Search Results (229)

Nuclear energy can help stop climate change by generating large amounts of emission-free electricity. Nuclear reactor designs are continually being developed to be more fuel efficient, safer, easier to construct, and to produce less nuclear waste. The term advanced nuclear reactors refers either to Generation III+ and Generation IV or small modular reactors. Every reactor is associated with the nuclear fuel cycle that must be economically viable and competitive. An important matter is optimization of fissile materials used in reactor and/or reprocessing of spent fuel and reuse. Currently operating reactors use the open cycle or partially closed cycle. Generation IV reactors are intended to play a significant role in reaching a fully closed cycle. At the same time, we can observe the growing interest in development of small modular reactors worldwide. SMRs can adopt either fuel cycle; they can be flexible depending on their design and fuel type. Spent nuclear fuel management should be an integral part of the development of new reactors. The proper management methods of the radioactive waste and spent fuel should be considered at an early stage of construction. The aim of this paper is to highlight the challenges related to reprocessing of new forms of nuclear fuel. Full article

Traditional covalently cross-linked solid-state electrolytes exhibit desirable mechanical durability but suffer from limited processability and recyclability due to their permanent network structures. Incorporating dynamic covalent bonds offers a promising solution to these challenges. In this study, we report a reprocessable and recyclable polymer electrolyte based on a dynamic ester bond network, synthesized from commercially available materials. Polyethylene glycol diglycidyl ether (PEGDE) and glutaric anhydride (GA) were cross-linked and cured in the presence of benzyl dimethylamine (BDMA), forming an ester-rich polymer backbone. Subsequently, 1,5,7-triazabicyclo[4.4.0]dec-5-ene (TBD) was introduced as a transesterification catalyst to facilitate network rearrangement. Lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) was incorporated to establish efficient ion transport pathways. By tuning the cross-linking density and catalyst ratio, the electrolyte achieved an ionic conductivity of 1.89 × 10⁻⁵ S/cm at room temperature along with excellent reprocessability. Full article

The reprocessing of metallurgical wastes to recover much-needed metals such as copper not only ensures an adequate supply of metals but also contributes to the cleaning of the environment. A copper smelter in Namibia accumulated significant amounts of spent refractory bricks that are enriched with metal values including copper. This supposedly waste material can potentially serve as a supplement to the ore concentrate, as a smelter feedstock for this toll smelter. Representative samples of crushed bricks, designated as Sample 1 and Sample 2, were used for mineralogical characterisation and flotation test work. The assays for Sample 1 and Sample 2 were 14% Cu and 18% Cu, respectively. Microscopy results identified various copper phases including metallic Cu, bornite, malachite and chalcopyrite. Batch flotation tests were conducted to investigate the effect of grind size (P₈₀ of 53, 75 and 106 μm), pulp pH (natural pulp pH, 10, 10.5 and 11) and collector (potassium amyl xanthate, PAX) dosage (70, 100 and 130 g/t) on the recovery of copper, concentrate grade and weight recovery. In some tests, a co-collector (dithiophosphate, DTP) and sulphidiser (Na₂S) were also added in the quest to maximise the recovery of copper. Based on the test conditions investigated in this study, the grind size is the key variable affecting the recovery of copper. The best copper recovery of 86% (with a weight recovery in the range of 42 to 45% (w/w) and concentrate grade of 37% Cu) was achieved for the finest grind size of 53 μm. The reagent suite that yielded the best recovery was 70 g/t PAX with no addition of the sulphidiser while the pH was 10. There is scope for developing the process routes to recover other valuable metals such as iron, lead and zinc that are also in the spent bricks, as well as potential reuse of the spent bricks (after recovering valuable metals) to make new refractory bricks. Full article

The effective adoption of quality assurance and traceability systems is increasingly recognised as a critical enabler of circular economy (CE) outcomes in the plastics sector. This study examines the factors that influence the implementation of such systems within Australia’s recycled plastics industry, with a focus on how these factors vary by company size, supply chain role, and adoption of CE strategy. Recycled plastics are defined here as post-consumer or post-industrial polymers that have been reprocessed for reintegration into manufacturing applications. A mixed-methods survey was conducted with 65 stakeholders across the Australian plastics value chain, comprising recyclers, compounders, converters, and end-users. Respondents assessed a structured set of regulatory, technical, economic, and systemic factors, identifying whether each currently operates as an enabler or barrier in their organisational context. The analysis employed a comparative framework adapted from a 2022 European study, enabling a cross-regional interpretation of patterns and a comparison between CE-aligned and non-CE firms. The results show that firms with CE strategies report greater alignment with innovation-oriented enablers such as digital traceability, standardisation, and closed-loop models. However, these firms also express heightened sensitivity to systemic weaknesses, particularly in areas such as infrastructure limitations, inconsistent material quality, and data fragmentation. Small- and medium-sized enterprises (SMEs) highlighted compliance costs and operational uncertainty as primary barriers, while larger firms frequently cited frustration with regulatory inconsistency and infrastructure underperformance. These findings underscore the need for differentiated policy mechanisms that account for sectoral and organisational disparities in capacity, scale, and readiness for traceability. The study also cautions against the direct transfer of European circular economy models into the Australian context without consideration of local structural, regulatory, and geographic complexities. Full article

Bio-based polydithioacetal nanocomposites were synthesized to address the critical need for materials that simultaneously achieve enhanced thermomechanical properties and excellent reprocessing capabilities. Using vanillin and cellulose nanocrystals (CNCs) as starting materials, linear polydithioacetals (PDTAs) were prepared via acid-catalyzed polycondensation of vanillin with various dithiols including 1,6-hexanedithiol, 1,10-decanedithiol, 3,6-dioxa-1,8-octanedithiol and 2,2′-thiodiethanethiol. These PDTAs were then crosslinked with a diepoxide (i.e., diglycidyl ether of bisphenol A, DGEBA) via the reaction of phenolic hydroxyl groups of PDTAs with epoxide groups of DGEBA. To create the nanocomposites, cellulose nanocrystals (CNCs) were surface-functionalized with thiol groups and then incorporated as the reinforcing nanofillers of the networks. The results of morphological observation showed that the fine dispersion of CNCs in the polymer matrix was attained. Owing to the incorporation of CNCs, the nanocomposites displayed improved thermomechanical properties. Compared to the network without CNCs, the nanocomposite containing 20 wt% CNCs exhibited an increase of more than tenfold in modulus and threefold in tensile strength. In addition, the nanocomposites exhibited excellent reprocessing properties, attributable to the dynamic exchange of dithioacetal bonds. This work presents a promising strategy for developing bio-based nanocomposites that have not only improved thermomechanical properties but also excellent reprocessing (or recycling) properties. Full article

Polyimine-based composites have emerged as a promising class of dynamic covalent thermosets, combining high mechanical strength, thermal stability, self-healing, recyclability, and reprocessability. This review systematically summarizes recent advances in polyimine synthesis, highlighting dynamic covalent chemistry (DCC) strategies such as imine exchange and reversible Schiff base reactions. Structural customization can be achieved by incorporating reinforcing phases such as carbon nanotubes, graphene, and bio-based fibers. Advanced fabrication methods—including solution casting, hot pressing, and interfacial polymerization—enable precise integration of these components while preserving structural integrity and adaptability. Mechanical performance analysis emphasizes the interplay between dynamic bonds, interfacial engineering, and multiscale design strategies. Polyimine composites exhibit outstanding performance characteristics, including a self-healing efficiency exceeding 90%, a tensile strength reaching 96.2 MPa, and remarkable chemical recyclability. Emerging engineering applications encompass sustainable green materials, flexible electronics, energy storage devices, and flame-retardant systems. Key challenges include balancing multifunctionality, enhancing large-scale processability, and developing low-energy recycling strategies. Future efforts should focus on interfacial optimization and network adaptivity to accelerate the industrial translation of polyimine composites, advancing next-generation sustainable materials. Full article

This study reviews life cycle assessments (LCAs) of reprocessed single-use devices (rSUDs) in healthcare to quantify their greenhouse gas (GHG) emission reductions compared to original equipment manufacturer (OEM) SUDs (single-use devices). rSUDs offer notable reductions in solid waste generation, but, until recently, a reduction in greenhouse gases and other emissions from the reprocessing process was only hypothesized. Emerging LCAs in this space can help validate the assumptions of better environmental performance from greater circularity in the medical device industry. Four LCAs analyzing eight devices found consistent and significant GHG reductions ranging from 23% to 60% with rSUD use. Primary data from rSUD manufacturers were utilized in all studies, with SimaPro v9.3.0.2 and Ecoinvent v3.8 being the predominant LCA software and database. Raw material extraction and production dominated SUD emissions, while electricity use and packaging materials were key contributors for rSUDs. Sensitivity analyses highlighted the influence of electricity sources, collection rates, and reprocessing yields on rSUD environmental performance. A comparison with economic input–output-based models revealed an alignment at the time between price differentials and LCA-derived GHG differences, though this may not always hold true. This review demonstrates the substantial environmental benefits of rSUDs, supporting their role as a readily achievable step towards more sustainable and circular healthcare systems. Full article

The geopolitical and economic situation impacts raw materials demand. As principal ore deposits reach exhaustion, the study of new sources of raw materials becomes essential. Therefore, mining wastes emerge as alternative sources of raw materials. Their physicochemical properties, such as small particle size or concentration of some metals of interest, enhance reprocessing. A number of critical raw materials (As, Co, Cu, Sb) and base metals (Pb, Zn), as well as precious metals (Ag), were found present in an abandoned tailing deposit composed by finely grounded washed roasted pyrites within the Iberian Pyrite Belt. Copper leaching from a sample of this deposit was investigated. Two hydrometallurgical approaches were studied: acidic leaching with and without activated carbon; and alkaline leaching with glycine solutions. Leaching tests were carried out during 24 h at ambient and moderate temperatures (60 °C). In acidic medium, the maximum copper extraction varied from 88 to 92.5%, while in alkaline medium, the maximum copper extraction was in the range of 71%–76%. Using activated carbon and H₂O₂ seemed to slightly promote the copper extraction with the maximum extraction (92.5%) after 2 h of leaching at 60 °C. Complementarily, above 50% of the zinc and cobalt contained were extracted. In contrast, temperature in alkaline conditions played a key role in reaction speed, but also in precipitation of copper insoluble compounds. In addition, the glycine solution at pH 10–10.5 showed high selectivity for copper over zinc, iron, lead, arsenic, and antimony. Two extra tests at pH above 12 showed arsenic dissolution (up to 51% at pH 12.5). Full article

As the global push for renewable energy intensifies, the materials used in the generation, transmission, and storage of renewable energy systems have come under scrutiny due to their environmental impact. In particular, crosslinked polymers are extensively utilized in these systems because of their excellent thermal, mechanical, and electrical properties. However, their non-recyclable nature and significant waste generation at the end of their service life present severe sustainability challenges. This review employs a citation network-based methodology to analyze the role of crosslinked polymers in renewable energy systems, with a focus mainly on two critical applications: (1) production, specifically in the manufacturing of wind turbine blades; and (2) transmission, where they are integral to high-voltage cable insulation. Our complex network analysis reveals the major themes within the field of sustainability, providing a structured approach to understanding the lifecycle challenges of crosslinked polymers. The first part explores the primary polymers used, their typical lifespans, and the environmental burden of generated waste. We then describe both traditional recycling strategies and innovative approaches, such as supercritical water processing and thermoplasticizing technologies, which offer potential solutions to mitigate these impacts. Finally, we highlight emerging reprocessable materials, including vitrimers, ionomers, and specialty thermoplastic alternatives, which provide recyclability while maintaining performance. This comprehensive assessment emphasizes the urgent need for innovation in polymer science to achieve a circular economy for renewable energy systems. Full article

Polyvinyl chloride (PVC) recycling poses significant engineering challenges and opportunities, particularly regarding material integrity, energy efficiency, and integration into circular manufacturing systems. This systematic review evaluates recent advancements in mechanical innovations, tooling strategies, and intelligent technologies reshaping PVC recycling. An emphasis is placed on machinery-driven solutions—including high-efficiency shredders, granulators, extrusion moulders, and advanced sorting systems employing hyperspectral imaging and robotics. This review further explores chemical recycling technologies, such as pyrolysis, gasification, and supercritical fluid extraction, for managing contamination and additive removal. The integration of Industry 4.0 technologies, notably digital twins and artificial intelligence, is highlighted for its role in predictive maintenance, real-time quality assurance, and process optimisation. A combined PRISMA approach and ontological mapping are applied to classify technological pathways and lifecycle optimisation strategies. Critical engineering constraints—including thermal degradation, additive leaching, and feedstock heterogeneity—are examined alongside emerging innovations, like additive manufacturing and microwave-assisted depolymerisation, offering scalable, low-emission solutions. Regulatory instruments, such as REACH and Extended Producer Responsibility (EPR), are analysed for their influence on machinery compliance and design standards. Drawing from sustainable manufacturing frameworks, this study also promotes energy efficiency, eco-designs, and modular integration in recycling systems. This paper concludes by proposing a digitally optimized, machinery-integrated recycling model aligned with circular economy principles to support the development of future-ready PVC reprocessing infrastructures. This review serves as a comprehensive resource for researchers, practitioners, and policymakers, advancing sustainable polymer recycling. Full article

This study presents a sustainable approach to transform waste cooking oil (WCO) into a multifunctional 3D-printable photocurable elastomer with integrated self-healing capabilities. A linear monomer, WCO-based methacrylate fatty acid ethyl ester (WMFAEE), was synthesized via a sequential strategy of transesterification, epoxidation, and ring-opening esterification. By copolymerizing WMFAEE with hydroxypropyl acrylate (HPA), a novel photocurable elastomer was developed, which could be amenable to molding using an LCD light-curing 3D printer. The resulting WMFAEE-HPA elastomer exhibits exceptional mechanical flexibility (elongation at break: 645.09%) and autonomous room-temperature self-healing properties, achieving 57.82% recovery of elongation after 24 h at 25 °C. Furthermore, the material demonstrates weldability (19.97% retained elongation after 12 h at 80 °C) and physical reprocessability (7.75% elongation retention after initial reprocessing). Additional functionalities include pressure-sensitive adhesion (interfacial toughness: 70.06 J/m² on glass), thermally triggered shape memory behavior (fixed at −25 °C with reversible deformation/recovery at ambient conditions), and notable biodegradability (13.25% mass loss after 45-day soil burial). Molecular simulations reveal that the unique structure of the WMFAEE monomer enables a dual mechanism of autonomous self-healing at room temperature without external stimuli: chain diffusion and entanglement-driven gap closure, followed by hydrogen bond-mediated network reorganization. Furthermore, the synergy between monomer chain diffusion/entanglement and dynamic hydrogen bond reorganization allows the WMFAEE-HPA system to achieve a balance of multifunctional integration. Moreover, the integration of these multifunctional attributes highlights the potential of this WCO-derived photocurable elastomer for various possible 3D printing applications, such as flexible electronics, adaptive robotics, environmentally benign adhesives, and so on. It also establishes a paradigm for converting low-cost biowastes into high-performance smart materials through precision molecular engineering. Full article

Integrating thermochromic pigments (TPs) into food packaging offers significant benefits for monitoring temperature variations, improving food safety, and reducing waste. However, the recyclability of such materials remains underexplored, particularly regarding the retention of their optical and mechanical properties after repeated recycling. Addressing this gap, this research aims to evaluate how mechanical recycling affects key properties of polypropylene (PP) blends containing varying TP concentrations. Three formulations, PP100/TP0 (0% TP), PP98/TP2 (2% TP), and PP92/TP8 (8% TP), were subjected to five recycling cycles, with changes in thermal stability, color transition behavior, mechanical integrity, and surface morphology analyzed. The results indicate that PP100/TP0 maintained its mechanical integrity with minimal degradation (6% absolute crystallinity loss; color difference ΔE*_ab = 1.45) across recycling cycles. However, blends containing TPs exhibited progressive deterioration. P98/TP2 displayed moderate reductions in mechanical strength (−10.8%) and thermochromic efficiency (color change ΔE*_ab = 6.52), while PP92/TP8 showed significant degradation, including increased activation temperatures (+3.8 °C) and color vibrancy loss (42.9% loss in saturation). These effects were attributed to polymer breakdown, pigment aggregation, and altered crystallinity. Despite the limitations of recyclability, this study provides critical insights into the feasibility of TPs in sustainable, intelligent food packaging. Further research is required to enhance TP stability during reprocessing, ensuring long-term functionality in circular packaging systems. Full article

The growing demand for green and, therefore, sustainable technologies present new challenges for our society. The European Union (EU) identified the critical raw materials (CRMs) and strategic raw materials (SRMs) necessary for these technologies and introduced policies to reduce reliance on external suppliers, which includes investigating the recovery of CRMs from extractive waste. This study assesses the recovery potential of mine waste collected in the Traversella mine district (Piedmont, Italy), known for its polymetallic Fe-Cu-W deposit. The characterization of waste rock samples involved chemical and mineralogical analyses, revealing metallic-bearing minerals such as magnetite and scheelite. Laboratory-scale magnetic and gravity separation tests were carried out and compared. Magnetic separation resulted in a recovery of 75.4% of Fe, 72.3% of Cu, and 83.7% of W, with a weak concentration. Instead, gravity separation produced high-grade Fe (67.6%) and W (1289 ppm) concentrate with lower recovery rates. Full article

In the industry, the robotic gas metal arc welding (GMAW) process has a huge range of applications, including in the automotive sector, construction companies, the shipping industry, and many more. Automatic quality inspection in robotic welding is crucial because it ensures the uniformity, strength, and safety of welded joints without the need for constant human intervention. Detecting defects in real time prevents defective products from reaching advanced production stages, reducing reprocessing costs. In addition, the use of materials is optimized by avoiding defective welds that require rework, contributing to cleaner production. This paper presents a novel dataset of robot GMAW images for experimental purposes, including human-expert segmentation and human knowledge labeling regarding the different errors that may appear in welding. In addition, it tests an automatic segmentation approach for robot GMAW quality assessment. The results presented confirm that automatic segmentation is comparable to human segmentation, guaranteeing a correct welding quality assessment to provide feedback on the robot welding process. Full article

The significant waste generated by the fashion industry necessitates sustainable textile recycling strategies. Polyester, made from poly(ethylene terephthalate) (PET), is abundant in post-consumer textiles. Technologies have been developed to convert low-density garment waste into flakes, but the role of color sorting in achieving uniform aesthetics in injection-moldable plastics remains underexplored. This study compares materials extruded from dark color-sorted polyester garment flakes with those from light-color flakes in terms of processability in extrusion and injection molding. The properties examined include melt fluidity, injection molding shrinkage, and mechanical and thermal properties. Commercial chain extenders with anhydride, oxazoline, or epoxide reactive groups were added during extrusion. Interestingly, only dark-colored extruded pellets showed significant degradation, but all the chain extenders allowed melt fluidity to be controlled during reprocessing. The bisoxazoline-based additive was the most promising, due to the highly improved ductility of the samples, regardless of whether they were dark-colored or light-colored. The results indicate significant potential for the industrial recycling of post-consumer textiles and highlight the industrial feasibility of repurposing post-consumer polyester garments. This approach not only supports initiatives of circular economy but also offers a viable solution for managing textile waste, particularly in the fashion industry. Additionally, the suggested recycling route combats the production of microplastics. Full article