Search Results (623)

Kalanchoe laetivirens is widely consumed as a medicinal plant in rural and urban communities, traditionally used in folk medicine for treating inflammatory conditions and cancer. However, little is known about its elemental composition and the potential health risks associated with different preparation methods. This study aimed to evaluate concentrations of Al, As, Ba, Co, Cu, Fe, Mg, Mn, Mo, Na, Ni, P, Pb, Se, V, and Zn in raw leaves, tea infusions, and aqueous extracts, and to assess associated health risks. Elemental analysis revealed significant differences among preparations, with raw leaves presenting the highest concentrations, tea showing intermediate values, and aqueous extracts the lowest. For example, potassium (K) reached 15,399.31 ± 131.55 mg/kg in leaves and 12,249.97 ± 240.17 mg/L in tea, while arsenic (As) and lead (Pb) were also detected at concerning levels, with As at 5.98 ± 1.64 mg/L and Pb at 3.82 ± 0.179 mg/L in tea. Risk assessment was performed using the Chronic Daily Intake (CDI), Hazard Quotients (HQs), Hazard Index (HI), and Incremental Lifetime Cancer Risk (ILCR), considering different exposure frequencies. Results indicated phosphorus (P) as the dominant contributor to non-carcinogenic risk, with HI values exceeding safety thresholds in all scenarios, while arsenic was the primary carcinogenic element, with ILCR values up to 10⁻³ in tea. These findings highlight the influence of preparation methods on exposure levels and reinforce the need for continuous monitoring and regulatory guidelines to ensure the safe medicinal use of K. laetivirens. Full article

Wastewater generated in municipal rendering facilities requires multi-step treatment, but it may also serve as a source of nutrients and water and thus may be valorized before or instead of the necessary wastewater treatment operations. In this work, wastewaters from a composting plant were utilized to support the growth of Miscanthus x giganteus, known as both a remediation plant and an energy biomass source. A pot experiment was established to compare the effects of different wastewater doses (0, 50, 100, and 200 mL per pot per week) on the miscanthus biomass yield, phytoextraction of heavy metals, biomass heat of combustion, and plant condition. The increase in the wastewater dose resulted in increases in both biomass yield (from about 44 to 139%) and biomass heat of combustion (from 7 to 17%) when compared to the control sample, with no adverse effects on plant physiological parameters. The highest concentrations of metals were found in miscanthus grown with the highest dose of wastewaters. It was found that higher wastewater dose correlates to both higher phytoextraction and phytorecovery of metals from plant substrate and wastewaters. The highest metal uptake was identified for Fe (431 mg·pot⁻¹), followed by Al, Zn, Mn, Cu, Ni, Cr. The lowest metal uptake was noted for Pb, Co and Cd (0.88, 0.11, and 0.95 mg·pot⁻¹, respectively). The results indicate that miscanthus can be recommended for industrial wastewater treatment. In addition, due to high absorption efficiency of the substrate components, miscanthus can be used as a remediation tool, e.g., for the ecological stabilization of remediation of metal-polluted soils, especially in municipal facilities like rendering plants. This presents a circular perspective for the valorization of post-fermentation wastewaters with subsequent growth of energy crops, with other potential benefits for the environment, such as soil treatment, absorption of CO₂, and air purification. Full article

In this study, a duplex lightweight steel with the compositions of Fe-30Mn-9Al-1C-1V-5Ni (wt.%) was designed, and its microstructure and mechanical properties were analyzed after simple rolling and heat treatment. The microstructure of duplex lightweight steel consists of austenite and B2 phases, with the dual-nanoprecipitation of L′1₂ type long-range ordered domains and VC carbides within the austenite. The steel exhibits an ultra-high strength-ductility combination, with a yield strength of 1316 ± 16 MPa, a tensile strength of 1458 ± 11 MPa, and a total elongation of 11.7 ± 1.2%. Its high strength is primarily attributed to hetero-deformation induced (HDI) strengthening, solid solution strengthening, and precipitation strengthening. Meanwhile, the substantial dislocation accumulation in both austenite and B2 phases, coupled with the HDI hardening from intense heterogeneous deformation near grain/phase boundaries, collectively confers the steel with excellent ductility. Full article

In the manufacturing sector, energy loss often stems mainly from wear. By improving the surface characteristics of alloys, we can substantially cut down on this kind of loss, which in turn boosts the efficiency of energy use. In this study, Fe₄₀Mn₁₉Cr₂₀Ni₂₀Mo₁ high-entropy alloy (HEA) with a face-centered cubic (FCC) structure was subjected to aluminum–nitrogen co-infiltration treatment via pack aluminizing and plasma nitriding, forming an aluminum–nitrogen co-infiltrated layer with a thickness of approximately 17 μm. An analysis was carried out on the microstructure, growth dynamics, and tribological behavior of the Al-N co-infiltrated layer across a broad temperature spectrum. The results showed that the surface hardness of the samples treated by aluminizing and Al-N co-infiltration reached 592 HV and 993 HV, respectively, which were significantly higher than that of the hot-rolled alloy (178 HV). The Al-N co-infiltrated HEA exhibited a low and stable friction coefficient as well as wear rate over a wide temperature range (20–500 °C), which was attributed to the formation of the Al-N co-infiltrated layer composed of AlN, CrN, and FeN phases. This study demonstrates that Al-N co-infiltration treatment is an effective surface modification technique, which can significantly enhance the hardness and tribological properties of high-entropy alloys over a wide temperature range. Full article

Due to climate change, electromobility and thus lithium-ion batteries are attracting increased interest. With a simultaneous increase in demand for raw materials like Li, Ni, Co, and Mn, their hydrometallurgical recycling is also gaining attention. The associated recoveries must be improved due to EU regulations. In a lab scale, metals are lost to the wrong filter cakes after leaching, cementation, and precipitations. Therefore, this work investigates the question of how many wash steps are suitable after each process step to optimize the recoveries and purity of filter cakes by comparing a reference process and a process with extended washing. The comparison showed that it is possible to recover up to 3.5% of Ni, Co, and Mn by extended washing at each step and in total nearly 100% of Li if wash water is recirculated. An investigation of the substeps of washing demonstrated that single wash steps are able to recover from 0.5% to 3.5% of Ni, Co, and Mn and from 1.6% to 8.7% of Li. The impact of extended washing on purity is shown by the analysis of filter cakes, where the purity of Fe and Al could be improved by 43.0% and for Ni, Co, and Mn by 48.0%. The paper closes with recommendations on how many wash steps are suitable after each process step. Full article

The longevity, site fidelity, and trophic position of freshwater turtles have led to their increasing recognition as useful bioindicators of environmental contamination. Mauremys leprosa (n = 25) shells from a Northern African wetland system were examined for trace element concentrations in order to assess shell composition as a non-invasive biomonitoring method. Micro x-ray fluorescence (μXRF) method was used to measure the shell concentrations of 17 elements, including Ca, P, Fe, Zn, Mn, Sr, Pb, Sb, and Al. As would be expected from the structural composition of bony tissues, calcium and phosphorus were the predominant constituents. In addition to bulk concentrations, micro-XRF elemental mapping revealed heterogeneous spatial distributions of essential and toxic elements within the shells, providing visual evidence of bioaccumulation patterns and supporting the use of shells as non-invasive bioindicators. There were statistically significant sex-related differences in the levels of trace elements, with males exhibiting higher concentrations of Mg, Mn, Sb, Pb, and Al (p < 0.05). Spearman correlations revealed strong associations between certain shell elements (e.g., Fe, Mn, Ti, Zn) and morphometric parameters. Comparisons with environmental samples (water and sediment) showed moderate to strong correlations, particularly with sediment metal concentrations, supporting the utility of shell chemistry as an integrative exposure matrix. Nonetheless, there were significant percentages of censored or missing values for certain metals (Cu, Ni, and As). This study emphasizes how viable turtle shells are as non-lethal markers of bioaccumulation and stresses how crucial it is to take environmental matrices, element-specific variability, and sex into account when assessing contamination. Longitudinal monitoring, physiological biomarkers, and isotopic analysis should all be used in future studies to bolster the causal relationships between environmental exposure and turtle health. Full article

Metals have a crucial impact on the environment and the economy. They constitute macro- and microelements essential for the proper functioning of living organisms. On the other hand, their excess can pose a life-threatening risk. Of particular economic importance are metals such as Co, Ni, Mn, Ti, Al, Cd, Fe, and Li, which are used, among other things, to build batteries in electric and hybrid cars. In the event of a cell fire, significant amounts of metals are rapidly released into the environment. The magnitude of emissions depends on the type of chemistry used in the battery and the type of extinguishing agent used to extinguish the fire. It should be noted that the available literature only provides information on the total amount or concentration of a given metal in the analyzed samples. However, there is no information on the speciation of metals, including their macro and nano forms, which is crucial for determining the toxicity and biological and chemical activity of a given element. Full article

Heavy metal pollution threatens coastal ecosystems. Mangrove sediments, as transitional zones, are prone to contaminant accumulation. This study investigated eight heavy metals (Cu, Pb, Ni, As, Cr, Zn, Cd, Co) in Liusha Bay (Leizhou Peninsula, China). Field sampling, lab analysis, and multivariate statistics were used to assess pollution sources and ecological risks. The results show Al and Fe dominate sediment composition, with elevated P, Mn, and Sr. Arsenic (As) exhibiting the highest pollution severity (50% sites moderately contaminated by I_geo). Enrichment factors (EF) indicate anthropogenic contributions to As, Cu, Ni, and Co, while Cd and Pb originate mainly from natural sources. Ecological risk assessments highlight moderate risks for As and Cd at some sites. Source analysis identifies three dominant pathways: (1) lithogenic inputs (volcanic rock weathering) contributing Fe, Zn, Cr, and Ni; (2) biogenic materials (calcium carbonate-secreting organisms) influencing Cu, Mn, and Cd; and (3) anthropogenic activities (aquaculture, maritime traffic) linked to Cu and Pb. This study emphasizes localized monitoring of As and Cd in mangroves and calls for the integrated management of natural and anthropogenic drivers to mitigate pollution risks. Full article

Hair dyes are widely used cosmetic products that can contain trace metals and metalloids, posing potential health risks through dermal exposure. This study aimed to assess and compare the concentrations of selected metals and metalloids in six brands of commercial hair dyes sold in Brazil and Paraguay and to evaluate their average daily dermal exposure doses, hazard quotients, hazard indices, and carcinogenic risk. Concentrations of Cr, Cd, Co, Cu, Fe, Mn, Mo, Ni, As, Al, Pb, Ba, Ag, and Zn in hair dye were quantified by standardized analytical methods. The Paraguayan brand showed the highest levels for several elements, including As (4.17 mg/kg), Al (130.276 mg/kg), and Fe (30.033 mg/kg). Estimated dermal exposure doses reached up to 3.35 × 10⁻⁶ mg/kg/day for arsenic, 1.68 × 10⁻³ mg/kg/day for aluminum, and 8.59 × 10⁻⁸ mg/kg/day for chromium. Although all hazard indices remained below 1, suggesting low non-carcinogenic risk, the calculated carcinogenic risk for arsenic in the Paraguayan product was 1.23 × 10⁻⁵, entering the medium-risk range. These findings highlight relevant differences in raw material control and potential cumulative health risks, especially for frequent users. Continuous quality control, harmonized regulatory standards, clear labeling, and further biomonitoring studies are strongly recommended to minimize long-term exposure to toxic elements in hair dye formulations and to ensure safer consumer products. 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

FeCoNiCuAl high-entropy alloys exhibit remarkable mechanical properties; nevertheless, these materials struggle to withstand harsh environments because of their insufficient resistance to wear and corrosion. The addition of Si can significantly enhance the alloy’s high-temperature performance, hardness, and wear resistance, thereby making it more suitable for applications in high-temperature or corrosive environments. To overcome these drawbacks, this research investigates how varying Si content affects the microstructure and properties of FeCoNiCuAl coatings. Composite coatings of FeCoNiCuAlSi_x (x = 0, 0.5, 1.0, 1.5, 2.0) were fabricated on 65 Mn substrates using laser cladding. Various testing methods, including metallographic microscopy, Vickers hardness testing, friction and wear testing, and electrochemical analysis, were employed to examine the phase structure, microstructure, and hardness of the coating. It is observed that the FeCoNiCuAl coating begins with a uniform FCC phase structure. However, as the Si content increases, a phase transformation to the BCC structure occurs. The microstructure is primarily composed of isometric crystals and dendrites that become finer and more compact with higher Si content. For the FeCoNiCuAlSi_2.0 coating, the microhardness reaches 581.05 HV_0.2. Additionally, wear resistance shows a positive correlation with Si content. Electrochemical testing in NS4 solution shows that the corrosion potential of the coating increases from −0.471 V for FeCoNiCuAl to −0.344 V for FeCoNiCuAlSi_2.0, while the corrosion current density decreases from 1.566 × 10⁻⁶ A/cm² to 4.073 × 10⁻⁶ A/cm². These results indicate that Si addition plays a crucial role in enhancing the mechanical properties and corrosion resistance of FeCoNiCuAl coatings, making them more suitable for high-performance applications in extreme environments. Full article

This study investigated water quality, metal ion concentrations, and antibiotic residues specifically enrofloxacin (ENR) and its metabolite ciprofloxacin (CIP), across six American shad (Alosa sapidissima) aquaculture sites over a one-year period. Water and sediment samples were analyzed to determine contamination levels, and ENR-degrading bacteria were isolated from the culture environment to explore their potential use in bioremediation. Findings showed that NH₃-N and total suspended solids (TSS) exceeded recommended standards at all sampling sites. Elevated levels of Li, Na (except S1), Fe, Ni (except S2 and S4), Sr, and Cu were found at site S3. Site S5 recorded the highest concentrations of Al, As, and Pb, while Cd was most abundant at S6. In sediments, S5 showed higher levels of Mg, K (except S3), Ca, Cr, Mn, Fe, Ni, As, Pb, Cu, and Zn (except S3). ENR and CIP were detected in all water and sediment samples, with a 100% detection rate. The highest ENR (16.68–3215.95 mg·kg⁻¹) and CIP (3.90–459.60 mg·kg⁻¹) concentrations in water occurred at site S6, following a seasonal pattern of autumn > winter > summer > spring. In sediments, the maximum ENR (41.43–133.67 mg·kg⁻¹) and CIP (12.36–23.71 mg·kg⁻¹) levels were observed in spring. Two ENR-degrading bacterial strains were successfully isolated and identified as Enterococcus and Bacillus. Optimal degradation was achieved at 30 °C, pH 8.0, 6% inoculum, and 3000 Lux, resulting in a 64.2% reduction in ENR after 72 h. Under slightly different conditions (25 °C, pH 10), degradation reached 58.5%. This study provides an efficient strain resource for the bioremediation of ENR pollution in the aquaculture water of American shad. Full article

Highly developed countries generate large volumes of industrial waste, the type and quantity of which are strongly linked to the characteristics of the industries that produce it. Industrial waste can adversely affect the environment, so its disposal and management are a major challenge. Understanding the characteristics of a given waste type (e.g., its chemical and phase composition, technical parameters and likelihood of releasing constituents into aquatic and soil environments) allows its potential economic applications to be determined. A simple application of mineral waste is in the production of artificial aggregates, which are increasingly used as a substitute for natural aggregates. In Poland, artificial aggregates are widely produced from metallurgical waste from steel and non-ferrous metallurgy, which may contain numerous components that are potentially environmentally damaging. Depending on their occurrence form (i.e., mineral composition), these contaminants have varying potential to be released into aquatic and soil environments. This study presents the results of mineral and chemical composition analyses and leachability tests conducted on aggregates produced from metallurgical waste, including slags from blast furnaces, steelmaking, Zn and Pb production, and Ni production. The studied aggregates are characterised by chemical and phase composition differences, resulting from the type of slag from which they originate. The chemical composition of blast furnace slag is dominated by CaO, SiO₂, Fe₂O₃, and MgO; steelmaking slag by CaO, Fe₂O₃, and SiO₂; Zn and Pb production slag by SiO₂, Fe₂O₃, SO₃, and CaO; and Ni production slag by SiO₂, Fe₂O₃, CaO, and Al₂O₃. The phase composition of all the tested aggregates is dominated by silicates resistant to leaching (weathering), which results in low levels of Al, Ca, Cr, Mn, Zn, Pb, Cu, As, Sr and Ni leaching, not exceeding 1.6%. Full article

This study investigated how metal concentrations and microplastic abundance co-vary temporally and spatially in sediments in Durban Harbour, South Africa. The effects of sediment contamination on the amphipod Grandidierella lignorum was additionally investigated. Sediments from five sites in the harbour, namely Little Lagoon (LL), Yacht Bank (YB), Marina Bank (MB), Western Bank (WB), and Central Bank (CB), were analysed for metals using ICP-OES, and microplastic particles were counted. Sediment metal concentrations varied across sites and seasons, with Al and Fe dominating. Elevated levels of Cu, Zn, and Pb were observed, particularly in areas with high industrial activity, suggesting point-source contamination. Trace concentrations of As, Cd, and Ni were found and these metals were excluded from further analysis. Abundance ranged from 0.2 to 2.5 particles per gram dry weight, and differed significantly among sites (p < 0.01) with the highest concentrations in LL and YB. Amphipod survival rates following exposure to sediment did not significantly differ among sites but correlated moderately with microplastic abundance (p > 0.05, R² = 0.57). Tissue analysis revealed selective metal accumulation, following the trend Al > Fe > Zn > Cu > Cr, with Mn, As, and Pb undetected. These results highlight the spatial heterogeneity of sediment contamination in Durban Harbour and demonstrate the bioaccumulation potential and ability to regulate metals in G. lignorum, particularly for essential metals like Fe and Zn. Despite no clear evidence linking microplastics to metal concentrations, the findings highlight the complex interactions between contaminants and their potential ecological impact. Full article

High-entropy alloys (HEAs) are highly concentrated, multicomponent alloys that have received significant attention due to their superior properties compared to conventional alloys. The mechanical properties and hardness are interrelated, and it is widely known that the hardness of HEAs depends on the principal alloying elements and their composition. Therefore, the desired hardness prediction to develop new HEAs is more interesting. However, the relationship of these compositions with the HEA hardness is very complex and nonlinear. In this study, we develop an artificial neural network (ANN) model using experimental data sets (535). The compositional elements—Al, Co, Cr, Cu, Mn, Ni, Fe, W, Mo, and Ti—are considered input parameters, and hardness is considered as an output parameter. The developed model shows excellent correlation coefficients (Adj R2) of 99.84% and 99.3% for training and testing data sets, respectively. We developed a user-friendly graphical interface for the model. The developed model was used to understand the effect of alloying elements on hardness. It was identified that the Al, Cr, and Mn were found to significantly enhance hardness by promoting the formation and stabilization of BCC and B2 phases, which are inherently harder due to limited active slip systems. In contrast, elements such as Co, Cu, Fe, and Ni led to a reduction in hardness, primarily due to their role in stabilizing the ductile FCC phase. The addition of W markedly increased the hardness by inducing severe lattice distortion and promoting the formation of hard intermetallic compounds. Full article