Search Results (19,608)

The deinking of plastic packaging waste offers the potential of decreasing contamination and thus increasing the overall quality of recycled plastics, enabling their use in more demanding applications. However, for flexible polyethylene packaging waste, deinking is not yet implemented on an industrial scale and there is currently no objective methodology to evaluate the deinking effect on those inhomogeneous flakes. In this study, a novel approach for the objective assessment of ink removal on flexible post-consumer waste (PCW) is proposed. Via an image-based analysis, the transparency of the flakes is transformed into the 8-bit grey scale, and the deinking efficiency of several experiments is compared via the skewness and median of grey value distributions. The method is compared to the International Commission on Illumination (CIE) Lab-method and its robustness against wrinkles and overlaps is critically discussed. Using this analysis method enables the investigation of the general behaviour of contaminated PCW materials in deinking and identifies the most effective parameters for ink removal on inhomogeneous flakes. Full article

In this study, the potential for re-mixing and re-vulcanizing waste natural rubber glove (WNRG) material by using it as the primary matrix was investigated. Alternative types of vulcanization systems, namely, sulfur, phenolic resin, and peroxide, were employed. The results unequivocally demonstrated that residual vulcanizing agents contained in the WNRG were not sufficient to cause crosslinking reactions without re-mixing with vulcanizing agents. Among the various vulcanization approaches, sulfur produced the greatest properties, whereas phenolic resin gave moderate performance. The WNRG vulcanized with sulfur demonstrated the highest crosslink density, tear strength, tensile strength, hardness, and strain-induced crystallization ability among the tested alternatives. The tensile strength of WNRG vulcanized with sulfur was approximately 16.23 MPa, which was 31.7% and 51.1% greater than the WNRG vulcanizates made with phenolic resin and peroxide, respectively. Because of its highest crosslink density, the WNRG vulcanizate with sulfur also offers the greatest storage modulus among the tested cases. The results clearly suggest that the WNRG can potentially be re-compounded, re-vulcanized, and used as the primary matrix. WNRG could be used as a matrix at an industrial scale, to minimize the environmental issues and increase the added value from waste gloves. The findings provide practical guidance for recycling waste rubber gloves in industrial applications, which would be a more sustainable solution for solving the problems associated with WNRG. Full article

To investigate the sulfate corrosion resistance of cast-in-place repair concrete incorporating recycled coarse aggregate (RCA) under partially exposed conditions, cast-in-place repair concrete specimens with different RCA contents (0%, 30%, and 50%) were immersed in Na₂SO₄ solution. The study systematically investigated the changes in apparent morphology, dimensions, mass, and mechanical properties of the specimens under sulfate corrosion. SEM, XRD, TG/DTG, and MIP were used to characterize the microstructure and mineral composition of the specimens at different corrosion ages. Results indicate that RCA cast-in-place repair concrete partially exposed to a sulfate corrosion environment undergoes coupled physical and chemical corrosion, and the interfacial zone between the recycled aggregate concrete to the base concrete represents the most vulnerable region in the composite system. Incorporating 30% RCA can effectively reduce the degradation rate of specimens under sulfate corrosion, enhance the compactness of the bonding interface, and optimize the interfacial bond strength, compressive strength, and pore structure of the specimens. Excessive RCA content disrupts the internal pore structure, accelerates sulfate ion ingress, and weakens the interfacial bond strength. The presence of RCA significantly reduces the interfacial shear strength of the specimens. After 360 days of sulfate corrosion, specimens featuring 30% and 50% RCA contents exhibit a reduction in shear strength of 15.91% and 40.0%, respectively, compared with the 0% RCA content specimen. Research findings provide a theoretical basis for the application of RCA in concrete repair engineering. Full article

This study addresses the severe durability challenges for asphalt pavements in extreme, arid continental climates like Turpan, Xinjiang, where summer surface temperatures exceed 80 °C and winter lows drop below −20 °C. It evaluates Qingchuan rock asphalt (QRA) as a modifier to enhance the durability of plant-mixed hot recycled asphalt mixtures containing reclaimed asphalt pavement (RAP). Laboratory tests at binder and mixture levels evaluated the performance of QRA-modified binder and recycled mixtures. The program included binder specifications, performance grading, dynamic modulus, dynamic stability, and residual stability. Results indicate that increasing QRA dosage raises the softening point, G*/sin δ, and high-temperature PG, enhancing stiffness and rutting resistance. Although blending with RAP binder further improves high-temperature performance, it reduces workability and low-temperature resistance. In mixtures, dynamic stability, residual Marshall stability, and TSR increased by 115%, 6.59%, and 14.38%, respectively, while failure strain decreased by 30.8%. Dynamic modulus master curves confirm improved modulus retention at high temperatures. Considering the local PG 76–22 requirement and relevant specifications, a mixture containing 10% QRA and 50% RAP is recommended for durable plant-mixed hot recycled asphalt pavements in Turpan and similar arid climate regions. Full article

The electric vehicle revolution has created an urgent need for lithium-ion battery (LIB) recycling, with projections exceeding 11 million tons of end-of-life batteries annually by 2030. However, progress toward a circular economy remains fragmented. This perspective article introduces the concept of a ‘Recycling Trilemma,’ arguing that technological advancements in material separation are systematically undermined by economic volatility and regulatory fragmentation. While current literature focuses on isolated domains—chemistry, business models, or policy—this work provides a systems-level synthesis. By analyzing the friction points between material science (e.g., binder removal, impurity sensitivity), economic realities (e.g., logistics costs, LFP profitability), and regulatory frameworks (e.g., EU vs. US divergence), we propose that true circularity requires synchronized design-for-recycling, market stabilization mechanisms, and harmonized digital product passports. The paper concludes that overcoming the trilemma demands a shift from isolated fixes to integrated, cross-sectoral coordination. Full article

To address natural aggregate scarcity and improve the high-value utilization of Reclaimed Asphalt Pavement (RAP), this study proposes a steel slag–RAP hot recycled asphalt mixture (SSRM) as a sustainable alternative to conventional limestone–RAP mixtures (RM). Unlike previous studies mainly focusing on performance verification, an integrated environmental–economic evaluation framework was developed based on real highway expansion project data under a “cradle-to-gate” boundary and incorporating transportation distance thresholds. SSRM containing 50% RAP and 23% steel slag as coarse aggregate replacement was evaluated through rutting, semi-circular bending (SCB), freeze–thaw splitting (TSR), and skid resistance tests. Compared with RM, SSRM exhibited 14–16% higher dynamic stability and 20–25% higher fracture energy at −10 °C, along with improved moisture stability and skid resistance, mainly attributed to the rough and alkaline characteristics of steel slag enhancing adhesion and aggregate interlocking. Life-cycle assessment (GWP100) and cost analysis indicate that SSRM reduces carbon emissions by 10–11% relative to RM and about 40% compared with conventional virgin mixtures, while initial construction costs decrease by 9–10%. Transportation sensitivity analysis identifies equal-emission and equal-cost thresholds of approximately 590 km and 380 km, respectively. Within typical material supply radii (300–400 km), SSRM demonstrates both environmental and economic advantages, providing a practical framework for low-carbon material selection in highway construction. Full article

Polyethylene terephthalate (PET) is a synthetic polymer that is widely used in the production of textiles, packaging materials, and beverage bottles. However, its high durability and resistance to abiotic degradation result in serious environmental and health problems. PETase is an enzyme that can depolymerize PET into value-added products, thereby providing an environmentally friendly strategy for PET recycling. PETaseSM14 from a marine sponge, Streptomyces sp. SM14, has a high salt tolerance and thermal stability, thus suggesting its potential for PET degradation applications. However, the substrate recognition mechanism of PETase remains unclear because the catalytic residue is buried within residues that form the substrate-binding cleft. To elucidate the molecular mechanism of PETaseSM14, all-atom molecular dynamics simulations were performed at 300, 320, and 340 K. The results revealed that the overall α/β fold remained stable at all temperatures, whereas temperature-dependent local fluctuations and conformational changes were observed in the substrate-binding cleft and N-terminal region. At 300 and 320 K, positional shifts and conformational changes in Tyr88 exposed the catalytic Ser156 to the solvent, thereby forming a potential substrate-binding cleft. In contrast, at 340 K, which is higher than the melting temperature of PETaseSM14, disruption of the charge-relay system of the catalytic triad occurs through conformational changes in His234. Substantial temperature-dependent conformational and positional changes in the N-terminal region of PETaseSM14 were observed at 320 and 340 K. These results provide mechanistic insight into the temperature-dependent active-site rearrangements and offer rational engineering strategies to enhance the efficiency of PETase for PET biodegradation. Full article

Glycosaminoglycans (GAGs) and their degrading enzymes have extensive applications and biotechnology and medicine, and play a crucial role in the recycling of organic matter in oceans. In this study, a potential GAG utilization gene cluster was identified in the genome of a novel marine Bacteroidetes, Roseihalotalea indica gen. nov. sp. nov. TK19036^T, through sole carbon source cultivation and differential proteomic analysis. Multiple GAG-lyases within this locus were purified and characterized. RiPL8 comprises a functionally unknown N-terminal domain and a catalytic C-terminal domain, exhibiting specificity for degrading hyaluronic acid (HA). The activity of RiPL35 is sensitive to Ca²⁺ ion concentration with an optimum at 10 mM. RiPL38 is the first reported member of the PL38 family capable of degrading HA and chondroitin sulfate (CS). In summary, our study reveals Roseihalotalea indica gen. nov. sp. nov. TK19036^T harbors an unpredicted GAG degradation gene cluster, and the encoded GAG-lyases exhibit distinct substrate specificities compared to the host organism. Full article

The restricted availability of raw materials underscores the significance of recycling asphalt materials that have reached the end of their service life, facilitating their reuse with additives for economic and sustainability benefits. The study includes both empirical investigations and numerical analyses. Empirical studies were conducted in four stages to evaluate the binder and mixture. First, the rheological properties of binders obtained from various sources were assessed in both unmodified and modified states. Second, the binders were subjected to different levels of aging. Third, the presence of additives in the binders was investigated. In the final stage, the analysis of asphalt pavement layers was conducted using the finite element method (FEM) for both modified and unmodified binders. Performance tests were carried out to evaluate the binder’s properties, and physical examinations were conducted to compare these properties. The binders were tested under both unaged and aged conditions using linear amplitude sweep (LAS), frequency sweep (FS), multiple stress creep recovery (MSCR), and bending beam rheometer (BBR) tests. The results indicated that aging increased the stiffness of the binders, regardless of their source. Additionally, the introduction of a rejuvenator reduced the binder’s stiffness, particularly at low temperatures. Findings showed that the growth rate (GR) and rutting parameters increased with binder aging, while the frequency decreased. The R² value of 0.92 demonstrates a strong correlation between the parameters. Polymer-modified binders demonstrated superior deformation resistance and higher stiffness stability. Overall, aging reduced asphalt flexibility, whereas modified binders improved long-term pavement deformation performance. Full article

Agricultural biomass recycling efficiency is central to advancing the green and sustainable transition of agriculture. Drawing on panel data for 30 Chinese provinces from 2019 to 2023, this study measures recycling efficiency using a three-stage super-efficiency SBM model with undesirable output and examines its determinants with a panel Tobit model. The second-stage SFA indicates that the effects of external conditions on input slacks are input-specific. In particular, GDP is statistically significant only in the biomass-generation slack equation, whereas topographic relief and rural road network density do not show robust associations with any slack measure once controls are included. After removing the influence of environmental factors and random shocks, the overall national level of agricultural biomass recycling efficiency remains moderate. The national mean Stage 3 efficiency decreased from 0.586 in 2019 to 0.427 in 2022 and recovered to 0.543 in 2023. The five-year average was 0.510, which is close to the Stage 1 average of 0.503. Spatial analysis indicates weak global spatial autocorrelation, with only occasional local clustering. The efficiency centroid oscillated during the study period rather than following a one-way migration path, with a total displacement of 70.05 km. The determinant analysis indicates that the number of specialised agricultural machinery has the most stable positive association with recycling efficiency, while other policy, market, and human capital variables do not show robust significance in the short panel. These findings underline the need to align equipment deployment and collection systems with local terrain and transport conditions, expand machinery leasing and service provision, and strengthen capacity building in low-efficiency regions. Establishing a national information sharing and dispatch platform would facilitate cross-regional resource flows and more efficient allocation, while improving local service outlets would make participation more convenient for farmers and reduce transaction costs. Full article

In the automotive industry, the push for lightweighting, sustainability, and performance underpins the need for continuous improvement of materials and processes; thus, this research explores the introduction of different approaches for processing optimization. The Finite Element Method (FEM) excels at enhancing structural efficiency and reducing material use in composite tooling like stamping dies, while Life Cycle Assessment (LCA) quantifies environmental impacts over the product life cycle. Coupling these approaches is promising but challenging due to difficult integration into well-established industrial practices. In this framework, the study presents the combination of FEM-LCA analyses on a tool for a composite car bonnet, considering an industrial case. The reduction in weight (−85%) obtained through FEM topology optimization, along with novel materials (thermoplastic polymers) and processes (3D printing, internal recycling), results in an environmental impact reduction over the tooling process (−43% in climate change). The two analyses enable a holistic tool design that balances mechanical performance with reduced carbon footprint, aligning with the European regulatory framework and emission targets. The results demonstrate the feasibility of a coupled FEM-LCA approach to optimize composite tooling in the automotive context, with a positive prospect of full-scale integration into the industrial value chain. Full article

Coal gangue, the primary solid by-product of coal mining, presents severe environmental challenges due to massive accumulation. At the same time, it represents potential as a secondary resource if properly utilized. This review systematically summarizes the mineralogical characteristics, modification strategies, and utilization pathways of coal gangue. Current treatment methods, including thermal, chemical, and microbial activation, are discussed, highlighting their respective efficiencies, economic feasibility, and environmental impacts. Furthermore, this review emphasizes the transition of coal gangue from low-value disposal to high-value utilization. Representative applications are summarized, including its use as a precursor for advanced construction materials, as a functional material for environmental remediation, and as a feedstock for energy recovery. Finally, the major technological challenges and research gaps are identified. Future development should focus on intelligent sorting technologies, low-carbon activation processes, and synergistic multi-waste integration. These directions are expected to promote the transformation of coal gangue from an environmental liability into a valuable resource for the circular economy. Full article

With the rapid development of technology and increasing material consumption, the efficient management of waste streams has become a critical challenge within the circular economy, particularly in resource-intensive sectors such as electronic waste recycling. This study examines how artificial intelligence can improve the assessment and forecasting of circular economy investment efficiency, with particular attention paid to resource-intensive sectors such as electronic waste recycling. The study reviews data from European Union countries for the period 2010–2024, including economic, technological, and environmental indicators. A machine learning model system based on ensemble predictive methods was developed to assess the effectiveness of circular economy investments. The results show that artificial intelligence-based models have higher forecasting accuracy than traditional econometric methods, and the most important factors determining investment efficiency are the level of automation, recycling efficiency, and the stringency of environmental policies. The study provides a new, data-driven methodological approach to assessing circular economy investments and discusses their implications for sustainable real estate development and resource management. Full article

Given the rising demand for phosphate, a critical mineral for many countries due to its essential role in fertilizer production and global food security, reprocessing waste generated during phosphate mining has become increasingly important to mitigate demand pressures and reduce the environmental impact of the mining industry. This study aims to develop a sustainable hydrometallurgical process to recover residual phosphate from a lithology present in mining waste rock. To this end, a thermodynamic analysis was first performed to assess reaction feasibility during leaching and precipitation. A two-step process was then proposed: the first step involves leaching carbonates (mainly calcite) using acetic acid, optimized through response surface methodology based on a Box–Behnken design; the second step consists of precipitating calcium with phosphoric acid to produce a value-added by-product (brushite) while simultaneously regenerating the acetic acid. A preliminary economic assessment was conducted to evaluate process feasibility. The results show that acetic acid is highly selective for carbonates, yielding a phosphate concentrate containing 30% P₂O₅ with complete phosphate recovery under the following conditions: 3.4 molL⁻¹ acid concentration, 28 °C reaction temperature, a liquid-to-solid ratio of 6 mLg⁻¹ (14.2% solids), and a reaction time of 49 min. In the precipitation step, a calcium recovery of 97% was achieved under optimal conditions (20 °C, 15 min, 500 rpm stirring, and a P:Ca ratio of 1). Furthermore, the preliminary economic assessment indicates that the developed process, based on the use of an organic acid and its recycling, generates a net profit, confirming its economic viability and its contribution to environmentally sustainable phosphate processing. Full article

Nanoparticle-catalysed microwave-aided multicomponent reactions (MCRs) have been demonstrated to be competent and environmentally benign tools for the quick synthesis of a wide spectrum of fused heterocyclic systems. The distinctive physicochemical properties of nanoparticles, including a substantial surface area, readily modifiable surface functionality, and heightened catalytic activities, when coupled with microwave irradiation, have enabled a marked improvement in reaction rates, product yields, and selectivity compared to conventional heating methods. This review highlights recent advancements in microwave-assisted MCRs facilitated by diverse nanomaterials, such as magnetic nanocatalysts, metal and metal oxide nanoparticles, mesoporous silica systems, and nanohybrids. It emphasises catalyst design, catalytic efficacy, scope, recyclability, and alignment with green chemistry principles in both solvent-free and aqueous environments, as well as the utilisation of recyclable catalysts. In summary, microwave-assisted multi-component reactions catalysed by nanoparticles are ecofriendly and versatile methods for the sustainable synthesis of such fused heterocycles containing bioactive pyridine, pyrazole, phenazine, pyrimidine, pyran, imidazole, and relevant pyridine derivatives, possessing potential in medicinal and material chemistry. Full article