Search Results (763)

Quartz purification is a key driver of the silicon-based industrial sector. This study used typical vein quartz from Jiangxi Province, China as a raw material to systematically investigated the occurrence states of impurities and conducted an in-depth chemical purification study. The effects of various parameters on impurity removal via acid leaching were investigated. The results revealed distinct removal patterns: independent minerals were effectively removed with low-concentration acid; inclusion impurities were efficiently eliminated by optimizing temperature and acid concentration; and lattice impurities proved resistant to removal. The optimal acid-leaching conditions were identified as follows: 80 °C leaching temperature, mixed acid system of HF-HCl-H₂SO₄ (volume ratio 1:1:1), 7 wt% acid concentration, 6 h leaching time, and a 1:1 solid–liquid ratio. The removal efficiencies of Al, K, and Fe reached 77.0%, 87.5%, and 80.0%, respectively, and the product (the quartz particles after acid leaching) purity was elevated to 99.92%. Furthermore, this study clarified the influence of acid-leaching parameters on purifying high-aluminum low-iron quartz sand, providing a valuable theoretical basis and technical reference for the deep processing of similar quartz ores. Full article

The limited availability of high-quality ore deposits and the environmental hazards of metallurgical wastes highlight the importance of developing resource-efficient metal recovery technologies. Zinc kiln slag (ZKS), also known as Waelz slag, a by-product material enriched in non-ferrous metals, was processed through oxidative HCl leaching with H₂O₂ as an oxidant. Thermodynamic simulation and laboratory experiments were applied to determine optimal leaching conditions to dissolve copper, zinc, and iron. Optimal leaching efficiency was achieved with consumptions of 0.8 g HCl and 0.1 g H₂O₂ per gram of ZKS, a liquid-to-solid (L/S) ratio of 5 mL/g, a temperature of 70 °C, and a duration of 180 min, which resulted in recoveries of 96.3% Cu, 93.6% Fe, and 76.8% Zn. The solid residue with 43.5 wt.% C is promising for reuse as a reductant material in pyrometallurgical processes. Copper and arsenic were separated from the leachate via cementation with iron powder, achieving recovery rates of 98.9% and 91.2%, respectively. A subsequent two-step iron precipitation produced ferric hydroxide with 52.2 wt.% Fe and low levels of impurities. As a result, the developed novel hydrochloric acid oxidative leaching and metal precipitation route for ZKS recycling provides an efficient and sustainable alternative to conventional treatment methods. Full article

Quartz in high-purity form, i.e., with an iron content <100 mg/kg, has valuable properties such as superior UV transmission, thermal stability, and resistance to devitrification, which are highly useful for optical applications. In this study, acid leaching was tested to optimize the production of optical-grade quartz from mined quartz, transforming an environmentally polluting process into a sustainable one, aligning with several United Nations Sustainable Development Goals (SDGs). Initially, when iron removal was obtained with direct, cross-current, and counter-current leaching methods, the results were unsatisfactory. However, a variation consisting of incorporating sulfuric acid regenerated via membrane filtration into the typical counter-current scheme was proven effective, reducing acid consumption and enhancing water recycling in the process, mitigating the environmental impact. The best optimized combination was the three-step counter-current method, with acid regeneration and fresh make-up after each cycle. The conditions were temperature 90 °C, solid-to-liquid ratio 30% wt/vol, time 3 h, and H₂SO₄ concentration of 1 M. The iron extraction yield was close to 89%. Full article

The recovery of rare earth elements (REEs) from the spent NdFeB magnets has great strategic significance for ensuring the security of critical mineral resources. This process requires scientifically designed separation technologies to ensure high output and purity of the obtained rare earths. Hydrometallurgy has been widely applied to extract REEs from spent permanent magnets. This paper summarizes and reviews hydrometallurgical technologies, mechanisms, and applications for the separation and recovery of REEs and iron (Fe) from the spent permanent magnets. Key methods include: The hydrochloric acid total solution method, where the spent NdFeB is completely dissolved in hydrochloric acid, iron is precipitated and removed, and then REEs are extracted. The hydrochloric acid preferential dissolution method, where spent NdFeB magnets are first fully oxidized by oxidative roasting, converting Fe²⁺ to Fe³⁺, which hydrolyzes to Fe(OH)₃, and is precipitated and removed, allowing for the subsequent extraction of REEs to obtain rare earth oxides. Acid baking and water leaching, where spent NdFeB is calcined with acidification reagents, and the calcined products are dissolved in water to leach out REEs. At the same time, Fe is retained in the leaching residue. Electrolysis in aqueous solution, where Fe is electrolyzed at the anode or deposited at the cathode to separate it from REES. Organic acids leaching, where organic acids dissolve metals through acidolysis and complexation. Bioleaching, which utilizes microorganisms to recover metal through biological oxidation and complexation. Ionic liquid systems, where Fe or REEs are extracted using ionic liquid or leached by deep eutectic solvents. This paper provides an in-depth discussion on the challenges, advantages, and disadvantages of these strategies for recycling spent NdFeB magnets, as well as the leaching and extraction behavior of REEs. It focuses on environmental impact assessment, improving recovery efficiency, and decreasing reagent consumption. The future development direction for recycling spent NdFeB magnets is proposed, and a research idea of proposing a combined process to avoid the drawbacks of a single recycling method is introduced. Full article

Epitaxial thick films of yttrium iron garnet (YIG) are ideal for use in microwave devices due to their low losses at high frequencies. This report is on the growth of strain-engineered YIG films by liquid-phase epitaxy (LPE) on yttrium aluminum garnet (YAG) substrates with −3% lattice mismatch with YIG. Since the use of a lattice-matched substrate is preferred for LPE growths, a seed layer of YIG, 370–400 nm in thickness, was deposited by pulsed laser deposition (PLD) on (100), (110), and (111) YAG substrates. The seed layers were stoichiometric with magnetic parameters in agreement with the parameters for bulk single-crystal YIG and with strain-induced perpendicular magnetic anisotropy field H_a = 0.19–0.43 kOe. YIG films, 4 to 8.4 μm in thickness, were grown by LPE at 870 °C on YAG substrates with the seed layers using the PbO+B₂O₃ flux and annealed in air at 1000 °C. The films were Y-rich and Fe-deficient and confirmed to be epitaxial single crystals by X-ray diffraction. The saturation magnetization 4πM_s at room temperature was rather high and ranged from 1.9 kG to 2.3 kG. Ferromagnetic resonance at 5–15 GHz showed the absence of significant magneto-crystalline anisotropy in the LPE films with the line-width ΔH in the range 85–160 Oe, and H_a = 0.27–0.80 kOe which is much higher than for the seed layers. The high magnetization and H_a-values for the LPE films could be partially attributed to the off-stoichiometry. Although the strain due to the film–substrate lattice mismatch contributes to H_a, the mismatch in the thermal expansion coefficients for YIG and YAG is also a likely cause of H_a due to the high growth and annealing temperatures. The LPE-grown YIG films with high strain-induced anisotropy fields have the potential for use in self-biased microwave devices. Full article

This study investigates the physicochemical processes in aqueous solutions treated with a high-current (up to 300 A) pulsed multispark discharge. Pulse length was 2 μs at a 50 Hz repetition rate. The discharge occurred within bubbles of argon injected between the stainless-steel electrodes at the constant flow rate. The erosion of electrode material during the discharge led to iron and other alloy components entering the liquid. Optical emission spectra confirmed the erosion of electrode material (Fe, Cr, Ni atoms and ions). EDTA and its disodium salt were used in order to study their effect on the metal particle formation process. Treatment with deionized water led to an increase in conductivity and the generation of hydrogen peroxide (up to 1200 µM). In contrast, the presence of EDTA and its disodium salt drastically altered the reaction pathways: the H₂O₂ yield decreased, and the solution conductivity dropped substantially for the acidic form of EDTA, while the decrease was minor for EDTA-Na₂. This effect is attributed to the buffered chelation of eroded metal ions, forming stable Fe-EDTA complexes, as confirmed by a characteristic absorption band at 260 nm. The results demonstrate the critical role of complex-forming agents in modulating plasma–liquid interactions, shifting the process from direct erosion products to the formation of stable coordination compounds. Full article

Asbestos tailings represent a historical liability in many countries. Canada aims at transforming this industrial legacy into an opportunity to both mitigate the environmental footprint and recover critical (such as magnesium, nickel, chromium, and cobalt) and strategic metals, which represent significant economic development potential. This study aimed to investigate the recovery of critical and strategic metals (CSMs) from asbestos tailings using hydrochloric (HCl) acid leaching, with acid concentration (2–12 mol/L), leaching temperature (20–90 °C), and solid–liquid ratio (10–40%) as key process parameters. The tailing samples studied is composed mostly of chrysotile and lizardite. It contains about 40% magnesium (as its oxide MgO) and nickel and chromium showing contents 52 and 60 times higher than their respective average crustal abundances (Clarke values). Iron content is 8.7% (expressed as its ferric oxide Fe₂O₃). To optimize key factors influencing the leaching process, a statistical experimental design was employed. The designed leaching experiments were subsequently performed, and results were used to define leaching conditions aiming at maximizing Mg and Ni recoveries while minimizing iron contamination using response surface methodology (RSM) based on the central composite design (CCD). A quadratic polynomial model was developed to describe the relationship between the process parameters and metal recoveries. Among the tested effects of acid concentration, temperature, and pulp density on magnesium recovery, the modeling indicated that both hydrochloric acid concentration and leaching temperature significantly enhanced metal recovery, whereas increasing pulp density had a negative effect at low temperature. The empirical mathematical model derived from the experimental data, accounting for the uncertainties on chemical data, indicated that high magnesium recovery was achieved at 90 °C, with 10–12 N hydrochloric acid and a solid-to-liquid ratio of 33.6–40%. These findings reveal the potential for the recovery of critical and strategic metals, both in terms of efficiency and economic viability. Full article

The residual cake obtained after extracting oil from Moringa oleifera seeds is a promising source of plant-based proteins due to its high content of proteins, dietary fibre and essential minerals. However, its food applications are limited by a strong bitter taste that affects consumer acceptance and antinutritional compounds that reduce mineral bioavailability such as phytates. This study aimed to evaluate the effect of saline and ethanol treatments of moringa cake—reported in the literature as improving its sensory properties—on its nutritional profile. Proximal composition was determined by gravimetry for moisture, muffle incineration for ash, and solvent extraction with the Randall method for lipids. Protein content was analyzed using the Dumas combustion method. Mineral elements (calcium, iron, zinc, sodium) were quantified by Inductively Coupled Plasma Mass Spectrometry (ICP-MS) and phytates by High-Performance Liquid Chromatography (HPLC). The untreated cake revealed a favourable nutritional profile, mainly due to its protein content, but also contained high phytate levels. Both treatments slightly reduced phytates (5–12%), with saline extraction proving more effective. Nevertheless, mineral loss was observed, while there was a notable increase in sodium in the saline-treated samples. Ethanol treatment, in contrast, led to a statistically marked reduction in residual lipids. Importantly, both treatments diminished the bitter taste, improving sensory acceptability. Although neither method completely eliminated phytates, the overall improvements in protein quality, mineral profile, and sensory properties highlight the potential of moringa residual cake as a valuable ingredient. Thus, it emerges as a sustainable, high-nutritional-value source of plant proteins for the development of innovative food products. Full article

Composites in which finely dispersed particles of the metallic phase are uniformly distributed over the surface of expanded graphite can be used as magnetic sorbents for crude oil and petroleum products, as well as a basis for creating screens that protect against electromagnetic radiation. The literature describes various approaches to obtaining such materials, but from a technological point of view, the most promising is the method in which the formation of a metal-containing phase on the surface of expanded graphite is directly combined with its expansion. For this purpose, graphite intercalation compounds with chlorides of metals of the iron triad (GIC-MCl_x) were obtained: GIC-FeCl₃ of I-VII stages, GIC-CoCl₂ of I/II stage and GIC-NiCl₂ of II/III stage, which were treated with liquid NH₃ or CH₃NH₂ in order to obtain an occlusive complex, which, due to the presence of a large amount of bound RNH₂, would be capable of effective thermal expansion during heating in an inert atmosphere with the formation of low-density expanded graphite, and the presence of reducing properties in ammonia and methylamine would lead to the reduction of the metal from chloride. The structure of GIC-MCl_x and GIC-MCl_x treated by NH₃ and CH₃NH₂ was investigated by XRD analysis and Mossbauer spectroscopy. The composition of the metal-containing phase in expanded graphite/metal composite was determined by XRD analysis and its quantity by the gravimetric method. The distribution of metals particles is investigated by SEM, TEM and EDX methods. Expanded graphite/metal composites are characterized by the high saturation magnetization (up to ≈ 50 emu/g) at a bulk density of 4–6 g/L. Full article

Background: Flaxseed (Linum usitatissimum L.) represents a unique source of bioactive compounds with demonstrated health benefits. The main aim of the research was to investigate the chemical composition, content of bioactive compounds and biological activities of various types of flaxseed and their defatted forms. Methods: Proximate composition (crude fat, protein, ash, digestible carbohydrates, fiber) was determined, and fatty acid profiles were analyzed via GC-MS (gas chromatography–mass spectrometry). Mineral content was measured by atomic absorption spectrometry, while total and individual polyphenols were quantified spectrophotometrically and by HPLC (high-performance liquid chromatography). Antioxidant activity was assessed using three assays. In vitro functional assays evaluated the effects of flaxseed extracts on lactic acid bacteria adhesion in two cellular models, nitric oxide production in liposaccharide (LPS)-stimulated RAW 264.7 macrophages, proliferation and apoptosis of MCF-7 breast cancer cells. Results: Significant differences (p ≤ 0.05) were observed in the proximate composition: brown flaxseed exhibited the highest crude fat content, whereas defatted seeds had higher levels of digestible carbohydrates and ash. α-Linolenic acid was the dominant fatty acid, with the highest concentration in defatted golden flaxseed. Defatted forms generally displayed increased mineral concentrations, particularly calcium, magnesium, potassium, and iron. The polyphenolic content and antioxidant activity were highest in defatted brown flaxseed, which also exhibited the greatest diversity of individual polyphenols. Flaxseed extracts modulated the adhesion of lactic acid bacteria, reduced the production of nitric oxide in RAW 264.7 macrophages, inhibited the proliferation of MCF-7 breast cancer cells in a dose- and time-dependent manner, and induced apoptosis of the mentioned cells. Conclusions: Flaxseed, especially the brown type, could be a promising source of bioactive compounds with antioxidant, anti-inflammatory and anticancer potential, supporting its use in nutritional and functional applications. Full article

Late-Archean seawater functioned as a vast, redox-tuned colloidal system for which its kinetics were largely governed by the surface chemistry of silica–iron nanoparticles. By reproducing Archean seawater (≈0.7 M ionic strength, 25 °C) in laboratory anoxic-to-mildly oxic reactors, the ζ potential (zeta-potential(ζ)) of silica–iron nanoparticles was investigated, and we tracked how transient O₂ pulses (≤9 mg L⁻¹) regulated it. The zeta (ζ) potential was applied as the key diagnostic parameter to quantify both the sign of the ζ potential and the colloidal stability of simulated silica–iron particles in dispersion. Under strictly anoxic conditions, silica colloids (SiO₂(aq)) exhibit a persistently negative ζ potential (ζ ≈ −25 mV) in the simulated seawater (pH 6.5), arising from deprotonated silanol groups (≡Si–O⁻). Upon the addition of Fe²⁺, the inner-sphere complexation of ferrous ions on SiO₂ colloids partially replaces ≡Si–O⁻ with ≡Si–O–Fe⁺/≡Si–O–Fe–OH sites; the net negative charge density at the outer Stern plane nevertheless increases, and the ζ potential shifts from −25 mV to −30 mV. As the simulated seawater was oxygenated, the dissolved and surface-bound Fe²⁺ ions were oxidized to Fe³⁺, causing the ζ potential to exceed −30 mV. This study demonstrates that Fe²⁺–silica interactions generate electrostatic destabilization, suspending micron-scale aggregates and thus modulating the solubility and speciation of SiO₂ in early oceans. Also, transient micro-oxic pulses are shown to shift silica–iron colloids between metastable aggregation and dispersion by modulating their ζ potential. Subsequently, AFM and TEM were used to characterize the morphological changes in the colloidal particles from the liquid state to the dry state. Furthermore, infrared and XPS analyses were conducted on the colloidal samples. These findings provide certain reference significance for reconstructing the chemical evolution process of seawater in the Late-Archean period and for understanding the factors influencing the silicon–iron cycle of seawater in the Late-Archean era. Full article

The steel industry is responsible for 7–9% of global CO₂ emissions. Shifting from primary iron ore to recycled scrap in electric arc furnace (EAF) steelmaking offers significant decarbonization potential, reducing carbon intensity by 60–70%. However, increased scrap use in EAF operations leads to higher nitrogen absorption, which can degrade mechanical properties. Nitrogen dissolves into molten steel, where it forms Cottrell atmospheres at dislocations in the following processing steps, intensifying strain aging and reducing ductility. This study establishes a precipitation criterion based on the TiN solubility product to prevent harmful liquid TiN formation, enabling effective nitrogen fixation via fine TiN precipitates (5–20 nm). Multiscale characterization techniques, such as TEM and EBSD, show that Ti reduces the number of mobile N atoms by 60–70%, evidenced by a 50–65% decrease in Snoek/SKK peak intensities. Excessive titanium can refine ferrite grain size and prevents harmful TiN inclusions. Titanium microalloying presents a cost-effective, sustainable strategy to reduce strain aging in scrap-rich EAF steels, enabling more sustainable steel production without sacrificing material properties. Full article

As electric vehicles (EVs) face increasing power demands, rapid charging requirements, and harsh operating conditions, efficient thermal management of lithium-ion batteries is critical for safety and performance. This study evaluates a liquid-cooled thermal management system for dry battery packs using computational fluid dynamics (CFD) simulations and experimentation. The battery pack was modeled in SolidWorks and analyzed using ANSYS Fluent. Simulation results showed a peak battery temperature of 47 °C, with coolant temperature rising from 17.1 °C to 37.4 °C, achieving a 10 °C reduction in battery temperature. Experimental validation yielded comparable outcomes, with a maximum battery surface temperature of 47.2 °C and coolant outlet temperature of 26.1 °C, indicating a 21.1 °C temperature drop. The strong correlation between simulation and experimental data confirms the system’s effectiveness in maintaining safe thermal conditions. Additionally, a low-cost prototype was developed, underscoring the practical viability and scalability of the proposed solution. Full article

Background: Haemoglobinopathies are among the most common monogenic disorders worldwide. Early identification of asymptomatic carriers through reliable screening and molecular diagnostics is crucial for prevention programmes, especially in high-prevalence regions such as Southern Italy. Methods: A total of 5243 individuals were analysed between 2013 and 2024 using both biochemical and genetic parameters. First-level screening included full blood count, iron status, and high-performance liquid chromatography (HPLC) for haemoglobin variant quantification. Molecular analyses were performed using next-generation sequencing (NGS) for the HBA1, HBA2, and HBB genes. Results: We identified 267 individuals (11.2%) as carriers of α-thalassaemia and 473 individuals (16.7%) as carriers of β-thalassaemia. Among them, 5 were compound heterozygotes and 3 homozygous for the α-3.7 deletion. A rare case of HbG Philadelphia in association with a triplicated α-gene was also observed. The most common β-globin mutations included c.118C>T (β⁰39, 44%), IVS-I-110 (17.7%), IVS-I-6 (12.7%), and IVS-I-1 (12.3%). Among α-globin mutations, the most prevalent were -α^3.7 (48%), α2 IVS1 -5nt (15.4%), -20.5 Kb (14.2%), and triplicated α (11%). In total, 18.7% of individuals were found to carry either α- or β-thalassaemia traits. Conclusion: Our findings highlight the limitations of traditional diagnostic methods—such as the osmotic fragility test—and the importance of integrating haematological, biochemical, and molecular data to accurately identify thalassaemia carriers. The variability of genotype–phenotype correlations, especially in the context of immigration and genetic diversity, underscores the need for comprehensive molecular analysis. We propose a three-step diagnostic algorithm combining first-level screening, iron status assessment, and NGS-based sequencing for inconclusive cases. Full article

The chemical profile of coffee depends on numerous factors, the complexity of which makes it difficult to clearly assess their influence. The aim of this study was to comprehensively evaluate the impact of selected coffee brewing methods (Espresso, Simple Infusion, French Press, V60), taking into account the coffee species (Arabica, Robusta, Blends), the degree of roasting (light, medium, dark) and the geographical origin (single-origin and multi-origin) on the chemical composition of the brew. Eighteen different types of coffee, which differ in the aforementioned characteristics, were analyzed. The caffeine content (using high-performance liquid chromatography), the total phenolic content (TPC; using a spectrophotometric method), and selected minerals (calcium, iron, potassium, magnesium, sodium, phosphorus, zinc; using Inductively Coupled Plasma–Optical Emission Spectrometry) were analyzed. The analysis showed that both the brewing method and the species had a significant influence on the chemical profile of the resulting brews, while the degree of roasting and the origin showed no significant influence. The Espresso method showed the highest caffeine, TPC, potassium, magnesium, and phosphorus content, the V60 method—calcium, iron, and sodium, and the French Press and Simple Infusion methods showed intermediate values. Robusta coffee contained more caffeine and TPC, Arabica contained more magnesium, and Blend showed medium values for both species. The results obtained may have practical implications for both consumers and the coffee industry, supporting informed decision-making and the refinement of brewing methods. Full article