination of Pd0 and Pd2+ species by TPd is successively acquired. • TPd displays several practical applications such as smartphone and TLC kit. • TPd can practically detect Pd0 in water, drug, soil and living cell samples. [ABSTRACT FROM AUTHOR]

This work investigates the performance of the nickel sulfide fire assay (NiS-FA) for the pyrometallurgical analysis of platinum group elements (PGEs) from mixtures of automotive exhaust catalytic converters (e.g., gasoline, diesel, and diesel particular filter) by assessing the effects of various flux materials and reaction parameters on platinum, palladium, and rhodium recovery. Inductively coupled plasma mass spectrometry and atomic absorption spectroscopy (AAS) are used for the analysis of the NiS-FA beads. We found that the optimum recovery (at least 99.0%) was achieved with reaction of 11.5 g of flux (0.53 w/w ratio, sodium tetraborate:sodium carbonate), 1 g nickel, and 0.84 g sulfur (1.2 w/w ratio, Ni:S) per gram of sample for 90 min at 975°C. Reference standards (NIST SRM 2557) were used to compare efficiencies and identify the optimum conditions. The results are consistent with certified values and PGEs could be recovered within the 95% confidence level. The precision (<4.0% RSD) of all measurements, expressed as percentage relative standard deviation (SD), ranged up to 3.0%. [ABSTRACT FROM PUBLISHER]

Current synthesis routes of bismuth oxide nanosheets (BiONS) are relatively complicated, requiring the use of halogens or metalloids. Herein, a facile method to synthesize BiONS without the addition of halogens or other metalloids was developed. The synthesized BiONS were identified to have flake-shaped structures (300–1000 nm in width) with the thickness of 6–10 nm, which were predominantly made of β-Bi 2 O 3. Such BiONS were applied to modify the surface of screen-printed carbon electrodes (BiONS-SPCEs) for the development of a robust palladium (Pd2+) sensor. After optimizing the electrochemical parameters of the sensor, it was found that the linear sensor response range and limit of detection for Pd2+ were 40–400 and 1.4 ppb, respectively. The electrocatalytic activity of the Pd2+-sensor was validated in the competing environment of other metal and metalloid ions. Real samples collected during a Pd recovery process from pharmaceutical wastewater were used to verify the application of BiONS-SPCEs in control of palladium recovery process. The quantitative results of post recovery palladium concentrations obtained using BiONS-SPCEs in treated pharmaceutical wastewater samples were in good agreement with those obtained by inductively coupled plasma-optical emission spectrometry (ICP-OES). Thus, such Pd2+-sensor provided the possibility of on-site process control of complex industrial samples for obtaining near-instant information that would lead to better management of resources used in the process, and same time assure environmental standards for both recovered products and processed discharge. [Display omitted] • Novel method of synthesizing ultra-thin Bi2O3 nanosheet (BiONS) was developed. •New of BiONS modified electrochemical sensor was designed and fabricated. •Pretreatment method was developed for real Pd containing wastewater. •The sensor was successfully applied to monitor Pd2+ in Pd recovery processes. •The purity of Pd recovered from real wastewater was 98.8%. [ABSTRACT FROM AUTHOR]

Automobile exhaust catalysts containing only Pd have significant advantages over other types of catalysts, including exceptionally high activity at low temperatures, superior thermal stability at high temperatures, and resistance to sulfur toxicity. The present study employs the electron probe microanalysis (EPMA) technique to determine the trace elemental Pd in such catalysts. The particle size distribution and homogeneity of Pd in synthesised standard samples were studied after ball milling, which improved the sample uniformity. Furthermore, the impact of measurement parameters on the analysis precision was investigated. It was found that the optimal conditions are an acceleration voltage of 18 kV, a beam current of 140 nA, and a beam spot size of 40 μm. To avoid potential background interference when choosing background positions in the ZAF method, a calibration curve was established with a correlation coefficient higher than 0.99. This analysis method can be of substantial significance in the production process of automobile exhaust catalysts and in the recovery of precious metals from spent catalysts. Therefore, there is high potential to expand the applications of EPMA in this field. [Display omitted] • Optimal parameters for measuring trace Pd in samples using EPMA were determined. • Ball milling technique was found to be effective in increasing sample homogeneity. • Calibration curve for standard Pd samples was established. • EPMA is an effective method for determining trace amounts of Pd in catalysts. [ABSTRACT FROM AUTHOR]

Abstract: Platinum group metals find extensive use in automobile catalysts, space materials and cancer therapy. Their natural resources are limited thus their recovery from the secondary sector has assumed a great significance. Liquid–liquid extraction provides an effective methodology for the said purpose. The present paper discusses the extraction behavior of platinum(IV), rhodium(III) and palladium(II) from HCl, H2SO4 and HNO3 (0.10–6.0molL−1) media by toluene solution of Cyanex 923. Detailed studies have been conducted by varying the equilibration time, temperature, diluent and concentration of extractant. An assessment of the loading capacity, regeneration power and stability of extractant has been made. The extraction behavior of associated metals namely gold, silver, iron, nickel, cobalt, chromium, copper and aluminum has been investigated and the conditions for the binary separations involving platinum metals have been optimized. The stoichiometric ratio of the extracting species for platinum and palladium has been worked out. Based on the extraction data platinum, palladium and rhodium have been recovered from some spent commercial materials. [Copyright &y& Elsevier]

Environmental concentrations of platinum group elements (PGE) have been increasing since the introduction of automotive catalytic converters to control harmful emissions. Assessments of the human health risks of exposures to these elements, especially through the inhalation of PGE-associated airborne particulate matter (PM), have been hampered by a lack of data on their bioaccessibility. The purpose of this study is to apply in vitro methods using simulated human lung fluids [artificial lysosomal fluid (ALF) and Gamble's solution] to assess the mobility of the PGE, platinum (Pt), palladium (Pd), and rhodium (Rh) in airborne PM of human health concern. Airborne PM samples (PM10, PM2.5, and PM1) were collected in Frankfurt am Main, Germany. For comparison, the same extraction experiments were conducted using the standard reference material, Used Auto Catalyst (monolith) (NIST 2557). Pt and Pd concentrations were measured using isotope dilution ICP-Q-MS, while Rh was measured directly with ICP-Q-MS (in collision mode with He), following established matrix separation and enrichment procedures, for both solid (filtered residues) and extracted sample phases. The mobilized fractions measured for PGE in PM10, PM2.5, and PM1 were highly variable, which can be attributed to the heterogenic nature of airborne PM and its composition. Overall, the mobility of PGE in airborne PM samples was notable, with a mean of 51% Rh, 22% Pt, and 29% Pd present in PM1 being mobilized by ALF after 24 h. For PM1 exposed to Gamble's solution, a mean of 44% Rh, 18% Pt, and 17% Pd was measured in solution after 24 h. The mobility of PGE associated with airborne PM was also determined to be much higher compared to that measured for the auto catalyst standard reference material. The results suggest that PGE emitted from automotive catalytic converters are likely to undergo chemical transformations during and/or after being emitted in the environment. This study highlights the need to conduct bioaccessibility experiments using samples collected in the field to enable an adequate assessment of risk. [ABSTRACT FROM AUTHOR]

Platinum, palladium, and rhodium are emitted from vehicle catalytic converters. Until now, the form of precious metal particles in road dust and urban waste has not been identified. This study has located, imaged, and analyzed these particles in road dust and gully waste. Two fragments of catalytic converter have been observed in road dust. They are 40-80 μm in size and covered in many minute particles (<0.3 μm) of either platinum with minor rhodium or palladium. One fragment identified in gully sediment is smaller, 25 μm in diameter, hosting only one attached particle of palladium with minor rhodium. As fragments are washed off roads they begin to disintegrate and the precious metals become detached. Also precious metal-bearing particles have been located in incinerated sewage ash including a 20 μm diameter cluster of <3 μm sized platinum particles that may be the remains of a catalytic converter fragment that has survived incineration. The form of these precious metal-bearing particles described here reveals that as they are dispersed from roads they are likely to be present predominantly as two particle sizes. Either they are attached to larger fragments of catalytic converter or they are released as individual detached tiny <0.3 μm to nanoparticle sizes. [ABSTRACT FROM AUTHOR]

This paper presents the first study of accessing the Pt, Pd and Rh levels in road dusts collected from Hyderabad city, India, as these metals, emitted from automobile catalytic converters, are accumulating in the environment causing concern about human health and ecological risks. Samples were analyzed by ICP-MS following preconcentration by NiS-fire assay and Te coprecipitation. Pt (1.5-43 ng/g), Pd (1.2-58 ng/g) and Rh (0.2-14.2 ng/g) concentrations obtained were above upper crust values, but were lower when compared with several other cities around the world. Dust samples from road junctions and traffic signals with heavy and erratic traffic flow showed higher PGE levels than those from roads with low and free flow traffic suggesting that traffic flow conditions greatly influenced emission of PGE from the catalyst. Significant correlation of Pt, Pd and Rh indicate a common source for these metals. PGE were also positively correlated with Ce, Zr, Hf and Y. These positive inter-element correlations identified traffic as the main source of PGE emission to the roadway environment. The results obtained indicate to an appreciable increase in auto catalyst-derived PGE. In consideration of the adverse effects of PGE, monitoring their level and transformation paths is of prime importance. [ABSTRACT FROM AUTHOR]

A one-dimensional monolithic catalyst model was used to evaluate the effect of space between two bricks on the thermal efficiency of a dual-monolithic catalytic converter with a Palladium-only (Pd-only) catalyst and a Palladium/Rhodium (Pd/Rh) catalyst butted together, and which are, in turn, mounted on a commercial vehicle equipped with a 2-L, four-cylinder spark ignition (SI) engine. Prior to the numerical investigation of the converter, tuning of the preexponential factor and activation energy of each reaction for each catalyst was performed to achieve acceptable agreement with experimental data under typical operating condition of automobile application. Two higher cell density 600 cpsi/4 mil substrates were used for faster light-off and improved warm-up performance of the catalytic converter, and the two monoliths have been connected without a space between them. As a result of the constriction of the monoliths, a slight temperature decrease occurred at the substrate interface due to thermal contact resistance. Therefore, to examine the heat transfer mechanism throughout the conforming rough surfaces, the thermal joint conductance between adjacent monoliths was determined using existing theory and correlation. The adequacy of the theory and correlation for thermal joint conductance was elucidated by analyzing heat transfer across the joint. Additionally, parametric investigations were performed to examine how the apparent contact pressure and mass flow rate of the exhaust gas affects the overall temperature drop across the joint. Over a wide range of operating conditions, temperature drop across the interface in the dual-catalyst converter with an air-gap is smaller than that without an air-gap. The relatively large temperature drop across the interface occurs especially during the early warmup period with a lower mass flow rate, that is, under conditions of cold-start and warmup at idle. [ABSTRACT FROM AUTHOR]

The emission of platinum group elements (PGEs) from automobile catalytic converters has led to rapid increases in Pt, Pd, and Rh concentrations in roadside media. This article represents the first systematic study in Greece to assess PGE levels in road dust and roadside soil and their temporal variation on a seasonal basis over a 12-month period. Road dust and roadside soil samples were analyzed by graphite furnace atomic absorption spectrometry following microwave digestion. Concentrations of PGE in all samples were above the average upper crust values and local background levels, with maximum values of 306.4 ng/g Pt, 18.2 ng/g Pd, and 64.6 ng/g Rh in road dust and 225 ng/g Pt, 14.0 ng/g Pd, and 49.5 ng/g Rh in roadside soil. PGE ratios were not consistent with known catalytic converter composition throughout the sampling period reflecting the high emission of Rh from new catalytic converters. Spatial variations were influenced by various factors like driving style, matrix composition, diurnal change in traffic volume, and climatic conditions. With regard to seasonal variations, systematic changes in the temporal distribution of PGE levels were observed and followed a similar pattern between the two matrices. Except PGEs, Pb levels were determined, since it has been a typical indicator of vehicle-derived environmental lead pollution. The data indicate that despite the use of unleaded gasoline, traffic-related sources of Pb that induce levels above the local background have not been eliminated. [ABSTRACT FROM AUTHOR]

Forty paired road dust and gully sediments from the city of Sheffield in NE England show that high platinum, palladium and rhodium concentrations derived from catalytic converters depend on proximity to both roundabouts rather than traffic lights and to topographic lows. Road dust outside schools and control samples, further away on the same road, show that Pt, Pd and Rh concentrations are dependant on passing traffic flow rather than numbers of stopping vehicles. Highest values of Pt+Pd in road dust are 852 ppb and 694 ppb in gullies. Rh has maximum values of 113 ppb in road dust and 49 ppb in gullies. Pt and Pd values of a few ppb to just over 100 ppb occur in road dust where traffic does not stop, on roads away from junctions. Pt, Pd, Rh and Au are all picked up by road sweepers and gully flushers both with maximum values of just over 100 ppb Pt and Pd. High Au values (maximum 610 ppb in a road dust) were located on pavements, in suburbs, outside schools and in road sweepers collecting in residential areas rather than on high traffic flow roads. Stratification of Pt and Pd in gullies was not observed whereas a high Au value was recorded at the bottom of a gully suggesting gravity concentration for Au. Anomalous Pd grades of 1050 ppb in road dust from a school entrance and 2040 ppb in a street sweeper sample were recorded. These high Pd- and Au-bearing samples do not have anomalous Pt or Rh values and may be sourced from jewellery or dental fillings. However, most samples have consistent Pt/Pd ratios of about 1 and Pt/Rh values of 4 to 5 indicating a catalytic converter source. Pt and Pd are concentrated in road dust at levels well above background in all the samples, including on high and low traffic flow roads. [Copyright &y& Elsevier]

Abstract: Twelve road-deposited sediment samples were analyzed for platinum-group elements (PGEs) and Pb in the <63μm fraction of an urban watershed in Hawaii. Three samples were further fractionated into five size classes, from 63–125μm to 1000–2000μm, and these were analyzed for PGEs and Pb. Concentrations in the <63μm fraction reached 174μg/kg (Pt), 101μg/kg (Pd), 16μg/kg (Rh), and 1.3μg/kg (Ir). Enrichment ratios followed the sequence Rh>Pt=Pd>Ir. Iridium was geogenic in origin, while the remaining PGEs indicated significant anthropogenic contamination. Palladium, Pt and Rh concentrations and enrichment signals were consistent with PGE bivariate ratios and PGE partitioning in three-way catalysts. Size partitioning indicated that the <63μm fraction had the lowest PGE concentrations and mass loading percentages. These data suggest that autocatalyst PGE flux estimates into the environment will be significantly underestimated if only a fine grain size fraction is analyzed. [Copyright &y& Elsevier]

Platinum (Pt) and Palladium (Pd) concentrations have been analysed in 194 samples from within the city of Sheffield in the UK. The samples were taken from road dust, gully pots (also known as drains), soils, a motorway drainage pipe, rivers, lakes, sewage sludge, incinerator ash, incinerator ash in landfill, street cleansers and gully cleansers. The introduction of Pt-and Pd-bearing automobile catalysts, has been cited as the cause of a rise in the concentration of urban Pt and Pd accumulations. Geochemical analyses for the different sample types are used here to show how the Pt and Pd accumulate in different urban environments as they are transported from their catalytic source. Initially Pt and Pd collect in road dust and gully pots at values of up to 450 ppb although most analyses for both elements are around 100 ppb. The four roadside soils analysed, have a great range in values, the highest with a value of over 600 ppb Pt and 1000 ppb Pd. Then the fate of the Pt and Pd is either to be removed by gully flushers and road sweepers (which contain around half the concentration of that in road dust) or to be washed from the roads, through the gully pots, into either the river or urban drainage systems. Due to the addition of terrestrial sediments, river samples contain much reduced values of Pt and Pd, at approximately an order of magnitude lower than in road dust. Similarly, sewage sludge contains Pt and Pd values which are lower than road dust. However, the Pt and Pd analyses are much higher in incinerated sewage (with many samples over 150 ppb for both metals), probably due to the loss of the mass of other material during the incineration process. Weathered incinerator ash in landfill has lower values of Pt and Pd than fresh ash from the incinerator. Although the range in values of Pt and Pd is similar for road dust and gully pot sediments their modal values tell a different story. The mode for Pt is very similar for both road dust and gully pot sediments, at around 100 ppb, whereas there is a drop of 50 ppb in the mode for Pd in the gully pots (from 80 ppb to around 40 ppb). Given that gully pot sediment is derived from road dust, it is suggested that in gully pots, Pd is preferentially mobilized over Pt. Furthermore, a comparison of the modal values of Pt and Pd in river sediments suggests that this process continues into the natural drainage system of the city. [Copyright &y& Elsevier]

Platinum (Pt) and Palladium (Pd) are massively used in catalytic converters, emitted with exhaust fumes and deposited on roadsides in particle sizes. If they are ingested by ruminants grazing in agricultural fields located along roads they may enter the food chain. The objective of this study is to assess the potential transfer of Pt (PtCl2) and Pd (PdCl2) towards milk, tissues (muscle) and organs (kidney, liver and mammary gland). Three lactating goats received orally a single dose of 200mg of Pd and 200mg of Pt at the beginning of the experiment. The milk was collected each day during eight days. On the eighth day, organs and tissues were sampled to analyse the metal concentrations by ICP-MS (quantification limit of 0. 25ng/g for Pd and Pt, detection limit of 0. 08ng/g). The experiment demonstrated a significant transfer of Pd and Pt to kidney. The detected concentration was, respectively, of 73. 9ng/g DW and 268. 5n/g DW (factor 22 and factor 73 compared to the control kidney). The amounts of metals were : in the liver,18. 1ng/g DW for the Pd and 8. 1ng/g DW for the Pt, in the mammary gland, 14. 9ng/g DW fort the Pd and 2. 5ng/g DW for the Pt and in the muscle, 4. 9ng/g DW for the Pd and 0. 6ng/g DW for the Pt. The Pd concentration detected in milk was higher (from 5ng/g DW to 9ng/g DW) than in control milk but the transfer factor remained very low (0. 02%). The Pt in milk could not be detected because it was below the quantification limit (<0. 25ng/g DW). [Copyright &y& Elsevier]

The use of catalytic converters in automobiles is mandatory to reach current emission limits for toxic engine byproducts. The goal of zero-emissions remains elusive for internal combustion engines, yet tightening of legislation towards this ideal continues. To meet this demand, scientists and engineers must further their understanding of the operation of catalytic converters to improve their performance. This literature review describes the research on gaseous reactions catalysed by platinum, rhodium and palladium metals. While results using 'conventional' single crystal surface science techniques are explored, much of this review considers results obtained using field ion microscopy/atom probe (FIM/AP) nanocrystalline systems, which are excellent methods for examining catalytic particles in a similar form to which they exist commercially. To conclude, areas requiring further investigation are identified, such as lean burn reduction, improving light-off temperatures, increasing resistance to poisoning and improving understanding of the effects of gaseous reactant pressure. A great deal of fundamental work has still to be carried out in order to appreciate reaction mechanisms at an atomic level. [ABSTRACT FROM AUTHOR]

A comparison of platinum-group element (PGE) emission between gasoline and diesel engine catalytic converters is reported within this work. Whole raw exhaust fumes from four catalysts of three different types were examined during their useful lifetime, from fresh to 80 000 km. Two were gasoline engine catalysts (Pt–Pd–Rh and Pd–Rh), while the other two were diesel engine catalysts (Pt). Samples were collected following the 91441 EUDC driving cycle for light-duty vehicle testing, and the sample collection device used allowed differentiation between the particulate and soluble fractions, the latter being the most relevant from an environmental point of view. Analyses were performed by inductively coupled plasma-mass spectrometry (ICP-MS) (quadrupole and high resolution), and special attention was paid to the control of spectral interference, especially in the case of Pd and Rh. The results obtained show that, for fresh catalysts, the release of particulate PGE through car exhaust fumes does not follow any particular trend, with a wide range (one–two orders of magnitude) for the content of noble metals emitted. The samples collected from 30 000–80 000 km present a more homogeneous PGE release for all catalysts studied. A decrease of approximately one order of magnitude is observed with respect to the release from fresh catalysts, except in the case of the diesel engine catalyst, for which PGE emission continued to be higher than in the case of gasoline engines. The fraction of soluble PGE was found to represent less than 10% of the total amount released from fresh catalysts. For aged catalysts, the figures are significantly higher, especially for Pd and Rh. Particulate PGE can be considered as virtually biologically inert, while soluble PGE forms can represent an environmental risk due to their bioavailability, which leads them to accumulate in the environment. [Copyright &y& Elsevier]

Focuses on a study concerning the utilization of palladium-perovskite as a catalytic converter in automotive emissions control. Application of catalytic converter to reduce the amount of nitrogen oxides, carbon monoxide and hydrocarbons in car emissions; Exhaust-gas composition used in petrol engines; Changes in the structure of re-oxidized catalysts.

Palladium, as a member of platinum group metals, has very little reserve in nature. It usually plays a role in corrosion resistance in the electroplating industry, and is easily discharged into electroplating wastewater during processing. Therefore, it is of great significance to develop efficient functional materials which can rapidly and selectively capture Pd(II). Herein, a mesoporous ion exchange resin (SiAaC) based on a silica framework was designed and synthesized by in situ polymerization method to efficiently remove Pd(II) from simulated electroplating wastewater. SiAaC exhibited unique advantages over traditional commercial resins, such as high adsorption capacity (121.8 mg/g), high selectivity (SF Pd/M >230 in 0.01 M HNO 3 solution) and excellent reusability (n > 5). The adsorption results of SiAaC resin on Pd(II) are consistent with Langmuir isotherm and pseudo-second-order kinetic models. In addition, the column experiment can efficiently separate Pd(II) from simulated electroplating wastewater. Furthermore, FT-IR and XPS spectra proved an ion exchange mechanism between SiAaC and Pd(II). In general, this research not only demonstrated an excellent material which can effectively and efficiently remove low-level palladium from simulated electroplating wastewater, but also provided a new perspective for the synthesis or improvement of ion exchange resins. [Display omitted] • A novel mesoporous ion-exchange resin (SiAaC) was first prepared by in-situ polymerization method. • SiAaC exhibited high adsorption capacity of 121.8 mg/g Pd, good reusability, and high selectivity with SF Pd/M > 230. • A method for recovering Pd(Ⅱ) from simulated electroplating wastewater was proposed and verified. [ABSTRACT FROM AUTHOR]

The paper presents basic studies on the precipitation of platinum, palladium, rhodium, and ruthenium nanoparticles from model acidic solutions using sodium borohydride, ascorbic acid, and sodium formate as reducing agents and polyvinylpyrrolidone as a stabilizing agent. The size of the obtained PGM particles after precipitation with NaBH4 solution does not exceed 55 nm. NaBH4 is an efficient reducer; the precipitation yields for Pt, Pd, Ru, Rh are 75, 90, 65 and 85%, respectively. By precipitation with ascorbic acid, it is possible to efficiently separate Pt, Rh, and Ru from Pd from the two-component mixtures. The obtained Pt, Pd, and Rh precipitates have the catalytic ability of the catalytic reaction of p-nitrophenol to p-aminophenol. The morphological characteristic of the PGM precipitates was analyzed by AFM, SEM-EDS, and TEM. [ABSTRACT FROM AUTHOR]

Discusses the use of laser-induced breakdown spectrometry for spatial distribution analysis of platinum, rhodium and palladium in car catalytic converters. Extraction of converters from the car exhaust system; Optimization of spectral detection, pulse energy and beam focal conditions; Spatial distribution of the active metals in axial directions.

Pt, Pd, and Rh platinum group metals (PGMs) are utilized in automotive catalytic converters to reduce the level of harmful gas emissions. To evaluate the separation efficiencies of PGMs from the leach liquors of automotive catalysts, their extractabilities from both single-component solutions and leach liquors were determined using three p-dialkylaminomethylcalix[4]arenes (alkyl: n-hexyl~n-octyl; 3–5) as extractants, and the obtained results were compared with the data of acyclic p-di-n-octylaminomethyldimethylphenol (6) and those previously reported for macrocyclic calix[4]arene- and thiacalix[n]arene-based amine and amide extractants. Various extraction parameters, including the contact time, HCl concentration, and concentrations of Pd(II) and Pt(IV) ions, were examined, and the distributions and stoichiometry ratios of the recovered Pd(II) and Pt(IV) species were calculated. All macrocyclic extractants 3–5 exhibited high and selective extractabilities of Pd(II) and Pt(IV) ions contained in the leach liquors of automotive catalysts. The E% values of 3–5 from the leach liquors were 94.2, 93.0, and 97.7 for Pd(II) and 91.7, 94.0, and 92.5 for Pt(IV), respectively. Acyclic compound 6 did not perform well even though higher ratios of extractant used. Furthermore, the results of reusability testing demonstrated relatively large extractability values obtained for these two metals even after five extraction/stripping cycles. [ABSTRACT FROM AUTHOR]

Platinum group elements (PGE), in particular platinum (Pt), palladium (Pd) and rhodium (Rh) have a significant role in the operation of automotive catalytic converters whose purpose is to reduce emissions of gaseous pollutants into the air. Hot exhaust gases passing through catalytic converters cause damage to these systems leading to emissions of Pt, Pd and Rh in the environment and increase their levels in the air. Weekly PM10 samples were collected in 2017 at two monitoring stations (North - urban background and South - urban traffic) in Zagreb and mass concentrations of Pt, Pd and Rh were measured by inductively coupled plasma mass spectrometry (ICP-MS). The average annual mass concentrations for Pt, Pd and Rh were 0.373 pg m-3, 2.053 pg m-3 and 0.316 pg m-3 for monitoring station North and 0.681 pg m-3, 3.843 pg m-3 and 0.574 pg m-3 for monitoring station South, respectively. In this study, the relationship between Pt, Pd and Rh mass concentrations and meteorological parameters, including air temperature, relative humidity, precipitation, air pressure, wind direction and wind speed was analysed. The wind roses at both monitoring stations pointed to a common source for all three of the measured metals. At monitoring site North, the pollution was connected with winds from north and northeast, while at monitoring station South with winds from the southeast. [ABSTRACT FROM AUTHOR]