Search Results (616)

In this study, CaO-SiO₂-Al₂O₃-MgO-TiO₂ slag was used as the research object to simulate the blast furnace ironmaking process. Based on the experimental data, the influences of basicity (R(w(CaO)/w(SiO₂))) and the magnesia–alumina ratio (w(MgO)/w(Al₂O₃)) on desulfurization ability are discussed. Additionally, the influences of dissimilarity, basicity, and the magnesia–alumina ratio on slag structure were analyzed using Fourier transform infrared spectroscopy (FT-IR). The results show that when w(Al₂O₃) = 20% and w(MgO)/w(Al₂O₃) = 0.50, sulfide capacity (lgC_s) accretion with the increment in R. Moreover, when w(Al₂O₃) = 20% and R = 1.30, sulfide capacity accretion with the increment in w(MgO)/w(Al₂O₃). Fourier transform infrared spectroscopy was used to confirm that, with increasing basicity and the magnesia–alumina ratio, the concentration of dissociated free oxygen ions (O²⁻) in slag increases, and these ions interact with the bridging oxygen (O⁰) of silicate to depolymerize the complex Si-O structure into simpler units. Full article

The effect of palladium addition to a hybrid Co/SiO₂ + HZSM-5 + Al₂O₃ catalyst on the combined Fischer–Tropsch (FT) synthesis and hydrocarbon hydroconversion process was studied. Catalysts with a Pd content of 0.075–0.3 wt.% were characterized by a complex of physicochemical methods, including synchrotron radiation X-ray diffraction (SR-XRD), temperature-programmed reduction with hydrogen (H₂-TPR), temperature-programmed desorption of hydrogen with oxygen titration (H₂-TPD/O₂ titration), IR spectroscopy of adsorbed pyridine, and STEM-EDX analysis. It was found that the addition of palladium decreases the cobalt oxide reduction temperature due to interphase hydrogen transfer. Tests in hydrocarbon synthesis at 240–250 °C, a pressure of 2 MPa, and an H₂/CO ratio of 2 showed that the sample with 0.15% Pd exhibits the highest selectivity for C₅+ hydrocarbons (66.8% at 240 °C) and stability for 150 h. Analysis of the synthesis products revealed a fivefold decrease in the proportion of alkenes and an increase in isoalkanes with increasing Pd concentration. This effect enables the in situ hydroprocessing of primary FT products in a single reactor. The results demonstrate that the targeted introduction of palladium into the hybrid system is an effective strategy for regulating its functionality, allowing for the one-stage production of high-quality fuels with a controlled hydrocarbon composition from syngas. Full article

This study presents integrated zircon U-Pb geochronology, whole-rock geochemistry, and Sr-Nd-Hf isotopic investigations of quartz diorite and gneissic quartz diorite from the Datian Complex along the western Yangtze Block, elucidating their petrogenesis and tectonic implications. Key findings reveal: (1) The crystallization ages of the Datian Complex (~770–755 Ma) record episodic magmatic activity over a ~16 Ma period, indicating a multi-stage tectonic evolution; (2) Both rock types exhibit intermediate SiO₂ (57–64.58 wt.%), high Al₂O₃ (15.44–17.80 wt.%), and MgO (2.18–3.67 wt.%; Mg# = 47.41–52.65) with calc-alkaline signatures (Na₂O/K₂O = 1.14–2.65), coupled with adakitic traits including pronounced LREE/HREE fractionation (La_N/Yb_N = 3.83–26.4), negative Eu anomalies (δEu = 0.61–1.05), elevated Sr (372–701 ppm), and Sr/Y ratios (24.6–56.2), collectively classifying the complex as high-Si adakite; (3) The isotopic homogeneity (whole-rock Sr-Nd: ⁸⁷Sr/⁸⁶Sr(i) = 0.7038–0.7048, εNd(t) = −1.5 to–3.8; zircon Hf: εHf(t) = 1.24–6.88) supports a two-stage petrogenetic model involving partial melting of subducted oceanic slab, followed by mantle wedge metasomatism during magma ascent. These results position the Datian Complex as a Neoproterozoic arc-related adakitic magmatic system within the active continental margin of the Yangtze Block. Full article

Valorizing construction and demolition waste (CDW) via alkaline activation enables low-carbon binders. This study assesses binary geopolymers formulated with recycled brick powder (PLR) and recycled concrete powder (PCR) in seven precursor ratios (0–100% PCR), activated with a ternary NaOH/Na₂SiO₃/KOH solution (silicate modulus M_s ≈ 3.2) at L/B = 0.15, and cured for 7, 14, and 28 days. Compressive strength (fc), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and scanning electron microscopy with energy-dispersive X-ray spectroscopy (SEM-EDS) were used to link microstructure–phases–properties. A local maximum in fc at ~30% PCR (16.2 MPa at 28 d) was observed versus 0% PCR (14.2 MPa) and ≥50% PCR (13.8 → 10.1 MPa at 28 d). XRD indicated a reduction in inherited crystalline phases and an increased amorphous fraction at ~30% PCR; FTIR (normalized peak position and FWHM of the T–O–Si band, not absolute intensity) suggested higher network extension; SEM-EDS (local/semiquantitative) showed a moderate rise in Ca that supports C-A-S-H domains bridging the N-A-S-H network. At a high PCR, excess Ca simplified mineralogy (quartz/portlandite dominance), promoted competitive routes (C-S-H/carbonation), reintroduced microdefects, and reduced fc. A theoretical oxide balance per mix identified a compositional window where Ca/(Si + Al) ≈ 0.35–0.45 coincides with the mechanical optimum and with XRD/FTIR tracers. Overall, a ~30% PCR window maximizes co-reticulation of N-A-S-H/C-A-S-H and densification without compromising aluminosilicate continuity, providing transferrable design and process-control criteria for CDW-based geopolymer binders. Full article

This study explores a sustainable synthesis route for FAU-type zeolite X using acid-treated ladle slag as a silicon source and waste aluminum cans as an alternative aluminum precursor. Conventional zeolite synthesis relies on high-purity reagents, which are costly and environmentally intensive to produce. Previous research has rarely addressed the valorization of ladle slag and metallic aluminum waste for zeolite formation, leaving their potential largely unexplored. The study focuses on the effective utilization of industrial and post-consumer wastes—acid-treated ladle slag and aluminum cans—as precursors for FAU-type NaX zeolite, demonstrating their feasibility as alternative silicon and aluminum sources. Here, zeolite X was synthesized hydrothermally from treated slag combined with either dissolved aluminum cans and commercial sodium aluminate at 90 °C for 6 h. FAU-type zeolite X was successfully synthesized using both aluminum sources, with a SiO₂/Al₂O₃ ratio of approximately 1.4. The results demonstrate that waste-derived precursors can effectively replace conventional chemicals, yielding predominantly NaX zeolite with high crystallinity and minor NaA impurity (as observed by XRD), with experimental yields of 1.47 g for aluminum cans and 1.266 g for sodium aluminate. The obtained zeolite X samples were structurally and texturally characterized by XRD, FTIR, XRF, BET surface area analysis, and thermogravimetric analysis (TG). Full article

Chromium (Cr) exists in multiple oxidation states, with Cr(III) and Cr(VI) being the most environmentally and industrially relevant due to their distinct toxicity profiles and chemical behaviour. This study presents a comprehensive method that combines chemical simulation modelling, emission spectroscopy for quantification, and the controlled laboratory production of Cr species. Key findings include that acid digestion effectively extracted the Cr(III) and total Cr species, while thermodynamic modelling forecasted their stability and speciation under various environmental conditions. Thematic analysis indicates that the current quantification of Cr species is still in early development and remains centralized. Mineralogical and surface investigations showed that samples 1 and 2 have a BET surface area below 1 m²/g, whereas samples 3 and 4 exceed this. All samples are crystalline, with approximately 54.3 weight percent Cr₂O₃, 7.3 weight percent SiO₂, 17.75 weight percent of MgO, and 8.3 weight percent Al₂O₃, suggesting Al and Fe²⁺ replacement of Cr in the spinel structure. Computational fluid dynamics (CFD) modelling revealed that longer residence times are necessary for higher Cr metallization under H₂-CH₄-reducing conditions, and accurately predicted carbon deposition on pellets. These results demonstrate that CFD can optimize the H₂:CH₄ ratio to minimize carbon deposition and enhance gas transport to reaction sites. Full article

Little is known of a large black shale belt within the Naij Tal Group in the East Kunlun region, which hosts polymetallic deposits, including manganese, vanadium, and cobalt. The recently discovered Dagangou vanadium mineralization is the first black rock series-type vanadium deposit in the East Kunlun region and Qinghai Province and represents a significant find owing to its intermediate scale. This study investigated the mineralogy, major and trace elements, rare earth elements, and platinum group element geochemistry of the Dagangou vanadium deposit. Scanning electron microscopy and energy-dispersive X-ray spectroscopy revealed that the main vanadium-bearing minerals are micas, followed by limonite, clay minerals, feldspar, and jarosite. The SiO₂/Al₂O₃, Co/Zn, Sr/Ba, and Pd/Ir ratios, as well as the Ir content of the ores, indicated strong involvement of hydrothermal activity in the mineralization process. The V/Cr, Ni/Co, and U/Th ratios, as well as the δU values and significant negative δCe anomalies, suggested that the vanadium-bearing black rock series formed in a strongly anoxic reducing environment. The Al₂O₃/(Al₂O₃ + Fe₂O₃) and MnO/TiO₂ ratios, along with weak positive δEu anomalies and strong enrichment of heavy rare earth elements, indicated that mineralization occurred in an extensional tectonic setting. The black shale-hosted vanadium polymetallic deposit formed in a setting that transitioned from an open oceanic deep-sea environment to a progressively shallower continental margin. Full article

Cemented tailings backfill (CTB) is widely used in mining operations due to its operational simplicity, reliable performance, and environmental benefits. However, the poor consolidation of fine tailings with ordinary Portland cement (OPC) remains a critical challenge, leading to excessive backfill costs. This study addresses the utilization of modified manganese slag (MMS) as a supplementary cementitious material (SCM) for fine tailings from an iron mine in Anhui, China. Sodium silicate (Na₂SiO₃) modification coupled with melt-water quenching was implemented to activate the pozzolanic reactivity of manganese slag (MS) through glassy structure alteration. The MMS underwent comprehensive characterization via physicochemical analysis, X-ray diffraction (XRD), and Fourier-transform infrared spectroscopy (FTIR) to elucidate its physicochemical attributes, mineralogical composition, and glassy phase architecture. The unconfined compressive strength (UCS) of the CTB samples prepared with MMS, OPC, tailings, and water (T-MMS) was systematically evaluated at curing ages of 7, 28, and 60 days. The results demonstrate that MMS predominantly consists of SiO₂, Al₂O₃, CaO, and MnO, exhibiting a high specific surface area and extensive vitrification. Na₂SiO₃ modification induced depolymerization of the highly polymerized Q⁴ network into less-polymerized Q² chain structures, thereby enhancing the pozzolanic reactivity of MMS. This structural depolymerization facilitated formation of stable gel products with low calcium–silicon ratios, conferring upon the T-MMS10 sample a 60-day strength of 3.85 MPa, representing a 94.4% enhancement over the T-OPC. Scanning electron microscopy–energy dispersive spectroscopy (SEM-EDS) analysis revealed that Na₂SiO₃ modification precipitated extensive calcium silicate hydrate (C-S-H) gel formation and pore refinement, forming a dense networked framework that superseded the porous microstructure of the control sample. Additionally, the elevated zeta potential for T-MMS10 engendered electrostatic repulsion, while the aluminosilicate gel provided imparted lubrication, collectively improving the flowability of the composite slurry exhibiting a 26.40 cm slump, which satisfies the requirements for pipeline transportation in backfill operations. Full article

Recent discoveries of fluorite–barite deposits in the Donghai–Linshu area in northern Jiangsu Province, China, underscore the region’s mineral potential, yet detailed geological investigations remain limited. In this study, we examined monzonite and quartz monzonite from drill cores in the Jiashan mining area using petrography, U–Pb zircon dating, zircon trace element geochemistry, whole-rock geochemistry, and zircon Lu–Hf isotopes. Laser ablation inductively coupled plasma mass spectrometry (LA–ICP–MS) zircon U–Pb analyses were conducted to constrain the crystallization ages of the monzonite (127.06 ± 0.54 Ma and 126.83 ± 0.75 Ma) and quartz monzonite (127.2 ± 0.5 Ma and 128.59 ± 0.62 Ma) to the Early Cretaceous, marking a significant magmatic event. Many of the zircons contain inherited Neoproterozoic cores (718–760 Ma and 800–860 Ma), indicating the assimilation of deep crustal materials of this age. The monzonite is metaluminous, with moderate SiO₂ (61.61–62.41 wt.%), high alkalis (Na₂O + K₂O = 7.48–7.92 wt.%), and A/CNK = 0.72–0.91. The quartz monzonite has higher SiO₂ (66.26–68.18 wt.%) and alkalis (8.32–9.33 wt.%). Both rock types exhibit similar trace and rare earth element patterns: enrichment in large-ion lithophile and light rare earth elements, depletions in Nb, Ta, and Ti, no significant Zr-Hf depletion, and weak negative Eu anomalies (δEu ≈ 0.84–1.00). Their low Zr + Nb + Ce + Y contents, Ga/Al ratios, and TFeO/MgO ratios indicate that they have an I-type granite affinity. The Early Cretaceous zircons have highly negative ε_Hf(t) values (−33.7 to −23.5) and ancient two-stage model ages (2622–3247 Ma), which are consistent with derivation from Archean crust. The inherited Neoproterozoic zircons have younger Paleo–Mesoproterozoic T_DM2 ages. The evidence suggests that both intrusions were mainly generated by partial melting of ancient Archean basement, with minor mantle input. The magma generation was likely triggered by crustal anatexis induced by the underplating of mantle-derived magmas in an extensional tectonic regime, coeval with Early Cretaceous magmatism in the Sulu orogen. Full article

The continued performance scaling of AI gigafactories requires the development of energy-efficient devices to meet the rapidly growing global demand for AI services. Emerging materials offer promising opportunities to reduce energy consumption in such systems. In this work, we propose an electro-optic microring modulator that exploits a graphene (Gr) and transition-metal dichalcogenide (TMD) interface for phase modulation of data-bit signals. The interface is configured as a capacitor composed of a top Gr layer and a bottom WSe₂ layer, separated by a dielectric Al₂O₃ film. This multilayer stack is integrated onto a silicon (Si) waveguide such that the microring is partially covered, with coverage ratios varying from 10% to 100%. In the design with the lowest power consumption, the device operates at 26.3 GHz and requires an energy of 5.8 fJ/bit under 10% Gr-TMD coverage while occupying an area of only 20 μm². Moreover, a modulation efficiency of V_πL = 0.203 V·cm and an insertion loss of 6.7 dB are reported for the 10% coverage. The Gr-TMD-based microring modulator can be manufactured with standard fabrication techniques. This work introduces a compact microring modulator designed for dense system integration, supporting high-speed, energy-efficient data modulation and positioning it as a promising solution for sustainable AI gigafactories. Full article

The efficient separation of H₂ from CH₄ is crucial for hydrogen purification from industrial off-gases using pressure swing adsorption (PSA). In this study, the competitive adsorption behavior of H₂/CH₄ on LTA zeolites was systematically investigated via grand canonical Monte Carlo (GCMC) simulations, with a focus on the effects of cation type (Na⁺, Li⁺, Ca²⁺, Mg²⁺), Si/Al ratio (1–1.5), temperature (298–318 K), and pressure (0.2–2 MPa). The results reveal that CH₄ favors β-cages as excellent adsorption sites with high population density, followed by the regions adjacent to the cations or framework oxygen atoms of the eight-membered rings. In contrast, H₂ is uniformly distributed throughout all the channels. Cations with higher valence and smaller ionic radii (e.g., Mg²⁺) enhance CH₄ adsorption capacity and diffusion more effectively than monovalent or larger cations. Increasing the Si/Al ratio reduces cation content and exposes more framework oxygen atoms, particularly those in Si–O–Si environments, which improve CH₄ adsorption. Elevated temperature weakens CH₄ adsorption while promoting H₂ diffusion and pore occupancy. Although higher pressure increases the uptake of both gases, H₂ adsorption rises more substantially and distributes more widely, leading to a decrease in CH₄/H₂ selectivity. Full article

The chemical composition, mineral composition, and mineral distribution characteristics of steel slag were characterized through petrographic analysis, X-ray diffraction (XRD), and particle size analysis. Limestone, silica, and silicomanganese slag were blended with converter steel slag to fabricate a reconstructed steel slag. Through burden calculation, the chemical composition ratio of this reconstructed steel slag approximated the silicate phase region. The high-temperature reconstruction process outside the furnace was simulated through reheating. The composition, structure, and cementitious characteristics of the reconstructed steel slag were investigated through X-ray diffraction (XRD), FactSage software (FactSage version 7.0 (GTT-Technologies, Aachen, Germany, 2015))analysis, scanning electron microscopy–energy dispersive spectroscopy (SEM–EDS) analysis, setting time determination, compressive strength measurement, and thermodynamic computation. The findings indicated that the primary mineral compositions of the reconstructed steel slag were predominantly silicates, such as Ca₃Al₂O₆, Ca₂SiO₄, Ca₂MgSi₂O₇, Ca₂Al(AlSiO₇), Ca₂(SiO₄), and FeAlMgO₄. In comparison with the original steel slag, these compositions underwent substantial alterations. The α′-C₂S phase appears at 1100 K and gradually transforms into α-C₂S at 1650 K. The liquid phase begins to precipitate at approximately 1550 K. Spinel exists in the temperature range from 1300 to 1700 K, and Ca₃MgSi₂O₈ melts into the liquid phase at 1400 K. As the temperature increases to 1600 K, the minerals C₂AF, Ca₂Fe₂O₅, and Ca₂Al₂O₅ gradually melt into the liquid phase. Melilite melts into the liquid phase at 1700 K. It was observed that the initial and final setting times of the reconstructed steel slag exhibited reductions of 7 and 43 min, respectively, in comparison to those of the original steel slag. In comparison with steel slag, the compressive strength of the reconstructed steel slag exhibited an increase of 0.6 MPa at the 3-day strength stage, 1.6 MPa at the 7-day strength stage, and 3.4 MPa at the 28-day strength stage. The reduction in setting time and the enhancement in compressive strength verified the improved cementitious activity of the reconstructed steel slag. Thermodynamic calculations of the principal reactions of the reconstructed steel slag at elevated temperatures verified that the primary reaction at 1748 K is thermodynamically favorable. Full article

High-density aviation fuels and diesel-range cycloalkanes are in high demand for the transportation sector, but the development of sustainable and high-efficiency synthesis routes from biomass-derived platform chemicals remains a key challenge. High-density aviation fuel and diesel-grade cycloalkanes were successfully synthesized from biomass-derived isophorone and furfural through a continuous process of selective hydrogenation, aldol condensation, and hydrodeoxygenation reaction. (E) 2-(Furan-2-methylene)-3,5,5-trimethylcyclohex-1-one (1A) was obtained by selective hydrogenation of isophorone to obtain 3,3,5-trimethylcyclohexanone (TMCH), which was then subjected to aldol condensation with furfural. The system studied key reaction parameters such as solvent type, temperature, catalyst type, catalyst loading, and reaction time that affect the aldol condensation of TMCH and furfural. The yield of 1A reached 98.69%, under optimized conditions using NaOH as the catalyst at a molar ratio of 3,3,5-trimethylcyclohexanone:furfural = 1:1, NaOH 0.15 g, anhydrous ethanol as the solvent, and a reaction temperature of 313 K for 1 h. A series of nickel-based catalysts supported on porous materials, including SiO₂, CeO₂, Al₂O₃, Hβ, and HZSM-5, were prepared and characterized by scanning electron microscopy (SEM) and X-ray diffraction (XRD). These catalysts were evaluated for the hydrodeoxygenation of 1A. Among them, the 10% Ni-SiO₂ catalyst exhibited the highest catalytic activity, affording a C₉–C₁₄ cycloalkane yield of 88.32% and a total carbon yield of 99.6%. This work demonstrates a promising and sustainable strategy for producing branched cycloalkanes in the diesel and jet fuel range from lignocellulosic biomass-derived platform chemicals. Full article

Al-rich NH₄-ZSM-5 with highly oriented crystals was directly synthesized through a one-pot hydrothermal technique, using ammonium nitrate as a metal-free mineralizer. The samples were characterized by XRD, N₂ adsorption–desorption, SEM, FTIR, Py-FTIR, ²⁷Al MAS NMR, ²⁹Si MAS NMR, ¹H MAS NMR, and TGA techniques. The impact of aluminum source, ammonium source, and H₂O/SiO₂ molar ratio was studied. XRD results showed that the ZSM-5 catalyst with a low Si/Al ratio (13) was successfully synthesized without any amorphous phase, including a microporous/mesoporous structure. A low H₂O/SiO₂ molar ratio (75) resulted in coffin-shape surface morphology, large b-axis-oriented particles (ca. 19 µm), and high specific surface area (>300 m² g⁻¹), providing a large portion of straight channels (90.5%). The catalytic activity of the catalysts was evaluated in the CO₂ hydrogenation reaction in tandem configuration with a Na/Fe₂O₃ catalyst. The results confirmed that highly b-oriented crystals improved the product shape selectivity to p-xylene by affecting the diffusion resistance. Therefore, the developed catalyst provided high CO₂ conversion (45%) and high aromatic selectivity (77%), with p-xylene accounting for 82% of the produced xylene compounds, over a long-term time on stream (17 h). These results demonstrate the effectiveness of the direct synthesis strategy in producing Al-rich ZSM-5 catalysts with tailored textural and acidic properties for tandem and shape-selective catalysis. Full article

This study assesses two Brazilian Type F fly ash samples (FA-A and FA-B), collected from the same thermoelectric complex in different years, to investigate their influence on the production of alkali-activated materials (AAMs). FA-A exhibited a slightly higher SiO₂/Al₂O₃ ratio (3.52 vs. 3.34) and a finer average particle size (D₅₀ = 19.7 μm vs. 30.8 μm) than FA-B. X-ray diffraction revealed that FA-A presented a broad amorphous halo between 15° and 35° (2θ), indicative of phases with low atomic ordering, which are more susceptible to dissolution and capable of supplying Si- and Al-rich species for the formation of alkali activation products. These differences directly affected reactivity and mechanical performance. After 1 day of curing, FA-A-based matrices achieved 88.5 MPa in compressive strength—approximately 100% higher than FA-B (44.2 MPa). However, FA-A suffered a 19.6% strength reduction after 28 days of curing, whereas FA-B showed only a 3.8% decrease over the same period, reflecting better long-term stability. FTIR confirmed Na₂CO₃ formation in FA-A, associated with excess sodium (Na/Al = 2.07 after 28 days), while SEM revealed unreacted spheres persisting in FA-B, consistent with its lower dissolution rate. Water absorption was also significantly different, with FA-B matrices reaching values up to 52% lower than FA-A after 7 days of curing. These results demonstrate that even slight variations in chemical composition and atomic ordering, even for ashes from the same plant, strongly influence the reactivity, microstructure, and mechanical performance of alkali-activated binders. Full article