Metal Impurities Research Articles

Design of a continuous ion exchange process in battery metals recycling: From single column experiments towards a simulated moving bed configuration

In hydrometallurgical recovery of LIB metals, ion exchange (IX) has hitherto played only a minor role. Separation experiments were conducted in single laboratory-scale IX columns with the aim of laying the foundation for a continuously operated multicolumn IX process similar to a simulated moving bed (SMB) configuration. In this study, the initial process developed earlier was improved by reducing the number of process steps and external streams. The desorption step with oxalate solution was examined in single-column batch experiments to ensure complete desorption of iron in the proposed continuous multicolumn IX process. Additionally, the volume flowrates were adjusted to achieve acceptable switch times of 25 min in an SMB configuration. It was found that the bead size of the resin is a critical factor in IX recovery of battery metals. The raffinate purity for the case of processing 2.5 BV lithium-ion battery waste leachate (LIBWL) improved from 97.2 % to 99.8 % when the resin bead size was reduced from 0.55 ± 0.05 mm to 0.4 ± 0.04 mm and a narrower bead size distribution. The LIBWL feed concentration was varied to mimic the dilution of fresh feed in an SMB set-up. The percentage recovery of Co and Ni decreased from 93.7 % and 96.6 % to 80.8 % and 89.4 %, respectively, when the LIBWL was diluted. This was a result of the decrease in concentration of impurity metals in the feed. Less impurity metals were sorbed and consequently, more ion exchange sites were available for the sorption of the target metals, which enhanced the retention of Co and Ni. The results were used to develop an IX column operation strategy and to suggest an initial SMB design. The multicolumn configuration presented in this work offers great potential for continuous production of high-purity Li, Ni and Co-containing raffinate (> 99.5 %).

Comparative study of physical properties of As2Se3 and (As2Se3)90Ge10 glassy alloys doped with metallic impurities

To examine the compositional and chemical effects on the glassy system, one must first understand its network structure. Alloying glassy systems cause significant conformal and configurational changes. The optical and physical parameters of As2Se3 and (As2Se3)90Ge10 glassy alloys doped with metallic impurities (X = Bi, Cd, Pb, Sb) have been evaluated. A comparison of the physical properties of glassy alloys has been made as the doping elements increase, i.e., from binary to ternary to quaternary system, and an effort has been made to correlate the optical and physical parameters. The optical density (Dop) and penetration depth (δ) have been calculated from the reported absorption coefficient (α) data. The mean coordination number (<r>) and the number of floppy modes (Mf) calculations show that the floppy regions are decreasing, and hence, the rigidity is increasing when As–Se is doped with Ge and As–Se-Ge is doped with X. The density (ρ) and packing density (PD) have also been evaluated, which are interrelated to the parameters like refractive index (n) and δ. Cohesive energy (CE), mean bond energy (<E>), and glass transition temperature (Tg) values give an insight into the stability and average crosslinking of the system with alloying. The conduction and valence band potentials have supported the optical bandgap (Egopt) values variation.

Defect Analysis of the Basin-type Insulator in a 500kV SF6 Current Transformer

Abstract A rigorous examination and analysis were conducted on a fault incident involving an SF6-insulated current transformer. The investigation revealed an intrinsic defect in the basin-type insulator within the current transformer, leading to a discharge pathway formation from the shell base flange to the secondary lead shielding tube. To further analyze the insulation characteristics of basin-type insulator, a three-dimensional simulation model of current transformers was established using simulation software to study the electric field distribution law of basin-type insulators with pores, metal impurity pollution, and microcracks. Simulation tests indicated that micro-cracks can result in severe electric field distortion in the basin-type insulator, followed by metal particle pollution, and bubbles cause the least degree of electric field distortion. The findings of this article can serve as a reference for the production of basin-type insulators and the operation, maintenance, and fault analysis of SF6-insulated current transformers.

Оптимизация технологических параметров хлорирующего обжига окисленной составляющей изгари

To date, in the world zinc production, the main share of zinc consumption up to 50% is accounted for by the processes of galvanizing products. An important factor affecting the efficiency of the hot-dip galvanizing process is the loss of zinc associated with the formation of surface (zinc burn) and bottom (gartzink) waste. Of great interest for the processing of dross is the use of metal chlorination technology. The optimal technological parameters of the firing process were established in the work, where deep sublimation of impurity metals was achieved to obtain pure zinc oxide, suitable for use as a mineral additive in animal and bird feed. It was found that the use of a mixture of chlorinating reagents with a consumption of CaCl2 and NH4Cl of 3% and 7%, respectively, provides high-quality commercial zinc oxide with a minimum content of impurities, % wt: 0.02 Pb; 0.04 Fe; 0.01 Ni; 0.01 Cu; Cd traces. Optimal technological parameters and firing process modes were established: temperature – 1000°C; duration – 60 minutes; chlorinating reagent – mixture (CaCl2 + NH4Cl): CaCl2 consumption – 3% of the weight of the initial sample; NH4Cl consumption – 7% of the weight of the initial sample; air consumption – 0.1 l/min. In this paper, the results obtained will be used to conduct balance experiments on firing the oxidized component of the dross together with chlorinating reagents.

Fate of Ca2+ and metal impurities of a typical coal fly ash in amino acid mediated CO2 mineralization and simultaneous CaCO3 recovery

CO2 mineralization is a promising technology to achieve a waste-to-resource chain by integrating CO2 sequestration and alkaline solid waste utilization. Amino acids as a multifunctional reagent was proposed to avoid the extensive consumption of acid and alkaline reagents in traditional processes. However, the detailed interaction between Ca-bearing minerals and amino acids are still not fully understood, as well as migration pathways of metal impurities. To fill these gaps, this paper investigated the leaching and carbonation behaviors of Ca2+ and metal impurities of a typical coal fly ash (CFA) at various reagent types, reagent concentrations and leaching temperatures, thereby exploring the fate of these metal impurities. Results showed that the leaching and carbonation of Ca2+ was influenced by various aspects such as initial pH, reagent pKa, complexation, and pH buffering. The CaCO3 products obtained from glycine (Gly) and alanine (Ala) were vaterite due to the stabilizing effect of these amino acids on vaterite preventing it from converting to calcite. The optimal reaction conditions were 1.0 M Gly and leaching temperature of 35 °C with 26.63 % leaching efficiency, 56.08 % carbonation efficiency, and 42.6 g/kg vaterite yield. In addition, Ala induced an unexpected high leaching efficiency of Cd (75.79 %), Pb (76.08 %), and Zn (41.62 %), respectively, indicating promising mitigation of the environment risk of leached residue and valuable metal recovery from CFA. Although Gly displayed limited metal leaching efficiency at 1.0 M and 25 °C, increasing leaching temperature induced a remarkable enhancement of Cd and Pb leaching, which were 88.54 % and near 100 % at 35 °C, indicating promising mitigation of the environment risk of leached CFA. However, the high binding affinity of amino acids to impurity metals led to the low purity of CaCO3 product. This study derives the migration pathways of various metal ions during the mineralization and utilization of CFA, making it of great significance for the resource management and utilization of solid wastes.

Research and design of a small self-heating high-temperature lithium plugging meter system

In the research of new reactors, lithium has become a research direction as a new coolant after sodium. Lithium working fluids introduce various metallic and non-metallic impurities such as oxygen, calcium, carbon, nitrogen, etc. to a greater or lesser extent during production, filling, and even operation. In addition, the processing, welding, and cleaning steps of the pipeline and equipment in the circuit during manufacturing inevitably result in residual dirt, grease, surface oxides, and moisture. These will have a certain impact on the performance of heat transfer and circuit safety through accelerated corrosion or plugging. Therefore, in high-temperature lithium circuits, the impurity concentration of lithium working fluid must be strictly controlled and purified before use. At present, the detection methods for impurity content in lithium working fluids can be divided into two categories: sampling analysis method and online measurement method. Sampling analysis is the most direct detection and analysis method, which can directly obtain the content of various impurities in lithium working fluids, and the results are relatively accurate; The online detection method can generally only detect non-metallic impurities, but it is relatively fast and simple, and is currently a commonly used measurement method on lithium working fluid devices. The plugging meter method has been studied and used as a rather convenient online detection method. This article introduces a small, self-heating, and mobile high-temperature lithium plugging meter system to meet the online detection of different points in the lithium circuit of system engineering.

Bis(pinacolato)diboron-Enabled Ni-Catalyzed Reductive Arylation/Vinylation of Alkyl Electrophiles.

Herein, the use of economically and environmentally friendly bis(pinacolato)diboron (B2Pin2) is described as a non-metallic reductant in mediating Ni-catalyzed C(sp3)-C(sp2) reductive cross-coupling of alkyl electrophiles with aryl/vinyl halides. This method exhibits excellent suitability for heteroaryl halides and alkyl halides/Katritzky salts. The present study is compatible with an in situ halogenation of alcohol method, allowing for selective mono-functionalization of diols and bio-relevant alcohols (e.g., carbohydrates). The use of B2Pin2 shows potential for easy scalability without introducing additional metal impurities into the products. It is observed for the first time in the realm of cross-electrophile coupling chemistry that B2Pin2 can sever as a reductantto reduce NiII to Ni0. This mechanistic insight may inspire the development of new reductive bond-forming methodologies that can otherwise be difficult to achieve with a metal reductant.

The Influence of Metal Impurities on NiOOH Electrocatalytic Activity in the Oxygen Evolution Reaction

AbstractThe energy transition and the implementation of new electrochemical technologies will result in an increased reliance on critical raw materials for electrodes. Their large‐scale application will ultimately mean working with lower grade materials. Here we study the influence of metal impurities on nickel foam electrocatalysts. We do this by electrodepositing known amounts of first‐row transition metals (Cu, Cr, Mn, Fe, Co and Ni) on nickel foam and studying their performance in the oxygen evolution reaction (OER) as a model reaction. The electrodes’ performance is studied using cyclic voltammetry (CV), linear sweep voltammetry (LSV), Tafel analysis, stepwise chronoamperometry (CA) and electrochemical impedance spectroscopy (EIS). Combining these results with microscopy analysis, we show that even small amounts of transition‐metal impurities have profound effects on the catalytic performance of nickel electrodes. The changes affect the OER onset potential (the energy that the system requires to convert OH– to O2) and the Tafel slope of each electrode (the electrode's initial activity in the OER onset region). Our results highlight the implications of such impurities on electrode design and future large‐scale application.

Continuous multicolumn ion exchange process for spent lithium-ion battery leachate: Recovery and purification of a Li+Ni+Co mixture

A continuously operated ion exchange process scheme for the recovery and purification of valuable metals from acid leachates of spent Lithium-ion battery cathodes was developed. The aim is to provide a versatile and industrially feasible alternative for liquid–liquid extraction and precipitation for recycling of spent Li-ion batteries. A chelating resin with aminomethylphosphonic acid functional group (Lewatit® MDS TP 260) was used in a laboratory-scale multicolumn configuration that combined counter-current and cross-current operations. The process was operated at 60 °C with a synthetic leachate with pH 1.8 as the feed. A two-step desorption procedure (1.0 M sulfuric acid (H2SO4) followed by 0.4 M potassium oxalate (K2C2O4)) was found to prevent accumulation of strongly bound metals in the resin. 1 M H2SO4 was found sufficient for regeneration. Pure raffinate containing Li, Ni, and Co was successfully separated from impurity metals (Mn, Cu, Al, and Fe). In steady state operation, no loss of ion exchange capacity was observed. The process was optimized experimentally with focus on the effect of fresh feed and eluent flow rates to increase the productivity and improve the recovery rates of the target metals while maintaining a raffinate purity of 100 %. Increasing the amount of leachate processed per switch was found to enhance the recovery of Co, Li and Ni due to the displacement effect. Very high recovery yields (96.97 % for Co, 99.15 % for Ni, and 100 % for Li) were achieved. The laboratory scale unit could process 1.64L(L·h)−1 of leachate to yield 34.04 g(L·h)−1 of Li+Ni+Co mixture in the raffinate. Moreover, Cu+Mn and Al+Fe rich extract streams with 84.74 % and 97.46 % purities were obtained as by-products. With respect to the recovery rates, the continuous ion exchange process is superior to batchwise operation of ion exchange columns, conventional solvent extraction and not to mention precipitation processes making it a viable alternative in hydrometallurgical LIB recycling.

Recycling of contaminated waste glass in ultra-high performance concrete: Impurities impact

The feasibility of recycling clean waste glass in construction products has been demonstrated. However, the direct utilization of contaminated waste glass from consumed beverage glass bottles may negatively affect the performance of concrete. This study aimed to investigate the effect of impurities in waste glass on the properties of ultra-high-performance concrete (UHPC). Washed and unwashed waste glass powder and sand were used as cement and river sand substitutes, respectively. Light particles, clay and fine silt, organic impurities and aluminium content in waste glass were determined. The results showed that the use of washed waste glass powder (W-WGP), washed waste glass sand (W-WGS) and unwashed waste glass powder (U-WGP) had a limited negative effect on the compressive strength of UHPC. In contrast, the use of unwashed U-WGS significantly decreased the compressive strength of UHPC due to the presence of impurities (e.g., paper and metallic aluminium). However, the impurities in the unwashed waste glass could positively reduce the autogenous and drying shrinkages of UHPC. The metallic impurities reacted with an alkaline solution to generate gases, resulting in the expansion of the matrix and reduction of autogenous shrinkage at the early stage. X-ray CT and microstructural images indicated that expansion resulting from the U-WGS caused cracks in the matrix and degraded the interfacial zone between the U-WGS and the paste. However, the incorporation of waste glass did not induce any alkali-silica reaction expansion in UHPC due to its low water-cement ratio and dense structure. The UHPC prepared with 30 % U-WGP as a replacement for cement was found to achieve satisfactory performance and lower carbon emissions.

ICRH-related impurity source and control across experiments in H, D, T plasmas at JET-ILW

The experimental and theoretical analysis were focused on experiments conducted to assess the effect of plasma isotopes, protium (H), deuterium (D), and tritium (T) on ion cyclotron resonance heating (ICRH) related plasma wall interactions. Comparison of L-mode discharges with N = 1 3He and N = 1 H minority ICRH heating scenarios were done for different isotopes. For the selected pulses, the behaviour of high-Z, mid-Z and low-Z intrinsic impurity and radiated power behaviour was investigated based on data from VUV, visible spectroscopy, and bolometry diagnostic at Joint European Torus. It was found that for N = 1 3He scenario during radiofrequency antennas operation, core W, Ni content, Be source and the radiated power are higher for π/2 in comparison to dipole antenna phasing. Lowest core Ni, W content and radiated power is clearly observed for H plasmas in comparison to D and T, where for this ICRH scenario behaviour was similar. However, lower Be photon flux is observed for T in comparison to D plasmas. Be sputtering by He particles is responsible for such an effect. Additionally, several computer simulations were conducted using the COREDIV code. The difference in the electron temperature was due to the difference in the isotope masses. Increased temperature in the central plasma in the case of T plasmas leads to higher radiation in the central plasma in comparison to H plasmas. As a result, the power across separatrix is lower and the temperature on the divertor plate decreases with the increase of the isotope mass. At these temperatures on the divertor plate, W is not sputtered by the main plasma ions H, D and T and by He. For the N = 1 H ICRH scenario clear difference between D and T plasma was observed with higher metallic impurity content for T plasma in comparison to D. Impurity content in the plasmas is found to be sensitive to the power balance between the antenna straps. Its minimum is observed for the maximum of P cen/P tot.

EXPLORING THE INFLUENCE OF B-SITE DOPANTS ON STRUCTURAL AND MAGNETIC PROPERIES IN La0.8Ag0.2Mn1-XCoxO3 (x: 0 and 0.1) COMPOUNDS

This study examines the structural, electrical, magnetic, and magnetocaloric properties of La0.8Ag0.2Mn0.9A0.1O3 (A: Mn, and Co) compounds under doping in the B-site. XRD results show that the compound containing Co ions directly replaced Mn ions in the B-site without forming a secondary phase containing higher metallic Ag impurities. The data obtained using Scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM-EDS), the temperature dependence of magnetization (M-T), the magnetic field dependence of magnetization (M-H), and the magnetic entropy change (SM) analysis reveal the effect of the doped element on the magnetic properties of the compounds due to the changes they create in the structural and Mn3+/Mn4+ ratio. It has been determined that the paramagnetic to ferromagnetic transition temperature (Curie temperature, TC) of the La0.8Ag0.2Mn0.9Co0.1O3 (LAMO-Co) is quite lower than the LAMO.

Effect of Alkali Metal Cations and Trace Metal Impurities on Cathodic Corrosion of Gold Electrode Surfaces

AbstractIn this work, we comprehensively studied the cathodic corrosion of Au electrodes as a function of the identity of alkali metal hydroxides at different concentrations and various negative potentials. We reveal that the ratio of free water and water bound in hydration shells controls the overall cathodic corrosion behavior, alongside the specific adsorption of alkali metal cations. Moreover, we highlight the crucial role of electrolyte cleanliness, particularly regarding the presence of trace metal impurities. Interestingly, the presence of trace amounts of nickel and iron in as‐received CsOH suppresses cathodic corrosion by their deposition onto Au surfaces. In contrast, after purification the polarization of Au surfaces in 10 M CsOH leads to the formation of nanoporous surfaces with high electrochemically active surface area, in which the degree of porosity can be tuned by varying the polarization time at −1.6 V vs. RHE.

Electrochemical methods for the removal of impurities from thegraphite anode in spent ternary lithium-ion batteries

The use of lithium-ion batteries (LIBs) is becoming increasingly widespread, and a large number are reaching their end of life. The recycling and re-use of spent LIBs has attracted great attention. Because of the unchanged layer structure of the graphite anode in these batteries, their recycling does not require high-temperature graphitization, and only focuses on the removal of internal impurities. We used electrochemical treatment for the deep removal of internal metal impurities after the heat treatment, ultrasonic separation, and acid leaching of spent graphite. By comparing and analyzing the graphite in different recovery stages, it was found that the presence of organic impurities seriously affects the electrochemical performance. The presence of trace inorganic impurities such as Cu and Fe has little effect on the initial discharge specific capacity, but reduces the cycling stability of graphite. The content of the main metal impurities in the final recycled graphite was less than 20 mg/kg. The discharge specific capacity reached358.7 mAh/g at 0.1 C, and the capacity remained at 95.85% after 150 cycles. Compared with the reported methods for recycling spent graphite, this method can efficiently remove impurities in the graphite, solve the current problems of high acid and alkali consumption, incomplete impurity removal and high energy consumption. The recycled graphite anode has a good electrochemical performance. Our work provides a new recycling and regeneration path for spent LIB graphite anodes.

Morphological and chemical changes in nuclear graphite target under vacuum and high-temperature conditions

Nuclear-grade graphite is a high-efficiency material, widely used for vacuum applications in nuclear reactors and accelerators as targets facing particle beams. In these contexts, graphite is often exposed to extreme thermal stresses altering its physical and chemical properties. The thermal-induced release of volatile contaminants from targets and the damage of structural components are critical issues that can affect the safety and operation efficiency of beamline facilities. Here, we provide for the first time a detailed picture of the chemical and morphological changes occurring in a nuclear-grade graphite target, obtained through Electrical Discharge Machining (EDM), when exposed in vacuum to high temperatures. The radial temperature gradient induced by the impact of a pulsed energetic (MeV- GeV range) focused particle beams was reproduced by cyclically heating, in the 1300–1800 K temperature range, a disc-shaped graphite target in a vacuum setup. An accurate surface and in-depth chemical analysis of the graphite target was obtained thanks to the high sensitivity (ppm/ppb) of the Time-of-Flight Secondary Ion Mass Spectrometry (ToF-SIMS) technique. The chemical maps clearly show the presence of several metal oxides and impurities in the surface and subsurface regions of the untreated sample. Such contaminants were removed because of the thermal treatment in vacuum more or less efficiently, as demonstrated by Thermogravimetric analysis (TGA), X-ray Photoelectron Spectroscopy (XPS), and ToF-SIMS. However, Raman spectroscopy and SEM-EDS revealed that the high-temperature treatment induces a decrease in the crystallite size of the graphite as well as changes in the target surface porosity with the appearance of microvoids, leading the graphite target to be more prone to the breakage.

Synthesis of nano-calcium carbonate from waste cement and techno-economic and environmental evaluation

Mineral carbonation stands out not only as an effective method for reducing CO2 emissions but also as a strategic approach to upcycling industrial waste. This study introduces a novel procedure for generating high-purity nano-calcium carbonate (nCaCO3) from waste cement powder, deploying hydrochloric acid (HCl), and sodium hydroxide (NaOH), both obtained through the electrolysis of sodium chloride (NaCl). Our approach, aimed at both environmental preservation and techno-economic feasibility, encompasses optimizing calcium extraction conditions through rigorous analysis of variables such as HCl concentration, solid-to-liquid ratio, and reaction temperature, subsequently proposing a rate law for the extraction process. Furthermore, the method emphasizes the production of high-purity CaCO3 by meticulously removing metallic impurities from the extracted solution with 1.0 M NaOH, culminating in pure calcium hydroxide and the generation of nCaCO3 particles with superior purity (>99 %) and a uniform particle size (80–140 nm). An exhaustive environmental and economic assessment indicates that our process, while consuming varying energy levels based on operational potentials, anticipates a significant reduction in CO2 emissions by 46.1 %, alongside a competitive production cost (335 USD/ton of nCaCO3), thereby demonstrating substantial advantages over traditional methods in terms of sustainability, efficiency, and cost-effectiveness.

Static corrosion of stainless steel 316H in chemically purified molten NaF-KF-UF4 salt

The purification of salt is indispensable for mitigating the corrosion of structural materials for molten salt reactors or other molten salt applications. This study develops a salt-purification system to synthesize and purify NaF-KF-UF4 salt (FUNaK) using Ar purging and hydrofluorination of impurities. Chronoamperometry is also used to remove metallic impurities in the hydrofluorinated FUNaK. This purified FUNaK is then used for a static corrosion test of stainless steel 316H (SS316H) to study the effectiveness of salt purification in mitigating its corrosion. For comparison, results from a previous study about the corrosion of SS316H by thermally purified FUNaK are used. FUNaK with UF3 is also synthesized for a static corrosion test with the same condition to investigate the impact of UF3 on corrosion. The results show that the corrosion of SS316H is significantly reduced by using the chemically purified FUNaK compared to thermally purified FUNaK.

Partial Discharge Signal Pattern Recognition of Composite Insulation Defects in Cross-Linked Polyethylene Cables.

To investigate the pattern recognition of complex defect types in XLPE (cross-linked polyethylene) cable partial discharges and analyze the effectiveness of identifying partial discharge signal patterns, this study employs the variational mode decomposition (VMD) algorithm alongside entropy theories such as power spectrum entropy, fuzzy entropy, and permutation entropy for feature extraction from partial discharge signals of composite insulation defects. The mean power spectrum entropy (PS), mean fuzzy entropy (FU), mean permutation entropy (PE), as well as the permutation entropy values of IMF2 and IMF13 (Pe) are selected as the characteristic quantities for four categories of partial discharge signals associated with composite defects. Six hundred samples are selected from the partial discharge signals of each type of compound defect, amounting to a total of 2400 samples for the four types of compound defects combined. Each sample comprises five feature values, which are compiled into a dataset. A Snake Optimization Algorithm-optimized Support Vector Machine (SO-SVM) model is designed and trained, using the extracted features from cable partial discharge datasets as case examples for recognizing cable partial discharge signals. The identification outcomes from the SO-SVM model are then compared with those from conventional learning models. The results demonstrate that for partial discharge signals of XLPE cable composite insulation defects, the SO-SVM model yields better identification results than traditional learning models. In terms of recognition accuracy, for scratch and water ingress defects, SO-SVM improves by 14.00% over BP (Back Propagation) neural networks, by 5.66% over GA-BP (Genetic Algorithm-Back Propagation), and by 12.50% over SVM (support vector machine). For defects involving metal impurities and scratches, SO-SVM improves by 13.39% over BP, 9.34% over GA-BP, and 12.56% over SVM. For defects with metal impurities and water ingress, SO-SVM shows enhancements of 13.80% over BP, 9.47% over GA-BP, and 13.97% over SVM. Lastly, for defects combining metal impurities, water ingress, and scratches, SO-SVM registers increases of 11.90% over BP, 9.59% over GA-BP, and 12.05% over SVM.

The Defects Genome of Janus Transition Metal Dichalcogenides.

2D Janus Transition Metal Dichalcogenides (TMDs) have attracted much interest due to their exciting quantum properties arising from their unique two-faced structure, broken-mirror symmetry, and consequent colossal polarization field within the monolayer. While efforts are made to achieve high-quality Janus monolayers, the existing methods rely on highly energetic processes that introduce unwanted grain-boundary and point defects with still unexplored effects on the material's structural and excitonic properties Through high-resolution scanning transmission electron microscopy (HRSTEM), density functional theory (DFT), and optical spectroscopy measurements; this work introduces the most encountered and energetically stable point defects. It establishes their impact on the material's optical properties. HRSTEM studies show that the most energetically stable point defects are single (VS and VSe) and double chalcogen vacancy (VS -VSe), interstitial defects (Mi), and metal impurities (MW) and establish their structural characteristics. DFT further establishes their formation energies and related localized bands within the forbidden band. Cryogenic excitonic studies on h-BN-encapsulated Janus monolayers offer a clear correlation between these structural defects and observed emission features, which closely align with the results of the theory. The overall results introduce the defect genome of Janus TMDs as an essential guideline for assessing their structural quality and device properties.

Iron bioleaching and polymers accumulation by an extreme acidophilic bacterium

In many European regions, both local metallic and non-metallic raw materials are poorly exploited due to their low quality and the lack of technologies to increase their economic value. In this context, the development of low cost and eco-friendly approaches, such as bioleaching of metal impurities, is crucial. The acidophilic strain Acidiphilium sp. SJH reduces Fe(III) to Fe(II) by coupling the oxidation of an organic substrate to the reduction of Fe(III) and can therefore be applied in the bioleaching of iron impurities from non-metallic raw materials. In this work, the physiology of Acidiphilium sp. SJH and the reduction of iron impurities from quartz sand and its derivatives have been studied during growth on media supplemented with various carbon sources and under different oxygenation conditions, highlighting that cell physiology and iron reduction are tightly coupled. Although the organism is known to be aerobic, maximum bioleaching performance was obtained by cultures cultivated until the exponential phase of growth under oxygen limitation. Among carbon sources, glucose has been shown to support faster biomass growth, while galactose allowed highest bioleaching. Moreover, Acidiphilium sp. SJH cells can synthesise and accumulate Poly-β-hydroxybutyrate (PHB) during the process, a polymer with relevant application in biotechnology. In summary, this work gives an insight into the physiology of Acidiphilium sp. SJH, able to use different carbon sources and to synthesise a technologically relevant polymer (PHB), while removing metals from sand without the need to introduce modifications in the process set up.