Search Results (5,825)

This study presents the design and simulation of an integrated pathway to produce Biodimethyl ether (Bio-DME) from biomethane derived from Agave sisalana residues, focusing on the downstream sections such as: (i) steam reforming of biogas and water-gas shift to generate syngas and (ii) indirect methanol synthesis followed by methanol dehydration to Bio-DME, including separation and recycle steps. The modeled scope excludes the anaerobic digestion stage. Benchmarking against the literature was used to validate model fidelity. The simulation delivered a single-pass methanol conversion of 81.8%, a Bio-DME reactor conversion of 44.6 mol%, and a Bio-DME yield/selectivity of ≈99 mol%; product purities reached ≈99.99 mol% Bio-DME at the first distillation column and ≈99.9 mol% MeOH in the recycle, indicating efficient separation. Compared to the literature, Bio-DME conversion in this study is slightly below the reported values (0.446 vs. 0.499, Δ = 0.053), while yield is very close to literature (0.99 vs. 0.9979, Δ = 0.0079). Incomplete methanol conversion emerges as the primary optimization lever, pointing to adjustments in operating conditions (T, p), recycle/purge strategy, and H₂/CO control. Overall, the results confirm the technical feasibility of the simulated sections and support the development of a sisal-based, low-carbon Bio-DME route relevant to Northeast Brazil. Full article

The reliance on carbon-based fuels remains a major contributor to greenhouse gas emissions, emphasizing the need for sustainable alternatives such as hydrogen. Sodium borohydride (NaBH₄), with a hydrogen content of 10.6 wt%, is a promising chemical hydrogen storage material capable of releasing four moles of H₂ per mole through hydrolysis; however, effective catalysts are essential for practical implementation. In this study, silver nanoparticles supported on glucose-derived carbon microspheres (AgSC) were synthesized and evaluated for catalytic NaBH₄ hydrolysis. Structural characterization (XRD, TEM, SEM, EDS) confirmed the uniform dispersion of metallic silver nanoparticles on the carbon support with no detectable Ag₂O phase. AgSC exhibited superior catalytic activity compared to unsupported Ag or bare carbon, achieving the highest hydrogen generation under neutral pH, elevated temperatures, and 835 µmol NaBH₄. The catalyst displayed an activation energy of 54 kJ mol⁻¹, turnover numbers (TONs) of 1.4 × 10⁵–1.9 × 10⁵, and turnover frequencies (TOFs) of 7.1 × 10⁴–9.3 × 10⁴ h⁻¹, demonstrating efficient utilization of active sites. pH-dependent studies revealed optimal hydrogen yield under neutral conditions, while acidic and basic media reduced performance due to surface poisoning and BH₄⁻ stabilization, respectively. Reusability tests showed only ~5% activity loss after five cycles. These findings establish AgSC as a stable, efficient, and recyclable catalyst for on-demand hydrogen generation, supporting sustainable clean fuel technologies. Full article

The widespread use of recycled fine aggregate (RFA) is hindered by its porous and weak adhered mortar. In this study, a nano-SiO₂–sodium silicate mixed solution (NMS) was used to soak and strengthen the adhered mortar. Alkali-activated slag was adopted as the cementitious material, and the resulting treated waste liquid (RNMS) was recycled as a sodium silicate source for the alkali activator. The effects of modified RFA (MRFA) incorporation and RNMS use on the performance, economic, and environmental benefits of alkali-activated slag recycled fine aggregate mortar (AASRM) were evaluated. Compared with the control group, mortars using only MRFA showed significantly improved performance, with a 28-day compressive strength increase of 57.6% (reaching 38.3 MPa) and enhanced workability. The capillary water absorption and 90-day drying shrinkage rates decreased by 49.5% and 40.2%, respectively. Microstructural analysis revealed that NMS treatment promoted the formation of additional C-(N)-A-S-H gel, thereby densifying the surface of the RFA and strengthening the interfacial transition zone (ITZ). More importantly, using RNMS as the alkali activator source maintained the excellent performance of the AASRM mortar, with the compressive strength reaching 95.6% of that prepared with a fresh alkali activator, while effectively reducing material costs and embodied carbon. This study not only successfully applies MRFA in alkali-activated mortar systems but also provides an effective approach for the in situ recycling of treated waste liquid. Full article

Panama, with nearly 3000 km of coastline and half its population living in coastal zones, faces high vulnerability to sea level rise, flooding, and extreme events. The most vulnerable areas include low-lying coastal provinces such as Panama, Colón, and Chiriquí. This review explores the use of sustainable concrete to address the effects of climate change in Panama towards coastal resilience. The methodology combined a bibliometric analysis using VOSviewer, a systematic literature review (2015–2025) of 99 sources including regulations and technical standards, and a socioeconomic SWOT analysis to assess adoption drivers and barriers. A 2050 permanent inundation map was examined to identify vulnerable areas, and an inventory of concrete-based protection structures was developed. The results highlight that concrete is already used in Panama for coastal resilience through structures such as breakwaters, dolos, and Xbloc units. However, as the country still needs to expand its coastal protection infrastructure, there is a crucial opportunity to implement lower-impact, sustainable concrete alternatives that minimize environmental burdens while ensuring long-term durability and performance. Sustainable options, including supplementary cementitious materials (SCMs), recycled aggregates, and CO₂ injection technologies, demonstrate strong mitigation potential, with national initiatives such as Vertua, Greentec, and Argos pozzolan offering early pathways. The conclusions emphasize the need to expand sustainable concrete applications, integrate nature-based solutions, and strengthen Panama’s regulatory and technical capacity to achieve resilient, low-carbon coastal infrastructure. Full article

Plastic recycling has been a challenge worldwide due to various reasons, including limited profit margins, the demand for high-quality plastic reprocessing techniques to make products comparable to those from virgin materials, and challenges in sorting and processing. This problem became particularly urgent in the small towns in the U.S., where plastic waste was shipped overseas for treatment, but now it is not accepted in some countries. This study aims to understand the plastic value chain and find the necessary factors for a circular economy model of both environmental and economic settings. In this study, an educational plastics reprocessing workspace was developed with manufacturing processes such as shredding, filament extruding, 3D printing, and injection molding. A series of products was developed to increase the value of the recycled polymers. In addition, quality control of recycled polymers such as polylactic acid (PLA), acrylonitrile butadiene styrene (ABS), polyethylene terephthalate (PET), and polyethylene terephthalate glycol (PETG) was examined. By collaborating with a university manufacturing lab, this work illustrates how plastics can be collected, prepared, and reprocessed, serving as a platform for student learning and community outreach. This study contributes to the body of knowledge by presenting a case-based educational model for community-level plastic recycling and reprocessing in a college town context. Full article

Advancements in flexible, low-cost, and recyclable alternatives to transparent conductive oxides (TCOs) are critical challenges in the sustainability of third-generation solar cells. This work introduces a copper mesh-based transparent electrode for dye-sensitized solar cells, replacing conventional fluorine doped-tin oxide (FTO)-coated glass to simultaneously reduce spectral reflection losses, enhance mechanical flexibility, and enable material recyclability. Titanium dioxide (TiO₂) photoanodes were synthesized and directly deposited onto the mesh via a single-step, low-energy ball milling process, which eliminates TiO₂ paste preparation and high-temperature annealing while reducing fabrication time from over three hours to 30 min. Structural and surface analyses confirmed the deposition of high-purity anatase-phase TiO₂ with strong adhesion to the mesh branches, enabling improved dye loading and electron injection pathways. Optical studies revealed higher visible light absorption for the copper mesh compared to FTO in the visible range, further enhanced upon TiO₂ and Ru-based dye deposition. Electrochemical measurements showed that TiO₂/Cu mesh electrodes exhibited significantly higher photocurrent densities and faster photo response rates than bare Cu mesh, with dye-sensitized Cu mesh achieving the lowest charge transfer resistance in impedance analysis. Techno–economic and sustainability assessments revealed a decrease of 7.8% in cost and 82% in CO₂ emissions associated with the fabrication of electrodes as compared to conventional TCO electrodes. The synergy between high conductivity, transparency, mechanical durability, and a scalable, recyclable fabrication route positions this architecture as a strong candidate for next-generation dye-sensitized solar modules that are both flexible and sustainable. Full article

To address the global plastic crisis, recycled plastics from food packaging were used as road materials by the dry method for practical application research. First, the main components of the recycled plastics were identified based on FTIR, and their thermal stability was evaluated through DSC, TG, and microscopic analysis. Then, the workability of the plastic–asphalt mixture was evaluated using the gyratory compaction indicator, void content, and compaction energy index (CEI). Finally, the effect of reused plastics on the cracking resistance of bituminous mixtures was examined with the Superpave IDT test. The results indicate that recycled plastics from food packaging are polyolefin composite materials, primarily consisting of Low-Density Polyethylene (LDPE), Linear Low-Density Polyethylene (LLDPE), High-Density Polyethylene (HDPE), and Polypropylene (PP), and that their thermal stability meets production requirements. Good compaction performance was observed with plastic content below 2% of the aggregate weight, while higher contents reduced void content due to the space occupied by plastics. When the plastic content increased from 0.5% to 2.0%, creep compliance decreased from 68.4% to 77.87%, while the m-value, tensile strength, and elastic energy maximum decreased by 30.77%, 5.6%, and 7%, respectively. In contrast, the failure strain, fracture energy, and maximum DSCE increased by 25.86%, 87.43%, and 133.05%, respectively. The recycled plastic enhanced the toughness of the asphalt mixture, increasing the dissipated energy during crack propagation and improving its resistance to permanent deformation. Moreover, the plastics hindered crack propagation through a bridging effect, leading to fewer cracks within plastic zones compared with surrounding areas. This study provides actionable guidance for the application of composite plastics in asphalt pavements and supports their sustainable development. Full article

Lithium-ion batteries are extensively used for energy storage in renewable, electronic, and automotive applications. However, once their electrical capacity is exhausted, they become hazardous waste that requires energy-intensive recycling processes. This study investigates the thermodynamic and exergetic behavior of LiMn₂O₄-based lithium-ion batteries subjected to controlled electrical overvoltage from renewable energy sources, aiming to quantify their potential for thermal energy generation and recovery. A detailed mathematical model was developed to describe the coupled heat transfer and electrochemical phenomena occurring during overvoltage conditions, and experimental validation was performed under various voltage levels and charging states. Energy and exergy analyses were applied to determine the configuration yielding the highest conversion efficiency for both new and aged cells. The maximum thermal energy efficiency reached 81% for new batteries and 4% for used batteries, while the corresponding exergetic efficiencies were 5% and 1.6%, respectively. Although this study does not propose the immediate large-scale reuse of spent batteries as thermal devices, the results provide quantitative insight into irreversible energy conversion processes and highlight their potential contribution to waste heat recovery and energy optimization strategies in sustainable industrial systems. This thermodynamic framework offers a novel approach for valorizing end-of-life batteries within circular energy models, reducing environmental impact, and advancing the integration of renewable energy-driven heat recovery technologies. Full article

In this study, spent LiFePO₄ (LFP) cathode materials were recycled and transformed into amorphous FePO₄ (a-FePO₄) via a leaching–precipitation method for further use as a high-performance cathode material in lithium-ion batteries. To enhance its electrochemical performance, a-FePO4 was composited with graphene oxide (GO) and subsequently reduced at different temperatures (250–450 °C) under N₂ atmosphere to obtain a series of a-FePO₄/rGO composites. Among them, the a-FePO₄-rGO-1 (reduced at 250 °C) exhibited the most superior performance, delivering a specific high discharge capacity of 117 mAh·g⁻¹ after 100 cycles at 1 C and an excellent rate capability of 98 mAh·g⁻¹ even at 10 C. Electrochemical impedance spectroscopy revealed that this composite possessed the lowest charge transfer resistance and most efficient Li⁺ diffusion kinetics. This study demonstrates that moderate-temperature thermal reduction is a critical strategy for optimizing the conductive network of a-FePO₄-rGO composites, thereby significantly improving the electrochemical properties of recycled FePO₄-based cathode materials. Full article

The steel industry is responsible for 7–9% of global CO₂ emissions. Shifting from primary iron ore to recycled scrap in electric arc furnace (EAF) steelmaking offers significant decarbonization potential, reducing carbon intensity by 60–70%. However, increased scrap use in EAF operations leads to higher nitrogen absorption, which can degrade mechanical properties. Nitrogen dissolves into molten steel, where it forms Cottrell atmospheres at dislocations in the following processing steps, intensifying strain aging and reducing ductility. This study establishes a precipitation criterion based on the TiN solubility product to prevent harmful liquid TiN formation, enabling effective nitrogen fixation via fine TiN precipitates (5–20 nm). Multiscale characterization techniques, such as TEM and EBSD, show that Ti reduces the number of mobile N atoms by 60–70%, evidenced by a 50–65% decrease in Snoek/SKK peak intensities. Excessive titanium can refine ferrite grain size and prevents harmful TiN inclusions. Titanium microalloying presents a cost-effective, sustainable strategy to reduce strain aging in scrap-rich EAF steels, enabling more sustainable steel production without sacrificing material properties. Full article

HDPE caps are collected together with PET bottles, which have been recycled into new bottles for decades. Due to Deposit Return Schemes, the bottle caps are sorted by type and are suitable to be recycled again for sensitive applications e.g., food contact. While there are evaluation criteria for mechanical PET recycling processes, no such evaluation crite-ria have been published for recycled HDPE caps in food contact. As part of the study, possible evaluation criteria are derived from other polymers or applications and critically discussed. Recycling of post-consumer caps from beverage bottles into new HDPE caps in direct contact with food is realistic even if worst-case considerations on the evaluation criteria are applied. The required cleaning efficiencies are within a range that is technically feasible for today’s mechanical HDPE recycling processes. The evaluation criteria can be used for a preliminary assessment of post-consumer HDPE recyclate in food contact. Based on the evaluation, the recycling of HDPE caps is to be submitted as a novel technology according to Regulation 2022/1616. Full article

As an important part of the circular economy, recycling old garments not only lessens resource waste, but also offers significant social benefits and environmental conservation. Taking Hefei City, Anhui Province, China, as a case, this study adopted the innovative Planned Behavior Theory (TPB) model and introduced innovative variable community promotion as the moderating variable to analyze the influencing factors of residents’ used clothing recycling behavior. It was found that residents’ attitudes, perceived behavioral control, and subjective norms were key factors influencing their intention to recycle used clothes. Community promotion activities play a positive role in improving residents’ perceived behavior control. However, there is also an interaction between community promotion and perceived behavior control, indicating that the effect of community promotion is affected by residents’ perceived behavior control level. This shows that the publicity and promotion of the community will improve residents’ enthusiasm for recycling old clothes, but if the publicity or promotion is too strong, it may lead to a decline in residents’ enthusiasm. The results show that improving residents’ environmental awareness, simplifying the recycling process, utilizing social influence, rationally planning community promotion activities, policy support and incentive measures, and establishing multi-party cooperation mechanisms are effective ways to promote the recycling of used clothing and resources. Through these measures, we can better promote the recycling of used clothing, realize the rational development, utilization, and protection of resources, and contribute to the realization of green and high-quality development. However, this study is limited to the research and investigation in Hefei, Anhui Province, and most of the respondents have a certain educational background, so the universal applicability of the data may not be significant. Full article

This study developed sustainable foam-type composites from recycled paper (P), corrugated cardboard (C), and their 1:1 mixture (PC) for use in thermal and acoustic insulation. The materials were produced by water-assisted defibration, gas foaming with sodium bicarbonate and yeast, and oven curing, resulting in lightweight porous panels without synthetic binders. The composites exhibited distinct density and porosity profiles that influenced moisture behavior and stability. Cardboard-based panels absorbed the most water and swelled the most, while paper-based panels were more resistant. Despite these differences, all materials showed uniformly low thermal conductivity, confirming their strong insulation capability. Acoustic performance was enhanced by perforation and multilayer assembly. Cardboard panels with a triple-layer perforated design achieved the highest sound absorption, while mixed paper–cardboard composites provided balanced broadband performance. Microscopy revealed that fiber morphology—coarse in cardboard, fine in paper, and interlaced in mixtures—shaped the porous structure and bonding. Mechanical tests indicated comparable stiffness and strength across all types, with cardboard showing the strongest internal bonding. Overall, the results demonstrate that fiber structure and porosity govern material performance. These foam composites combine effective thermal insulation, competitive sound absorption, and sufficient mechanical strength, positioning them as biodegradable, low-cost alternatives for sustainable construction and acoustic applications. Full article

When energy harvesting is not feasible or fails to provide sufficient power, the energy buffer of battery-powered Internet of Things (IoT) devices inevitably depletes. The proper disposal and/or replacement of depleted and end-of-life (EoL) batteries is challenging, especially in rural IoT deployments, where human intervention is cumbersome. When batteries are left in nature, they can pose a significant environmental risk, leaking harmful chemicals into the soil. This work proposes a novel contactless battery solution for longevity and recyclability, providing automated battery replacement using a short-range wireless power transfer (WPT) link instead of a direct battery-to-IoT node contact-based connection for powering the IoT device. It facilitates battery recovery at EoL by, e.g., an unmanned vehicle (UV), reducing the need for manual intervention. Unlike complex mechanical solutions or contacts prone to corrosion, a contactless approach enables easy replacement and improves reliability and longevity in harsh environments. A technical challenge is the need for an efficient contactless solution to enable the IoT node to get energy from the battery. This work elaborates an efficient wireless connection between the battery and IoT node, which ensures robustness in harsh environments. In addition, it examines the sustainability aspects of this approach. The WPT system is applied in two IoT node applications: polling-based and interrupt-based systems. The proposed solution achieves a transmitter-to-receiver efficiency of 72% and has an additional environmental impact of 2.34 kgCO2eq. However, its key advantage is the ease of battery replacement, which could significantly reduce the expected long-term environmental impact. Full article