Search Results (81)

In this study, a lanthanum-modified MgAl double-layer hydroxide (La-LDH) was synthesized and investigated as a novel inorganic consolidant for gypsum, lime and cement-based mortars. The material was characterized by X-ray diffraction, WDXRF, SEM, dispersion stability analyses and DLS. XRD confirmed the formation of a hydrotalcite-like structure with secondary phases of lanthanum carbonate and hydroxylcarbonate, while SEM observations revealed a platelet-like morphology, typical of LDH materials. DLS analysis revealed a polydisperse granular distribution, with particle populations centered at approximately 99 and 383 nm, indicating the coexistence of nanometer sized LDH particles and larger aggregates within the consolidant dispersion. The prepared material (0.5 g/L) was dispersed in ethanol–water solution (40%:60%) and applied by brushing onto the specimens made for this purpose. The treatment resulted in minor chromatic variations (ΔE* < 1.5 for all substrates). No surface crusting, visible deposits or adverse aesthetic changes after treatment or accelerated ageing were observed. Of the substrates investigated, lime mortar showed the most pronounced response, indicating a 26.4% increase in surface cohesion, together with a substantial improvement in water permeability (up to 87%). In contrast, gypsum and cement mortars showed only limited improvements. Artificial ageing tests demonstrated good visual stability of the treated surfaces, while freeze–thaw tests indicated only minor changes in frost resistance. Salt crystallization tests showed that the treatment did not negatively affect the strength of any of the substrates investigated and, in several cases, delayed crack propagation and material loss during cyclic exposure to sodium sulphate solution. Full article

The escalating global accumulation of plastic waste (PW) poses a critical obstacle to environmental sustainability, necessitating the development of viable valorization strategies. Pyrolysis process offers a thermo-chemical conversion pathway capable of transforming waste plastics into a potentially functional liquid product. This work presents a systematic and comprehensive investigation of the physicochemical, wettability, thermal stability, rheological, and tribological properties of pyrolysis oil (i.e., pyro-oil) derived from virgin linear low-density polyethylene (LLDPE) pellets to mimic the behavior of common polymers in such thermo-chemical conversion processes. Pyro-oil was produced under controlled slow pyrolysis conditions in a fixed-bed reactor at 700 °C, and its properties were benchmarked against tire-derived pyro-oil and a commercial engine oil. Chemical and structural characterization was conducted via Fourier transform infrared spectroscopy (FTIR), wavelength dispersive X-ray fluorescence (WDXRF), and scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy (SEM-EDS). Wettability was evaluated through temperature-dependent contact angle measurements, and thermal stability was assessed by thermogravimetric analysis (TGA). Rheological profiling of the plastic pyro-oil was investigated using a rheometer apparatus at different temperatures. Lastly, the tribological properties of plastic pyro-oils at various temperatures were examined using a tribometer instrument in a ball-on-disk configuration. Results demonstrate that plastic-derived pyro-oil exhibits a hydrocarbon-dominant chemical composition similar to that of tire pyro-oil and engine oil. Its absolute viscosity is nearly similar to that of the tire pyro-oil and is lower than that of engine oil across different temperatures. Tribological testing revealed that the plastic pyro-oil results in lower friction at elevated temperatures compared to both tire pyro-oil and commercial engine oil. However, the thermal examinations showed that plastic pyro-oil has lower thermal stability than tire pyro-oil and engine oil. Overall, these findings indicate that plastic pyro-oil holds promise as a functional lubricant for low-load and moderate-temperature industrial applications, positioning PW pyrolysis as a viable contributor to circular economy strategies in the lubricants sector. Full article

The study investigated and quantified the feasibility of using waste derived from shea tree fruit shells (Vitellaria paradoxa) as an organic multifunctional additive for building ceramic bodies, focusing on its influence on thermal behavior, pore formation, and mechanical performance. The scope of the research included sieve analysis, chemical analysis (WDXRF), phase composition analysis (XRD), thermal analysis coupled with evolved gas analysis (DTA–TG–EGA), and the evaluation of the physical and mechanical properties of the obtained ceramic materials. The analyses demonstrated that the shea waste was characterized by a high content of organic matter, a loss in ignition of 93.84%, and a calorific value of 19.421 kJ/g. The incorporation of biomass resulted in increased porosity and reduced apparent density of the ceramic materials. The relative porosity increased from 27.00% for the reference sample to 34.98% for the sample containing 30% shea waste. Simultaneously, the compressive strength decreased from 23.67 MPa to 10.10 MPa, while the flexural strength decreased from 8.96 MPa to 4.76 MPa. Partial replacement of conventional mineral additives and, in particular, partial substitution of fossil-derived kiln fuel demand with high-calorific biomass enabled a reduction in overall CO₂ emissions associated with ceramic production. This includes both process-related emissions from raw material decomposition and fuel-related emissions generated in the tunnel kiln. In addition, a reduced contribution of carbon originating from inorganic mineral sources (including carbonates) to total emissions covered by emission trading systems (ETSs) was observed. Despite the reduction in mechanical parameters, samples containing up to 20% shea waste retained properties suitable for application in the production of ceramic building materials. Full article

Historic blue bricks are fundamental to Beijing’s architectural heritage, yet cross-site compositional data for guiding material-compatible restoration remain scarce. This study applies WD-XRF, XRD, SEM, thermal expansion measurement, and physical property testing to 21 blue brick specimens from four Beijing-area sites spanning the Tang through Qing dynasties, with PCA and K-means clustering used to explore compositional grouping structures. Within this exploratory dataset, a compositional distinction separates the Ming and Qing Great Wall bricks: CaO falls from 7.7 to 1.5 wt.% as anorthite gives way to albite, while Qing specimens are denser (1.79 vs. 1.65 g·cm⁻³) with lower water absorption (15.9% vs. 20.9%). Two Wanping City bricks are strongly sulfate-enriched (SO₃ up to 9.8%), and WP-SE3 additionally carries a heavy chloride load (Cl 2.1%), masking their original clay signatures and illustrating how unrecognized weathering can distort compositional grouping and source-related interpretation from bulk chemistry. K-means clustering yields compositional types that overlap only partially with site boundaries, capturing raw material variation rather than site-specific manufacturing fingerprints. Despite constraints in sample size and physical property coverage, the integrated dataset offers preliminary compositional benchmarks and limited performance data to inform period-specific brick replacement at these heritage sites. Full article

Clay mineral authigenesis and transformation are key diagenetic processes that influence the evolution of sandstone reservoir quality. Although smectite formation and its transformation to illite have been widely studied in clay-rich and feldspathic systems, their development in highly quartz-rich sands remains less well constrained. This study investigates the experimental formation of authigenic smectite and its subsequent illitization in a quartz-dominated sand under controlled hydrothermal experiments. Quartz-rich glass sand from the Middle Jurassic Mariedal Formation (Skåne, Sweden) was reacted with natural Red Sea water in sealed reactors at 80, 150, 200, and 250 °C for 14 days to simulate progressive burial diagenesis. Mineralogical, textural, and geochemical changes were evaluated using thin-section petrography, SEM-EDS, WD-XRF, XRD, and ICP-OES. The starting material is composed predominantly of quartz (91.3%), with minor K-feldspar (6.2%) and muscovite (1.4%), providing limited but sufficient reactive components for clay mineral formation. Dissolution of K-feldspar and muscovite began at 80 °C and continued throughout the experiments. Authigenic smectite was first detected at 150 °C as discontinuous grain-coating phases, indicating nucleation through dissolution–precipitation reactions linked to feldspar alteration and uptake of Mg from the reacting fluid. At 200 °C, the smectite coating became thicker and more extensive, with the onset of transformation to illite through mixed layer stages. By 250 °C, illite becomes the dominant clay mineral, recording progressive smectite illitization with increasing temperature. Fluid chemistry shows systematic variations with temperature, including decreasing Mg and evolving K concentrations, reflecting progressive mass transfer between solid and fluid phases. These results demonstrate that even highly quartz-rich sands can generate authigenic clay minerals when minor reactive phases and suitable fluid chemistry are present. The experiments provide a process-based analogue for clay mineral evolution in quartz-rich sandstone reservoirs and highlight the importance of coupled mineral–fluid reactions during burial diagenesis. Full article

Recyclers worldwide face a common bottleneck: incoming mixed plastic bales are chemically opaque, yet the choice between mechanical recycling, chemical recycling, and energy recovery hinges on contaminant levels that cannot be judged by visual inspection alone. This study develops and validates a tiered analytical decision-support framework that translates standard laboratory measurements into explicit, actionable go/no-go routing criteria for any mixed polyolefin waste stream. The framework is organized into three successive analytical tiers of increasing specificity: Tier 1 uses FTIR and DSC for rapid polymer identification and thermal subclass confirmation; Tier 2 applies TGA/DTG for thermal stability assessment and filler quantification; and Tier 3 deploys ICP-OES, WD-XRF, CIC, and TG–MS for targeted heavy metal, halogen, and evolved gas profiling, triggered only when Tier 1/2 flags are raised. This staged logic minimizes unnecessary testing while ensuring that contaminant-relevant information is captured where it matters. The framework is demonstrated on nine blind mixed plastic waste streams (P1–P9) supplied by an industrial recycling facility without prior disclosure of polymer identity, filler content, or additive history—conditions that replicate the uncertainty encountered at any sorting plant globally. Application of the tiered protocol identified dominant polymers (HDPE, LDPE, PP), quantified inorganic fillers (CaCO₃ up to ~38 wt%), and detected hazardous contaminants, including chlorine (up to ~1900 ppm), lead, chromium, and titanium, enabling each stream to be assigned to a specific recycling route with defined contaminant thresholds. Because the method relies exclusively on commercially available, vendor-independent instrumentation and follows a reproducible, rule-based decision logic, it is directly transferable to recycling facilities in any geographic context without site-specific calibration. The proposed framework thus provides a practical, scalable decision-support tool for feedstock-level quality control under emerging regulations such as the UNEP Global Plastics Treaty. Full article

This paper presents the compositional characterisation of obsidian artefacts from the archaeological site of Maddalena di Muccia (Marche, Central Italy). The assemblage, spanning the Early Neolithic to the Copper Age, was chemically and petrographically investigated using two non-destructive X-ray analytical instruments: a wavelength-dispersive X-ray spectrometer and a scanning electron microscope equipped with an energy-dispersive X-ray spectrometer. Geochemical data allow secure attribution of the artefacts to their geological sources, confirming the predominant use of Palmarola obsidian during the Early Neolithic and documenting the continued circulation of obsidian also from other sources (Lipari and Monte Arci) into the Copper Age. Significantly, the Muccia assemblage provides the first evidence in the Adriatic area for the contemporaneous presence of multiple Monte Arci obsidian sub-sources (S.A. and S.C.). This compositional pattern suggests sustained long-term exchange networks involving obsidian, and highlights the role of central Adriatic sites within broader prehistoric interaction systems of the central Mediterranean. Full article

This study identifies the technological signature of ancient and alternative “Chu” and “Kriab” gold glass mosaic mirrors from Thailand. Although these mirrors play an important role in Thai decorative heritage, their production routes and interfacial chemistry at the lead-to-glass interface have remained unclear. A survey of 154 sites across Thailand shows mosaic glass was widely distributed and likely produced during the Ayutthaya period (~300 years ago). Portable X-Ray Fluorescence (pXRF), Wavelength-Dispersive XRF (WD-XRF), scanning electron microscopy (SEM), and X-ray Photoelectron Spectroscopy (XPS) were used to examine the material properties of observed Chu mirrors. Most samples can be classified as a mixed lead–alkaline glass type, with a PbO content ranging from 4.28 to 48.17 wt%. Their yellow tone is controlled by iron and manganese redox states. Chemical and physical analyses distinguish between Chu from the northern part of Thailand and Kriab from the central part of Thailand, which share a silica source but rely on different fluxes, pointing to different glass workshops. Crucially, XPS depth profiling reveals a well-defined interfacial reaction zone extending to approximately 6 nm in the ancient mirrors, predominantly characterized by disordered, chain-like Pb–O–Pb linkages. These polymeric structures enable a “chemical bridging” mechanism that effectively accommodates interfacial strain arising from thermal expansion mismatch, thereby ensuring exceptional long-term adhesion. Furthermore, the depth-dependent distribution of hydrated lead species and the emergence of photoelectron energy-loss features beyond ~6 nm distinguish the superior metallic integrity of the ancient coatings from the alternative reproductions. This distinct stratification confirms that ancient artisans achieved a sophisticated balance between a chemically bonded interface and a coherent metallic bulk. These findings offer significant insights into the ingenuity of ancient Thai artisans, providing a scientific foundation for the conservation, restoration, and replication of these culturally significant artifacts. Full article

The effect of CO₂ laser treatment on the surface composition and properties of a woven fabric (polyester (PET) fiber (59 wt%)/cotton (CO) fiber (31 wt%)/stainless-steel (SS) metal fibers (10 wt%)) was investigated across a range of laser intensities (19.1 × 10⁶ to 615.0 × 10⁶ W/m²). Elemental analysis using wavelength-dispersive X-ray fluorescence (WD-XRF) revealed that for an intensity up to 225.4 × 10⁶ W/m², the carbon content on the fabric surface increased while the oxygen content decreased, indicating thermally induced surface modification. Fourier transform infrared (FT-IR) spectroscopy confirmed that no new chemical bonds were formed, suggesting that the changes observed were predominantly physical in nature. High-resolution scanning electron microscopy (HR-SEM) showed progressive fiber fusion and surface smoothing with increasing laser intensity, consistent with polyester melting. Tensile testing demonstrated a significant decline in peak load and elongation at peak load with rising laser fluence, indicating mechanical embrittlement. Overall, CO₂ laser treatment alters the morphology and elemental composition of the fabric surface without inducing major chemical decomposition, markedly reducing its mechanical strength. Full article

Natural zeolites—clinoptilolite from Golobradovo and mordenite from Lyaskovets deposits, Bulgaria—were used for the preparation of zeolite-supported CeO₂@Polybenzimidazole (PBI) hybrid materials, incorporating green-synthesized ceria using Veronica officinalis L extract. In order to prepare the hybrid composites, the zeolites/CeO₂ were surface-impregnated with an ethanolic KOH solution of meta-PBI, which served as a dispersant medium. The composites were investigated by WDXRF, PXRD, FTIR, POM, and TG. The materials were tested in the photocatalytic degradation of 5 ppm Reactive Black 5 dye under UV light. The higher degree of degradation (98%) was achieved using mordenite/CeO₂@PBI as the photocatalyst compared to the clinoptilolite/CeO₂@PBI (14%). Full article

In this study, the photocatalytic performance of natural clinoptilolite was enhanced through copper modification, achieved via ion exchange followed by KOH-induced precipitation, leading to materials with different copper speciation. Physicochemical characterization using WDXRF, PXRD, FTIR and N₂ physisorption revealed a transition from exchanged Cu²⁺ species at low loading to the formation of copper-bearing phases such as brochantite, Cu(OH)₂ and CuO at higher alkalinity. The Cu-modified samples were evaluated for the photocatalytic degradation of Congo red under UV irradiation. Among them, sample NZ-Cu3 exhibited the highest activity, achieving approximately 91% dye degradation within 30–40 min. Kinetic analysis demonstrated that the degradation process is better described by the pseudo-second-order model, indicating that chemisorption plays a dominant role. Radical scavenger experiments revealed that photogenerated holes (h⁺) are the primary reactive species responsible for dye degradation, while hydroxyl radicals contribute to a lesser extent. The enhanced photocatalytic performance is attributed to the synergistic effect of photocatalytic degradation, improved charge separation and the presence of surface copper species, highlighting Cu-modified clinoptilolite as a promising low-cost photocatalyst for wastewater treatment. Full article

This study provides a seasonal and cross-shore characterization of sediments along the Ferrara coastal area (Italy). Four sites (Goro, Volano, Estensi, and Spina) were investigated through an integrated approach including textural and geochemical analyses. Surface sediments were sampled seasonally from summer 2023 to summer 2024 and analyzed to determine granulometry, major oxides composition, carbonate content, and potentially toxic element (PTE) contents. Results revealed that both grain-size and geochemistry vary seasonally and along the cross-shore profile, reflecting the combined effects of hydrodynamic forcing, sediment transport, and fluvial inputs. Elevated contents of Ce, Cr, La, V, and Zr were detected at various sites, seasons, and geomorphological zones. In some cases, the environmental quality indices applied allowed the sediments to be classified as polluted. Furthermore, some exceedances of the legal limits for Cr and V contents were observed at Goro and Volano. These pollution levels are attributable to the presence of PTE-bearing minerals originating from the source basins (geogenic sources). Overall, the results highlight the interplay between hydrodynamics and sediment provenance, emphasizing the dominance of geogenic contributions along the northern Adriatic coast, providing updated geochemical data for future monitoring and environmental management of coastal systems. Full article

The mineralogical, geochemical, and statistical characteristics of recent fluvial deposits from the Brahmaputra–Jamuna River, Bangladesh, were examined to determine their provenance, transport dynamics, and depositional environment. Sediments were analyzed using X-ray diffraction (XRD), wavelength dispersive X-ray fluorescence (WD-XRF), field emission scanning electron microscopy (FE-SEM), and electron probe microanalysis (EPMA). Grain size analysis revealed a predominance of medium-to-fine sand (mean grain size 1.77–3.43 ϕ), with moderately well-sorted textures (sorting: 0.33–0.77 ϕ), mesokurtic to leptokurtic distributions, and skewness values ranging from −0.21 to +0.30. Mineralogical results show a high quartz content with minor feldspar, mica, zircon, rutile, and iron-bearing minerals. Geochemical data indicates high SiO₂ (63.39%–70.94%) and Al₂O₃ (12.25%–14.20%) concentrations and calculated chemical index of alteration (CIA) values ranging from 60.90 to 66.82. The microstructural study revealed angular to sub-angular grains with conchoidal fractures and stepped microcracks, indicating brittle deformation under high-energy conditions, which is consistent with short transport distances, limited sedimentary recycling, and a derivation from mechanically weathered source rocks. Multivariate analyses (PCA and K-means clustering) of grain size parameters reveal two distinct sedimentary regimes, namely Cluster 1 as finer-grained (2.36 ϕ), poorly sorted sediments, and Cluster 2 as coarser (2.98 ϕ), well-sorted deposits. Discriminant function values (Y₂: 78.82–119.12; Y₃: −6.01 to −2.56; V₁: 1.457–2.442; V₂: 1.409–2.323) highlight shallow water, fluvial/deltaic aspects, and turbidite depositional environments. These findings advance the understanding of sedimentary dynamics within large, braided river basins and support future investigations into the sustainable management of fluvial depositional environments. Full article

Textile dye effluents containing toxic organic compounds pose serious environmental challenges. In this study, novel Poly(1-vinyl imidazole)-Bis[2-(methacryloyloxy)ethyl] phosphate (PVIB) polymers were synthesized with crosslinker molar fractions ranging from 5% to 80% and were subsequently investigated as advanced adsorbents for textile dye removal. Procion Red (PR), a widely used reactive dye, was selected as the model pollutant. The materials were characterized using FTIR, TGA, DTG, SEM-EDX, WD-XRF, TEM, and BET analyses. Adsorption mechanisms were examined through kinetic, isotherm, and thermodynamic models. Among the synthesized formulations, PVIB20% achieved the best dye removal, reaching an experimental adsorption capacity of 330 mg g⁻¹ within 60 min under acidic to neutral conditions. The kinetic modeling studies identified the pseudo-first-order model as the best fit, indicating a surface-controlled process involving both physical and chemical interactions. Isotherm studies showed that the Langmuir and Redlich–Peterson models provided the best fit, yielding a maximum monolayer adsorption capacity of 765 mg g⁻¹. Thermodynamic analysis revealed that the adsorption was spontaneous, endothermic, and entropy-driven. Overall, PVIB20% demonstrated superior adsorption capacity, rapid kinetics, and strong dye–polymer interactions compared with many conventional and modified adsorbents, which highlights its potential as an efficient and durable material for anionic dye removal from wastewater. Full article

In this study, high-energy milled (HEM) samples of natural phosphorites from Estonian deposits were investigated. The activation was performed via planetary mill with Cr-Ni grinders with a diameter of 20 mm. This method is an ecological alternative, since it eliminates the disadvantages of conventional acid methods, namely the release of gaseous and solid technogenic products. The aim of the study is to determine the changes in the structure to follow the solid-state transitions and the isomorphic substitutions in the anionic sub-lattice in the structure of the main mineral apatite in the samples from Estonia, under the influence of HEM activation. It is also interesting to investigate the influence of HEM on structural-phase transformations on the structure of impurity minerals-free calcite/dolomite, pyrite, quartz, as well as to assess their influence on the thermal behavior of the main mineral apatite. The effect of HEM is monitored by using a complex of analytical methods, such as chemical analysis, powder X-ray diffraction (PXRD), wavelength-dispersive X-ray fluorescence (WD-XRF) analysis, and Fourier-transformed infrared (FTIR) analysis. The obtained results prove the correlation in the behavior of the studied samples with regard to their quartz content and bonded or non-bonded carbonate ions. After HEM activation of the raw samples, the following is established: (i) anionic isomorphism with formation of A and A-B type carbonate-apatites and hydroxyl-fluorapatite; (ii) solid-phase synthesis of calcium orthophosphate-CaHPO₄ (monetite) and dicalcium diphosphate-β-Ca₂P₂O₇; (iii) enhanced chemical reactivity by approximately three times by increasing the solubility via HEM activation. The dry milling method used is a suitable approach for solving technological projects to improve the composition and structure of soils, increasing soil fertility by introducing soluble forms of calcium phosphates. It provides a variety of application purposes depending on the composition, impurities, and processing as a soil improver, natural mineral fertilizer, or activator. Full article