Search Results (1,533)

1,4-Dihydropyridines (1,4-DHPs) are privileged heterocycles with broad relevance in medicinal chemistry and redox-related applications. However, conventional Hantzsch syntheses typically require prolonged thermal heating and often suffer from limited efficiency and regioselectivity. Herein, we report a sustainable and efficient microwave-assisted protocol for the synthesis of 1,4-DHPs, employing phosphotungstic acid (HPW) as a heteropolyacid catalyst in PEG-400 as a green reaction medium. The multicomponent cyclocondensation proceeds rapidly under microwave irradiation, affording the desired 1,4-DHP derivatives in good to excellent yields within short reaction times. Compared with classical acid-catalyzed conditions, the HPW/PEG-400 system markedly enhances regioselectivity toward the 1,4-DHP framework while simultaneously reducing energy input. Moreover, the catalytic system exhibits good recyclability, underscoring its potential as a practical and environmentally responsible platform for the synthesis of bioactive 1,4-dihydropyridine scaffolds. Full article

Chloroplasts are key organelles in plants that carry out photosynthesis, convert light energy into chemical energy, and synthesize organic compounds. In this study, a stably heritable chlorophyll-deficient mutant was screened from the ethyl methanesulfonate-induced mutation library of Wuyunjing 21 (WYJ21). This mutant was designated as chlorophyll deficient 6 (cde6). The cde6 mutant exhibits a low chlorophyll content, photosynthetic defects, an impaired chloroplast structure, a significant reduction in the number of stacked thylakoid layers, and a yellow-green leaf phenotype in the early tillering stage. Through MutMap analysis, it was found that the cde6 mutant harbors a single-base mutation (T→A) in the LOC_Os07g38300 gene. This mutation results in an amino acid substitution from valine (Val) to aspartic acid (Asp) in the encoded protein, thereby affecting the protein’s structure and function. The mutation of CDE6 leads to decreased expression of genes related to chloroplast development and chlorophyll biosynthesis. Further studies revealed that the CDE6, a potential chloroplast ribosome recycle factor, leads to high temperature sensitivity in rice when mutated. As high-temperature stress is a primary constraint to global rice productivity, the identification of CDE6 provides a genetic target for improving thermotolerance. In conclusion, these findings demonstrate that CDE6 plays a crucial role in chloroplast biogenesis and provide new insights into its regulatory function in high-temperature tolerance. Full article

Polyurethanes (PUs) are indispensable polymeric materials widely employed across diverse industrial sectors due to their excellent thermal stability, chemical resistance, adhesion, and mechanical durability. However, the intrinsic three-dimensional crosslinked network that underpins their performance also presents a fundamental barrier to reprocessing and recycling. Consequently, most end-of-life PU waste is currently managed through landfilling or incineration, resulting in significant resource loss and environmental impact. To address these challenges, this review presents an integrated perspective on sustainable PU systems by unifying green synthesis strategies with closed-loop recovery approaches. First, recent advances in bio-based polyols and phosgene-free isocyanate synthesis derived from renewable resources—such as plant oils, carbohydrates, and lignin—are discussed as viable means to reduce dependence on petrochemical feedstocks and mitigate toxicity concerns. Next, emerging chemical recycling methodologies, including acidolysis and aminolysis, are reviewed with a focus on the selective recovery of high-purity monomers. Finally, PU vitrimers and dynamic covalent polymer networks (DCPNs) based on urethane bond exchange reactions are examined as reprocessable architectures that combine thermoplastic-like processability with the mechanical robustness of thermosets. By integrating synthesis, recovery, and reuse within a unified framework, this review aims to outline a coherent pathway toward establishing a sustainable circular economy for PU materials. Full article

A sustainable circular pathway was developed for poly(ethylene terephthalate) (PET) nanocomposites through a catalyst-driven polymerization and depolymerization process. In this study, calcium dodecylbenzene sulfonate with n-butyl alcohol modified ZnAl layered double hydroxides (LDHs) were utilized as bifunctional catalysts to synthesize highly exfoliated PET/LDH nanocomposites via in situ polycondensation of bis(2-hydroxyethyl) terephthalate (BHET). The organic modification of LDHs expanded interlayer spacing, improved interfacial compatibility, and promoted uniform dispersion, leading to enhanced mechanical, thermal, and barrier properties. In the second stage, the pristine LDH catalyst efficiently depolymerized the prepared PET/LDH nanocomposites back into BHET through glycolysis, completing a closed-loop BHET-to-BHET cycle. This integrated strategy demonstrates the reversible catalytic functionality of LDHs in both polymerization and depolymerization, reducing metal contamination and energy demand. The proposed approach represents a sustainable route for designing recyclable high-performance PET nanocomposites aligned with the principles of green chemistry and circular material systems. Full article

The circular economy represents a significant opportunity to enhance the mechanical properties of bituminous mixtures, thereby contributing to sustainable development. This research compares the behaviour of traditional bituminous mixtures with sustainable ones that reuse recycled materials, industrial waste products, or additives that improve mechanical or rheological properties. The methodology employed comprised the acquisition of fatigue resistance laws from 4-point bending tests on prismatic specimens. This facilitated the analytical determination of the number of axles of 13 tons that the section of pavement with sustainable material can support for comparison with the axles supported in the conventional mix. The findings corroborate the utilization of sustainable bituminous mixtures in pavement sections, employing the maximum circularity criterion. The fatigue laws calculated must permit the use of different calculation methods or other applications in green infrastructures, such as cycling lanes or pedestrian areas. On sections with an AADT of between 800 and 25 HV/day, all of the analyzed bituminous mixtures with sustainable materials prolong the service life of the road. There were increases in service life of between 25.5% and 6.6%, respectively, which satisfactorily achieved an increase in pavement service life based on the criterion of maximum circularity. Full article

The rapid expansion of China’s photovoltaic (PV) industry has led to a significant increase in decommissioned PV modules. To address the high energy consumption and environmental impact of traditional recycling techniques, this study proposes a novel method that integrates DMPU solvent recycling with pyrolysis for recovering PV cell sheets. DMPU, an organic solvent with low volatility, non-toxicity, and excellent recyclability, was used in this study. The effects of temperature and treatment duration on the structural integrity of silicon cell sheets were systematically evaluated, establishing optimal parameters: immersion in DMPU at 200 °C for 60 min, followed by pyrolysis at 480 °C for 60 min. A case study was conducted on a small-scale recycling facility with a daily processing capacity of 200 standard PV panels, encompassing system boundaries such as transportation, pretreatment, and pyrolysis. The recycling process consumed 2.14 × 10⁹ kJ of energy annually, reducing CO₂ emissions by 9357.2 tons. Compared to conventional methods such as pyrolysis, mechanical dismantling, and chemical dissolution, the proposed approach employing a green, recyclable solvent markedly reduces energy consumption and carbon emissions, offering notable environmental benefits. Full article

Based on the pressing need to develop efficient desulfurization technologies for fuel oils, this study presents a novel photoresponsive adsorbent for the removal of refractory thiophenic sulfides. Conventional hydrodesulfurization exhibits limited efficiency for such compounds, while adsorption–desorption processes often suffer from high energy consumption during regeneration. Inspired by natural stimuli-responsive systems, we designed a photothermal adsorbent by incorporating silver nanoparticles (Ag NPs) into a porous aromatic framework (PAF) via a green photoreduction method. The resulting materials, denoted as Ag(0)PBPAF-n (n = 1, 2, 3), were thoroughly characterized to confirm successful synthesis and structural integrity. The introduced Ag NPs serve as adsorption sites, enhancing uptake capacity through weak interactions with sulfur atoms in thiophenic molecules. More significantly, under light irradiation, the localized surface plasmon resonance (LSPR) of Ag NPs enables efficient photothermal conversion, triggering rapid desorption without conventional heating. Adsorption–desorption tests demonstrated that up to 48% of adsorbed thiophenic sulfur could be released upon illumination. Fixed-bed experiments further verified that light can effectively stimulate regeneration and improve energy efficiency. This work offers a promising strategy for designing recyclable adsorbents with low-energy regeneration driven by clean solar energy. Full article

In this study, ZnO–GO nanocomposites were synthesized from waste Zn–C batteries and used for the photocatalytic degradation of malachite green (MG) under UV light. ZnO–GO nanocomposites with different GO contents (1, 2.5, and 5 wt%) were prepared at room temperature and characterized by XRD, SEM, EDS, and UV–Vis spectroscopy. The GO content significantly affects the morphology, optical properties, and photocatalytic activity of the nanocomposites. In the presence of ZnO NPs, a malachite green degradation efficiency of 96.25% was achieved in 90 min, while ZnO–1%GO, ZnO–2.5%GO, and ZnO–5%GO achieved 95.35%, 97.27%, and 99.6% MG degradation, respectively, in just 30 min. The photocatalytic degradation process of MG was optimized using Response Surface Methodology (RSM). The effects of GO content, catalyst dosage, initial MG concentration, and irradiation time on the efficiency of photocatalytic degradation were investigated, and optimal conditions were determined. Under optimal conditions, a photocatalytic degradation efficiency of 98.51% was achieved. These results indicate that ZnO–GO nanocomposites synthesized from waste Zn–C batteries are efficient and environmentally friendly photocatalysts for the treatment of dye-contaminated wastewater. Full article

The textile industry is positioned as one of the most significant contributors to waste generation but remains with low implementation of post-consumer recycling practices. In response to this challenge, this study focuses on the physicochemical recycling of cotton derived from textile waste aided by a protic ionic liquid, 1,5-diazabicyclo [4.3.0]non-5-ene acetate ([DBNH][OAc]), as a green alternative solvent for dissolving cotton and generating a dope, which is then transformed into a filament through the wet spinning technique. A dedicated setup was developed for the spinning process, and an experimental design based on a statistical factorial approach was applied to optimise the spinning conditions, as temperature, die diameter and velocity of extrusion. The mechanical properties of the filaments, including tenacity and elongation at break, were analysed to assess their performance. The statistical model facilitated the simultaneous optimisation of both responses—tenacity and elongation—resulting in the following optimal conditions: a temperature of 95 °C, a flow rate of 70 μL·min⁻¹, and an extrusion diameter of 0.4 mm. The results demonstrate that both the selected solvent and wet spinning are effective in producing filaments suitable for reuse in the textile industry. Remarkably, filaments derived from textile waste exhibited superior mechanical properties compared to those obtained from virgin white cotton. Full article

The growing concern over plastic pollution and the widespread presence of micro- and nanoplastics has renewed interest in polyhydroxybutyrate (PHB) as a biodegradable alternative; however, its industrial deployment remains constrained by costly recovery operations with a high environmental burden. This study examines how PHB biosynthesis and intracellular organization, physicochemical properties, and the characteristics of the producing microorganism influence the performance of conventional recovery routes, including extraction with organic solvents, alkaline/oxidative chemical digestion, and enzymatic–physical schemes coupled with mechanical disruption. Based on this foundation, quantitative data are analyzed for PHB content in bacteria, mixed microbial cultures, cyanobacteria, and microalgae, along with extraction yields, polymer purity, and solvent recyclability in processes employing chlorine-free solvents, green solvents, and hydrophobic natural deep eutectic solvents (NaDESs) formulated with terpenes and organic acids. The analysis integrates mechanistic perspectives on NaDES–cell and NaDES–PHB interactions with solvent design criteria, biorefinery configurations, and preliminary evidence from technoeconomic and life cycle assessments. The findings identify NaDES as an up-and-coming platform capable of reconciling biopolymer quality with the principles of green chemistry while delineating critical gaps in recovery efficiency, viscosity management, solvent recycling, and pilot-scale validation. Full article

This study systematically examines the policy and technological pathways for the sustainable development of China’s 3D printing industry under the “Dual Carbon” goals. A three-dimensional sustainability framework is developed, integrating resource efficiency, environmental performance, and socio-economic value. Based on this framework, the study conducts a full-process analysis covering design, material preparation, manufacturing, post-processing, use, and recycling stages. The analysis identifies key carbon-reduction mechanisms of 3D printing, including material savings, reduced energy consumption, lightweight-enabled emission reduction, and distributed manufacturing. A comparative analysis of China, the European Union, and the United States reveals major constraints in China’s 3D printing sector, particularly in top-level policy design, standardization systems, legal frameworks, industrial coordination, and low-carbon core technologies. Based on these findings, the study proposes a dual-driven development pathway integrating policy optimization and technological innovation. From an institutional perspective, this pathway emphasizes green policy incentives, including strategic planning, standard setting, green finance, and collaborative governance. From a technological perspective, it highlights the importance of low-carbon material development, refined energy-efficiency management, life-cycle carbon accounting platforms, and value creation across the product life cycle. Overall, the study demonstrates that effective policy–technology synergy is essential for transforming theoretical carbon-reduction potential into scalable and practical outcomes, providing a systematic analytical framework for academic research and actionable guidance for policymakers and industry stakeholders. Full article

As the goal of carbon peak and carbon neutrality becomes a global consensus, the circular economy is gradually evolving from an environmental concept to a core lever for national strategy and industrial transformation. To achieve green and low-carbon development, China is accelerating the construction of a circular economy system, particularly in the fields of resource recycling and utilization. Industrial waste heat, a strategically critical supplementary energy resource, performs a pivotal role in advancing the circular economy. Based on an energy technology coupling model, this study assesses the waste heat utilization potential in China and quantitatively measures its impact on energy conservation and carbon reduction. The results show that: (1) The potential of industrial waste heat in China is characterized by an inverted U-shaped trajectory. Over the near-to-medium term, the steel and power industries remain the primary contributors to waste heat utilization potential. (2) Low-grade waste heat represents the majority of utilization potential in China’s industrial sector, mainly from power generation, fuel processing, and steel manufacturing. The model results indicate that the proportion of low temperature waste heat will increase from approximately 66% in 2025 to 83% in 2060. (3) Waste heat utilization significantly influences the energy transition pathway. The findings of this study demonstrate that energy-intensive industries have the potential to reduce primary energy consumption by more than 13%. Moreover, making full use of waste heat could accelerate China’s carbon peaking target to 2028, and reduce peak carbon emissions by an estimated 5.1%. Full article

The global shift toward renewable energy and circular economy models requires industrial systems that minimize waste and recover value across entire life cycles. This review synthesizes recent advances in by-product recovery technologies supporting renewable energy and circular industrial processes. Thermal, biological, chemical/electrochemical, and biotechnological routes are analyzed across battery and e-waste recycling, bioenergy, wastewater, and agri-food sectors, with emphasis on integration through Life Cycle Assessment (LCA), techno-economic analysis (TEA), and multi-criteria decision analysis (MCDA) coupled to process simulation, digital twins, and artificial intelligence tools. Policy and economic frameworks, including the European Green Deal and the Critical Raw Materials Act, are examined in relation to technology readiness and environmental performance. Hybrid recovery systems, such as pyro-hydro-bio configurations, enable higher resource efficiency and reduced environmental impact compared with stand-alone routes. Across all technologies, major hotspots include electricity demand, reagent use, gas handling, and concentrate management, while process integration, heat recovery, and realistic substitution credits significantly improve life cycle outcomes. Harmonized LCA-TEA-MCDA frameworks and digitalized optimization emerge as essential tools for scaling sustainable, resource-efficient, and low-impact industrial ecosystems consistent with circular economy and renewable energy objectives. Full article

Herein, we report the synthesis, characterization, and catalytic evaluation of cobalt hydroxide chloride [Co₂(OH)₃Cl] in the solvent-free synthesis of 2-substituted 2,3-dihydroperimidines. The presented method aligns with several green chemistry principles, offering operational simplicity, purification by recrystallization, no by-product formation, high yields (64–99%), and short reaction times. A total of 16 dihydroperimidines were synthesized to demonstrate substrate scope versatility. Additionally, the catalyst was successfully recycled and reused in multiple cycles without significant loss. Its robustness was further confirmed by gram-scale synthesis, achieving an 89% yield. Full article

Dysprosium is one of the most critical elements for global economies due to its essential role in the green energy transition. Although it is added in small quantities as an alloying element, dysprosium plays a crucial role in NdFeB magnets used in wind turbines and industrial motors. On the other hand, the limited resources and production capacity of dysprosium contribute to supply shortages and raise concerns about its long-term availability. Therefore, there is a need for efficient techniques that will enable the recovery of dysprosium from secondary materials to bridge the gap between supply and demand while addressing the risks associated with securing a stable supply. This review focuses on (bio)hydrometallurgical and solvometallurgical methods for recovering dysprosium from key secondary sources such as spent NdFeB magnets, phosphogypsum, and coal ash. Although these wastes do not always contain high concentrations of dysprosium, they can have a simpler elemental composition compared to primary sources (a few tens or hundreds of ppm Dy) and are more readily available. Spent NdFeB magnets, with a few percent Dy, show the most promise for recycling. In contrast, coal fly ashes (with several ppm Dy), although widely available, bind dysprosium in an inert phase, requiring substantial pretreatment to enhance the release of the desired element. Phosphogypsum, while not yet a significant source of dysprosium (several ppm Dy), is increasingly recognized as a potential source for other rare earth elements. Although conventional hydrometallurgical methods are commonly used, these are typically unselective for dysprosium recovery, whereas unconventional solvometallurgical approaches show preferential extraction of dysprosium over base metals. Full article