Search Results (970)

The transformation of waste plastics into hydrogen and functional carbon (C) materials represents a promising pathway for achieving both resource recycling and the production of value-added products. Owing to their tunable physicochemical properties, plastic-derived carbons have attracted significant attention in electrochemical energy storage applications. Various C nanostructures, including graphene, porous C, hard C, and C nanotubes (CNTs), can be generated from discarded plastics through thermochemical processes. The electrochemical performance of these materials is closely governed by their structural characteristics, such as pore architecture, specific surface area, heteroatom doping, surface functionalities, and dimensional morphology. This review aims to provide a comprehensive and systematic overview of the conversion of waste plastics into functional C nanomaterials via thermochemical routes, particularly catalytic pyrolysis and carbonization. The resulting C nanostructures are systematically categorized based on their dimensional architectures (0D, 1D, 2D, and 3D) and comparatively analyzed in terms of their structural features and electrochemical performance. Emphasis is placed on the transformation of diverse plastic feedstocks into high-value C materials with tailored dimensional architectures, including graphene, CNTs, C nanospheres, C nanosheets, porous carbons, and their composites. Furthermore, recent progress and critical challenges in utilizing these materials for electrochemical energy storage systems, such as supercapacitors and rechargeable batteries (Li-ion, Na-ion, K-ion, Li-S, and Zn-air), are discussed. Distinct from previous reports, this review highlights the correlation between thermochemical processing strategies, resulting structural features, and electrochemical performance, providing new insights into the rational design of high-performance C materials. These findings are expected to facilitate the advancement of sustainable energy storage technologies while contributing to effective plastic waste valorization. Full article

This work explores a sustainable route for producing recycled AlNiCo-based magnetic composites by incorporating end-of-life AlNiCo-5 particles into a polyamide 12 (PA12) matrix, thereby eliminating conventional debinding requirements. The study emphasizes material circularity through the reuse of mechanically recovered magnetic waste and polymeric residues. Virgin PA12 powder was used as the matrix material for high magnetic filler loadings of 40, 60, and 70 wt.% AlNiCo-5, while stearic acid was introduced to enhance interfacial compatibility and overall processability. The resulting composites were shaped into filaments and processed via material extrusion additive manufacturing, demonstrating that commercially available fused filament fabrication systems can successfully handle highly filled metal-polymer blends when supported by appropriate formulation and process parameter optimization. The findings confirm the feasibility of manufacturing flexible, functional, and resource-efficient magnetic components using widely accessible equipment, highlighting a promising pathway toward the cost-effective recycling and reuse of AlNiCo magnetic materials. Full article

Across the globe, companies are facing significant pressure to reduce waste, improve resource efficiency, and report their sustainability efforts transparently. ESG frameworks have become essential tools for sustainability transformation. However, traditional business models, based on a linear “take–make–dispose” approach, continue to dominate industries, limiting the impact of ESG efforts. The circular economy offers a compelling alternative: it encourages designing products for reuse, recycling, and regeneration, thus aligning closely with ESG principles. When businesses transition to circular models, they reduce their environmental footprint, create new green jobs and social inclusion opportunities, and strengthen accountability across business value chains. This study explores how selected firms in the mining, energy, consumer cyclical, technology, and healthcare sectors are aligning circular principles with ESG practices. Using a longitudinal, multi-sector comparative analysis of ESG indicators spanning 2014–2024, the research examines sector-level ESG evolution, firm-level ESG leadership, and the alignment of ESG performance with circular business model pathways. Rather than directly measuring circular transformation, ESG indicators are interpreted as signals of emerging circular business model pathways. This study identifies ESG-based ways and enabling conditions through which circularity may be increasingly embedded across different sectors. Full article

To address the accumulation of construction and demolition waste (W&D), this study recycled it into regenerated fine aggregate and prepared 3D-printed mortars with replacement ratios ranging from 0% to 100%. The mechanical properties of hardened specimens were tested, and the degradation mechanisms of mechanical performance were investigated through SEM, MIP, and microhardness analysis. The carbon emissions of the materials were evaluated. The results indicated that while the 3D-printed mortar exhibited excellent buildability, its compressive strength, flexural strength, and interlayer bond strength gradually decreased with increasing replacement ratio. MIP results showed that as the replacement ratio of the W&D increased from 0% to 100%, the total porosity of the 3D-printed specimens significantly increased from 14.7433% to 27.5903%. SEM and microhardness images confirmed severe ITZ deterioration, and the average ITZ width increased from 31 to 79 μm. As the W&D replacement ratio increased from 0% to 100%, the total GWP decreased from 0.4043 to 0.3800 kg CO₂-eq/kg mortar. Maximizing the utilization of W&D is key to achieving efficient utilization of solid waste. Considering printability, mechanical performance, interlayer behavior, microstructural characteristics, and environmental impact in a comprehensive manner, the 80% W&D replacement ratio can be regarded as a relatively balanced and promising selection. This work not only suggests the technical feasibility of recycling W&D in 3D printing mortar, but also proposes a sustainable pathway to reduce carbon emissions in construction. Full article

This study aims to show a detailed life cycle assessment (LCA) approach of battery electric vehicles (BEVs) and internal combustion engine vehicles (ICEVs), with an emphasis on determining the electrical carbon intensity at which these vehicles reach life-cycle greenhouse gas (GHG) parity. The analysis was conducted in openLCA v2.0.3 using the Ecoinvent v3.9.1 database under a European use-phase context, with a functional unit of 150,000 km. BEVs were evaluated for two representative lithium-ion battery chemistries (NMC622 and LFP) under three electricity carbon intensity scenarios (50, 400, and 850 g CO₂/kWh), while ICEVs were modeled for both gasoline and diesel pathways. Results show that BEV life-cycle GHG emissions vary between 91 and 221 g CO₂-eq/km across different combinations of electricity mix, battery chemistry, and end-of-life conditions. When isolating electricity carbon intensity as the primary variable under a fixed BEV configuration, emissions increase approximately linearly with grid emission factor. Under average European electricity conditions (400 g CO₂/kWh), BEVs exhibit lower life-cycle GHG emissions than gasoline ICEVs, whereas under coal-intensive electricity conditions (850 g CO₂/kWh) this advantage may be reduced or reversed. The break-even electricity carbon intensity is derived by linear interpolation under a fixed BEV configuration (NMC622, 60 kWh, constant lifetime and EoL conditions), yielding a threshold of approximately 600 g CO₂/kWh. The results further indicate that this threshold is influenced by battery chemistry, production-related emissions, recycling efficiency, and assumed vehicle lifetime. These findings highlight the importance of simultaneous progress in electricity decarbonization and end-of-life recycling to secure the environmental benefits of vehicle electrification, and they provide a threshold-oriented framework for policy-relevant interpretation of comparative vehicle LCA results. Full article

Sustainable structural composites can significantly lower vehicle-related emissions. To evaluate the recycling of different composite materials, laboratory-scale pyrolysis was conducted and assessed both technically and environmentally. Two demonstrators were studied: a truck side skirt made from natural flax and hemp fibres with polypropylene (PP), and a car front header composed of glass fibres and PP. Additional materials examined included thermoplastic composites containing polyamide 6 (PA6), bio-based polyamide 11 (PA11) and thermoset polyester. Results showed that material type strongly influenced the pyrolysis outcome, product composition and recycling potential. Glass fibres could be recovered and reused as reinforced fibres, while natural fibres could be recovered as biooil for potential use in biofuel production. Polymers were recovered as pyrolysis products that, depending on their composition, can be used in different applications, from recovering monomers from PA6 to producing hydrocarbons that may replace naphtha (from PP) or aromatics (from polyester) in the petrochemical industry. Life cycle assessment (LCA) findings revealed that the climate impact of composite recycling is primarily driven by the environmental burdens of the recycling process itself and by the ability of recovered materials and chemicals to substitute conventional fossil-based alternatives. Efficient recycling pathways are therefore essential to maximising environmental benefits. Full article

The mechanical recycling of styrenic polymers from waste electrical and electronic equipment (WEEE) is often limited by thermomechanical degradation occurring during repeated processing. In this work, the degradation behaviour of acrylonitrile–butadiene–styrene (ABS) recovered from sorted WEEE streams was systematically investigated through multiple extrusion cycles, and the effectiveness of antioxidant stabilization was evaluated. Progressive degradation was assessed by chemical structure, rheological, thermal and mechanical testing, and colorimetric analysis. Repeated processing resulted in increased melt flow, altered viscoelastic behaviour, molecular weight reduction, deterioration of mechanical properties, and discoloration. To mitigate these effects, antioxidant-stabilized compounds were prepared and subjected to identical reprocessing pathways. The addition of antioxidants effectively reduced chain scission, stabilized rheological properties, and limited colour changes during reprocessing. Furthermore, the processability of the optimized recycled ABS is demonstrated through filament extrusion for fused filament fabrication, highlighting its potential for high-value additive manufacturing applications. These results demonstrate that appropriate stabilization strategies can significantly enhance the process stability and recyclability of styrenic polymers from WEEE streams, supporting their use in higher-value applications within a circular economy framework. Full article

This study develops a Life-Cycle Sustainability Framework for circular business models in the context of post-war economic reconstruction and sustainable value chain transformation. Ukraine is used as the main case study due to its post-war reconstruction context and the need for resource-efficient economic recovery strategies. Under conditions of disrupted supply systems, resource constraints, and structural economic change, circular economy principles are conceptualized as strategic mechanisms for enhancing resilience, resource efficiency, and long-term competitiveness rather than solely as environmental policy instruments. Building on a structured hierarchy of circular business models aligned with product life-cycle stages, the framework emphasizes value retention through functional and usage extension beyond material recovery. The framework includes a hierarchical classification of 12 circular business models and a sustainability evaluation approach based on four criteria (K1–K4), which allow for the comparative assessment of circular business models and their combinations across life-cycle stages. Using secondary statistical data and policy review as analytical inputs, the study identifies sectors with high potential for circular transformation and sustainable investment, including agriculture, energy, industry, construction, and logistics. The results indicate that circular business models applied at early life-cycle stages, such as reuse, repair, and remanufacturing, provide the highest potential for reducing resource intensity and improving long-term economic sustainability, while recycling and energy recovery play a supporting role. These findings highlight how life-cycle-oriented circular strategies can support sustainable reconstruction pathways, strengthen international cooperation, and inform policy and managerial decision-making in transitional economic contexts. Full article

Construction industry remains a major driver of global resource use and waste generation, therefore, identifying sustainable material alternatives is increasingly important. Recycled-textile-based insulation presents a promising pathway to support circular economy principles by diverting post-consumer waste from landfills and reducing reliance on virgin petrochemical materials. This study conducts a cradle-to-gate life cycle assessment (LCA) using SimaPro to compare polyurethane (PU) foam and recycled denim (cotton fiber) insulation. The system boundary includes raw material extraction, transportation, and manufacturing. A functional unit of 1 m² of installed insulation with a thermal resistance of RSI = 1 m²·K/W at the factory gate ensures comparability, with mass-based results reported as secondary metrics. The results indicate that recycled denim exhibits higher embodied carbon per unit mass, despite lower production energy and lower cradle-to-gate impacts per installed area, reinforcing the need for a declared-unit-based comparison tied to thermal performance. Air leakage is evaluated separately as a complementary performance indicator influencing in-service energy behavior showing significantly lower air leakage for PU; but is not included in the cradle-to-gate normalization. However, it could be argued that materials with improved airtightness may enable the use of reduced insulation thickness while still achieving equivalent performance, thereby potentially lowering overall material demand. Nevertheless, recycled denim offers environmental advantages by reducing landfill waste and promoting resource conservation through material reuse. A transient coupled heat–moisture model in COMSOL Multiphysics, using climate data from Arizona and Florida, further reveals that denim absorbs more moisture than polyurethane. This leads to larger heat flux fluctuations, highlighting a trade-off between denim’s sustainability advantages and its reduced hygrothermal durability. Overall, these findings demonstrate the limitations of single-metric comparisons and emphasize the need for performance-based, multi-criteria assessments that integrate functional efficiency with circularity. Future research should incorporate occupant health and comfort to enable a more comprehensive evaluation of insulation sustainability. Full article

This review critically evaluates current PA6 recycling technologies, with a specific focus on caprolactam-oriented chemical recycling pathways, including hydrolysis, pyrolysis, glycolysis, ammonolysis, hydrothermal treatment, ionic-liquid-assisted depolymerization, and microwave-assisted processes. Reported caprolactam yields vary significantly depending on reaction conditions and catalyst systems, ranging from below 60 wt% in conventional hydrolysis to above 90 wt% under optimized catalytic, hydrothermal, or microwave-assisted conditions. Among these approaches, microwave-assisted hydrolysis and catalytic depolymerization have emerged as particularly promising, offering substantially reduced reaction times (minutes rather than hours), improved energy efficiency, and high monomer selectivity at moderate temperatures (typically 200–350 °C). This review integrates kinetic modeling approaches, analytical methods for monitoring depolymerization, and downstream separation considerations that govern monomer purity and recyclability. Key challenges, including energy demand, feedstock contamination, scalability, and economic competitiveness, are critically discussed in relation to industrial implementation. Overall, hydrolysis-based and microwave-assisted chemical recycling routes are the most viable pathways for closed-loop recycling of PA6. Future progress will rely on integrated reaction–separation–repolymerization designs, catalyst optimization, and process intensification to enable sustainable and industrially relevant PA6 circularity. Full article

Internal phosphorus loading is a key process sustaining eutrophication in stratified Baltic Sea coastal systems, yet its long-term dynamics in the Archipelago Sea remain poorly quantified due to limited deep-water monitoring and the absence of sediment time series. This study provides a multidecadal assessment of internal loading from the early 1980s to 2025 using two complementary indicators: (i) seasonal accumulation of total phosphorus in the surface layer (ΔTP) and (ii) the covariation between near-bottom oxygen depletion and dissolved inorganic phosphorus (DIP) release. Temporal associations with external phosphorus inputs from marine fish farming—highly variable during the study period—were analyzed to evaluate whether cumulative loading trajectories coincided with phases of intensified ΔTP. New measurements of drifting filamentous macroalgae from 2025 were additionally used to assess their seasonal contribution to the internal phosphorus pool and their relevance for mitigation. Results show a pronounced multidecadal strengthening of internal loading signals in the mid and inner Archipelago Sea. At the Seili station, ΔTP increased by approximately 6.8 µg L⁻¹ (≈3.4-fold) since the early 1980s. This trend coincided with long-term deterioration of near-bottom oxygen conditions and increasing DIP concentrations, consistent with enhanced sediment phosphorus release. Although cumulative aquaculture loading exhibited simple correlations with ΔTP, detrended analyses indicate that these relationships largely reflect shared long-term trends rather than direct causal linkages. Drifting filamentous macroalgae formed a substantial seasonal phosphorus reservoir (≈146 t P). Overall, internal phosphorus input to the Archipelago Sea has intensified markedly—by an estimated ~70% since the 1980s—highlighting the growing importance of sediment–water feedbacks and legacy phosphorus. Effective mitigation therefore requires strategies that address both internal recycling processes and external nutrient inputs. Targeted removal of drifting filamentous macroalgae may provide a complementary nutrient-export pathway in coastal management. Full article

The management of end-of-life photovoltaic panels has become a focal point for circular economy initiatives, given the significant waste volumes generated by the global energy transition. This study addressed the challenge of identifying optimal recycling solutions characterized by conflicting objectives, such as material recovery efficiency, economic feasibility, and environmental impact. Given that photovoltaic waste contains valuable materials alongside elements requiring specialized handling, the selection of appropriate processing technologies has been prioritized by research and industrial sectors. To resolve these trade-offs, a hybrid Multi-Criteria Decision-Making (MCDM) framework was implemented, combining the Best–Worst Method (BWM) with the Preference Ranking Organization Method for Enrichment Evaluations (PROMETHEE II). The BWM was employed to determine criteria weights based on expert evaluations, focusing on the relationships between the most and least significant factors to ensure mathematical consistency. Subsequently, the PROMETHEE II facilitated a complete ranking of technological alternatives by calculating net preference flows, allowing for a nuanced comparative analysis of diverse recovery processes. Through this approach, the research established a clear performance hierarchy among established and emerging recycling pathways. These findings provided a structured quantitative basis for decision-makers to identify balanced solutions for industrial implementation, supporting long-term sustainability goals and the preservation of secondary raw materials. Full article

Polyamide (PA) is widely used as a high-performance engineering thermoplastic in automotive components and textiles, due to its superior mechanical strength and chemical resistance. However, the increase in PA waste has posed significant challenges to resource sustainability and environmental protection. Despite breakthrough development achieved in PA recycling, key barriers remain in process scale-up and high-value recovery. This review examines the current state of PA recycling, analyzing the research prospects of mechanical and chemical recycling from economic feasibility and environmental impact. We present discussions on innovative recycling approaches for PA, including upcycling, molecular design of novel PA derivatives, chemo-biological coupling and solvent-based recovery, offering potential solutions to the sustainable circular economy and green cycles. Finally, by presenting case studies, we highlight pathways toward future innovation that inform industrial-scale implementation. Full article

Polyethylene terephthalate is a prominent polymer known for its mechanical properties, chemical resistance, and recyclability, and it is widely utilized across various industries. Enhancing the properties of polyethylene terephthalate (PET) through nanocomposite technology, particularly with the inclusion of nanoscale fillers, has garnered significant attention. This study investigates synthetic layered double hydroxides (LDHs), specifically MgAl LDH modified with calcium dodecylbenzene sulphonate in n-butyl alcohol (CDS) organic surfactant, as an alternative to natural clays for PET nanocomposites. Additionally, modified LDH serves a dual role as both a catalyst and a dispersive agent, promoting effective exfoliation within the PET matrix. A polymerization process was employed to ensure proportional and effective dispersion of the nanofillers, addressing the critical challenge of achieving uniform distribution. The resulting nanocomposites demonstrated superior mechanical strength, thermal stability, and barrier properties compared to traditional intercalated counterparts. Moreover, synthetic LDHs present a more sustainable solution, reducing the environmental footprint associated with natural clay mining, which includes land degradation, water pollution, energy consumption, and biodiversity loss. This research provides a promising pathway for developing high-performance, environmentally friendly PET nanocomposites, with significant implications for various industrial applications, from packaging to automotive and electronics. The findings highlight the potential of synthetic LDHs to advance material science while aligning sustainable development goals. Full article

Nano- and microplastic contamination poses a growing challenge to aquatic environments, driving the need for efficient and sustainable removal technologies. In this study, carbon–silica hybrid nanoparticles (CSNPs) were synthesized from rice husk-derived black liquor via controlled lignin–silica self-assembly followed by thermal carbonization, providing a waste-recycling biorefinery route for value-added material production. Structural characterizations revealed that carbonization generates a hierarchically porous carbon–silica hybrid with enhanced surface area. The CSNPs exhibited rapid and size-dependent adsorption toward nano- and microplastics (200–1000 nm), with optimal performance observed for 500 nm particles. Microscopic observations further demonstrated a size-adaptive capture mechanism, involving pore filling and surface adsorption for nanoplastics and aggregate-assisted encapsulation for larger microplastics. This study highlights CSNPs as low-cost and effective adsorbents for broad-spectrum plastic removal while offering a sustainable pathway for the high-value utilization of black liquor and rice husk biomass in water purification applications. Full article