Metal Impurities Research Articles

Porous PbBr2 films modulation by indium tribromide additive for the fabrication of SnO2-based CsPbBr3 perovskite solar cells

The achievement of complete conversion of PbBr2 films presents a significant challenge in the development of CsPbBr3 films with consistent growth, comprehensive coverage, and controllable components. To address this challenge, introducing a porous structure in the planar PbBr2 film is advantageous for facilitating the immersion of CsBr precursor, thereby reducing impurity phase formation and mitigating strain caused by the film volume expansion. In order to accomplish this, indium tribromide (InBr3) was employed as an additive and the InBr3(DMF)3 adduct was utilized to expedite the release of organic molecules in PbBr2(DMF), resulting in the transformation of planar PbBr2 film into porous structures. The growth orientation of PbBr2 crystals was altered by this transformation, effectively suppressing the generation of metallic Pb impurities in the film. Additionally, it not only optimizes the morphology of CsPbBr3 film but also reduces impurity phase. As a result, the InBr3:CsPbBr3 perovskite solar cell achieved an efficiency of 7.28 %. The majority of In3+ ions were concentrated near the buried interface between SnO2 and InBr3:CsPbBr3, leading to significant improvements in both non-radiative recombination defect states within the perovskite film and electron injection and collection capabilities within the device.

Enhancing Metal Impurity Removal in Diamond Wire-Sawing Silicon Kerf-Loss through Sonifier-Assisted Acid Leaching Process

Enhancing Metal Impurity Removal in Diamond Wire-Sawing Silicon Kerf-Loss through Sonifier-Assisted Acid Leaching Process

Hydrogen permeation of single layer graphene with substitutional metal impurity defects

Two-dimensional materials have recently emerged as promising candidates for blocking hydrogen isotopes, with pristine graphene showing the most promising attributes. Nevertheless, synthesized graphene typically harbors various defects. In this study, we conducted a systematic investigation employing a first-principles approach to assess the permeation of hydrogen through single-layer graphene featuring a single-atom vacancy and diverse substitutional metal impurity defects. Our findings indicate that most substitutional metal impurities in a carbon vacancy effectively enhance graphene's ability to obstruct hydrogen when it harbors vacancy defects, resulting in elevated hydrogen penetration barriers in contrast to graphene with a single-atom vacancy. The hydrogen penetration barriers are contingent upon both the atomic size and the number of outermost electrons in the metal defects. Transition metals characterized by larger atoms and more outermost electrons exhibit heightened penetration barriers, while non-transition metals exhibit a relatively diminished impact of outermost electrons on hydrogen penetration barriers due to reduced charge transfer to graphene. This study underscores the pivotal role played by metal defects in obstructing the infiltration of hydrogen and its isotopes into graphene.

Compressing of experimental and simulated results of electron beam interaction with FFF-printed samples

One of the important parameters characterizing the interaction of electron beams with matter is the depth dose distribution. To develop a new approach for shaping electron beams using specially created materials suitable for the manufacture of complex 3D-printed devices, it is necessary to analyze the features of ionizing radiation propagation. In this work, numerical simulations and experimental studies of the interaction between electron beams and plastic materials weighted with metallic impurities of different concentrations, suitable for fabricating samples using the rapid prototyping method, were carried out. Sets of plates made from the investigated plastics were created using the fused filament fabrication (FFF) technique. Since the FFF sample fabrication process involves forming objects from a thermoplastic mass through layer-by-layer alignment, a distinctive feature of the printed samples is their lower actual density compared to the density of the material (filament) from which they are made. Taking this fact into account, the actual density of the polymer plates was calculated. Based on this data, numerical models of the plastic materials weighted with metallic impurities were developed, and virtual models of the experimental setup were created to calculate the electron beam depth dose distributions in the materials. In the next step of the investigation, experimental studies were performed using electron beams with energies of 6 and 10 MeV. Pre-calibrated GafChromic EBT3 dosimetry films were used as detectors to obtain the experimental data on the electron beam depth dose distributions in the materials under consideration. It was observed that with an increasing concentration of metal impurities in the plastic base, the depth dose distribution moves into smaller thicknesses. It was observed that the simulation and experimental results are in good agreement.

Hydrometallurgical Method of Producing Lithium Perrhenate from Solutions Obtained during the Processing of Li-Ion Battery Scrap

The work presents the research results regarding the development of an innovative technology for the production of lithium perrhenate. The new technology is based entirely on hydrometallurgical processes. The source of lithium was solutions created during the processing of Li-ion battery masses, and the source of rhenium was perrhenic acid, produced from the scraps of Ni-based superalloys. The research showed that with the use of lithium carbonate, obtained from post-leaching solutions of Li-ion battery waste and properly purified (by washing with water, alcohol, and cyclic purification with CO2), and perrhenic acid, lithium perrhenate can be obtained. The following conditions: room temperature, time 1 h, 30% excess of lithium carbonate, and rhenium concentration in the acid from 20 g/dm3 to 300 g/dm3, allowed to produce a compound containing a total of 1000 ppm of metal impurities. The developed technology is characterized by the management of all aqueous waste solutions and solid waste and the lack of loss of valuable metals such as rhenium and lithium after the initial precipitation step of lithium carbonate.

A facile approach for regeneration of graphite anodes from spent lithium-ion battery

Recycling of lithium-ion battery anodes has become a topic of interest due to the retirement of batteries. However, existing recycling methods have either been environmentally unfriendly or lacked high purity levels. Here, a simple and low-cost recycling method is developed. Firstly, organic matter in graphite is eliminated through heat treatment. The removal of metal impurities in graphite is then carried out by utilizing sulfuric acid (H2SO4) leaching. Lastly, potassium hydroxide (KOH) etching is utilized to restore the structural defects of graphite. This comprehensive process enhances the cycling stability and rate capability of graphite. The initial discharge capacity at 0.1 C can reach a specific capacity of 422.42 mAh/g, and the specific capacity of the discharge after 100 cycles is 365.97 mAh/g, which reaches the standard of commercial graphite (CG). The results demonstrate that the method effectively purifies and regenerates waste graphite (WG). This process can alleviate resource pressure while being suitable for industrial applications due to its simplicity and low cost.

Elucidating the impact of sanitary waste on the formation of fat, oil and grease deposits in sewer systems

The accumulation of fat, oil and grease (FOG) deposits in sanitary sewer systems is a significant cause of sewer overflows, mainly due to their tendency to adhere to pipe walls. The aim of this study is to (i) develop laboratory-prepared FOG deposits using a mixture of iron (Fe) and aluminium (Al) metal ions, fatty acids, saccharides and cooked oils, in addition to various sanitary waste materials such as paper towels, wipes and pads and (ii) examine the characteristics of these FOG deposits. The goals of this study were to (i) gain a deeper understanding of the impact of sanitary waste on the formation of FOG deposits and (ii) discuss the detailed physiochemical properties of these FOG deposits. The findings revealed that FOG deposits can vary in nature, appearing as either a smooth, paste-like substance or a coarse, semi-solid material, depending on the types of waste present in the sewer. Analysis of the fatty acid profile indicated that the FOG deposits with wipes have the highest viscosity (3.2 × 104 Pa s) and larger composition of smaller chain saturated fatty acids (caprylic acid 0.64%, undecanoic acid 5.61%, lauric acid 4.65%, myristic acid 3.21% and palmitic 8.38%). In contrast, FOG deposits with Fe and Al metal impurities have higher heat resistance and thermal stability (melting point of 125 °C) and have larger composition of long chain fatty acids. Furthermore, FTIR analysis confirmed that these FOG deposits are composed of metallic salts of fatty acids, aligning with samples from sewer lines. Our results suggest that FOG deposit formation involves the aggregation of excess calcium, which compresses free fatty acid micelles, and a saponification reaction between the calcium aggregates and free fatty acids. This research illuminates the complex processes behind FOG deposit formation and their varied characteristics, providing valuable insights into potential strategies for preventing FOG-related sewer blockages.

Determination of non-combustible impurities in detonation nanodiamond powder

The study of the physicochemical (including adsorption) properties of nanodiamond requires the possibility of reproducible generation of the carbon surface of an individual particle without metal impurities of unknown composition. This kind of surface can be obtained through an additional deep cleaning of a commercially available sample. This article is dedicated to the study of the composition of non-combustible impurities of detonation nanodiamond powder. Using inductively coupled plasma mass spectrometry, iron and titanium were identified as the main metal components of the unburned residue, and the presence of Cr, Ni, Zr, As, and Sb was qualitatively established. The expected composition of the main molecular ions formed on the surface of the unburned residue in the course of laser desorption/ionisation mass spectrometry was presented. Based on the results of mass spectrometry analysis, a method of two-stage chemical treatment of detonation nanodiamond powder was proposed, which allowed reducing the mass fraction of non-combustible impurities during annealing in air from 2.0 to 0.1%.

Metallothermic reduction of Cerium Chloride in molten Salt using Li, Na, and Ca Metal

Options for reducing purified metal chlorides to metallic form were evaluated in support of the development of a metal purification process based on the conversion of impure metal via hydriding followed by chlorination. Metallothermic reduction of CeCl3 was tested using Li, Ca, and Na as reductant metals with and without a molten salt solvent in MgO and Y2O3-coated MgO crucibles. The effects of added reductant metal form, crucible material and dimensions, and mixture hold times above Ce melting temperature were studied. Direct contact of Li and CeCl3 was ineffective due to their immiscibility. A low-density alloy was formed between Li and Ce using Li in a LiCl solvent. Na was ineffective at reducing CeCl3 to any measurable degree. The highest percent recovery (71.4 %) and consolidation of Ce was achieved when using Ca in a CaCl2-NaCl solvent with 99.8 % removal of CeCl3 from the salt. Side reaction with MgO crucibles was found to be at least partially responsible for reduced Ce recovery.

Fundamental experimental and thermodynamic modelling study in support of the lead battery recycling slag

Antimony, tin, and other higher value metals, as well as elements such as arsenic and lead, can be found in the slags produced during the lead battery recycling process. Gopher Resources operates lead battery recycling furnaces that use sodium slag systems for which there has been less thermodynamic research than more common slag systems. Better thermodynamic information could help improve the process efficiency and control of these furnaces, as well as the recovery of higher value metals. The present study focuses on experimental research and thermodynamic modeling of slags belonging to the Na-Si-Fe-O system, with minor elements including S, Sb, Sn, Pb, and As. Examples of important systems studied extensively for the first time include Fe-Sb-Si-O and Na-Sn-Si-O. Phase equilibria methods are used to determine all the interaction parameters between the impurity metals and the main components of the slag. The experimental methodology involves equilibration, quenching, and electron-probe X-ray microanalysis of the samples. The modified Quasichemical model is used to describe the thermodynamics of the slags. The model also takes into account possible formation of matte/metal/speiss liquids, and numerous solid phases, which is important for understanding of fundamentals operation of various process units.

Dual plate-like grains of (Ti, Zr)B2 and W2B5 toughened solid solution composites fabricated via in-situ reaction spark plasma sintering of (Ti, W)C and ZrB2 powders

Novel dual plate-like grains of (Ti, Zr)B2 and W2B5 toughened solid solution composites were fabricated by the in-situ reaction spark plasma sintering at 1800 °C using (Ti, W)C and ZrB2 powders. The composites were predominated and composed of the (Zr, Ti, W)C solid solutions and plate-like (Ti, Zr)B2. In the (Ti, W)C-ZrB2 reaction system, W promotes the anisotropic growth of (Ti, Zr)B2 grains, while Ti makes the formation reactions of WxBy thermodynamically feasible. When the addition of ZrB2 exceeds 40 mol%, W begins to be boronized into WxBy which is mainly composed of plate-like W2B5. The (Ti, W)C-50 mol% ZrB2 composite with dual plate-like grains of (Ti, Zr)B2 and W2B5 exhibited the best comprehensive mechanical properties of hardness of 26.5 GPa, flexural strength of 620 MPa, and fracture toughness of 6.6 MPa·m1/2, which provide a new approach for the enhanced toughness without the introducing of metal impurities.

Element partitioning and stabilization for impurities removal between liquid silicon and silicate melts: Ab initio insights into electronic structure

The partitioning and stabilization of common impurity elements challenge the impurity removal process during slag refining for developing high-purity metals. The role of electronic properties remains indistinct in the stability of non-metallic, alkaline earth metal, and transition metal impurity clusters in silicon and silicate melts, impeding the advancement of separation medium and purification process. Herein, local structures of impurity atoms are explored through ab initio molecular dynamics, and notable configurations are [PSi4], [TiSi10], [MgSi12] in silicon melts and [PO4], [TiO5], [MgO5] in silicate melts. A novel partition model based on impurity coordination predicted the impurity atoms’ distribution behavior consistent with industrial experiments. Furthermore, this model proposes a critical parameter k that evaluates impurity oxidation levels in coexisting systems and establishes a quantitative link between melt structures and distribution ratio, enabling precise predictions from two-phase ab initio calculations. Innovatively, the electronic structure analysis assessed element partitioning through bonding characteristics and interactions within impurity clusters via parameters: electron density distribution, partial density of states, electron localization function, and Mayer bond order. This yields a distinctive mapping relationship between impurity distribution ratio and stability, evidenced by quantitative associations with 12 key ab initio-derived descriptors through Pearson correlation analysis. This work unveils the electronic properties governing partitioning and endows modeling approach for distribution, driven by cluster structure analysis and ab initio calculations.

Unraveling the coordination behavior and transformation mechanism of Cr3+ in Fe–Cr redox flow battery electrolytes

Currently, the iron chromium redox flow battery (ICRFB) has become a research hotspot in the energy storage field owing to its low cost and easily-scaled-up. However, the activity of electrolyte is still ambiguous due to its complicated solution environment. Herein, we performed a pioneering investigation on the coordination behavior and transformation mechanism of Cr3+ in electrolyte and prediction of impurity ions impact through quantum chemistry computations. Based on the structure and symmetry of electrostatic potential distribution, the activity of different Cr3+ complex ions is confirmed as [Cr(H2O)5Cl]2+ > [Cr(H2O)4Cl2]+ > [Cr(H2O)6]3+. The transformation mechanism between [Cr(H2O)6]3+ and [Cr(H2O)5Cl]2+ is revealed. We find the metal impurity ions (especially Mg2+) can exacerbate the electrolyte deactivation by reducing the transformation energy barrier from [Cr(H2O)5Cl]2+ (24.38 kcal mol−1) to [Cr(H2O)6]3+ (16.23 kcal mol−1). The solvent radial distribution and mean square displacement in different solvent environments are discussed and we conclude that the coordination configuration limits the diffusivity of Cr3+. This work provides new insights into the activity of electrolyte, laying a fundamental sense for the electrolyte in ICRFB.

New azo dyes for detection of metallic impurities

In the world of molecular sensing, the ability to detect and differentiate between various analyte is a crucial aspect of scientific exploration. In this study, two novel azo dyes Dye-1 and Dye-2 that exhibit distinct sensing capabilities were synthesized and characterized. Dye-1 and Dye-2, each possess unique sensing capabilities. Dye-1 demonstrates an impressive affinity for the metal ion sensing and reveals differential colorimetric detection of metal ions based on the solvent system. Dye-2 on the other hand do not reveal significant color changes on addition of different metal ions, however it does reveal a selective and specific detection for dichromate (Cr2O72−) ions exclusively. The limit of detection (LOD) values obtained highlights the considerable sensitivity of Dye-1 and Dye-2 as a chemosensor. Finally, the utility of both the dyes for the detection of metallic impurities in real water samples has been demonstrated. The mechanism by which Dye-1 and Dye-2 binds to different metallic ions was also explored and studied through Density Functional Theory (DFT) computational modelling. This research contributes to the understanding of molecular sensing and offers potential applications in the field of analytical chemistry and environmental monitoring.

Metal-Free Click-Chemistry: A Powerful Tool for Fabricating Hydrogels for Biomedical Applications.

Increasing interest in the utilization of hydrogels in various areas of biomedical sciences ranging from biosensing and drug delivery to tissue engineering has necessitated the synthesis of these materials using efficient and benign chemical transformations. In this regard, the advent of "click" chemistry revolutionized the design of hydrogels and a range of efficient reactions was utilized to obtain hydrogels with increased control over their physicochemical properties. The ability to apply the "click" chemistry paradigm to both synthetic and natural polymers as hydrogel precursors further expanded the utility of this chemistry in network formation. In particular, the ability to integrate clickable handles at predetermined locations in polymeric components enables the formation of well-defined networks. Although, in the early years of "click" chemistry, the copper-catalyzed azide-alkyne cycloaddition was widely employed, recent years have focused on the use of metal-free "click" transformations, since residual metal impurities may interfere with or compromise the biological function of such materials. Furthermore, many of the non-metal-catalyzed "click" transformations enable the fabrication of injectable hydrogels, as well as the fabrication of microstructured gels using spatial and temporal control. This review article summarizes the recent advances in the fabrication of hydrogels using various metal-free "click" reactions and highlights the applications of thus obtained materials. One could envision that the use of these versatile metal-free "click" reactions would continue to revolutionize the design of functional hydrogels geared to address unmet needs in biomedical sciences.

Electrochemical CO2 conversion in eutectic Li-Ba and Li-Ca carbonate mixtures

Here, the impact of electrolyte selection and electrolysis temperature on carbon morphology, energy consumption, and voltage efficiency in molten Li2CO3-BaCO3 and Li2CO3-CaCO3 electrolytes during 90 min 10 A constant current electrolysis are investigated. The scarcity of experimental investigations into these binary electrolytes, coupled with a lack of systematic investigation of temperature effects, necessitates further examination. The comprehensive analysis of the produced carbon reveals that both electrolyte composition and temperature influence carbon morphology. At lower temperatures the effect of electrolyte composition to the morphology is a more significant. The type and amount of metallic impurities mixed with the carbon vary depending on the electrolyte composition and electrolysis temperatures. The results from Li2CO3-CaCO3 electrolyte show more promising compared to results from Li2CO3-BaCO3 electrolyte in terms of product quality. Regarding electrolysis power and voltage efficiency, Li2CO3-CaCO3 proves equal or superior to other electrolytes, depending on temperature. Heat generation occurs in all the experiments, which emphasizes the importance maintaining a constant electrolysis temperature in industrial processes to manage heat generation effectively.

Carbon sequestration through mineral carbonation: Using commercial FGD-gypsum from a copper smelter for sustainable waste management and environmental impact mitigation

In this study, we conducted a comprehensive examination of a commercial FGD gypsum produced in a Copper (Cu) smelter process and delved into its potential use as a Calcium (Ca)-rich material for ex-situ mineral carbonation by exploring the partitioning and fate of these metal impurities. The resulting carbonation end-product displayed a calcium carbonate (CaCO3) content of 71.1%, featuring a relatively low CO2 conversion, which may be attributed to the presence of metallic impurities in the commercial FGD-gypsum. Most of these metallic impurities, acting as inputs to the carbonation process, originate from the parent FGD-gypsum matrix. This results in an increased ionic strength within the FGD gypsum, potentially impeding the diffusion of carbon dioxide (CO2) from the gas phase to the aqueous phase. The partitioning and examination of the speciation of major, minor, and trace elements at all stages of CO2 conversion allowed us to propose four potential reaction pathways influencing carbonation efficiency: (i) the formation of metal carbonates, (ii) the production of metal oxides and oxyhydroxides, (iii) the development of metal multiform compounds, and (iv) elements deviating from the outlined patterns. Commercial FGD-gypsum is suitable for acceptance at non-hazardous waste landfills. However, it's essential to highlight that leaching values of As exceed the inert range and non-hazardous waste standards in commercial FGD-gypsum. Although most heavy metal leaching values from the carbonate end-product stay below non-hazardous limits, the release of some heavy metal leachates from the carbonate end-product may limit reuse options for these materials.

The temperature dependence investigation of the frequency dispersion of the electrical properties of lithium-iron spinel doped with La, Y

The temperature-frequency dependences of the electrical characteristics of Li2 Fe2,5-x Mex O4 (Ме=La;Y, x=0.01; 0.03; 0.05) spinels synthesized by the «sol-gel» autocombustion technology were obtained by the method of impedance spectroscopy in the temperature range of 298-473 K.
 Based on their analysis, the main mechanisms of conductivity of these materials in the studied temperature range were identified: hopping and activation, which are competing. The effect of doping lithium-iron spinels with rare-earth metal impurities on these conductivity mechanisms has been investigated. It has been established that the presence of impurities in small concentrations in the synthesized samples significantly decreases their conductivity, mainly due to destruction of the hopping mechanism of electronic conductivity.

Manufacture of Eco-cleaner Based on Eco-enzyme Reinforced Catalyst as Reduction of Metals and Impurities on Roller and Blanked to Improve Offset Quality

Offset printing machines play an important role in the printing process in the printing industry, so many industrial players make various efforts to maintain the quality of offset machine printouts. One of the efforts made is to keep the rollers and blankets on the offset machine clean from metal impurities that come from printing inks. To keep rollers and blankets clean, industry players usually use chemical fluids that can clean rollers and blankets on offset machines. However, the continuous use of chemical fluids can damage the rollers and blankets due to oxidation of these chemicals over time. This affects the printing results, such as the paper getting easily damaged, the blanket becoming sticky, the print being uneven, and the density becoming low. In addition, the cleaning chemicals used can cause environmental damage such as water pollution and soil pollution. This research synthesizes an eco-cleaner from an organic waste fermentation process reinforced with a catalyst that can be used as a substitute for the chemicals used today. This research aims to produce an eco-cleaner product that can reduce metal impurities on rollers and blankets to improve the printing quality of offset machines. The resulting product works effectively to remove metal impurities without damaging the rollers and blankets because the eco-cleaner is non-corrosive. The resulting products can be used by the public and the printing industry. The method used in this research is an experiment with the fermentation synthesis method. Furthermore, the eco-cleaner is tested for characterization for feasibility according to SNI standards. The tests carried out are the organic plating test, physical properties test, test and then analysis of the test results to see the feasibility of the eco-cleaner.
 Keywords: eco-cleaner, roller-blanket, printing quality, offset printing

Unraveling the Prominent Existence of Trace Metals in Photocatalysis: Exploring Iron Impurity Effects.

Metal impurities can complicate the identification of active catalyst species in transition metal catalysis and electrocatalysis, potentially leading to misleading findings. This study investigates the influence of metal impurities on photocatalysis. Specifically, the photocatalytic reaction of inert alkanes using chlorides without the use of an external photocatalyst was studied, achieving successful C(sp3)-H functionalization. The observations reveal that Fe and Cu impurities are challenging to avoid in a typical laboratory environment and are prominently present in normal reaction systems, and iron impurities play a dominant role in the aforementioned apparent 'metal-free' reaction. Additionally, iron exhibits significantly higher catalytic activity compared to Cu, Ce, and Ni at low metal concentrations in the photocatalytic C(sp3)-H functionalization using chlorides. Considering the widespread presence of Fe and Cu impurities in typical laboratory environments, this study serves as a reminder of their involvement in reaction processes.