Search Results (206)

Seaweeds are photosynthetic organisms with ecological, social, and economic significance, and they serve as effective bioindicators in marine ecosystems. This study assessed trace element concentrations in beach-cast seaweeds collected from four beaches along the Espírito Santo coast in southeastern Brazil—an area impacted by mining-related contamination. Samples of Zonaria tournefortii (J.V. Lamouroux) Montagne and Sargassum natans (Linnaeus) Gaillon, gathered during low tide (July–August 2022), were analyzed for 15 elements. Statistical analysis using the Kruskal–Wallis test revealed significant interspecific differences in the accumulation of several metals. Aluminum (Al), iron (Fe), and magnesium (Mg) were the most abundant (>100 mg/kg), while minor elements (<100 mg/kg) included barium (Ba), arsenic (As), zinc (Zn), vanadium (V), nickel (Ni), chromium (Cr), copper (Cu), lead (Pb), cobalt (Co), cadmium (Cd), silver (Ag), and mercury (Hg). Elemental profiles exceeded those reported in other global regions and closely resembled iron ore tailings. Most elements had relatively higher concentrations on the beaches of Imigrantes, in the north of the state. These findings are the first for beach-cast seaweeds in this region, suggesting that this contamination indicates the legacy of the mining industry from southeastern Brazil. Full article

Powder bed fusion (PBF) and directed energy deposition (DED) additive manufacturing use feedstock powders that contain metals associated with skin diseases. We performed a survey of surface contamination and limited task-based dermal exposure assessment (four employees) at a PBF and DED facility. Skin wipes of wrists for two employees in the PBF room had higher post-task levels of chromium, cobalt, molybdenum, and nickel. Personal clothing worn by PBF employees showed evidence of contamination with metals as did personal protective equipment (PPE). Microscopy analysis documented contamination of metals throughout most areas of the facility. Levels of metals on surfaces throughout the facility were (ng/cm²) <5.0–7247 (aluminum), <0.2–4899 (chromium), <background-6.0 (chromium VI), 0.03–468.1 (cobalt), 1.6–100.0 (copper), 32.9–19,000 (iron), 0.01–789.0 (molybdenum), 0.1–12,058 (nickel), 0.1–482.8 (titanium), and 0.07–9.3 (vanadium). Levels were significantly lower in administrative areas compared with the production area but generally did not differ among powder handling and non-powder handling rooms in production. The small number of participants in the dermal exposure assessment and uniqueness of the facility might limit generalizability of the results. At least for this facility, steps to lower skin contact with metals can include washing, consistent use of PPE, and increasing awareness of dermal hazards among workers. Approaches to reduce migration of metals throughout a facility can include using adhesive (“tacky”) mats and boot covers and frequent wet cleaning of floors, tools, handles, and high touch surfaces. Full article

In recent years, flow batteries have emerged as a crucial technological solution for large-scale energy storage, leveraging their unique power-capacity decoupling characteristics and long cycle life to demonstrate significant potential in applications such as renewable energy integration and grid frequency regulation. Based on differences in electrolyte systems, mainstream flow battery technologies are primarily categorized into three types: all-vanadium redox flow batteries (VRFBs), iron-chromium redox flow batteries (ICFBs), and zinc-based redox flow batteries (ZRFBs). However, each of these technologies faces critical challenges in practical commercialization: VRFBs are constrained by cost pressures due to fluctuations in vanadium resource prices and relatively low energy efficiency; ICFBs require urgent solutions to issues such as hydrogen evolution side reactions at the negative electrode and the sluggish kinetic responses of the Cr³⁺/Cr²⁺ redox couple; while ZRFBs grapple with safety concerns such as zinc dendrite growth and morphology instability. To overcome these technical bottlenecks, extensive innovative research has been conducted in key materials (electrodes, ion-exchange membranes, electrolytes). Against this backdrop, this paper systematically reviews recent advances in the modification and optimization of flow battery technologies and conducts an extended discussion on the emerging organic redox flow batteries in recent years. Full article

Spent fluid catalytic cracking catalysts (E-cat) are a challenging waste from the petroleum refining industry, enriched with heavy metals such as nickel, vanadium, and iron. This study proposes a circular valorization strategy by incorporating E-cat into a chemically bonded iron phosphate ceramic matrix, known for its excellent waste stabilization properties. Composites were synthesized at room temperature using E-cat, hematite, and phosphoric acid, with E-cat contents from 0% to 35%. Characterization by XRF, XRD, SEM, compressive strength, and water absorption tests identified an optimal formulation containing 16% E-cat, achieving a maximum compressive strength of 16.6 MPa, 35% higher than the control. This improvement can be attributed to the dual function of E-cat, acting both as a micro-aggregate that promotes matrix densification and as a pozzolanic component that enhances mechanical reinforcement. These results demonstrate that iron phosphate ceramics represent a low-energy and sustainable strategy for the immobilization of spent catalysts and the production of durable construction composites. Full article

Magnetite-rich iron ores present analytical challenges due to mineralogical complexity, including titanium–vanadium (Ti-V) substitution within magnetite and variable silicate gangue contributions. Reliable iron (Fe) quantification in such systems is essential for accurate resource evaluation and beneficiation planning, particularly in layered intrusion-hosted deposits. This study compares fusion-based inductively coupled plasma optical emission spectroscopy (ICP-OES) and fused-bead X-ray fluorescence (XRF) methods for the determination of Fe and associated major elements in magnetite-bearing Fe ores from the Bushveld Igneous Complex, South Africa. Four representative ore samples and certified reference materials were analysed using both techniques. Comparative statistical parameters like the t-test and F-test exhibit no significant differences in either precision and mean concentration between fused-based ICP-OES and fused-based XRF methods for the determination of Fe and other elements. The results indicate that, despite the existence of titanomagnetite and lithologies that are rich in silicates, both fusion-based methods provide consistent and reliable bulk chemical analysis datasets. While both approaches show suitability for routine chemical analysis, fusion-based ICP-OES offers a practical advantage in terms of throughput and operational efficiency. This work emphasises the importance of matching analytical methods with mineral ore characterisation in order to ensure reliable Fe grade determination in complicated oxide deposits. Full article

Vanadium (V), molybdenum (Mo), iron (Fe), and aluminum (Al) are crucial alloying elements in certain high-performance titanium alloys. Traditionally, these elements are added to titanium alloys in the form of binary master alloys such as V-Al, Mo-Al, and Ti-Fe. The preparation and use of multiple master alloys complicates titanium alloy production and increases cost. It is therefore desirable to introduce a single multi-component master alloy containing several alloying elements into the titanium alloy smelting process. This study proposes an aluminothermic co-reduction process for V₂O₅ and MoO₃ to form a V-Al-Mo-Fe alloy with Al and Fe. Thermodynamic analysis indicates that the reduction of MoO₃ by aluminum takes precedence over that of Fe₂O₃ and V₂O₅. Utilizing metallic iron as the iron source can effectively control the heat release of the system and reduce aluminum consumption. The formation of an Al-Fe alloy prior to the aluminothermic reactions decreases the reducibility of Al. Experiments confirmed that a specific Al/O ratio in the starting materials is necessary to complete the aluminothermic reduction of V₂O₅ and MoO₃. The results show that the recovery rates of V, Mo, and Fe are strongly influenced by the Al/O ratio. When the Al/O ratio exceeds 1.6, recovery rates over 99% can be achieved for all alloying elements, with complete reduction of vanadium oxide and clear slag–alloy separation. This research provides a fundamental basis for preparing V-Al-Mo-Fe multi-component master alloys, demonstrating significant potential for applying the aluminothermic process to the preparation of other alloys. Full article

Vanadium–titanium magnetite is a strategically important resource for iron, vanadium, and titanium production, yet its utilization in conventional blast furnace–basic oxygen furnace routes is limited by the dilution of titanium into low-value slag. This study investigates an integrated process route combining pellet preparation, hydrogen-based shaft furnace reduction conducted in the temperature range of 800–1000 °C, and subsequent electric furnace smelting for efficient recovery of Fe, V, and Ti. Pellets prepared from 100 wt.% vanadium–titanium magnetite exhibited sufficient mechanical strength but showed poor reducibility and severe low-temperature reduction disintegration, rendering them unsuitable for hydrogen-based shaft furnace operation. To overcome these limitations, systematic ore blending was applied. An optimized pellet composition comprising 40 wt.% vanadium–titanium magnetite, 50 wt.% high-grade iron ore, and 10 wt.% titanium concentrate achieved reduction degrees above 90%, acceptable swelling and bonding behavior, and low reduction disintegration indices meeting industrial HYL requirements. Industrial trials in a hydrogen-based shaft furnace demonstrated stable operation and consistent product quality, producing direct reduced iron with controlled metallization and enrichment of titanium and vanadium. Subsequent electric furnace smelting achieved clear slag–metal separation, yielding hot metal with high iron and vanadium recovery and a TiO₂-rich slag containing approximately 45 wt.% TiO₂. Recovery rates of Fe, V, and Ti exceeded 90%, confirming the technical feasibility of the proposed process route. Full article

Selenium contamination in arid agricultural basins remains a key ecological concern, yet the Wister Unit of the Imperial Wildlife Area has received comparatively little hydrochemical study. This investigation provides the most integrated assessment to date of selenium, salinity, nitrate, stable water isotopes (δ²H and δ¹⁸O), and selected redox-sensitive trace elements within the Wister Unit and its contributing open agricultural drains, with the goal of identifying controls on selenium concentrations and mobility. Water samples from open agricultural drains, shallow groundwater tile drains, canal project water, and tailwater return flow were analyzed for Total Dissolved Solids (TDS), major ions, nutrients, selenium, and stable water isotopes. A subset of samples was anlayzed for iron, manganese, and vanadium. Overall, 71% of open drain and tile drain samples collected in this study exceeded the U.S. Environmental Protection Agency aquatic-life criterion of 5 µg/L, indicating persistent ecological risk. All waters plotted along an evaporation trajectory originating from imported Colorado River irrigation water; however, isotopic enrichment did not scale directly with salinity. Pure evaporation models predicted much lower TDS values than observed, and the most evaporated samples were not the most saline or selenium-rich. These results demonstrate that simple soil water evaporation alone cannot explain the data. Instead, the broad isotopic range at similar salinities reflects a secondary process in which salts that accumulated in soils during dry or average years are later mobilized and flushed during periods of surplus water and heavy irrigation. Low dissolved iron, manganese, and vanadium concentrations in a subset of water samples indicate predominantly oxidizing conditions, under which selenium behaves conservatively during salt leaching, producing a strong correlation with TDS. Selenium levels measured in Wister Unit are generally lower than those reported in nearby areas during the 1990s–2000s, implying changes in salt accumulation, hydrologic routing, or agricultural practices. These results refine the conceptual model for the Wister Unit and motivate future work on selenium speciation, nitrate isotope tracing, time series monitoring, and soil-salt interactions. Full article

In this study, we investigated the bioaccumulation of 17 heavy metals—titanium, vanadium, chromium, manganese, iron, cobalt, nickel, copper, zinc, arsenic, selenium, molybdenum, antimony, cadmium, tin, mercury, and lead—in the liver and kidney tissues of the least weasel, based on samples (n = 129) collected from adjacent intensive agricultural environments in Hungary and Austria. To explore the structure of the bioaccumulation data, principal component analysis (PCA) was performed. The PCA score plot based on national-level elemental profiles revealed no differentiation between Austria and Hungary. In contrast, a clear and unambiguous distinction was observed between the two examined tissues within individuals for Ti, Mn, Fe, Co, Zn, Se, Mo, Cd, and Hg (p < 0.001), as well as for Pb (p < 0.05). The biological relevance of the accumulation results was adjusted using the MCID approach. As heavy metal accumulation in the least weasel has not yet been investigated, our results could only be compared with concentrations reported for predatory mammals occurring in similar habitats. Based on the relevant literature, we highlight predominantly anthropogenic exposure pathways affecting agroecosystems—organic and mineral fertilizers, plant protection products, wastewater, and fossil fuels—which underscore the necessity of regular biomonitoring studies in agricultural landscapes. Full article

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

While vanadium-extracted tailings contain valuable components, their utilization is difficult due to their high sodium content. In this work, a new oxygen-pressure calcification and alkaline leaching strategy to achieve barium orthovanadate vanadium precipitation is developed to realize the resourceful recycling and utilization of vanadium-extracted tailings. First, the preparation of barium orthovanadate via calcified alkaline leaching and vanadium precipitation was studied, and the effects of CaO addition, NaOH concentration, leaching temperature, and liquid–solid ratio on the leaching rates of sodium and vanadium were evaluated in single-factor experiments. Under the optimum leaching conditions (CaO addition of 20%, alkali concentration of 150 g·L⁻¹, leaching temperature of 180 °C, and liquid–solid ratio of 10:1), the leaching rates of vanadium and sodium reached 85.25% and 82.36%, respectively. Subsequently, the vanadium-containing leaching solution was subjected to a vanadium precipitation test, and the effects of pH, Ba(OH)₂ addition (expressed as ${\mathrm{n}}_{\mathrm{Ba}}/{\mathrm{n}}_{\mathrm{V}}$), vanadium precipitation temperature, and vanadium precipitation time on the vanadium precipitation rate were investigated. Under the optimum vanadium precipitation conditions (pH 14, ${\mathrm{n}}_{\mathrm{Ba}}/{\mathrm{n}}_{\mathrm{V}}$ = 1.5:1, temperature of 30 °C, reaction time of 60 min), a vanadium precipitation rate of more than 99% was achieved. The precipitated vanadium product of this reaction was confirmed to be Ba₃(VO₄)₂ with a purity of more than 99%. Notably, the wastewater generated during the test process can be mixed with an alkali and returned to the leaching process for reuse, and the dealkalized residue can be used as a raw material for ore reduction in iron smelting processes. Full article

Redox flow batteries (RFBs) are an emerging class of large-scale energy storage devices, yet the commercial benchmark—vanadium redox flow batteries (VRFBs)—is highly constrained by a modest open-circuit potential (1.26 V) while posing an expensive and volatile material procurement costs. This review focuses on recent progress in diversifying redox-active species to overcome these limits, highlighting chemistries that increase overall cell voltage, energy density, and efficiency while maintaining long cycle life and safety. The study dwells deeper into manganese-based systems (e.g., Mn/Ti, Mn/V, Mn/S, M/Zn) that leverage Mn’s high positive potential while addressing Mn(III) disproportionation reactions; iron-based hybrids (Fe/Cr, Fe/Zn, Fe/Pb, Fe/V, Fe/S, Fe/Cd) that exploit the low cost, and its abundance, along with membrane and electrolyte strategies to prevent the potential issue involving crossover; cerium-anchored catholytes (Ce/Pb, V/Ce, Eu/Ce, Ce/S, Ce/Zn) that deliver high operational voltage by implementing an acid-base media, along with selective zeolite membranes; and halide systems (Zn–I, Zn–Br, Sn–Br, polysulfide–bromine/iodide) that combine fast redox kinetics and high solubility with advances such as carbon-coated membranes, bromine complexation, and ambipolar electrolytes. Across these various families of RFBs, the review highlights the modifications made to the flow-fields, membranes, and electrodes by utilizing a zero-gap serpentine flow field, sulfonated poly(ether ether ketone) (SPEEK) membranes, carbon-modified and zeolite separators, electrolyte additives to enhance the voltage (VE%), and thereby energy (EE%) efficiency, while reducing the overall system cost. These modifications to the existing RFB technology offer a promising alternative to traditional approaches, paving the way for improved performance and widespread adoption of RFB technology in large-scale grid-based energy storage solutions. Full article

This study assessed the concentrations and spatial patterns of heavy metals in fine particulate matter with aerodynamic diameter below 2.5 $\mu$m and coarse particulate matter with aerodynamic diameter below 10 $\mu$m in Santo Domingo, Dominican Republic, during 2022. Thirty 24 h samples were collected using portable low-volume samplers across representative urban environments. Elemental concentrations of arsenic, cadmium, chromium, copper, iron, manganese, nickel, lead, vanadium, and zinc were quantified by energy-dispersive X-ray fluorescence. To address data below detection limits, regression on order statistics was applied. Copper and zinc exhibited the highest mean concentrations, pointing to strong anthropogenic inputs, while vanadium and iron showed pronounced spatial variability. Principal component analysis identified traffic and industrial activities as dominant sources. These findings provide baseline evidence for heavy metal pollution in Caribbean urban air and emphasize the need for continuous monitoring and effective regulatory strategies to mitigate potential health risks. Full article

Vanadium is a strategic metal with critical applications in steel alloys, aerospace, chemical catalysis, and energy storage. However, conventional extraction methods such as high-temperature salt roasting are energy-intensive and environmentally challenging. This study investigated the extraction of V, Ti, and Fe from titanomagnetite ore using aqueous solutions of two ionic liquids (IL), 1-butyl-3-imidazolium hydrogen sulphate ([Bmim][HSO₄], and 1-butyl-3-methylimidazolium hexafluorophosphate [Bmim][PF₆]) as well as two deep eutectic solvents (DESs) (choline chloride:oxalic acid and choline chloride:succinic acid). Na₂CO₃ and Na₂SO₄ roasting were used as benchmarks for comparison purposes. Leaching was performed across a range of concentrations and temperatures, and metal recoveries were quantified by atomic absorption spectroscopy (AAS). Among all methods, ChCl:OA DES achieved the best leaching efficiencies of 97.6% for V, 76.1% for Ti, and 68.8% for Fe at 50% (v/v) and 100 °C, outperforming [Bmim][HSO₄] and conventional roasting. Kinetic analysis using the shrinking core model indicated that leaching is predominantly diffusion-controlled, with apparent activation energies of 35.1 kJ/mol for V, 28.3 kJ/mol for Ti, and 29.8 kJ/mol for Fe. The results demonstrate that ChCl:OA DES provides a low-temperature, biodegradable, and cost-effective approach for V, Ti and Fe extraction, offering a sustainable alternative to conventional salt roasting methods. Full article

Heavy metal contamination in rivers is a serious environmental and public health concern, especially in areas affected by mining. This study evaluated the levels of contamination and the associated ecological and carcinogenic risks in the sediments of the Cunas River, located in the central highlands of Peru. Sediment samples were collected from upstream and downstream sections. Several metals and metalloids were analyzed, including copper (Cu), chromium (Cr), iron (Fe), manganese (Mn), molybdenum (Mo), nickel (Ni), lead (Pb), vanadium (V), zinc (Zn), antimony (Sb), arsenic (As), and cadmium (Cd). The ecological risk assessment focused on ten of these elements, while carcinogenic and non-carcinogenic risks were assessed for seven metals selected based on their toxicological importance. The results showed that Cd and Pb concentrations were higher in the downstream section. Cd and As exceeded ecological risk thresholds. Regarding human health, As and Pb surpassed the acceptable limits for both the Hazard Index (HI) and the Potential Carcinogenic Risk (PCR). According to EPA guidelines, these values indicate a potentially significant lifetime cancer risk. The main exposure routes include direct contact with sediments and the consumption of aquatic organisms. Continuous monitoring, phytoremediation actions, and restrictions on the use of contaminated water are strongly recommended to reduce ecological and health risks. Full article