Search Results (462)

This study (Part B) examines the potential utilization of municipal solid waste (MSW) ash, produced in a semi-industrial incinerator in Israel, as a partial substitute for cement and natural sand in industrial concrete mixtures. The ash was produced at the temperature range 600–850 °C, and the ash was characterized using XRD and SEM to determine its mineralogical composition and morphology. The results indicate that ash composition is dominated by calcium-rich phases, with hatrurite (Ca₃SiO₅) representing approximately 51–66 wt.% of the identified crystalline phases, along with calcite, MgO, and silica phases. The ash consists of irregular, porous particles with a broad distribution. Concrete performance was evaluated in both fresh and hardened states. In terms of fresh concrete properties, it is observed that concrete containing ash showed improved workability, better workability retention, and better concrete density compared to concrete without ash. In terms of hardened concrete properties, the use of MSW ash as a partial sand replacement preserved the mechanical performance of the concrete, with compressive strength remaining within approximately 2% of the reference mixture. These findings suggest that semi-industrially produced MSW ash is more suitable as a fine aggregate replacement than as a supplementary cementitious material and represents a promising route for reducing landfill disposal and promoting circular economy practices in the construction industry. Full article

Against the background of blast furnace burden optimization and the low-carbon transition of the steel industry, the development of high-quality Mg-bearing fluxed pellets is of great significance for the efficient utilization of medium-high silica iron ore concentrates. In this study, Mg-bearing medium-high silica fluxed pellets with a fixed SiO₂ content of 5.5% were prepared, and the effect of basicity in the range of R = 1.0–1.4 on compressive strength, liquid phase behavior, slag phase composition, and pore structure evolution was systematically investigated. The results showed that the compressive strength of the pellets decreased from 2527 N/pellet to 2079 N/pellet as the basicity increased from 1.0 to 1.4. At 1250 °C, the liquid phase content first decreased from 2.66% to 1.30% and then increased to 7.38%, while the liquid phase viscosity decreased continuously. Meanwhile, the liquid phase composition evolved from a SiO₂-rich calcium–iron silicate system to a Fe₂O₃⁻ and CaO-rich system. XRD results indicated that Fe₂O₃ was the dominant crystalline phase in the pellets, accompanied by a small amount of Fe₃O₄, whereas no distinct highly crystalline slag phase was detected. The slag phase was mainly a Fe-Ca-Si composite slag, in which the Fe₂O₃ content increased and the SiO₂ content decreased with increasing basicity. At higher basicity, the number and size of pores increased, and the pore morphology evolved from dispersed fine pores to irregular large pores and locally connected pores. Meanwhile, the slag phase became more widely distributed and locally enriched, weakening the continuity of the iron oxide load-bearing skeleton, which was the main reason for the decrease in compressive strength. This study provides a theoretical basis for preparing high-quality Mg-bearing fluxed pellets from medium-high silica iron ore concentrates. Full article

Oil recovery from carbonate reservoirs is one of the critical challenges in the oil industry due to the strongly oil-wet nature, natural fractures, and the heterogeneity of carbonate rocks. Subsequently, waterflooding can only displace oil from large fractures, leaving the majority of oil trapped in the rock matrix. This work suggests that nanofluid flooding, as a predesigned flooding method, is an alternative to conventional waterflooding. Various concentrations of silica nanofluid at different nanoparticle concentrations were formulated and systematically investigated for their characteristics, stability at reservoir conditions, and their influence on wettability and oil recovery. Silica nanoparticles were sustainably synthesized from waste materials to ensure the feasibility and environmental friendliness of the process. Results indicated that the synthesized silica has an amorphous crystalline nature characterized by nano-sized particles. Additionally, treating silica nanoparticles with a silane group significantly enhances the stability of nanofluids in a high-salinity environment. Most interestingly, by comparing the amount of oil recovered, the results revealed that implementing nanofluid flooding as a secondary oil recovery, rather than waterflooding, can produce around 12% more oil, in addition to eliminating a whole waterflooding step. This is the first study to alter the traditional flooding scenario and directly conduct nanofluid flooding as secondary oil recovery, without being preceded by waterflooding, using sustainably synthesized nanoparticles. Considering the water crisis in the Middle East, this approach can save substantial amounts of water, which improves the sustainable development of communities. Full article

Background: Exposure to respirable crystalline silica dust remains a significant occupational health challenge in the Southern African Development Community region, leading to high incidences of silicosis and pulmonary tuberculosis, particularly among mining workers. This study evaluated the knowledge, attitudes, and practices (KAP) of mineworkers regarding silica dust risks across Lesotho, Malawi, Mozambique, and Zambia. Methods: A cross-sectional analytical study was conducted involving 1440 mineworkers exposed to silica dust in mines across four SADC countries. Data were collected using structured questionnaires covering socio-demographic traits and knowledge, attitude, and practices. Data analysis was conducted using Stata version 18. Results: While 91% of participants exhibited adequate knowledge and 88% demonstrated acceptable practices, 51% maintained negative safety attitudes. Knowledge scores were positively correlated with company training (r = 0.386). However, a “Training Paradox” emerged in the regression model: compulsory company training was significantly associated with a 1.20-unit decrease in practice scores, whereas external training and higher education levels (+2.98 units) predicted improved compliance. Technicians and younger workers were identified as higher-risk cohorts. Conclusions: The findings suggest that top-down mandatory training may trigger psychological reactance, undermining behavioural safety. To mitigate silica-related diseases, industry stakeholders should transition toward participatory, role-specific safety interventions that prioritize worker autonomy and cognitive engagement over administrative compliance. Full article

Rice husk ash (RHA) is a silica-rich agricultural byproduct with significant potential in the development of sustainable porous materials. This study investigated the effect of calcination temperature and impregnation duration on the physicochemical and textural properties of KOH-modified RHA materials. The method used was calcination at different temperatures (500, 600, and 700 °C) combined with KOH impregnation for 19, 22, and 24 h. The prepared materials were characterized using Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy (SEM–EDX), Brunauer–Emmett–Teller (BET) surface analysis, and X-ray diffraction (XRD). FTIR analysis showed that increasing calcination temperature promoted the reduction in residual carbon-containing functional groups and enhanced the dominance of silica-related Si–O–Si vibrations. SEM observations revealed significant morphological evolution from heterogeneous fragmented structures at 500 °C to more interconnected porous frameworks at 600 °C, followed by partial densification and agglomeration at 700 °C. Semi-quantitative EDX analysis confirmed the silica-rich surface composition of the prepared materials, while XRD patterns indicated structural transformation from partially crystalline phases toward more stabilized silica-rich structures. BET analysis demonstrated that sample 2B, calcined at 600 °C with 22 h impregnation, exhibited the most favorable textural characteristics among the selected BET-analyzed samples, with the highest surface area and pore volume. Overall, calcination temperature and impregnation duration significantly influenced the structural evolution, pore development, and physicochemical characteristics of KOH-modified RHA materials. This study contributes to the development of sustainable biomass-derived materials and supports Sustainable Development Goal (SDG) 12, which is related to responsible consumption and production through the valorization of agricultural waste into value-added silica-rich materials. Full article

Bismuth is widely recognized for its natural abundance, moderate cost, and low toxicity, making it an attractive alternative to the expensive and toxic transition metals commonly employed in heterogeneous catalysis. In this work, we report the immobilization of bismuth onto a series of SBA-15 materials and their application for nitrophenol reduction and iodine uptake. Particular attention was given to anchoring bismuth on three nitrogen-containing mesostructured silicas in comparison with its deposition on the unmodified silica support. Remarkably, nitrogen-containing ligands directed the nucleation and growth of crystalline bismuth nanosheets, whereas the pristine SBA-15 afforded atomically dispersed and amorphous metal particulates. Bismuth loaded on SBA-NNH₂ represents an optimal balance between porosity, accessibility, and metal–ligand interaction. Crystalline nanosheets displayed interesting catalytic activity for the reduction of nitrophenol to the corresponding aromatic amine, even at low bismuth loading (k_app = 3.8 × 10⁻³ s⁻¹), and exhibited recyclability. Upon reduction, bismuth loaded on SBA-NNH₂ stands as the best scavenger for iodine adsorption, reaching 442 mg.g⁻¹. On the whole, these findings highlight the role of the N-ligands in directing the growth of bismuth particles and the capability of the resulting bismuth-supported materials for iodine scavenging and for sustainable catalysis in fine and pharmaceutical chemistry. Full article

This work investigated the potential of different natural fillers, i.e., clay, calcium carbonate, and silica, as sustainable alternatives to glass fibers (GFs) in polyamide 6 (PA6) for Large-Format Additive Manufacturing (LFAM) applications in order to guarantee the chemical recyclability of the produced materials. Specifically, PA6-based composites containing ≤ 10 wt% natural fillers were compared with a conventional system (30 wt% GF-reinforced PA6) from rheological, morphological and thermo-mechanical perspectives. Rheological analysis showed that silica- and clay-filled samples displayed similar rheological response to the GF-filled reference due to their large particle size. Thermal analyses revealed a slight increase in crystallinity (up to 32%) for filled samples, indicating a potential nucleating effect of the natural fillers. Calcium carbonate-filled composites achieved thermal conductivity values comparable to the GF-filled reference (≥0.42 W/mK) indicating a high heat dissipation capability during printing operations. Morphological analysis performed on preliminary LFAM components revealed satisfactory printing quality and good filler dispersion. Flexural tests showed that silica and calcium carbonate could provide a balanced mechanical response, thereby reducing the anisotropy of printed components. These results demonstrated that the addition of suitable natural fillers at limited concentrations (≤10 wt%) can represent a lightweight and eco-sustainable alternative to GF reinforcement in LFAM applications. Full article

Glazes primarily utilize raw minerals like kaolinite. However, considering sustainable development, employing industrial solid waste offers greener design solutions and high economic efficiency. This study employs multiple analytical methods, including XRF, XRD, and SEM, to investigate the feasibility of replacing traditional glaze materials entirely with solid waste. It elucidates the mechanisms underlying changes in texture and color resulting from alterations in microstructure and chemical composition. Research on five different ratios of ceramic glaze composed of fly ash, blast furnace slag, silica fume, coal gangue, and desulfurization gypsum reveals that the implementation of solid waste-based glazes is feasible. The glazes formed a SiO₂–Al₂O₃–CaO system surface, all exhibiting anorthite and diopside as the primary crystalline forms. The results are as follows: 1. The content of Ca and Mg depends on the overall proportion of elements, with a Ca threshold of approximately 28%. Below this threshold, characteristics such as surface roughness and porosity are observed. Above this threshold, as seen in G3 and G4, crystal distribution becomes more dense. 2. Si is the key factor controlling crystal variation. Sample G5 exhibits good crystal continuity. Visually, its color appears distinctly deep red. 3. Samples G1 and G2 both contain approximately 4.8 wt% Fe₂O₃, but G2 exhibits more crystalline precipitation. Visually, G2 appears more reddish-yellow than G1. Higher crystallinity yields superior coloration. Full article

Mining practices and operating conditions are continually evolving, and the respirable fraction of coal mine dust is accordingly expected to change in composition and particle characteristics over time. Between the early 2000s and late 2010s, several regulatory and operational changes occurred in U.S. underground coal mining that could plausibly influence respirable coal mine dust (RCMD), including expanded rock-dusting practices, increased emphasis on respirable crystalline silica, and reductions in diesel emissions. This study evaluated temporal differences in RCMD by comparing samples collected in 2003–2005 and 2018–2020 using particle-level scanning electron microscopy with energy-dispersive X-ray spectroscopy (SEM–EDX). The most consistent temporal change observed was an increase in carbonate particles, consistent with expanded rock-dusting practices. Shifts in coal- and rock-strata-derived dust were observed but were not consistent across regions, and no consistent trend toward finer particle sizes was identified. These results demonstrate the value of particle-level analysis for evaluating changes in RCMD characteristics over time. Full article

This study aimed to evaluate the impact of liquid–solid (LS) systems on the dissolution profiles of a poorly soluble drug—suvorexant (SUV). In the first stage of this study, LS systems were prepared by using two different non-volatile solvents: ethylene glycol diethyl ether and polyethylene glycol 400 (PEG 400). To compare the properties of different types of LS systems, formulations were prepared that differed in the content of SUV (10 and 20 mg) as well as in the ratio of excipients (microcrystalline cellulose and colloidal silica), which was 10:1 or 1:1. The physicochemical properties of the prepared formulations were characterized by X-ray diffractometry (XRD), thermogravimetry (TGA) and differential scanning calorimetry (DSC). This was followed by a dissolution study of SUV from prepared LS systems, using a 0.4% sodium lauryl sulfate solution as the medium to maintain sink conditions. Results showed that the LS systems change the crystalline structure of SUV to an amorphous one and improve the dissolution rate of SUV. The greatest improvement was achieved by using the microcrystalline cellulose and colloidal silica in a 10:1 ratio for the preparation of the system (CCA variant). It was observed that the type of solvent used and the order of combining excipients during the preparation of LS systems are also important for the properties. The main point was that physicochemical characterization of the prepared formulations lead to a loss of crystallinity of SUV associated with its introduction into liquid–solid systems. Full article

The rational design of supported ruthenium catalysts for sustainable energy applications requires precise control over metal nanoparticle size, dispersion, and metal–support interactions. This study investigates the influence of mesoporous silica support topology—SBA-15 (2D hexagonal, cylindrical pores), SBA-12 (3D hexagonal structure), and SBA-3 (2D hexagonal)—on the structure and catalytic performance of 1 wt% ruthenium catalysts in CO₂ methanation and gas-phase toluene hydrogenation. Comprehensive characterization by nitrogen physisorption, low- and high-angle X-ray diffraction (XRD), H₂ temperature-programmed reduction (H₂-TPR), CO chemisorption, and transmission electron microscopy (TEM) revealed that support pore architecture dictates ruthenium particle size (1.2 nm for Ru/SBA-15, 2.8 nm for Ru/SBA-3, 4.3 nm for Ru/SBA-12) and dispersion (80%, 35%, 23%, respectively) through geometric confinement effects. Catalytic testing demonstrated contrasting structure–activity relationships: CO₂ methanation exhibited strong structure sensitivity with turnover frequency (TOF) increasing with particle size (Pearson’s r = 0.96), favoring Ru/SBA-3 and Ru/SBA-12 with near-optimal 3–4 nm particles, while toluene hydrogenation showed weaker structure sensitivity, with Ru/SBA-12 achieving the highest TOF owing to its larger particle size and higher crystallinity. These findings underscore the critical importance of tailoring mesoporous support topology to match reaction-specific structure sensitivity, providing fundamental insights for the design of bifunctional catalysts for hydrogenation reactions. Full article

Attenuated Total Reflection–Fourier Transform Infrared (ATR-FTIR) spectroscopy and Inductively Coupled Plasma–Optical Emission Spectrometry (ICP-OES) are widely used to investigate the chemical structure and elemental composition of materials. However, the combined application of both methods to examine scale deposits in the water supply network has not yet been explored. In this study, scale deposits collected from the inlets of six pipes (steel, cast iron, lead, wooden) were analysed using both techniques. The application of ATR-FTIR and ICP-OES enabled the identification of mineral phases, organics, and structural differences between individual scale layers. Iron oxyhydroxides, together with silica and aluminosilicates, dominated most samples, whereas shower faucet deposit was primarily composed of carbonates and stearates. The combined analytical approach helped to avoid misinterpretation of FTIR data: although the spectrum of lead pipe deposit resembled hydrated lead carbonates, ICP-OES revealed only trace amounts of lead. Differences in crystallinity between successive layers allowed the reconstruction of the deposition process within the pipes. Poorly crystalline iron oxyhydroxides and silica occurred near pipe walls, while more crystalline phases developed closer to the water interface. These results demonstrate that combining ATR-FTIR and ICP-OES provides a reliable framework for interpreting scale deposit composition and formation in water distribution systems. Full article

Open-air asphalt milling generates hazardous respirable crystalline silica (RCS), posing severe risks to operators of legacy machines lacking enclosed cabs. This study evaluates a novel, standalone retrofit water spray system designed to intercept fugitive dust. Field validation across 11 road maintenance sites involved particle characterization and paired system-off/on exposure monitoring. Results indicated a Mass Median Aerodynamic Diameter (MMAD) of 6.12 µm, confirming the efficacy of fine-atomizing nozzles (0.3 mm) for capturing respirable fractions. The system achieved RCS suppression efficiencies ranging from 60% to over 85% under low-to-moderate wind conditions (<2.5 m/s). A comparative analysis revealed no significant performance gain from larger 0.5 mm nozzles, supporting the use of smaller orifices for optimal water conservation. However, suppression efficacy degraded significantly when crosswinds exceeded 2.5 m/s, indicating a potential operational boundary. This retrofit solution provides a scientifically validated, cost-effective engineering control for reducing occupational silica exposure in aging road maintenance fleets. Full article

This work investigates the potential of wollastonite-based brushite cement (WBC) for the stabilization and solidification of radioactive waste contaminated by ⁹⁰Sr. This phosphate binder was formed by the reaction of wollastonite (CaSiO₃) with a phosphoric acid solution containing borax and metallic cations (Al³⁺, Zn²⁺). Two cement pastes were investigated: a commercial binder (WBC-C) and an optimized formulation (WBC-O), produced using a zinc-free mixing solution with a higher aluminum content than that of WBC-C. Mineralogical characterizations using XRD, TGA, XRF, SEM-EDX, and Raman spectroscopy showed that both materials mainly contained amorphous hydrated silica and calcium aluminophosphate, along with crystalline brushite, residual wollastonite, and quartz. The stability of WBC-C under γ-irradiation was evaluated up to a dose of 1 MGy. The only observable effect was water radiolysis, leading to dihydrogen production at yields comparable to Portland cement matrices and geopolymers. Strontium leaching, assessed using the ANSI/ANS-16.1-2003 (R2008) procedure, followed a two-stage release mechanism combining surface wash-off and diffusion. The apparent diffusion coefficient D_a of Sr in WBC-C was markedly lower than typical values reported for Portland cement matrices. WBC-O exhibited enhanced Sr retention, possibly due to its higher aluminum content, which refines mesopores and reduces diffusion pathways accessible to Sr. WBC binders therefore appear to be promising candidates for strontium immobilization. Full article

Background: Silicosis is a progressive fibrotic lung disease caused by chronic inhalation of crystalline silica. Increasing evidence indicates that oxidative stress plays a central role in linking silica exposure to inflammation, tissue injury, and fibrosis. We conducted a systematic review to critically appraise the current evidence on the imbalance between oxidant and antioxidant markers in patients with silicosis compared with unexposed healthy controls. Methods: A systematic literature search was conducted in PubMed, Scopus, and Google Scholar from their inception to 30 November 2025. Eligible studies assessed oxidative stress biomarkers in biological samples from patients with silicosis and non-exposed controls. Results: Malondialdehyde (MDA) and Superoxide Dismutase (SOD) were the most frequently assessed oxidative and antioxidant markers, respectively, with MDA significantly increased and SOD decreased in patients with silicosis, highlighting amplified lipid peroxidation and impaired antioxidant defense. In addition, elevated levels of other oxidant molecules confirmed the presence of lipid, nitrosative, and DNA oxidative damage. Overall, antioxidant defenses were compromised, although some markers appeared to vary with disease stage. Conclusions: This review highlights the central role of oxidative stress in the pathogenesis and progression of silicosis. Future studies with larger cohorts and a broader range of biomarkers are needed to better understand oxidative imbalance and its potential utility for monitoring disease progression and assessing severity in this population. Full article