Search Results (6,801)

The rapid increase in electronic waste poses a significant environmental issue, with copper-rich residues considered among the most valuable fractions. Extracting copper of high purity from these materials is critical for advancing sustainable resource utilization. In this work, an oxidative refining approach employing a FeO–CaO–SiO₂ slag matrix was investigated to purify copper-bearing sludge. The method facilitated stable slag generation and ensured distinct separation between the metallic phase and slag. Although Fe and Si were removed effectively at relatively low processing temperatures, complete removal of Sn and S occurred only at 1300 °C, with traces of copper oxides persisting in the refined alloy. Overall, the findings suggest that the proposed slag system offers a reliable strategy for producing high-purity copper from secondary sources, underscoring its relevance in sustainable recycling of copper-enriched wastes. Full article

This study investigates the effects of ultrasonic surface rolling process (USRP) parameters—static load, indentation depth—on the surface integrity, mechanical properties, and high-temperature oxidation properties of laser-clad NiCrAl coatings. Comprehensive experimental results demonstrate that USRP treatment effectively eliminates surface cracks and significantly enhances surface integrity. The process simultaneously improves mechanical properties, with microhardness increasing by 24.6% due to grain refinement-induced strengthening and elevated dislocation density. Under constant preload, increasing the ultrasonic rolling indentation depth effectively transforms residual tensile stress into beneficial compressive stress (from +69.8 MPa to −1315.3 MPa), with higher preload further enhancing this effect. Moreover, USRP-treated coatings achieve complete oxidation resistance at elevated temperatures by forming a denser and more continuous oxide layer while effectively suppressing internal oxidation, resulting in markedly improved high-temperature oxidation performance. Quantitative analysis confirms that the enhancement in surface mechanical properties is primarily attributed to microstructural refinement and dislocation strengthening mechanisms. Full article

This study explores the catalytic performance of V³⁺-modified Mg/Al hydrotalcite-derived materials in the oxidative dehydrogenation (ODH) of n-butane, compared with catalysts derived from pyrovanadate and decavanadate precursors. Different methods for preparing hydrotalcite-like materials were applied to obtain vanadium-containing Mg-Al mixed oxide catalysts for n-butane ODH. The hydrotalcite-like precursors were doped with vanadates (V⁵⁺) via ion exchange or co-precipitation or with V³⁺ cations incorporated into brucite-like layers. During calcination in air or argon flow, different vanadium-containing phases were obtained. Our findings demonstrate that V³⁺-doped hydrotalcites exhibit superior activity and selectivity toward the total C₄H₈ products, with enhanced selectivity for 1,3-butadiene. The highest n-butane conversion was observed for catalysts with an MgO structure and vanadium dispersed in the oxide matrix. A similar conversion level (~44%) was obtained for a spinel-like Mg₂VO₄ catalyst, but only a 15% level was found for the highly crystalline α-Mg₂V₂O₇ catalyst. In contrast, the highest selectivities toward dehydrogenated products were observed for V³⁺-containing and α-Mg₂V₂O₇ catalysts. NH₃- and CO₂-temperature programmed desorption (TPD) analyses showed that high basicity combined with low acidity favors the formation of butene isomers and 1,3-butadiene. This work highlights the strategic potential of tailoring vanadium speciation and hydrotalcite-based catalyst design for low-carbon chemical manufacturing, supporting the transition toward a circular economy. Full article

In this study, a novel low-temperature (300–500 °C) carbothermal reduction route employing potassium ferrate and sodium hydroxide was developed to synthesize magnetic zero-valent iron-doped biochar for removing tetracycline and ciprofloxacin from aqueous solutions. Carbothermal reduction occurred effectively at 400 °C, generating sufficient small reductive molecules for the reduction of iron species into zero-valent iron. This process led to the impregnation of abundant zero-valent iron along with nano-magnetite into the carbon matrix, while nano-magnetite was also dispersed and stabilized on zero-valent iron. Simultaneously, abundant functional groups were formed, contributing to anchoring iron species and adsorbing pollutants. The magnetic biochar exhibited high adsorption capacities for tetracycline (1106.25 mg/g) and ciprofloxacin (182.03 mg/g), along with high saturation magnetization (56.3 emu/g) and superior reusability. Moreover, the magnetic biochar showed broad applicability for efficient removal of tetracycline and ciprofloxacin derivatives. Overall, carbothermal reduction efficiently transformed iron oxides into zero-valent iron at a relatively low temperature, providing a viable approach for manufacturing magnetic biochar doped with zero-valent iron. Full article

By integrating cathodic arc evaporation (CAE) with magnetron sputtering (MS) or high-power impulse magnetron sputtering (HiPIMS), hard coatings with diverse multicomponent compositions can be fabricated. Depending on the deposition conditions, the coatings with nano-composite or nano-multilayered microstructures are produced. During the mixing deposition conditions, nano-composite coatings are fabricated, which can be tailored to possess combining properties of super hardness, low friction coefficient, and excellent thermal/chemical stability. For the deposition with larger rotating periods, layer-by-layer deposition was observed. By the nano-multilayered coating design, superior mechanical properties (hardness ≥ 35 GPa), modulated residual stresses, and enhanced high-temperature properties can be obtained. In addition, lubricious elements, low friction (friction coefficient < 0.4), and low wear (<10⁻⁵ mm³/N∙m) both at ambient temperature and high temperature can be realized. Among these coatings, some have been specifically designed to achieve outstanding cutting performance in high-speed cutting applications. Several nitride and oxide hard coatings, such as AlTiN, TiAlN/TiSiN, AlCrN/Cu, and AlCrO, were deposited using a hybrid industrial physical vapor deposition (PVD) coating system. The microstructure, mechanical properties, and cutting performance of these coatings will be discussed. Full article

In this study, glucose is used as the source of C; through cathode plasma electrolytic deposition technology, a carbon nano coating is prepared on the surface of carbon fiber. The carbon coating is analyzed using scanning electron microscopy, transmission electron microscopy, and X-ray photoelectron spectroscopy to investigate the effect of pH on the microstructure of the carbon coating on the surface of carbon fiber. At the same time, the oxidation resistance of the coating and the changes in the tensile properties of carbon fiber after high-temperature heat treatment were also investigated. The results showed that reducing the pH value can improve the microstructure of the carbon coating, and the best performance of the carbon coating sample was obtained at pH = 3. The initial oxidation temperature and oxidation termination temperature increased by 156 °C and 110 °C, respectively, compared to the treated carbon fiber but without coating, and the tensile property remains a high value (2740 MPa) after high-temperature heat treatment. Full article

RMB₆-TMB₂ (RM = rare earth elements, TM = transition metal elements) composites retain superior field emission properties of RMB₆ while addressing its inherent mechanical limitations by constructing a eutectic structure with TMB₂. Herein, an in situ route for synthesizing RMB₆-TMB₂ composite nanopowders with homogeneous phase distribution using reduction reactions was proposed. The LaB₆-ZrB₂ composite nanopowders were synthesized in situ for the first time using sodium borohydride (NaBH₄) as both a reducing agent and boron source, with lanthanum oxide (La₂O₃) and zirconium dioxide (ZrO₂) serving as metal sources. The effects of the synthesis temperature on phase compositions and microstructure of the composites were systematically investigated. The LaB₆-ZrB₂ system with a eutectic weight ratio exhibited an accelerated reaction rate, achieving a complete reaction at 1000 °C, 300 °C lower than that of single-phase ZrB₂ synthesis. The composite phases were uniformly distributed even at nanoscale. The composite powder displayed an average particle size of ~170 nm when synthesized at 1300 °C. With the benefit of the in situ synthesis method, LaB₆-TiB₂, CeB₆-ZrB₂, and CeB₆-TiB₂ composite powders were successfully synthesized. This process effectively addresses phase separation and contamination issues typically associated with traditional mixing methods, providing a scalable precursor for high-performance RMB₆-TMB₂ composites. Full article

The efficient purification of Pb(II)-containing wastewater is essential for safeguarding public health and maintaining the aquatic environment. In this study, novel hydrous ferric oxide (HFO) nanoparticle-embedded poly(vinylidene fluoride) (PVDF) composite adsorption membranes were developed through a simple blending method for efficient Pb(II) removal. This composite membrane (denoted as HFO-PVDF) combines the excellent selectivity of HFO nanoparticles for Pb(II) with the membrane’s advantage of easy scalability. The optimized HFO-PVDF_(1.5) membrane achieved adsorption equilibrium within 20 h and exhibited excellent adsorption capacity. Moreover, adsorption capacity markedly enhanced with increasing temperature, confirming the endothermic nature of the process. The developed HFO-PVDF membranes demonstrate significant potential for real-world wastewater treatment applications, exhibiting exceptional selectivity for Pb(II) in complex ionic matrices and could be effectively regenerated via a relatively straightforward process. Furthermore, filtration and dynamic regeneration tests demonstrated that at an initial Pb(II) concentration of 5 mg/L, the membrane operated continuously for 10–13 h before regeneration, treating up to 200 L/m² of wastewater before breakthrough, highlighting potential for cost-effective industrial wastewater treatment. This study not only demonstrates the high efficiency of the HFO-PVDF membrane for heavy metal ion removal but also provides a theoretical foundation and technical support for its practical application in water treatment. Full article

The chromium-free oxide precursor strategy effectively avoids chromium volatilization and electrode contamination in metal-supported solid oxide fuel cells (MS-SOFCs), while enabling high-temperature co-sintering in air to simplify the fabrication process. However, the drastic microstructural coarsening, dimensional shrinkage, and thermal expansion mismatch with adjacent components of such substrates during high-temperature sintering, reduction, and thermal cycling collectively contribute to the interfacial instability and structural degradation of MS-SOFCs. Herein, we address these issues by incorporating a small amount of Gd_0.1Ce_0.9O_1.95 (GDC) to the NiO-Fe₂O₃ (NFO) substrate. The incorporation of GDC significantly enhances the sintering compatibility and reduction stability of the MS-SOFCs, alleviating the stress-induced warping and distortion. Moreover, the GDC phase has a pinning effect to suppressing the coarsening of the substrates during high-temperature sintering and reduction processes, enhancing mechanical integrity and structural robustness of the single cell. With 15 wt% GDC incorporated into the NiFe substrate, the corresponding MS-SOFC with GDC electrolyte film achieves a peak power density of 0.56 W cm⁻² at 600 °C, along with markedly improved structural integrity and operational reliability. This work demonstrates a viable pathway for designing heterophase-engineered supports with matched thermomechanical properties, offering promising prospects for enhancing the durability of MS-SOFCs. Full article

The effective and rapid separation of oil–water emulsions at room temperature, particularly under harsh environmental conditions like acid–base fluctuations, high salinity, and the coexistence of surfactants, remains a significant challenge in oily wastewater treatment. To address this, a novel amphiphilic demulsifier, MOF-74@SiO₂-GPTMS grafted ANP (MSG-ANP), was synthesized by first modifying MOF-74@SiO₂ (MS) with γ-glycidoxypropyltrimethoxysilane (GPTMS) to create epoxy-functionalized MSG particles, followed by grafting the non-ionic polyether C₁₂–C₁₄ aliphatic polyethylene oxide polyoxypropylene (ANP) onto MSG. Bottle tests demonstrated that MSG-ANP achieved a high demulsification efficiency of 93% within 15 min for oil-in-water emulsions at room temperature. It exhibited excellent environmental tolerance, maintaining efficiencies of 89% at pH 3.0, 82% at pH 11.0, and 95% under high salinity (50,000 mg/L, pH 6.8). Furthermore, MSG-ANP effectively treated surfactant-stabilized emulsions, exceeding 96% efficiency against both cetyltrimethylammonium bromide and sodium dodecyl sulfate after 30 min, outperforming commercial demulsifiers SP-169 and AR-331 by factors of 1.2 and 1.6, respectively. This superior performance stems from synergistic hydrogen bonding (via hydroxyl, ether, ester, Fe-O, and Si-O groups) destabilizing the interfacial film and electrostatic neutralization of coalescing charged droplets. Consequently, MSG-ANP presents a promising solution for rapid, room-temperature demulsification across a wide pH range and under high-salinity conditions. Full article

Climate change is having a significant impact on vine physiology and grape composition, leading to notable alterations in wine quality, such as reduced acidity, increased ethanol content, and higher pH levels. These effects are particularly problematic in arid and semi-arid regions, such as Mediterranean areas, where high summer temperatures and low rainfall accelerate the degradation of organic acids in grapes. As a result, wines produced under these conditions often lack the acidity required to preserve their freshness and enological quality. This study evaluated the effect of must acidification using cation-exchange resins on the composition and quality of red wines made from the Monastrell variety, comparing them with wines acidified using tartaric acid to reach the same target pH. The results showed that treating a portion of the must (20% and 30%) with cation-exchange resins significantly reduced wine pH values and increased total acidity compared to the control wine. A similar result was observed in wines acidified with tartaric acid. However, as an additional effect, the treatment with resin more markedly reduced the concentration of pro-oxidant metal cations such as iron, copper, and manganese, contributing to lower values of volatile acidity and a greater stability against oxidation of phenolic compounds. Must acidification with both methods improved wine color quality by increasing color intensity and decreasing hue values. Although no significant differences were found in the total concentration of phenolic compounds, variations were detected in their compositional profile. Furthermore, the acidification also affected the concentration and composition of aromatic compounds in the final wine. Sensory analysis revealed that the treated wines—particularly those made with must acidified using cation-exchange resins—exhibited greater aromatic intensity, more pronounced fruity notes, and reduced astringency, resulting in a fresher mouthfeel. In conclusion, must treatment with cation-exchange resins appears to be a low-cost good alternative compared tartaric acid addition for reducing pH and increasing acidity in Monastrell red wines, thereby enhancing their quality in winegrowing regions with arid or semi-arid climates. Full article

Transition-metal oxides (TMOs) possess pronounced optoelectronic properties and are widely exploited in photovoltaics and photocatalysis. Here, we introduce a hot wire oxidation sublimation deposition (HWOSD) that directly converts elemental Mo and W into amorphous MoO_x and WO_x films on various substrates. Scanning electron microscopy and atomic force microscopy reveal uniform thickness and conformal coverage over textured and planar surfaces. X-ray photoelectron spectroscopy indicates high oxygen contents with stoichiometric ratios of 2.94 (MoO_x) and 2.91 (WO_x). Optical measurements show transmittances > 94% across 400–1200 nm, yielding optical band gaps of 1.86 eV (MoO_x) and 2.67 eV (WO_x). The conductivities of MoO_x and WO_x were 2.58 × 10⁻⁶ S cm⁻¹ and 5.14 × 10⁻⁷ S cm⁻¹ at room temperature, and the TMO/Si surface potential differences are 200 mV and 114 mV, respectively. Minority-carrier-lifetime measurements indicate that MoO_x films confer an additional passivation benefit to the i a-Si:H/c-Si/i a-Si:H stack. Annealing of MoO_x and WO_x realized their phase transition from an amorphous state to a polycrystalline state, with changes in their optical transmittance in the visible light region. Investigation of the photovoltaic performances of MoO_x and WO_x as HTLs deposited by HWOSD demonstrates their excellent electronic functionality in optoelectronics. These results establish HWOSD as a scalable, low-temperature method to fabricate high-quality TMO films and expand their potential in advanced optoelectronic devices. Full article

Blast furnace (BF) ironmaking remains one of the most efficient countercurrent processes; however, achieving further CO₂ emission reductions through conventional methods is increasingly challenging. Currently, BF ironmaking emits approximately 2.33 tonnes of fossil-derived CO₂ per tonne of crude steel cast. Integrating briquettes composed of biochar and in-plant fines into the BF process offers a promising short- to medium-term strategy for lowering emissions. This approach enables efficient recycling of fine residues and the substitution of fossil reductants with bio-based alternatives, thereby improving productivity while reducing energy and carbon intensity. This study investigates the reduction behavior of (i) biochar mixed with pellet fines, (ii) various in-plant residues individually, and (iii) briquettes composed of biochar and in-plant fines. The reduction rate of biochar–pellet fine mixtures was found to depend on biochar type, with pyrolyzed pine sawdust exhibiting the highest reactivity, and pyrolyzed contorta wood chips the lowest. A correlation between reduction rate and the alkali index of each char was established, although other factors such as char origin and physical properties also influenced reactivity. The effect of biochar addition (0, 5, and 10 wt.%) on the reduction of steelmaking residues was also studied. In general, biochar enhanced the reduction degree and shifted the reaction onset to lower temperatures. The produced briquettes maintained high mechanical integrity during and after reduction, regardless of biochar origin. Thermogravimetric and XRD analyses revealed that mass loss initiates with the dehydroxylation of cement phases and release of volatiles, followed by carbonate decomposition and reduction of higher oxides above 500 °C. At temperatures ≥ 850 °C, the remaining iron oxides were further reduced to metallic iron. Full article

This study characterized the physicochemical properties of cocoa butter (CB) extracted from cocoa beans of the Criollo Nativo (Peru), Criollo (Mexico), and Forastero (Brazil) varieties subjected to spontaneous fermentation under traditional local conditions in each country. Cocoa samples were collected at 24-h intervals, and CB was extracted to evaluate its lipid composition through fatty acid profiling and spectroscopic techniques (FT-IR and NMR). Also, the thermal and structural properties via differential scanning calorimetry (DSC), including melting and crystallization profiles, crystallization kinetics, and polymorphism, were determined. The results revealed that stearic, oleic, and palmitic acids were predominant in all varieties, while trace levels of myristic and pentadecanoic acids contributed to molecular packing. FT-IR identified bands associated with glycerol chain formation in TAGs, which were confirmed by NMR through chemical shifts linked to the distribution of POS, SOS, and POP species. CB exhibited melting temperatures between 19.6 and 20.5 °C, favoring polymorphic transitions toward more stable forms. Form I (γ) predominated during early fermentation, while Forms II (α) and III (β′₂) were subsequently identified, particularly in Criollo varieties. These findings demonstrate that fermentation time significantly influences the chemical composition, oxidative stability, and crystalline structure of CB, providing valuable insights for optimizing cocoa processing and the development of high-quality chocolate products. Full article

Aging of asphalt is a major cause of pavement distress. While regenerators restore aged asphalt, their mechanisms and efficacy differences remain unclear. This study quantified the repair effects of waste bio-oil (WBO) and mineral oil (MO) rejuvenators on aged asphalt binder using a comprehensive characterization approach. Conventional properties (penetration, softening point, ductility), functional groups (FT-IR), thermal stability (TG), differential scanning calorimetry (DSC), and dynamic shear rheology (DSR) were analyzed. Results reveal distinct mechanisms: WBO acts chemically via polar molecules, selectively reducing oxygen-containing groups and significantly improving ductility, while MO acts physically through light components that dilute viscosity, exhibiting weaker chemical repair. WBO-regenerated asphalt showed a lower thermal-oxidative peak temperature, superior low-temperature ductility, and enhanced high-temperature rheological performance (higher rutting factor, optimized viscoelasticity). These mechanistic differences—chemical restoration (WBO) versus physical replenishment (MO)—determine performance outcomes at the binder level. The findings provide a theoretical basis for regenerator selection in pavement engineering, highlighting WBO’s advantages for functional group restoration and balanced thermal rheological properties, supporting sustainable road development. Full article