Search Results (1,607)

Managing phosphorus (P) in acidic paddy soils is crucial for sustaining rice yields. However, the effects of combined humic acid (HA) and flue gas desulfurization gypsum (FG), a by-product of coal-fired power plants, on P forms remain poorly understood. This study examined P forms using a sequential extraction procedure and XANES spectroscopy following the application of HA, FG, and HA + FG. HA increased organic labile P, while FG and HA + FG promoted HCl-extractable Pi and humic Po, respectively. XANES data revealed that P associated with aluminum (Al) (hydr)oxides was dominant in acidic paddy soils. Brushite (CaHPO₄·2(H₂O)) accounted for 25% and 19% of total P in the FG- and HA + FG-treated soil, respectively. Iron (Fe)-bound P was absent in control and FG-treated soils but was present as strengite (FePO₄·2H₂O) in HA- and HA + FG-treated soils (23% and 30% of the total P, respectively). Inositol hexakisphosphate (IHP), a non-labile Po, was in HA- and HA + FG-treated soil (12% and 31% of the total P, respectively). Archerite (KH₂PO₄) was 40% and 20% of the total P in HA- and HA + FG-treated soil, respectively. HA alone is an effective soil amendment that enhances P cycling and availability by increasing organic P mineralization, boosting rice yield in acidic paddy soil. Full article

Tool steels are critical for high-load applications, e.g., forging and metal-forming, where they face thermal cracking, fatigue, erosion, and wear. This study evaluates the impact of gas nitriding and S-phase PVD coatings on the mechanical and tribological properties of four tool steels: 40CrMnNiMo8-6-4, 60CrMoV18-5, X50CrMoV5-2, and X38CrMoV5-3. Samples were heat-treated (quenched and tempered at 600 °C), then gas-nitrided at 575 °C for 6 h with nitriding potentials (Kn) of 0.18, 0.79, or 2.18, or coated via reactive magnetron sputtering in Ar/N₂ or Ar/N₂/CH₄ atmospheres at 200 °C or 400 °C. Characterization involved XRD, LOM, FE-SEM, GDOES, Vickers hardness (HV0.1), and ball-on-disk wear testing with Al₂O₃_ counter-samples. Gas nitriding produced nitrogen diffusion layers (80–200 μm thick) and compound layers (ε-Fe_(2-3)N, γ’-Fe₄N) at higher Kn, increasing hardness by 80–100% (up to 1100 HV0.1 for steel X38CrMoV5-3). S-phase coatings (1.6–3.6 μm thick) formed expanded austenite with varying N content, achieving comparable hardness (up to 1100 HV0.1) in high-N₂ atmospheres, alongside substrate diffusion layers. Both types of treatment enhance load-bearing capacity, adhesion, and durability, offering superior wear resistance compared to conventional PVD coatings and addressing demands for extended tool life in industrial applications. Full article

The Otukpo Burnt Brick Factory has remained dormant for more than three decades despite repeated government interventions. In this context, the present study investigates the suitability of soils from Otukpo, Benue State, Nigeria, for unfired brick production and as supplementary cementitious materials (SCMs). Four representative samples (OT1–OT4) were subjected to X-ray fluorescence (XRF), thermogravimetric analysis (TGA), particle size distribution (PSD), X-ray diffraction (XRD), unconfined compressive strength (UCS), cube strength, shrinkage, and water absorption tests. The results revealed high reactive oxide contents (SiO₂ + Al₂O₃ + Fe₂O₃ > 93%) with low SO₃ and moderate loss on ignition (~6%), thus indicating strong pozzolanic potential. PSD residues on the 45 µm sieve ranged from 6.8 to 17%, which is well below the ASTM C618 limit of 34%. XRD confirmed quartz and kaolinite as dominant phases. Strength activity indices showed that only OT3 and OT4 exceeded Nigerian (NIS 693:2007) and Indian (IS 1725:2023) standards when stabilized with 5 wt.% cement or sodium hydroxide; while OT1 and OT2 were below these thresholds. Water absorption values for OT3 (18.69%) and OT4 (19.04%) marginally satisfied Indian standards but failed Nigerian requirements, which is reflective of high porosity. Linear shrinkage (~14%) met IS 1498 marginally, and pH values (6.14–6.34) were consistent with lateritic soils. Overall, OT3 and OT4 demonstrated promise for low-energy SCMs and unfired brick applications, though they must be restricted to non-load-bearing uses unless further stabilization is applied. Full article

The treatment of polychlorinated dibenzodioxins and polychlorinated dibenzofurans (PCDD/Fs) in incineration fly ash presents a significant challenge in solid hazardous waste management. This study systematically analyzed the influence mechanisms of multiple factors on the removal efficiency of PCDD/Fs during fly ash pyrolysis. It integrated 4068 datasets conducted between 2010 and 2025 through meta-analysis. Results show that Al₂O₃, CaO, SiO₂, and Cl in fly ash components enhance the removal efficiency by 14.0%, while Fe₂O₃ (Content greater than 5.7%) exhibits inhibitory effects. Cd and Cr demonstrate a bimodal response pattern: low/high concentrations promote removal, while medium concentrations inhibit it. Process optimization identified the optimal parameter combination as pyrolysis temperatures of 500–900 °C, residence time of 50–90 min, and a gas flow rate greater than or equal to 400 mL/min. A significant negative correlation was observed between the initial dioxin concentration and removal efficiency. This study established a structural equation modeling (SEM) model to describe how metallic and nonmetallic components, fly ash components, and pyrolysis conditions determine removal efficiency. Fly ash composition was confirmed as the most influential factor (total effect = 0.3194), with fixed carbon and ash content being the most reliable indicators. Among pyrolysis conditions, gas conditions (flow rate, gas type) also significantly affected removal efficiency (total effect = 0.2357). Conversely, nonmetallic components and excessively prolonged pyrolysis time (beyond the window) consistently reduced removal efficiency. These findings provide theoretical support for upgrading fly ash pyrolysis processes toward low-carbon and resource-efficient operations. Full article

The conventional production of electronic-grade, high-purity, spherical silicon dioxide (SiO₂) faces challenges of high raw material costs and poor control over particle morphology. This study presents an alternative route using low-cost, powdered quartz as a starting material. The quartz was first purified by flotation to remove any associated minerals, such as talc. Subsequently, deep purification was achieved through a hydrothermal alkaline process, which leveraged the distinct leaching kinetics of SiO₂ and impurity ions (Al³⁺, Ca²⁺, Fe³⁺) under precisely controlled hydrothermal conditions (10 mL/g liquid-to-solid ratio, 3 mol/L NaOH, 200 °C, 8 h). This step yielded a sodium silicate solution with a purity of 99.999%. Spherical SiO₂ particles were then synthesized from solutions of varying moduli via chemical precipitation. The condensation kinetics of silicate anionic species (Qn) during acidification were investigated, revealing how the Qn distribution governs the final particle size and morphology. The optimal product exhibited excellent characteristics: a sphericity ≥ 0.98, a median particle size (D₅₀) of 400–500 nm, and a narrow particle size distribution (polydispersity index, PDI of 0.178–0.192). These properties surpass the requirements for the QYG-H Type 002 grade specified in the Chinese National Standard GB/T 32661-2016 (“Spherical Silica Powder”) and meet the standard for electronic-grade spherical SiO₂. This work provides a fundamental insight into morphology control and a feasible technical pathway for the value-added utilization of powdered quartz and the production of electronic-grade spherical SiO₂ with a narrow particle size distribution. Full article

The floricultural value of Hydrangea macrophylla is significantly influenced by its distinctive blue flower coloration, which results from aluminum uptake and vacuolar complexation. However, commercial cultivation faces challenges in achieving consistent bluing while avoiding Al toxicity. This study investigated the effects of Al concentration (0–971.62 mg/L) and application period on six blue-modifiable cultivars. Optimal results were achieved with an Al₂(SO₄)₃·18H₂O concentration of 6 g/L applied from two weeks after pinching until bloom. This regimen successfully induced vibrant sepal bluing without impairing chlorophyll content or plant growth. Furthermore, it enhanced tissue concentration of essential nutrients, including N, K, Mg, Fe, Zn, Mn, Cu, B, and Co. This study proposes a robust technical and theoretical framework for optimizing Al application to ensure consistent sepal color, which provides technical support for commercial production. Full article

This review investigates how cell form factors (cylindrical, prismatic, and pouch) and electrode architecture (jelly-roll, stacked, and blade) influence the performance, safety, and manufacturability of lithium-ion batteries (LIBs) across the main commercial chemistries LiFePO₄ (LFP), Li (NiMnCo)O₂ (NMC), LiNiCoAlO₂ (NCA), and LiCoO₂ (LCO). Literature, OEM datasheets, and teardown analyses published between 2015 and 2025 were examined to map the interdependence among geometry, electrode design, and electrochemical behavior. The comparison shows trade-offs among gravimetric and volumetric energy density, thermal runaway tolerance, cycle lifespan, and cell-to-pack integration efficiency. LFP, despite its lower nominal voltage, offers superior thermal stability and a longer cycle life, making it suitable for both prismatic and blade configurations in EVs and stationary storage applications. NMC and NCA chemistries achieve higher specific energy and power by using jelly-roll architectures that are best suited for tabless or multi-tab current collection, enhancing uniform current distribution and manufacturability. Pouch cells provide high energy-to-weight ratios and flexible packaging for compact modules, though they require precise mechanical compression. LCO remains confined to small electronics owing to safety and cost limitations. Although LFP’s safety and affordability make it dominant in cost-sensitive applications, its low voltage and energy density limit broader adoption. LiMnFePO₄ (LMFP) cathodes offer a pathway to enhance voltage and energy while retaining cycle life and cost efficiency; however, their optimization across various form factors and electrode architecture remains underexplored. This study establishes an application-driven framework linking form factors and electrode design to guide the design and optimization of next-generation lithium-ion battery systems. Full article

Samples of flotation tailings generated during the exploitation and processing of Zn–Pb–Cu–Ag ore from the Rudnik mine (Serbia) were investigated for their mineralogical, geochemical, and magnetic susceptibility properties. The flotation tailings consist of a complex mineral assemblage, including silicates, carbonates, sulfides, phosphates, sulfates, oxides, hydroxides, and native elements. Quartz, calcite, and orthoclase dominate the coarse fraction (>400 µm), accompanied by epidote, Ca-garnet, and Ca-clinopyroxene. Sulfide minerals are concentrated in finer fractions (<400 µm), with pyrite and arsenopyrite being the most abundant, followed by pyrrhotite, sphalerite, galena, and chalcopyrite. These sulfides occur as dispersed grains within a silicate–carbonate matrix. Post-depositional oxidative alteration is moderately developed, with pyrite replaced by hematite, galena by cerussite, and chalcopyrite by malachite. Geochemical analyses reveal that SiO₂ (avg. 38.98 wt%), Fe₂O₃ (avg. 23.68 wt%), Al₂O₃ (avg. 8.95 wt%), CaO (avg. 9.03 wt%) and MgO (avg. 1.50 wt%) dominate the composition. Economically significant metals include Zn (avg. 0.47 wt%), Pb (avg. 0.20 wt%), Cu (avg. 0.11 wt%), Ag (max. 19 µg/g), and Bi (max. 130 µg/g). Mass magnetic susceptibility shows a strong correlation with S (r = 0.92), Co (r = 0.90), and Bi (r = 0.87); moderate correlation with Fe₂O₃, Al₂O₃, and As; and negative correlation with Mn, TiO₂, Zn, and Pb. The ferromagnetic phase most likely originates from pyrrhotite, as well as hematite formed during pyrite alteration and goethite. Full article

FeCoNiCrAl and FeCoNiCrAlScY high-entropy coatings were fabricated via electron beam physical vapor deposition. The microstructure and short-term isothermal oxidation behavior of the coatings were compared. Sc and Y inhibited coating element diffusion to the superalloy substrate and formed co-precipitated phases during coating manufacturing. The Sc/Y co-doped coating exhibited accelerated phase transformation from θ- to α-Al₂O₃ as compared to the undoped one. The effect mechanism associated with the nucleation of α-Al₂O₃ was discussed. The preferential formation of Sc/Y-rich oxides promoted the nucleation of α-Al₂O₃ beneath them, and the θ-α phase evolution process was directly skipped, which suppressed the rapid growth of θ-Al₂O₃ and the initial formation of cracks in the alumina film and provided the FeCoNiCrAl high-entropy coating with an improved oxidation property in the early oxidation stage. Full article

Yuanjiang County is one of the most important gem-producing areas in China. The authors of this study discovered and collected gem-quality andradite Garnsts in the epidote amphibolite from the periphery of the ruby deposit in Shaku Village, Yuanjiang County. After careful observation of the collected andradite, it was found that these andradite samples appear green when the thickness is less than 2 mm and reddish-brown when the thickness is greater than 2 mm, exhibiting the typical Usambara effect. To investigate the gemological and spectroscopic characteristics of Yuanjiang andradite, this study conducted basic gemological tests, microscopic observation, electron probe microanalysis (EPMA), ultraviolet–visible (UV-Vis) absorption spectroscopy, Fourier transform infrared (FTIR) spectroscopy, and laser Raman spectroscopy on the collected samples. Tests show that Yuanjiang andradite has a lower specific gravity than typical andradite, which is due to the presence of epidote inclusions inside. EPMA results indicate that the samples contain a certain amount of Cr element. The crystal chemical formula of the samples calculated from the EPMA results is (Ca_2.89–2.93, Mn_0.01–0.02, Fe_0.15–0.10)(Fe_1.69–1.95, Al_0.00–0.23, Cr_0.00–0.23, Si_0.05–0.08)(SiO₄)₃. UV-Vis tests show that the samples have transmission windows in both the green- and red-light regions, with Fe³⁺ and Cr³⁺ acting as the main chromogenic ions, among which Cr³⁺ is crucial for the occurrence of the Usambara effect. The FTIR and Raman test results are basically the same as previous research results, but some peak positions related to metal cations differ from the theoretical values, which may be caused by the presence of a certain amount of Cr³⁺ in the samples. Full article

Carbon dioxide reforming of methane is a promising technology to recycle and reduce greenhouse gases (CH₄, CO₂) into valuable chemicals and fuels. The Co-Fe catalysts modified with a small amount of Pt and supported on alumina were designed to be explored in dry reforming (DRM) and combined CO₂-steam reforming (bireforming, BRM) of methane to produce syngas. The catalysts were characterized by physico-chemical methods (i.e., BET, XRD, TEM, SEM, and TPR-H₂). The synthesized catalysts are the X-ray amorphous nanosized materials with particle sizes of less than 30 nm. The processes were carried out using a feed of CH₄/CO₂/H₂O = 1/1/0–0.5 at varying temperature (400–800 °C) at atmospheric pressure and GHSV = 1000 h⁻¹. The combination of Co and Fe in varying ratios with Pt allowed for high activity and selectivity to be maintained. Extents of methane and CO₂ conversion are varied within a range of 79.5–97.5 and 64.2–85.2%, respectively, at 700–800 °C, while the H₂/CO ratio in the resulting syngas ranged from 0.98 to 1.30, depending on the catalyst and feed composition. Stability tests conducted for up to 80 h on stream showed no loss of activity of the 10%Co-Fe-Pt/Al₂O₃ catalysts in BRM. We believe that high activity of the synthesized catalysts occurs due to synergy in the Co-Fe-Pt system. Full article

Fe-Cr-Al coatings were obtained by air plasma spraying (APS) from 85Fe-12Cr-3Al and 68Fe-26Cr-6Al powders at two hydrogen flow rates (8 and 13 L/min), which resulted in four deposition regimes (A1, A2, B1, B2). Stainless steel 20Kh13 (equivalent to AISI 420) was used as the substrate material. The microstructure of the coatings has a typical lamellar layering with molten and semi-molten particles. When the hydrogen flow rate is increased to 13 L/min, a denser and more homogeneous structure with reduced porosity is observed. X-ray phase analysis revealed the presence of metal and oxide phases (Fe,Cr), Fe₃O₄, FeO, Fe²⁺Cr₂O₄, which indicates partial oxidation of particles during the spraying process and stabilization of the structure. Electrochemical tests in 3.5% NaCl solution showed that the 85Fe-12Cr-3Al coatings are characterized by a corrosion potential of E_o ≈ −0.60…−0.67 V, a corrosion current density of i_o = (2.6–4.7) × 10⁻⁵ A/cm², and a corrosion rate of 0.30–0.55 mm/year, whereas the 68Fe-26Cr-6Al coatings exhibit lower values of i_o = (1.4–2.9) × 10⁻⁵ A/cm² and a corrosion rate of 0.17–0.34 mm/year, indicating the formation of a denser protective oxide film (Cr₂O₃ + Al₂O₃) and enhanced surface passivation. Tribological tests showed that 85Fe-12Cr-3Al coatings demonstrate more stable friction compared to 68Fe-26Cr-6Al, while for regime B2, after 180 m, an increase in the friction coefficient is observed, caused by brittleness and the local destruction of the oxide film. A comprehensive analysis of the results showed that increasing the hydrogen consumption to 13 L/min improves the density and corrosion–tribological characteristics of the coatings. Full article

To address the limitations of traditional photo-Fenton reactions in antibiotic wastewater treatment, this study designed a continuous flat-plate photo-Fenton reactor based on the Fe₃O₄/TiO₂@Al₂SiO₅ fiberboard photocatalyst and applied it to the degradation of tetracycline HCl (TCH). The supported catalyst Fe₃O₄/TiO₂@Al₂SiO₅ was prepared via a calcination method, using the Al₂SiO₅ fiberboard as the carrier. This not only effectively addresses the issue of catalyst recovery but also enhances the dispersion and stability of the Fe₃O₄/TiO₂ catalyst as a support. Moreover, the catalyst mainly exhibited an amorphous structure. TiO₂ and Fe₃O₄ were successfully loaded onto the surface of the carrier. The operating parameters of the reactor were systematically optimized, and the optimal conditions were determined as follows: TCH influent concentration of 50 mg/L, hydraulic retention time (HRT) of 120 min, initial pH of 4.5, H₂O₂ dosage of 10 mmol/L, and ultraviolet (UV) light intensity of 2.36 kW/m³. Under these conditions, the TCH removal efficiency could reach over 90%. Active species trapping experiments indicated that hydroxyl radicals (•OH) were the main active substances responsible for TCH degradation. With the assistance of HPLC-MS/MS and GC-MS analyses, 19 types of degradation intermediates were identified. It was proposed that the TCH degradation pathway mainly included •OH-mediated hydroxylation addition reactions and demethylation reactions initiated by •OH and h⁺. The toxicity assessment showed that the toxicity of the degradation intermediates gradually decreased with the progress of the reaction. This reactor features high efficiency, stability, and easy operation, providing a feasible solution for the large-scale treatment of antibiotic wastewater. Full article

This study prepares Ni₅₀(AlNbTiV)₅₀-xY₂O₃ complex concentrated alloy composite coatings and analyzes their microstructure, phase composition, and high-temperature performance. The results indicate that each coating is composed of FCC phases, including γ-FeNi, Ni₃Al, and Ni₃(Al, Ti), as well as BCC phases such as Ni₃Nb and Ni₃Ti. With increasing Y₂O₃ content, the lamellar structure in the inter-dendritic regions of the coatings first decreases and then increases. The wear mechanism of the coating without Y₂O₃ addition under high-temperature conditions involves the combined effects of abrasive wear and adhesive wear. The coating with a 0.6 wt.% addition exhibits the smallest cracks and the lowest oxidation rate in high-temperature oxidation and thermal shock tests, with the oxidation weight gain reduced by 26.2% compared to the coating without Y₂O₃ addition. The abrasive and adhesive wear of this coating is mitigated, and the average friction coefficient and mass loss are decreased. When the mass fraction of Y₂O₃ is 0.4 wt.%, the coating structure shows a significant refinement effect and exhibits the best performance in tensile strength and high-temperature friction and wear tests. Full article

Plastics are essential to technological and industrial development, yet their prevalent single-use life and poor recycling rates are contributing to escalating environmental concerns. Expanded polystyrene (EPS), although valued for being lightweight, durable, and insulating, poses a significant challenge as it is typically disposed of after a single use. Furthermore, traditional recycling is limited because it requires clean, well-separated waste. Therefore, it remains necessary to develop recycling strategies that maximize the value of plastics. To address this issue, the present work aims to provide a comparative evaluation of the synthesis and characterization of FeMg/Al₂O₃ and Fe/Al₂O₃-MgO as catalysts, along with an analysis of their catalytic performance in the pyrolysis of EPS waste at varying temperatures and catalyst loadings. The results showed an advantage in using catalysts in the pyrolysis of EPS waste; however, the FeMg/Al₂O₃ (15 wt.%) catalyst demonstrated the best efficiency in the pyrolysis of EPS waste at 400 °C, achieving 96% liquid yield and reducing reaction times by up to 45% due to its high metal dispersion and strong metal-support interaction, which promotes faster and more efficient conversion. In contrast, Fe/Al₂O₃-MgO showed lower catalytic performance, although it can offer lower synthesis costs and good thermal stability, making it more viable on a large scale. These findings represent a significant advance in catalytic EPS recycling, offering promising strategies to promote the circular economy of EPS and extend its useful life. Full article