Search Results (4,178)

This paper presents a sustainable recycling process for the separation and recovery of tempered glass from end-of-life photovoltaic (PV) modules. As glass accounts for 75% of the weight of a panel, its recovery is an important step in the recycling process. Current methods, such as mechanical, chemical and thermal processes, often lead to contamination of the glass and pose significant environmental risks. In response to these challenges, a thermal–mechanical delamination approach is proposed in this study. The method utilizes controlled heat application (hot air gun) to weaken the adhesive bond between the glass and encapsulant, allowing for separation with a thin stainless steel wire. Various analytical methods, including X-ray diffraction analysis (XRD), X-ray fluorescence (XRF) and scanning electron microscopy with energy-dispersive X-ray spectroscopy (SEM-EDS), were used to verify the effectiveness of the proposed method. The results show that the proposed method is effective. In less than a minute, the glass layer was separated and recovered with a success rate of over 99%, with no degradation of the material or release of gasses. The significance of this process lies in its ability to recover high-purity glass while minimizing the impact on the environment. This opens up the possibility of reusing the recovered tempered glass in new PV panels or other applications, reducing the need for virgin materials and lowering the overall environmental footprint of the solar energy industry. Full article

The circulation pump in a distillation column is a core device in a material circulation system, and its stable operation is crucial for the production process. The impeller of the circulation pump is prone to failure due to long-term contact with corrosive media, and subjected to a large amount of material erosion, which severely challenges the safety control of the distillation reaction system. Focusing on the corrosion failure phenomenon of circulation pump impellers, the failure mechanism was studied by means of macroscopic inspection, chemical composition analysis, metallographic examination, scanning electron microscopy (SEM), and energy dispersive spectrometer (EDS). Results indicated that the corrosion of circulation pump impellers was the result of the combined effects of surface wear, cavitation, and halogen element corrosion. The medium in contact with the impeller contained chloride ions, fluoride ions, and solid particles. During circulation pump operation, a low-pressure zone formed at the inlet, generating numerous water vapor bubbles. These bubbles burst in the high-pressure zone, creating highly localized impact forces. Combined with the abrasive action of solid particles on the impeller surface, this led to the destruction of the passivation film and the formation of numerous small pits. These corrosion pits and the surrounding environment formed micro-galvanic corrosion cells with small anodes and large cathodes. Under the accelerated corrosion caused by fluoride and chloride ions, the corrosion process towards the inner wall of the impeller intensified, ultimately leading to impeller failure. This study clarified the corrosion failure mechanism and its root causes in the 2507 duplex stainless steel circulation pump impeller and proposes corresponding improvement recommendations, providing a scientific basis for preventing similar issues from occurring in the future. Full article

This paper presents and demonstrates the development of a new lightweight coating for aluminum alloy from a novel multicomponent alloy based on the AlSiMgCu system. The coating was applied using a newly designed approach that combined high velocity oxy-fuel (HVOF) and plasma spraying processes. This hybrid technique enables the deposition of coatings with enhanced performance characteristics. The optical microscopy (OM) and scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM + EDS) revealed a strong adhesion and compaction between the multicomponent coating and the A6061 substrate. The new coating improved hardness by 50% and increased electrical conductivity by approximately 3.3 times compared to the as-cast alloy. Corrosion tests showed a lower corrosion rate, comparable to thermally treated A6061 alloy. Tribological tests indicated over 20% reduction in friction and over 50% reduction in wear rate. This suggests that multicomponent aluminum coatings could improve automotive and parts in contact with hydrogen by enhancing hydrogen fragilization resistance, corrosion resistance, electrical conductivity, and wear properties, with further optimization of thermal spraying potentially boosting performance even further. Full article

The increased exploitation of ores leads to the generation of mining waste, which has a negative impact on the environment and human health. For this reason, it is necessary to take care of it in an adequate way by applying some of the possible treatments. In addition to protecting the environment by applying appropriate treatment, there is also the possibility of making a profit by valorizing useful elements from mining waste. In order to choose the most adequate treatment, it is necessary to perform the characterization of mining waste. This paper contains a detailed characterization of the flotation tailings deposited at the Old Flotation Tailings in eastern Serbia, originating from copper ore processing. Characterization includes physico-chemical analysis, polarizing microscope analysis, X-ray Diffraction analysis (XRD) and Scanning Electron Microscopy with Energy Dispersive Spectroscopy (SEM-EDS) analysis analysis. The obtained results indicate that the investigated flotation tailings can be used as a secondary raw material for metal recovery, in this case primarily copper (whose content is about 0.24%), gold (with a content of about 0.43 ppm) and silver (with a content of about 1.7 ppm). Considering that the content of valuable elements is quite low, it is suggested to apply hydrometallurgical treatment for their recovery. Full article

Biomass diesel is one of the sustainable and renewable sources of energy envisaged to hold a prominent position in the world energy infrastructure. In this study, biodiesel was production from baobab seed oil by transesterification using biogenic heterogeneous catalyst, derived from mixed wastes of white chicken eggshells and banana fruit peels. The production process was analyzed and statistically analyzed using Box-Behnken Design-Response Surface Methodology (BBD-RSM). The influential transesterification reaction parameters investigated with their ranges include reaction time (40–80 min), molar ratio of oil to methanol (1:9–1:15) and catalyst weight (3–5 wt%). The nano-catalyst (CaO-BFP-850 NPs) was prepared by calcination at high temperature of 850 °C for 4 h, and its properties were found to contain majorly the basic elements of Ca and K when investigated with analytical instruments such as SEM, EDS, DSC-TGA, FT-IR, and XRD. The regeneration test of the CaO-BFP-850 NPs conducted showed it could be reused for more than four cycles with less catalytic efficiency reduction. The ideal conditions instituted by BBD-RSM was 75 min of reaction time, 12.8:1 molar ratio of oil to methanol, and 4.08 wt% CaO-BFP-850 at 65 °C and 650 rpm constant temperature and agitation speed respectively, with the validated biodiesel yield of 96.70 wt%. The assessment of the quality of the biodiesel produced showed compliance with the standard specifications of ASTM D6751, EN 14241, and SANS 833. Full article

This investigation focuses on the impact of Sm³⁺ dopants on BaBi₂Nb₂O₉ (BBN) ceramics. These ceramics were obtained using the traditional solid state reaction approach. Techniques like scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS) were employed to explore the structure and morphology of the ceramics. The results showed that the chemical composition of the ceramic samples matched well with the initial ceramic powder stoichiometry. Increasing the amount of samarium resulted in a slight reduction in the average ceramic grain size. The ceramics exhibited a tetragonal structure categorized under the space group I4/mmm. The electrical properties were analyzed using complex impedance spectroscopy (SI) across various temperatures and frequencies, revealing that both grains and intergranular boundaries are significant in the material’s conductivity. Full article

Commercial NH₄-Beta and Na-ZSM-5 zeolites were fluorinated with different amounts of NH₄F and using different procedures (room temperature, conventional refluxing, microwave refluxing). Samples were characterized by XRD, N₂ physisorption, FTIR, ¹H NMR, SEM-EDS, and TGA of adsorbed cyclohexylamine. An increase in the concentration of NH₄F led to fluorinated zeolites with higher surface areas and slightly lower amounts of Brønsted acid sites due to some dealumination. Fluorination by conventional or microwave refluxing at shorter times did not dealuminate ZSM-5, resulting in the formation of higher particle sizes. Ni/fluorinated beta catalysts were more active than Ni/fluorinated ZSM-5 catalysts for the hydrodeoxygenation of guaiacol at 180 °C and 15 bar of H₂ for 1 h due to their higher amount of acid sites. The appropriate proportion of metallic and Brønsted acid centers allowed for the selective obtention of cyclohexane (58%) for the Ni supported on beta fluorinated with NH₄F 0.1 M catalyst. The combination of this fluorinated beta to a Ni/ordered mesoporous carbon catalyst significantly boosted its selectivity to cyclohexane from 0 to 65%. Fluorinated ZSM-5 samples, although having stronger Brønsted acid sites, as observed by ¹H NMR, they had lower amounts, leading to higher selectivity to cyclohexanol when used as catalytic supports. Full article

A colored superhydrophobic surface on a stainless steel substrate was achieved by means of high temperature oxidation combined with subsequent spraying modification by superhydrophobic nano-silica film. Comprehensive characterizations of the surface were performed in terms of color, morphology, composition, wettability, and corrosion resistance by optical microscopy, X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive spectroscopy (EDS), contact angle, potentiodynamic polarization, and electrochemical impedance spectroscopy measurement. At 400 °C, the surface was pale yellow, gradually turning yellow and then red as the temperature increased. At 700 °C and 800 °C, the surface colors were blue and dark brown, respectively. The samples with oxide films demonstrated lower contact angles, specifically 80.5° ± 2.5 at 400 °C, 79.1° ± 2.8 at 500 °C, and 75.6° ± 3.4 at 600 °C. The polarization resistance measured on the oxidized film formed at 600 °C exceeded 7.93 × 10⁴ Ω·cm². After spraying the treatment, these colorful surfaces exhibited superhydrophobicity, they were self-cleaning, and they satisfied anti-corrosion properties. The treatment performs as an excellent barrier and exhibits a high corrosion resistance of 4.68 × 10⁶ Ω·cm². The successful preparation of superhydrophobic colored surfaces offers the possibility of providing stainless steel with both decoration value and self-cleaning function simultaneously by our proposed chromium-free fabrication process. Full article

Offshore wind turbine generators usually demand higher requirements for key component materials because of the adverse working environment. Therefore, in this study, electromagnetic-assisted laser cladding technology was introduced to prepare the nickel-based composite coating on the Q345R matrix of wind turbine generator key component material. By means of Scanning Electron Microscope (SEM), X-ray diffraction (XRD), Energy Dispersive Spectrometer (EDS), the Vickers hardness tester, friction and wear tester, and electrochemical workstation, the effects of different magnetic field intensities on the macroscopic morphology, microstructure, phase composition, microhardness, wear resistance, and corrosion resistance of the coating were analyzed. The experimental results show that the addition of a magnetic field can effectively reduce the surface defects, improve the surface morphology, and not change the phase composition of the coating. With the increase in magnetic field intensity, the microstructure is gradually refined, and the average microhardness increases gradually, reaching a maximum of 944HV_0.5 at 8 T. The wear resistance gradually increases with the increase in magnetic field intensity, especially when the magnetic field intensity reaches 12 T, the wear rate of the coating is reduced by 81.13%, and the corrosion current density is reduced by 43.7% compared with the coating without a magnetic field. The addition of an electromagnetic field can enhance the wear resistance and corrosion resistance of the nickel-based laser cladding layer. Full article

This study focuses on investigating the strength recovery of fire-damaged fly ash concrete (FAC) with a low substitution rate of 10% through post-fire curing. The chemical and microstructural changes were analyzed using X-ray diffraction (XRD), derivative thermogravimetry (DTG), scanning electron microscopy (SEM), energy dispersive X-ray spectrometry (EDS), and nitrogen adsorption. The findings indicate that the incorporation of fly ash slightly enhanced the strength after exposure to 400 °C; this was attributed to improved pozzolanic reactions, which were not observed at higher temperatures of 600 °C and 800 °C. Moreover, a positive effect on the recovery of compressive strength was observed due to the pozzolanic reaction. However, due to the relatively low fly ash content, depletion occurred at a later age, resulting in the inability to inhibit microstructural damage caused by the production of portlandite, thereby weakening the compressive strength. Interestingly, fly ash influenced the morphology of calcium carbonate and calcium silicate hydrate crystals, which is potentially ascribed to the role of high aluminum content acting as a crystallization-guiding agent. Full article

Titanium-Niobium (TiNb) alloys are commonly employed in a number of implantable devices, yet concerns exist regarding their use in implantology owing to the biomechanical mismatch between the implant and the host tissue. Therefore, to balance the mechanical performance of the load-bearing implant with bone, TiNb alloys with differing porosities were fabricated by powder metallurgy combined with spacer material. Microstructures and phase constituents were characterized with energy dispersive spectroscopy (EDS), scanning electron microscopy (SEM), and X-ray diffraction (XRD). The mechanical properties were tested by uniaxial compression, and the corrosion performance was determined via a potentiodynamic polarization experiment. To evaluate a highly matched potential implant with the host, biocompatibilities such as cell viability and proliferation rate, fibronectin adsorption, plasmid-DNA interaction, and an SEM micrograph showing the cell morphology were examined in detail. The results showed that the alloys displayed open and closed pores with a uniform pore size and distribution, which allowed for cell adherence and other cellular activities. The alloys with low porosity displayed compressive strength between 618 MPa and 1295 MPa, while the alloys with high porosity showed significantly lower strength, ranging from 48 MPa to 331 MPa. The biological evaluation of the alloys demonstrated good cell attachment and proliferation rates. Full article

The abundant pore structure and carbon composition of sphagnum peat moss render it a bio-based adsorbent for efficient methylene blue removal from wastewater. By utilizing sphagnum moss sourced from Guizhou, China, as raw material, a cost-effective and highly efficient bio-based adsorbent material was prepared through chemical modification. The structure and performance of the modified sphagnum moss were characterized using SEM, EDS, FTIR, and TGA techniques. Batch adsorption experiments explored the effects of contact time, adsorbent dosage, pH, initial dye concentration, and temperature on adsorption performance. Kinetics, isotherm models, and thermodynamics elucidated the adsorption behavior and mechanism. The modified sphagnum moss exhibited increased surface roughness and uniform surface modification, enhancing active site availability for improved adsorption. Experimental data aligned well with the Freundlich isotherm model and pseudo-second-order kinetic model, indicating efficient adsorption. The study elucidated the adsorption mechanism, laying a foundation for effective methylene blue removal. The utilization of modified sphagnum moss demonstrates significant potential in effectively removing MB from contaminated solutions due to its robust adsorption capability and efficient reusability. Full article

Environmental barrier coatings (EBCs) are widely used to protect ceramic matrix composites (CMCs, SiC_f/SiC, and Al₂O_3f/Al₂O₃), and they should have low thermal expansion coefficients (TECs) matching the CMCs and excellent mechanical properties to prolong their lifetime. Current EBC materials have disadvantages of phase transitions and insufficient mechanical properties, which affect their working temperatures and lifetime. It is necessary to develop new oxide EBCs. Ytterbium tantalate (YbTaO₄) is a stable and novel EBC material, and we have improved the mechanical properties and TECs of Yb_1−xAl_xTaO₄ (x = 0.05, 0.1, 0.2, 0.3, 0.4, 0.5) ceramics by replacing Yb with Al. XRD, SEM, and EDS are used to verify the crystal and microstructures, and nano-indentation is used to measure the modulus and hardness when changes in TECs are measured within a thermal expansion device. The results show that the phase structure of Yb_1−xAl_xTaO₄ (x = 0.05, 0.1, 0.2, 0.3, 0.4, 0.5) is stable at 25–1400 °C within air atmosphere, and their high-temperature TECs (6.4–8.9 × 10⁻⁶ K⁻¹, 1400 °C) are effectively regulated by introductions of different contents of Al, which enlarge their engineering applications for SiC_f/SiC and Al₂O_3f/Al₂O₃ CMCs. The evolutions of TECs are analyzed from structural characteristics and phase compositions, and the increased TECs make Yb_1−xAl_xTaO₄ potential EBCs for Al₂O₃ matrixes. Due to the high bonding strength of Al–O bonds, hardness, as well as Young’s modulus, are enhanced with the increasing Al content, with Yb_1−xAl_xTaO₄ (x = 0.05, 0.1, 0.2, 0.3, 0.4, 0.5) having a nano-hardness of 3.7–12.8 GPa and a Young’s modulus of 100.9–236.6 GPa. The TECs of YbTaO₄ are successfully regulated to expand their applications, and they match those of Al₂O₃ and SiC matrixes, as well as displaying improved mechanical properties. This work promotes applications of YbTaO₄ as potential EBCs and provides a new way to regulate the TECs of tantalates. Full article

In the 19th century, the weighting of silk with metal salts, such as tin, was a common practice to enhance certain properties of silk fabrics and compensate for the weight loss incurred during the degumming process. This technique induces both physical and chemical modifications to the fibres, contributing to their long-term degradation, which requires thorough investigation. This study aims to examine the structural changes in silk fibres caused by the accumulation of metal salts from the tin-weighting process, using mock-up samples prepared through successive loading with weighting agents using a traditional tin-phosphate treatment method. Unweighted and tin-weighted silk samples were compared using scanning electron (SEM) micrographs, which presented the dispersed nanoparticles on the fibres, while through energy-dispersive X-ray spectroscopy (EDS) elemental mapping, the presence and uniform distribution of the weighting agents were confirmed. Fourier-transform infrared spectroscopy (FTIR) analysis revealed structural changes in tin-weighted silk samples compared to untreated ones, including shifts in amide bands, altered water/hydroxyl and skeletal stretching regions, and increased skeletal band intensities suggesting modifications in hydrogen bonding, β-sheet content, and structural disorder without significantly impacting the overall crystallinity index. X-ray diffraction (XRD) analysis of both pristine and tin-weighted silk samples revealed significant alterations, predominantly in the amorphous regions of the silk upon weighting. These structural changes were further examined using small-angle X-ray scattering (SAXS) and small- and wide-angle X-ray scattering (SWAXS), which provided detailed insights into modifications occurring at the nanometre scale. The analyses suggested disruptions in β-sheet crystals and intermolecular packing, especially in the amorphous regions, with increasing amounts of tin-weighting. Contact angle analysis (CA) revealed that the tin-phosphate-weighting process significantly impacted silk surface properties, transforming it from moderately hydrophobic to highly hydrophilic. These changes indicate that the incorporation of tin-phosphate nanoparticles on and within silk fibres could restrict the flexibility of polymer chains, impacting the physical properties and potentially the degradation behaviour of silk textiles. By studying these structural changes, we aim to deepen our understanding of how tin-weighting impacts silk fibre structure, contributing valuable insights into the longevity, conservation, and preservation strategies of silk textiles in the context of cultural heritage. Full article

Air pollution is a global health issue and a cause of premature mortality. There is an urgent need to develop air quality monitoring networks and to implement standards enabling dependable testing and delivering reliable results. European standards provide reference methods for testing ambient air quality, which are used in accredited laboratories. In this paper, we present an example of research conducted with the use of a mobile, automated station Airpointer^® in an industrial area under pressure from the lime and cement industry located in southeastern Poland. During the measurement campaign, the concentrations of the studied pollutants did not exceed the permissible thresholds, yet they strongly depended on meteorological conditions. The air filter was analysed with an energy dispersive spectroscopy (EDS) microanalyzer in the scanning electron microscope (SEM). The results confirmed that dust particles present in ambient air are connected with local emission sources—industry based on the extraction and processing of minerals. The equipment and measurement techniques used in this study are effective in identifying the potential threat of air pollution. Automated, short-term measurements of air pollution can be a significant source of information, indispensable for drawing up action plans aimed at air quality protection in order to achieve sustainable development goals. Full article