Search Results (238)

Background/Objectives: Ash made from juniper trees and added to cornmeal-based dishes may have provided calcium (Ca) to traditional Indigenous diets. Few studies have quantified the mineral content of juniper ash, including its Ca content. The objective of this study was to determine whether juniper ash could serve as a safe source of non-dairy Ca in an intervention study. Methods: Branches from two varieties of Juniper (Rocky Mountain Juniper, or Juniperus scopulorum and Eastern Red Cedar, or Juniperus virginiana) were harvested and burned to ash in a laboratory setting. Juniper ash from the southwestern U.S. available for retail purchase was used for comparison. All samples were tested for content of 10 nutritive elements (Ca, copper, iron, potassium, magnesium, manganese, sodium, phosphorus, selenium, and zinc) and 20 potentially toxic elements (silver, aluminum, arsenic, barium, beryllium, cadmium, cobalt, chromium, mercury, lithium, molybdenum, nickel, lead, antimony, tin, strontium, thallium, uranium, and vanadium) as well as n = 576 pesticide residues. Results: All samples contained both nutritive and potentially toxic elements. Each teaspoon of ash contained an average of 445 ± 141 mg Ca. However, the samples also contained lead in amounts ranging from 1.09 ppm to 15 ppm. Conclusions: Information on the nutritive and potentially toxic elemental content of juniper ash and how it may interact within a food matrix is insufficient to determine its safety as a Ca source. Further investigation is needed on the bioavailability of calcium oxide and its interaction with other dietary components to clarify the potential role of juniper ash in contemporary food patterns. Full article

The field of electrochemical devices, encompassing energy storage, fuel cells, electrolysis, and sensing, is fundamentally reliant on the electrode materials that govern their performance, efficiency, and sustainability. Traditional materials, while foundational, often face limitations such as restricted reaction kinetics, structural deterioration, and dependence on costly or scarce elements, driving the need for continuous innovation. Emerging electrode materials are designed to overcome these challenges by delivering enhanced reaction activity, superior mechanical robustness, accelerated ion diffusion kinetics, and improved economic feasibility. In energy storage, for example, the shift from conventional graphite in lithium-ion batteries has led to the exploration of silicon-based anodes, offering a theoretical capacity more than tenfold higher despite the challenge of massive volume expansion, which is being mitigated through nanostructuring and carbon composites. Simultaneously, the rise of sodium-ion batteries, appealing due to sodium’s abundance, necessitates materials like hard carbon for the anode, as sodium’s larger ionic radius prevents efficient intercalation into graphite. In electrocatalysis, the high cost of platinum in fuel cells is being addressed by developing Platinum-Group-Metal-free (PGM-free) catalysts like metal–nitrogen–carbon (M-N-C) materials for the oxygen reduction reaction (ORR). Similarly, for the oxygen evolution reaction (OER) in water electrolysis, cost-effective alternatives such as nickel–iron hydroxides are replacing iridium and ruthenium oxides in alkaline environments. Furthermore, advancements in materials architecture, such as MXenes—two-dimensional transition metal carbides with metallic conductivity and high volumetric capacitance—and Single-Atom Catalysts (SACs)—which maximize metal utilization—are paving the way for significantly improved supercapacitor and catalytic performance. While significant progress has been made, challenges related to fundamental understanding, long-term stability, and the scalability of lab-based synthesis methods remain paramount for widespread commercial deployment. The future trajectory involves rational design leveraging advanced characterization, computational modeling, and machine learning to achieve holistic, system-level optimization for sustainable, next-generation electrochemical devices. Full article

The oxygen evolution reaction (OER) in water splitting involves complex multi-electron–proton transfer processes and represents the rate-determining step limiting overall electrolysis efficiency. Developing non-noble-metal catalysts with high activity and stability is therefore essential. Herein, a heterogeneous synthesis strategy was employed to in situ construct an iron-rich layered sulfate precursor (Fe_0.42Co_0.58-SO₄/NF) on nickel foam, which underwent deep self-reconstruction in alkaline electrolyte to form nanoflower-like Fe_0.42Co_0.58OOH/NF. The optimized catalyst maintained its iron-rich composition and hierarchical structure, delivering outstanding OER performance with an overpotential of 220 mV at 10 mA·cm⁻², a Tafel slope of 31.9 mV·dec⁻¹, and stability exceeding 12 h at 600 mA·cm⁻². Synchrotron analyses revealed dynamic transitions between mono-μ-O and di-μ-O Fe–M (M = Fe, Co) oxygen bridges during reconstruction, which enhanced both structural robustness and active-site density. The Fe-rich environment promoted the formation of Fe³⁺–O–Fe³⁺ units that synergized with Co⁴⁺ species to activate the lattice oxygen mechanism (LOM), thereby accelerating OER kinetics. This work elucidates the key role of oxygen-bridge geometry in optimizing catalytic activity and durability, providing valuable insights into the rational design of Fe–Co-based non-noble-metal catalysts with high iron content for efficient water oxidation. Full article

Prussian blue (PB) and its analogs (PBAs) are interesting materials for electrochemical applications due to their tunable redox chemistry and open framework structure. In this study, hexacyanoferrates (HCF) containing iron (FeHCF), cobalt (CoHCF), and nickel (NiHCF) were synthesized via potentiostatic electrodeposition. Cyclic voltammetry revealed distinct redox behaviors. Morphological characterization (SEM, EDX) demonstrated uniform, pyramidal film growth for FeHCF and CoHCF. Otherwise, NiHCF presented a cracked film with cubic clusters on top due to residual stress. Despite this, homogeneous element distribution was found for all samples. Structural characterization (TEM and XRD) confirmed a cubic lattice crystal structure for all films, with systematic lattice contraction from Fe to Co to Ni due to decreasing atomic radius. Raman and XPS data revealed a shift toward Fe²⁺ dominant oxidation states and modifications in C≡N bonding, with the influence of K⁺ and water occupancy in the PBAs framework. These findings illustrate how metal substitution and deposition parameters can tune the structural and electrochemical properties of PBA films, presenting a strategic route to design tailored electrodes. Full article

During their stay at the surface of the Earth, meteorites undergo terrestrial weathering. In particular, the iron-nickel alloys and iron sulfides that are abundant in many types of meteorites transform into oxides and oxihydroxides (magnetite, maghemite, akaganeite, etc.). Mössbauer spectroscopy is a powerful tool to identify these weathering products. However, distinguishing signals from different phases summed up in the Fe³⁺ paramagnetic doublets in the central part of the spectrum remains challenging. This study focuses on a detailed investigation of meteorite weathering products to separate signals from different secondary minerals formed on Earth in a series of weathered meteorites. We carried out a room-temperature Mössbauer spectroscopy study on seventy ordinary chondrites collected in the Atacama Desert, Chile, in order to make a comparative qualitative analysis of the mineralogy of their terrestrial weathering products. Based on these results, three samples showing a variety of weathering products (Catalina 146, Catalina 535, and El Médano 070) were selected for a detailed study and two of them for low-temperature Mössbauer study. We found that, above 200 K, most meteorites exhibit superparamagnetic magnetization dynamics attributable to strong dispersed maghemite–magnetite phase formed as a weathering product. On the other hand, other iron-bearing weathering products (goethite, akaganeite, hematite) demonstrate line shapes of the corresponding partial components that are close to the shapes of the bulk samples. Only two of the 70 measured meteorites showed no superparamagnetic behavior at room temperature. Full article

It is well known that nitrite is widely used in industrial and agricultural sectors as a preservative, corrosion inhibitor, and intermediate in chemical synthesis; consequently, nitrite residues are often present in food, water, and the environment as a result of meat curing, fertilizer use, and wastewater discharge. Despite having several applications, nitrite exerts toxic effects on human beings and aquatic life. Therefore, the monitoring of nitrite is of particular significance to avoid negative impacts on human health, the environment, and aquatic life. Previously, the electrochemical method has been extensively used for the development of nitrite sensors using various advanced electrode materials. Additionally, zinc oxide (ZnO), cerium oxide (CeO₂), titanium dioxide (TiO₂), copper oxide (CuO), iron oxides, nickel oxide (NiO), polymers, MXenes, reduced graphene oxide (rGO), carbon nanotubes (CNTs), graphitic carbon nitride (gCN), metal–organic frameworks (MOFs), and other composites have been utilized as electrocatalysts for the fabrication of nitrite electrochemical sensors. This review article provides an overview of the construction of nitrite sensors using advanced electrode materials. The electrochemical activities of the reported nitrite sensors are discussed. Furthermore, limitations and future perspectives regarding the determination of nitrite are discussed. Full article

Aluminum anodizing has been a well-established method of corrosion protection for over a century. A nanoporous and hexagonally arranged anodic aluminum oxide has become one of the most important template materials in nanotechnology. A totally new branch of research in anodizing was sparked by purple gold anodizing. This pioneering research showed that metal aluminides can be anodized and result in new classes of nanomaterials. Simultaneously, materials from Ti-Al systems were anodized, and the transition from nanopores to the nanotubes was mechanistically understood. Also, materials like Ni₃Al were anodized; however, the most frequently used aluminides are materials from the Fe-Al binary phase diagram, from Fe₃Al to FeAl₃. The research on metal aluminides has shown that it is possible to obtain mixed oxides with a highly developed nanostructured morphology. A significant amount of fundamental research has shown it is possible to obtain such mixed oxides with tunable band gaps, depending on the substrate material, anodizing conditions, and heat treatment. Despite significant progress in fundamental research, there is a noticeable lack of applied research on this class of materials. Full article

Lithium-ion batteries (LIBs) are vital for modern energy storage applications. Lithium iron phosphate (LFP) is a promising cathode material due to its safety, low cost, and environmental friendliness compared to the widely used nickel manganese cobalt oxide (NMC), which contains hazardous nickel and cobalt compounds. However, challenges remain in enhancing the performance of LFP cathodes due to their low electronic and ionic conductivity. To improve both the safety and sustainability of the battery, this work presents a water-based LFP cathode utilizing the bio-based binder carboxymethyl cellulose (CMC), eliminating the need for polyvinylidene fluoride (PVDF) and the toxic solvent N-methyl-2-pyrrolidone (NMP). This study investigates the impact of different dispersing methods—dissolver mixing and wet jet milling—on slurry properties, electrode morphology, and battery performance. Slurries were characterized by rheology, particle size distribution, and sedimentation behavior, while coated and calendered electrodes were examined via thickness measurements and scanning electron microscopy (SEM). Electrochemical performance of the electrodes was evaluated by means of C-Rate testing. The results reveal that dispersing methods significantly influence slurry characteristics but marginally affect electrochemical performance. Compared to dissolver mixing, wet jet milling reduced the median particle size by 39% (ΔD50 = 3.1 µm) and lowered viscosity by 96% at 1 s⁻¹, 80% at 105 s⁻¹, and 64% at 1000 s⁻¹. In contrast, the electrochemical performance of the resulting electrodes differed only slightly, with discharge capacity varying by approximately 12.8% at 1.0 C (Δcapacity = 10.7 mAh g⁻¹). This research highlights the importance of optimizing not only material selection but also processing techniques to advance safer and more sustainable energy storage solutions. 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

Over the next 5–10 years, the feedstock to lithium-ion battery recycling facilities will shift from Co- and Ni-rich chemistries to lower-value battery chemistries, such as lithium iron phosphate (LFP). Traditional recycling processes use toxic and corrosive inorganic acids for leaching, generating toxic waste streams. The low-value feedstocks will be LFP-rich with contamination from lithium cobalt oxide (LCO) and lithium–nickel–manganese–cobalt oxide (NMC) battery chemistries. Overall, the lower-value feedstock coupled with the need to reduce environmentally damaging waste streams requires the development of robust, green leaching processes capable of selectively targeting the LFP and LCO/NMC battery chemistries. This research concluded that a first-stage oxalic acid leach could selectively extract Al, Li, and P from the industrially sourced LFP-rich black mass. When operating at the optimal conditions (0.5 M oxalic acid, 5% solids, pH 0.8, and an agitation speed of 600 rpm), >99% of the Li and P and >97% of the Al were selectively extracted after 2 h, while Mn, Fe, Cu, Ni, and Co extractions were kept relatively low, namely, at 19%, <3%, <1%, 0%, and 0%. This research also explored a second-stage leach to treat the first-stage leach residue using ascorbic acid, citric acid, and glycine. It was concluded that when leaching with glycine (30 g/L glycine, a temperature of 40 °C, an agitation speed of 600 rpm, and 2% solids at pH 9.6), that >97% of the Co, >77% of the Ni, and 41% of the Mn were extracted, while the co-extraction percentages of Cu, Fe, and Al were <27%, <4%, and <2%. Full article

Machine learning algorithms are essential tools for developing Mineral Prospectivity Models (MPMs), enabling a data-driven approach to mineral exploration. This study integrated airborne geophysical, topographic, and geological data with a mineral system framework to build MPMs for iron oxide–copper–gold (IOCG) and hydrothermal nickel deposits in the Southern Copper Belt of the Carajás Province, Brazil. Seven machine learning algorithms were tested using stratified 10-fold cross-validation: Logistic Regression, k-Nearest Neighbors, AdaBoost, Support Vector Machine (SVM), Random Forest, XGBoost, and Multilayer Perceptron. SVM delivered the highest classification accuracy and robustness, highlighting new mineralized zones while minimizing false positives and negatives, and accounting for geological complexity. SHapley Additive ExPlanations (SHAP) analysis revealed that structural controls (e.g., faults, shear zones, and geochronological contacts) exert a stronger influence on mineralization patterns than lithological factors. The resulting prospectivity maps identified geologically distinct zones of IOCG and hydrothermal nickel mineralization, with high-probability closely aligned with major structural corridors oriented E–W, NE–SW, and NW–SE. Results also suggest an indirect association with volcanic units, Orosirian A1-type granites and Neoarchean A2-type granites. Full article

Naproxen (NPX), a nonsteroidal anti-inflammatory drug, is considered an emerging contaminant due to its persistence and potential environmental risks. In this study, NPX degradation was investigated through ozonation using nickel–iron foam (NiFeF) and NiO-modified NiFeF (NiO/NiFeF). The effect of the foam size was investigated using three configurations: S1 (1 cm × 2.5 cm), S2 (2 cm × 2.5 cm), and S3 (2 cm × 5 cm). Complete NPX removal was achieved in all systems, with degradation times of 4 min for ozonation alone, 2 min for NiFeF-S1, and 1 min for NiO/NiFeF-S2 and NiO/NiFeF-S3. The NiO/NiFeF catalyst was synthesized via ultrasonic spray pyrolysis, resulting in a porous structure with abundant active sites. Compared with conventional ozonation, NiO/NiFeF-S1 improved the total organic carbon (TOC) removal rate by 6.2-fold and maintained 87.5% of its activity after five reuse cycles, demonstrating excellent stability. High-resolution mass spectrometry revealed that catalytic ozonation generated fewer by-products (22 vs. 27 for ozonation alone) and promoted more selective pathways, including demethylation, ring-opening oxidation, and partial mineralization to CO₂ and H₂O. This enhanced performance is attributed to the synergy between NiO and NiFeF, which facilitates reactive oxygen species generation and electron transfer. These results demonstrate the potential of NiO/NiFeF as an efficient and stable catalyst for pharmaceutical removal from water. Full article

Textile production contributes significantly to water pollution, making dye removal crucial for protecting water resources from toxic textile waste. The use of nano-adsorbents for water purification has emerged as a promising approach to removing pollutants from wastewater. Nickel Ferrite (NiFe₂O₄), Iron Oxide (Fe₂O₃), and Nickel Oxide (NiO) nanoparticles (NPs) were prepared via an auto-combustion sol–gel technique using chitosan as a capping and stabilizing agent. The prepared nanomaterials were characterized using various techniques such as XRD, UV-Vis DRS, FT-IR, Raman, EDX, SEM, and TEM to confirm their structure, particle size, morphology, functional groups on the surface, and optical properties. Subsequently, the adsorption of the methylene blue (MB) dye using the prepared nanomaterials was studied. NiFe₂O₄ NPs exhibited the best adsorption behavior compared to the mono-metal oxides. Moreover, all prepared nanomaterials were compatible with the pseudo-second-order model. Further investigations were conducted for NiFe₂O₄ NPs, showing that both the Freundlich and Langmuir isotherm models can explain the adsorption of the MB dye on the surface of NiFe₂O₄ NPs. Factors affecting MB dye adsorption were discussed, such as adsorbent dose, concentration of the MB dye, contact time, pH, and temperature. NiFe₂O₄ NPs exhibited a maximum removal efficiency of the MB dye, reaching 96.8% at pH 8. Different water sources were used to evaluate the ability of NiFe₂O₄ NPs to purify a wide range of water types. Full article

Despite intense interest in the catalytic potential of transition metal oxide heterostructures, originating from their large surface area and tunable chemistry, the fabrication of well-defined multicomponent oxide coatings with controlled architectures remains challenging. Here, we demonstrate a simple and effective swelling-assisted sequential infiltration synthesis (SIS) strategy to fabricate hierarchically porous multicomponent metal-oxide electrocatalysts with tunable bimetallic composition. A combination of solution-based infiltration (SBI) of transition metals, iron (Fe), nickel (Ni), and cobalt (Co), into a block copolymer (PS73-b-P4VP28) template, followed by vapor-phase infiltration of alumina using sequential infiltration synthesis (SIS), was employed to synthesize porous, robust, conformal and transparent multicomponent metal-oxide coatings like Fe/AlO_x, Fe+Ni/AlO_x, and Fe+Co/AlO_x. Electrochemical assessments for the oxygen evolution reaction (OER) in a 0.1 M KOH electrolyte demonstrated that the Fe+Ni/AlO_x composite exhibited markedly superior catalytic activity, achieving an impressive onset potential of 1.41 V and a peak current density of 3.29 mA/cm². This superior activity reflects the well-known synergistic effect of alloying transition metals with a trace of Fe, which facilitates OER kinetics. Overall, our approach offers a versatile and scalable path towards the design of stable and efficient catalysts with tunable nanostructures, opening new possibilities for a wide range of electrochemical energy applications. Full article

During the homogenization process of lithium battery slurry, the slurry shearing process causes the surface of the homogenization equipment to wear and generate metal containing debris, which poses a risk of inducing battery self-discharge and even explosion. Therefore, inhibiting wear of homogenizing equipment is imperative, and systematic investigation into the wear behavior and underlying mechanisms of SUS304 stainless steel during homogenization is urgently required. In this study, lithium iron phosphate (LFP) and lithium nickel cobalt manganese oxide (NCM) cathode slurries were used as research objects. Changes in surface parameters, microstructure, and elemental composition of the wear region on SUS304 stainless steel under different working conditions were characterized. The results indicate that in the SUS304-lithium-ion battery slurry system, the potential wear mechanism of SUS304 gradually evolves with changes in load and rotational speed, following the order: adhesive wear (low speed, low load) → abrasive wear (medium speed, high load) → fatigue wear (high speed). Under high-load and high-rotational-speed conditions, oxidative corrosion wear on the ball–disc contact surface is particularly pronounced. Additionally, wear of SUS304 is more severe in the LFP slurry system compared to the NCM system. Macroscopic experiments also revealed that the speed effect is a core factor influencing the wear of SUS304, and the increase in its wear rate is more than twice that caused by the load effect. This study helps to clarify the wear behavior and wear mechanism evolution of homogenization equipment during the lithium battery homogenization process, providing data support and optimization direction for subsequent material screening and surface strengthening treatment of homogenization equipment components. Full article