Search Results (8,795)

The rapid growth of populations and industrial activities has intensified the need to optimize resource management and reduce environmental impacts. A promising pathway toward sustainable development is the gradual replacement of fossil fuel vehicles with electric vehicles (EVs). However, managing EV operations, particularly regarding depot siting and vehicle routing, is a complex challenge that requires balancing economic, environmental, and social objectives. This research proposes a model for designing an intelligent and sustainable transportation system for waste collection using EV fleets. The model simultaneously determines optimal depot locations from a set of candidates and identifies efficient vehicle routes. Its dual objectives are to minimize total costs, including depot set-up, operation, and travel costs, and to minimize maximum travel time, ensuring equitable workload distribution among drivers. Beyond reducing costs and emissions, the model incorporates social equity considerations in balancing driver travel times. EV limitations, such as restricted range, are explicitly addressed. To solve small-scale instances, the $ϵ$-constraint method was applied, while medium- and large-scale instances were tackled with two multi-objective metaheuristics: the Non-dominated Sorting Genetic Algorithm II (NSGA-II) and Multi-Objective Particle Swarm Optimization (MOPSO). The results demonstrate the model’s sensitivity to system parameters such as vehicle capacity and demand rates. Statistical comparative analysis revealed that both algorithms successfully optimized the primary objective functions without significant differences. However, they exhibited distinct performance metric strengths; NSGA-II demonstrated statistically significant advantages in computational efficiency, solution quantity, and uniform distribution, while MOPSO excelled in convergence quality and closeness to the true Pareto front. Furthermore, the practical applicability of the proposed model is validated through a real-world case study of a municipal solid waste management network in Southern Tehran. This research contributes a comprehensive framework for optimizing EV-based waste collection systems, offering a meaningful step toward sustainable and intelligent urban transportation. The findings provide a theoretical framework and strategic insights for transportation managers and policymakers seeking effective strategies for environmentally responsible and socially equitable waste collection. Full article

Global food waste management necessitates circular bioeconomy solutions to transform organic residues into high-value nutrients to address nutritional demands. This study investigated the valorization of two abundant waste streams, stale bread and sunflower oil through solid state fermentation using food-grade filamentous fungi. Three strains, Neurospora intermedia, Aspergillus oryzae and Rhizopus oryzae were evaluated for the bioconversion of stale bread. Oil supplementation levels of 10, 20 and 30% (g/100 g dry matter) using both fresh and spent sunflower oil were tested to assess changes in proximate composition, characterizing fungal growth dynamics and mycelial development. Furthermore, modifications in fatty acid profiles and hydrolytic enzyme activities were analyzed to determine species responses to oil source and concentration. The results demonstrated that N. intermedia achieved peak protein levels of 36% (g/100 g) alongside efficient starch catabolism, while 10% fresh oil supplementation induced a significant protein increase (26%) in A. oryzae. Regarding lipid accumulation, 10% spent oil supported higher fat content in R. oryzae (19%) compared to fresh oil (17%). PUFA/SFA ratio reached its maximum in A. oryzae with the highest of 5.91 ± 0.56 under 10% fresh oil. Enzymatic analysis identified A. oryzae as the most efficient lipase producer, reaching a maximum activity of approximately 0.10 U/g at 10% spent oil supplementation. Conversely, R. oryzae lipase activity peaked at 20% supplementation (0.08 U/g), reflecting its high capacity for lipid accumulation. These findings establish a potent bioprocess for upcycling mixed food wastes into enhanced functional ingredients for sustainable food and feed systems. Full article

Synthetic textile dye solutions are commonly used as controlled model systems to evaluate adsorbent performance before application to real textile wastewater matrices. In this study, a magnetic adsorbent was developed by functionalizing pomegranate peel-derived biochar with iron oxide (Fe₃O₄) nanoparticles and was applied for chemical oxygen demand (COD) removal from synthetic aqueous solutions containing three individual acid dyes: Buracid Yellow BGL, Buracid Navy Blue RL, and Buracid Red FN. The effects of adsorbent loading, pH, contact time, and dye type on COD removal were systematically evaluated and optimized using Response Surface Methodology (RSM). The experimental results showed that adsorbent loading, pH, and contact time significantly influenced COD removal efficiency. The developed quadratic model showed good explanatory performance, with R² = 83.42% and adjusted R² = 79.28%, while the predicted R² value of 72.65% indicated moderate predictive capability. Under the identified optimum operating region (pH 7.4, contact time 35 min, and adsorbent loading 80 g/L), COD removal efficiency reached up to 84%, depending on dye type. These findings indicate that Fe₃O₄-modified pomegranate peel biochar is a promising adsorbent for COD reduction from synthetic textile dye solutions. However, further validation using real textile wastewater is required to evaluate matrix effects caused by salts, surfactants, suspended solids, mixed dyes, and other textile auxiliaries. Full article

An experimental setup has been developed that enables the conversion of a complex stream of polydisperse droplets generated by an ultrasonic dispenser into a stream of nearly identical droplets falling through a vertical channel. The fall of droplets of an aqueous NaCl solution in this channel, filled with heated dry air, is studied. Water from the droplets evaporates quickly, and crystals of a solid salt crust form on their surface. At a later stage of the process, the remaining solution is removed from the droplet using a jet of water vapor that passes through the pores of the polycrystalline crust. It was first observed that some of the drying droplets suddenly shifted to one side under the influence of the reactive force generated by the vapor jet. Images obtained using a scanning electron microscope show that the salt particles formed have a diameter of around 25 µm, are slightly porous, and consist of numerous crystals. It has been proven that these particles do not have a central cavity. The use of seawater and the role of salt particles in protecting against thermal radiation from fires are briefly discussed. Calculations based on Mie theory have shown that the contribution of light scattering by thin-walled hollow sea salt particles formed above the ocean surface during relatively slow evaporation of seawater droplets can be significant to the ocean’s heat balance. Full article

This study investigated the effect of brief mechanical homogenization using a household blender on the properties of nopal mucilage and its performance in removing potentially toxic elements (PTEs), specifically Pb, Ni, As, Cd, and Zn, from a real cyanidation barren solution. An aqueous extract from Opuntia ficus-indica cladodes was homogenized for 0, 30, or 60 s before spray drying, yielding powders designated as CA, CB, and CC. The powders and water-reconstituted dispersions were characterized and evaluated in coagulation–flocculation assays. Homogenization reduced water activity and average hydrodynamic diameter and significantly modified the ζ potential, although the effects were not proportional to processing time. At 10% w·v⁻¹, the reconstituted mucilages showed frequency-dependent viscoelastic behavior consistent with a transient gel-like organization. All treatments removed more than 98% of Pb, Ni, and As at doses of 200–800 mg·L⁻¹. Cd removal was more variable and significantly affected by mucilage type, whereas Zn showed lower, non-monotonic removal. ESEM–EDS detected PTE-bearing inorganic domains within the recovered flocs, corroborating transfer from the liquid to the solid phase. Overall, mechanical homogenization modified the colloidal, supramolecular, and gel-related properties of spray-dried nopal mucilage, which showed potential as a multifunctional hydrocolloid for treating chemically complex cyanidation process streams. Full article

The great impact of carbon dioxide emissions on climate change motivates the development of technologies for carbon capture and utilization. CO₂ methanation, which transforms CO₂ into methane using renewable hydrogen, is a promising power-to-gas and carbon utilization pathway. Achieving high activity, strong CH₄ selectivity, and long-term stability remains challenging, as well as pushes to tailor catalyst properties for the methanation reaction. Cerium oxide is therefore widely explored as a support or promoter due to its redox behaviour and oxygen vacancy chemistry. This review surveys recent literature on catalysts based and containing CeO₂ applied for CO₂ methanation, covering not only thermal operation but also non-conventional catalytic routes as photothermal, electrocatalytic, and plasma-assisted, with emphasis on how synthesis and role of Ce tune physicochemical properties and catalytic activity. Across reported systems, dispersing active metals (notably Ni and Ru, Cu for electrochemical systems) on ceria frequently yields to high CH₄ selectivity. Redox properties of ceria enable optimal metal–support interactions and surface basicity to achieve effective CO₂ activation in thermo-catalytic route. Further enhancement of oxygen mobility is associated with doped CeO₂ and solid solutions such as Ce-Zr. The high oxygen storage capacity of CeO₂ promotes photogenerated charge separation for light-driven performance and optimal plasma–catalyst interactions. Full article

The recycling of spent lithium-ion batteries and selected complex electronic waste fractions is commonly evaluated using isolated metrics such as leaching yield, metal removal efficiency, and reagent consumption. However, this approach fails to address the central challenge of sustainable valorization: integrating upstream conversion with downstream selective recovery without shifting environmental and separation burdens. This review focuses specifically on spent LIBs as the primary model system, while also drawing insights from related e-waste streams (e.g., printed circuit boards and polymer-containing residues) where the interface-driven framework applies. It examines how key interfaces—solid–fluid, polymer–metal–fluid, membrane–solution, electrode–electrolyte, and crystal–solution—govern metal mobilization, selectivity, effluent quality, product purity, and scalability. Emphasis is placed on hydrothermal and supercritical water processing, PVC/CPVC (Polyvinyl Chloride/Chlorinated Polyvinyl Chloride)-assisted metal mobilization and membrane-based recovery techniques, including nanofiltration, membrane distillation, membrane distillation crystallization, ion exchange, and electrochemical methods. Supercritical water and membrane processes are complementary only when upstream chemistry is designed to facilitate downstream separation. PVC-rich waste is reconsidered as a reactive chlorine source, provided that corrosion, HCl formation, and salt precipitation are controlled. Critical gaps include incomplete mass balances, limited multicomponent studies, weak integration between process stages, and scarce techno-economic and life-cycle analyses. A roadmap is proposed for scalable, integrated hydrothermal–membrane systems enabling efficient resource recovery and water reuse. Full article

In protracted humanitarian crises, solid waste management (SWM) becomes a major challenge due to limited resources, inadequate infrastructure, and competing response priorities. Waste generated in humanitarian settings typically consist of heterogeneous streams, where plastics, biodegradable fractions, and packaging materials represent the dominant components. Proper management of this waste is essential to reduce health risks and environmental impacts on local communities. Within this framework, sustainable bio-based alternatives and compostable solutions represent promising alternatives. The EU-funded Bio4HUMAN project promotes the integration of innovative bio-based solutions aligned with humanitarian and sustainability goals. An exploratory assessment focused on analyzing waste production, material composition, and handling practices in two case study locations in Sub-Saharan Africa (Democratic Republic of Congo (DRC) and South Sudan (SS)). The results indicate that humanitarian waste cannot be clearly distinguished from household or commercial waste, as streams are typically mixed. Waste composition is dominated by organic matter (43–65%), followed by plastics (15–33%), while other fractions such as paper, glass, metals, and textiles are less significant. Further insights into challenges and opportunities were obtained through a combination of quantitative surveys (n = 29), qualitative interviews with key informants (KIIs) (44) and group discussions sessions (FDG) (9), direct observations, and literature review. Subsequently, a scoping approach was applied to map and classify suitable sustainable solutions into two main categories: bio-based products (BBPs) and organic waste valorization technologies. These were assessed through life cycle assessment (LCA) in accordance with ISO 14040 and 14044, applying SimaPro v.10.2.0.3 software and the Ecoinvent 3.10 database, and compared against fossil-based alternatives. This study compares two case scenarios: a HDPE oil bottle versus PLA alternative (functional unit 6 L), and PE water container versus PLA alternative (functional unit 10 L). For the oil bottle, PLA shows a lower carbon footprint (1.33 kg CO₂-eq) than HDPE (2.37 kg CO₂-eq). In contrast, for the water container, PLA performs worse (2.22 kg CO₂-eq) compared to PE (1.59 kg CO₂-eq), due to higher material demand. The results suggest that benefits are context-dependent and most evident for lightweight products with high leakage risks, particularly when composting infrastructure is accessible. This study advances previous work on humanitarian SWM by integrating field-based waste flow characterization with context-specific screening and life cycle assessment of bio-based alternatives, providing quantitative evidence on the conditions under which these solutions can effectively reduce environmental burdens in protracted crisis settings. Full article

Phosphate tailings (PTs), a solid waste generated from phosphate flotation, are a low-grade phosphate resource rich in quartz and dolomite. Their long-term accumulation leads to both resource loss and environmental risks, making valorization increasingly important for the sustainable development of the phosphorus chemical industry. In this study, calcareous–magnesian PTs were used as raw materials, and selective hydrothermal leaching with weakly acidic AlCl₃ solution was employed to separate the dolomite phase and directly construct a Ca-Mg-Al precursor solution for layered double hydroxides (LDHs). The LDHs were subsequently synthesized by co-precipitation and evaluated for phosphate removal from wastewater. The results showed that the precipitation pH markedly affected the phase composition and platelet morphology of the LDHs, while appropriate aging conditions further improved their adsorption performance. Under the optimal conditions of pH 12, aging at 40 °C for 2 h, the obtained LDHs exhibited the best phosphate uptake. Adsorption kinetics followed the pseudo-second-order model, and the maximum adsorption capacity calculated from the Langmuir model reached 38.61 mg-P/g. Characterization by XRD, FTIR, TG-DTA, point of zero charge, and XPS indicated that phosphate removal was dominated by surface complexation, accompanied by anion exchange, ionic precipitation, and electrostatic attraction. Full article

Rapid urbanization, the pursuit of a higher quality of life, increasing energy and fuel demands, and remaining dependence on traditional fossil fuels, along with an increasingly pronounced negative impact on the environment, encourage society to seek new, lower-emission solutions. Among them, the biomass-to-biofuels process shows a promising pathway. Biomass, a renewable energy source, can be converted into a variety of biofuels in gas, liquid, or solid forms (e.g., syngas, bio-oil, biochar). There are two primary methods for converting biomass into biofuels: biochemical and thermochemical conversion. The latter is considered more flexible and efficient than biochemical conversion. Thus, this review aims to provide a summary of the most recent results from experimental research on biomass conversion to biofuels using various thermochemical conversion methods. Additionally, this review covers fundamentals and highlights the main evaluation parameters of thermochemical conversion systems, helping readers better understand the results reported by the researchers discussed in this article. This review also briefly addresses prospects and projections for future biofuel production, as well as measures to promote biofuel production. Full article

Despite its excellent impact toughness and work-hardening capacity, high-manganese steel (HMS) suffers from low initial hardness, limiting its wear resistance under low-stress conditions. Conventional surface hardening methods for HMS involve high cost and intensive energy consumption and produce only shallow hardened layers; moreover, the understanding of laser transformation hardening in HMS remains insufficient. To address these gaps, this study employs a high-energy-density laser for rapid and precise surface modification of Mn13 HMS. The studied Mn13 steel contains 1.98 wt.% Cr, which contributes to solid-solution strengthening and influences the phase transformation behavior during laser transformation hardening. By optimizing the laser power, a well-defined laser-quenched layer with a gradient microstructure along the thickness direction is obtained. Microhardness at the surface treated by laser transformation hardening at 1.5 kW improved significantly, primarily due to grain refinement and a dense dislocation network. The small fraction of martensite contributes indirectly by generating geometrically necessary dislocations and acting as local barriers to dislocation glide. Along the depth direction, the microhardness varies with the gradient microstructure: coarse columnar grains at intermediate depths cause a slight decrease in microhardness, while the substrate restores it. Correspondingly, the laser-quenched surface exhibits improved wear resistance, as indicated by reduced friction coefficient, wear depth, and wear volume, and the dominant wear mechanism shifts from adhesive to abrasive wear. Importantly, this gradient configuration maintains a mechanically compatible transition between the quenched layer and the substrate, preserving impact toughness comparable to that of the untreated material. Full article

In this study, CoCrFeNiMn high-entropy alloys (HEAs) with different aluminum (Al) contents were fabricated, and the effects of Al content on the microstructure evolution and mechanical properties were systematically explored. The microstructural characterization results indicated that the Al content exerted a crucial regulatory effect on the crystal structure of the alloy. With increasing Al content, shifts in the characteristic XRD peaks indicate lattice expansion of the alloy. Meanwhile, the phase structure continuously evolved from a single face-centered cubic (FCC) structure to an FCC/body-centered cubic (BCC) dual-phase structure, and then finally transformed into a BCC-dominated structure. Appropriate Al element addition could produce localized stress fields near dislocations and achieve prominent solid-solution strengthening, which effectively inhibited dislocation movement and further improved the yield strength, tensile strength, and hardness of the alloy. In contrast, excessive Al addition would break through the solid solubility limit of the alloy matrix, causing obvious phase separation and the precipitation of brittle B2-ordered NiAl-type intermetallic secondary phases. These brittle secondary phases easily induced crack initiation in the plastic deformation process, which significantly deteriorated the ductility, work-hardening ability, and impact toughness of the alloys. Full article

The dynamic strain aging (DSA) behavior of an extruded Mg–3Gd–1Zn (wt.%) alloy was investigated under compressive deformation at intermediate temperatures (150–250 °C) and strain rates ranging from 5 × 10⁻⁵ to 10⁻³ s⁻¹. The as-extruded alloy exhibited equiaxed grains (~20 µm), with all alloying elements retained in solid solution and a weak basal texture. Serrated flow was observed under different temperature and strain-rate conditions. The critical strain, which denotes the onset of serrations, decreased with increasing temperature and increased with strain rate. Notably, the temperature dependence of the critical strain exhibited anomalous non-linear behavior, with a sharp increase at 250 °C, attributed to the formation of low-mobility Gd–Zn clusters/precipitates that depleted mobile solutes from the matrix. In situ synchrotron radiation diffraction revealed the activation of {10.2}⟨10.1⟩ tensile twinning as the dominant deformation mechanism, with periodic plateaus in twin intensity coinciding with macroscopic stress serrations. HAADF-STEM analysis confirmed Gd and/or Zn segregation at twin boundaries and dislocations, leading to the formation of nanoscale clusters during deformation. The overall mechanical response is rationalized by a temperature-dependent competition between solute diffusion and solute clustering at elevated temperatures. Full article

In this study, the microstructural changes and coarsening behavior of Ag₃Sn in Sn-6.4Sb-3.9Ag-0.25Ni-0.003Ge (mass%) during high-temperature aging were investigated. Additionally, low-cycle fatigue tests were conducted to compare the fatigue behavior of Sn-6.4Sb-3.9Ag-0.25Ni-0.003Ge with that of Sn-3.0Ag-0.5Cu. At room temperature, SbSn phases are dispersed in the β-Sn matrix. As the temperature rises, Sb atoms dissolve in the β-Sn phase; thus, the SbSn phases disappear, and some of the atoms aggregate. The activation energy was 45 kJ/mol for the coarsening of Ag₃Sn in Sn-6.4Sb-3.9Ag-0.25Ni-0.003Ge due to aging. Ag₃Sn coarsening was estimated to be controlled by the lattice diffusion of Ag atoms in the β-Sn phase. Furthermore, it was confirmed that the solid solution of Sb atoms in the β-Sn phase reduces the solubility limit of Ag atoms in the β-Sn phase, which delays the coarsening of Ag₃Sn. Regarding fatigue properties, while both alloys exhibited comparable low-cycle fatigue behavior at room temperature, the fatigue ductility exponent’s increase was confirmed to be suppressed for the Sn-6.4Sb-3.9Ag-0.25Ni-0.003Ge alloy at 175 °C. This trend suggests that the delayed coarsening of Ag₃Sn maintains the cyclic strain-hardening exponent, thereby influencing high-temperature fatigue behavior. Full article

Natural Ophiocordyceps sinensis is a highly valued medicinal fungus known for its antitumor, immunomodulatory, and antiviral properties. Due to extensive overharvesting in Asia, cultivated alternatives have become increasingly important. This study aimed to evaluate the biological activity and chemical composition of extracts obtained from cultivated Ophiocordyceps sinensis grown using different rice substrates. Methanolic extracts were prepared from solid-state cultivated Ophiocordyceps sinensis grown on Oryza sativa var. indica and Oryza sativa var. japonica. Antioxidant activity was determined using the DPPH assay, while proteolytic activity was evaluated with the azocasein substrate. Chemical characterization of major compounds was performed using ¹D and ²D NMR spectroscopy, together with IR spectroscopy. UV/Vis spectrophotometry was employed to confirm the formation of silver nanoparticles in AgNO₃ solution. Antimicrobial activity was tested against bacterial strains, including Escherichia coli and Staphylococcus aureus. All prepared methanolic extracts exhibited measurable antioxidant and proteolytic activities. The dominant identified compounds were Z-oleic acid, linoleic acid, and D-mannitol. Selected extracts successfully induced the formation of silver nanoparticles. The highest antimicrobial activity against Escherichia coli was observed for sample 1OS, reaching a mean % RIZD value of 129.32 ± 0.58%. Full article