Sustainable Materials and Technologies最新文献

Rare earth elements (REEs)-based (NdFeB) magnets and lithium−ion batteries (LIBs) are critical for a low−carbon economy. Their production depends on critical elements like REEs, Li, Co and Ni. Recycling of these products have been explored separately as a potential solution. Conventional methods for recycling NdFeB magnets and LIBs face challenges like high energy consumption, lengthy processing, excessive reagent usage, and waste generation. In this study, a novel synergetic recycling methodology is proposed to minimize these challenges. The idea is based on using waste ferrous sulfate solution generated during magnet leaching as a reducing and leaching reagent for battery recycling thereby eliminating the need for additional reagents for oxidation of iron in NdFeB and reduction of cathode material in LIBs. The magnet is leached in diluted H₂SO₄ at 70 °C followed by double sulfate precipitation for REEs with Na₂SO₄. The REE-depleted but acidic ferrous solution is then used for reductive leaching of cathode material at 90 °C. The overall recovery rates of REEs, Li, Co, Ni, and Mn in this process are >95%. The iron from magnet material is recovered as crystalline and easily-filterable iron compound that can be converted to goethite and used as a byproduct. This synergetic approach not only reduces reagent consumption and waste generation aligning with the principles of circular economy but also offers improved efficiency, resource conservation, and environmental sustainability.

Environmental concerns have spurred a quest for more sustainable and safer solvents, aiming to replace aggressive and harmful chemical products in industrial processes. In response to this need, deep eutectic solvents (DES) have emerged as a progressive evolution from ionic liquids. These innovative solvents result from the synergistic combination of two or more chemical compounds, exhibiting a significant reduction in melting point when blended in specific molar fractions, ultimately achieving a liquid state at room temperature. In recent years, a natural variant known as Natural Deep Eutectic Solvents (NADES) has gained prominence. This environmentally friendly alternative is derived by skilfully combining compounds such as sugars, amino acids, or organic acids, presenting a promising avenue for sustainable and eco-friendly chemical processes. These “green” solvents go beyond applications in chemical or materials engineering, finding application in diverse fields such as biocatalysis, extraction processes, and carbon dioxide capture, among others. Despite their numerous advantages, including low cost, ease of preparation, tuneable properties, and biorenewability, the full potential of DES remains elusive due to insufficient understanding, hindering their seamless integration into industrial applications. While previous reviews have predominantly focused on defining and showcasing the applications of DES, they often overlook the crucial aspect of physicochemical characterization. Similar to other solvent classes, the physicochemical properties of DES such as polarity, viscosity, density, and conductivity play a pivotal role in determining their applicability. Recognizing this gap, the primary objective of this review is to provide a practical guide encompassing the preparation, characterization, and application of DES, thereby facilitating a comprehensive understanding of these solvents for both researchers and practitioners alike. Moreover, the manuscript will delve into the diverse types of DES, exploring their unique physicochemical properties and potential modifications tailored for various applications across different fields.

The conventional anti tubercular (anti-TB) treatment strategies constitute challenges in terms of patient compliance and treatment outcomes. Nano-therapeutics is an emerging field with increasing demand for the therapeutic management of tuberculosis (TB) and the challenges over acquired drug toxicity and poor availability. Nevertheless, studies based on nanopeptide drug carrier for the delivery of anti-TB drugs are scanty. The present work emphasizes on the development of a nanocarrier system through hydrothermal process for encapsulating anti-TB drugs (rifampicin, isoniazid, pyrazinamide, ethambutol) using carnosine dipeptide for the potential therapeutic application. The carnosine-anti-TB drug nanocomposites were synthesized by treating native carnosine and anti-TB drugs at an equal ratio (1:1) incubated at 65°C for 30 min (pH 5.3). The hybrid clusters were freeze dried and used further for characterization (physiochemical, biological, morphology and in silico methods). The structural and functional annotations of carnosine and anti-TB drug nanocomposites were confirmed from its terminal amine absorption stretching’s and its amino group fingerprinting regions. The homogenous nature of carnosine-anti-TB drug complexes in solutions was demonstrated with the particle size (>1 μm), that is suitable for macrophage uptake. SEM analysis demonstrated the interactions and functional group orientation between carnosine and anti-TB drugs during the self-assembly process. The drug release profile indicated that the carnosine-drug conjugation promoted the sustained release compared to free drugs. The quantum mechanical calculations define the structural modelling of drugs with carnosine to obtain a stable energy-minimized conformation. To conclude, the developed carnosine- anti-TB drug nanoclusters with enhanced stability and uniformity in size makes them suitable for macrophage uptake and targeted delivery approaches during TB treatment.

Asphalts for pavement and roofing are known to emit volatile organic compounds (VOCs), contributing to air pollution, including the formation of ozone and secondary organic aerosols, which further worsen air quality. These emissions become more pronounced with higher sun intensity and higher temperature, accelerating the loss of essential components and the aging of bitumen. Consequently, the durability and functionality of bitumen are compromised. In this study, we investigate the efficacy of nitrogen-carrying functional groups in biochar at retaining VOCs in bitumen and prolonging the service life of asphalt surfaces. Biochar derived by hydrothermal liquefaction of red microalgae, rich in N-functional groups, is compared with low-N biochar obtained through acid-washing. Laboratory tests demonstrate that bitumen modified with high-N biochar exhibits greater resistance to aging after 200 h of ultraviolet radiation exposure compared to bitumen modified with low-N biochar. The values of an aging index based on the crossover modulus and an aging index based on the crossover frequency indicate greater susceptibility to aging in neat bitumen compared to biochar-modified bitumen, and bitumen modified with high-N biochar showed the lowest aging index. Compared to neat bitumen, measurements of carbonyl and sulfoxide as aging indicators showed an improvement of 12.9% for high-N biochar in slowing bitumen aging, while low-N biochar provided only a 3.1% improvement. Dynamic vapor sorption analysis showed 35% less mass loss in bitumen with high-N biochar compared to bitumen with low-N biochar. These improvements can be attributed to the increased retention of VOCs in bitumen facilitated by the N-functional groups in high-N biochar. Modeling with density functional theory shows the mechanisms by which biochar rich in N-functional groups exhibits enhanced adsorption of VOCs. This modeling highlights the importance of biochar's nitrogen functional groups in biochar's electronic structure and molecular structure in retaining VOCs in the bitumen matrix. The study outcomes promote sustainability and resource conservation in the construction industry and align with goals of carbon neutrality.

With the expansion of shellfish aquaculture, there has been an increase in the number of discarded shells, leading to a range of issues, including environmental pollution, global warming, health risks, and the eutrophication of coastal waters. The recycling of discarded mussel shells holds great research significance. In this study, we present a method for preparing a functional shell powder-based superhydrophobic coating filler by modifying shell powder with Mg(OH)₂ and stearic acid (SA). Mg(OH)₂ crystals were utilized to modify shell powder and enhance the abrasion resistance of superhydrophobic coatings. Additionally, loading SA can decrease the free energy of the filler surface, thereby improving the hydrophobic properties of the coating. Moreover, the adhesion of water-based coatings can be enhanced by the functional shell powder (Shell powder/Mg(OH)₂@SA) filler through strong molecular forces between the aqueous fluorocarbon emulsion and the modified shell powder. The contact angle (CA) of the coating was approximately 150°, and the hydrophobic critical value of the coating was approximately 1550 times that of washing. Even after 1200 washes, the CA remained at 97°. This simple and environmentally friendly method was expected to enable the preparation of waterproof barriers with strong corrosion resistance on various substrates. The results demonstrated that the proposed filler is easy to store, simple to process, cost-effective in production, and environmentally friendly. Moreover, the coating utilizing the proposed filler exhibits excellent abrasion resistance, water resistance, adhesion, and thermal stability. This innovation provides an eco-friendly solution that repurposes discarded shells and mitigates environmental pollution. The recycling and reusing of discarded shells can significantly enhance the profitability of shellfish farming and contribute to sustainable development. Importantly, it will contribute to the mitigation of global warming and the achievement of carbon neutrality.

To broaden the usefulness of recycled carbon fibers and develop the high value-added product, the recycled carbon fiber-reinforced carbon-matrix composites were prepared using ultrafine-grain coke as a filler and coal tar pitch as a binder via a liquid mixing process. A comprehensive study and investigation of the microstructures and properties of recycled carbon fibers and composites were conducted. It was found that the recycled PAN-based carbon fiber (rPCF) outperformed the recycled rayon-based carbon fiber (rRCF) in terms of fiber integrity and pitch-coated effect in the recycling and forming processes. By relieving thermal stress, lowering stacking pores, and inhibiting the growth of shrinkage pores, the rCF can promote the sintering of the green body. The flexural strength of rPCF-reinforced carbon-matrix composite (30.70 MPa) and rRCF-reinforced carbon-matrix composite (20.75 MPa) increased by 60.6% and 8.6% than that of pristine carbon-matrix composite (19.11 MPa), respectively. The difference in mechanical properties between rPCF-reinforced carbon-matrix composite and rRCF-reinforced carbon-matrix composite is attributed to the mechanical interlock mechanism and fiber pull-out mechanism. This work provides a propagable, affordable, and environment-friendly idea for recycling waste carbon fiber and producing recycled carbon fiber reinforced composites.

Acidification has proven effective in minimizing NH₃ emissions during the drying of digestate bio-solids, but its impact on soil nutrient dynamics and plant growth is less understood. This study aimed to assess the nitrogen and phosphorus efficiency of acidified-dried digestate solids as starter fertilizer for maize through a pot experiment and a soil incubation study. Two types of digestates (MDS and SDS) and two acidifying agents (concentrated H₂SO₄ and alum) were used. Drying significantly lowered the nitrogen fertilizer replacement value (N-FRV) from 42% in untreated to 12% in the dried material, reducing maize biomass and N uptake by 34% and 54%, respectively. The decline mitigated by acidification, which doubled N-FRV to 28%. Drying enhanced maize P uptake by 25%, indicating dried MDS as an effective P fertilizer (P-FRV of 82%). However, alum negated the drying benefits for P uptake, aligning it with raw MDS levels. The SDS treatments showed no significant effects on maize growth or nutrient uptake, though dried SDS indicated a high N mineralization potential, N-FRV and P-FRV remained around 33% and 26%, respectively. The study concludes that H₂SO₄-acidified dried MDS could serves as a suitable starter fertilizer with balanced N and high P availability, supporting early maize development. Alum may serve to preserve N value while reducing P solubility to prevent runoff. Dried SDS is less effective as a mineral fertilizer replacement, better suited for sustaining soil organic N and P levels.

Chloride removal is crucial for industrial wastewater discharge, seawater purification and concrete structure durability. In this study, a novel hydrogel with excellent chloride adsorption property was prepared and the adsorption capacity in relation to external pH and other ions was evaluated. The hydrogel was synthesized using a one-pot method with quaternized chitosan (HACC), hydroxyethyl cellulose (HEC), and carboxymethyl chitosan (CMC) as monomers. By adjusting the material compositions, we effectively modulated the microstructure and charge characteristics of hydrogel, achieving a balanced swelling ratio and optimal adsorption performance. The optimal process conditions were identified as 25 °C and a chloride ion concentration of 40 mmol L⁻¹, achieving a maximum adsorption capacity of 1080 mg g⁻¹. Isotherm modeling showed that the adsorption fits well with the Freundlich isotherm, suggesting multilayer adsorption. The quaternary ammonium groups serve as fixed positive charge sites or active adsorption sites, enabling the hydrogel to efficiently adsorb anions through the synergistic effects of electrostatic interactions, physical adsorption, and amino protonation. The varied adsorption capacities of quaternary ammonium groups for different anions give rise to competitive adsorption phenomena among them. The incorporation of silver ions into the hydrogel greatly enhances its selective adsorption of chloride ions through chemical combination. This work presents a comprehensive strategy for designing a novel hydrogel with exceptional adsorption properties specifically tailored for chloride ions.

Thermoset materials and their reinforced composites are widely employed in the aircraft, wind energy and construction sectors. Their 3D-crosslinked network and their chemical and physical heterogeneity make them particularly difficult to be recycled. Nowadays, the management of composite scraps and end-of-life waste is still based on landfilling or incineration practices, which are clearly non-compliant with the principles of the circular economy. In this work, a catalysed solvolysis process in mild conditions (T = 180 °C, t = 1–3 h, catalyst 1–7 wt%) was applied for the chemical recycling (chemcycling) of anhydride-cured epoxy resins and their carbon fiber reinforced composites. The selection of the hydroxylated solvents followed thermodynamic considerations (Hansen solubility parameters) and green chemistry principles. The quality of the liberated fibers was studied through thermogravimetric analysis, scanning electron microscopy and single-fiber micromechanical testing, highlighting high surface purity and 100% retention of their pristine mechanical properties (Young's modulus, elongation at break and ultimate strength). The organic recyclates were characterized through gel permeation chromatography, Fourier-transform infrared spectroscopy and chemical titration, and directly reused as hydroxylated binders for the formulation and application of bicomponent polyurethane protective coatings. The resulting coatings were characterized by high chemical resistance (> 100 double rubs at methyl-ethyl ketone test), high surface scratch hardness (3H to 5H), good substrate adhesion (1.5–4 MPa), and excellent optical clarity and surface gloss. These results demonstrate the potential zero-waste reusability of all fractions derived from the chemical recycling of carbon fiber reinforced composites, in line with the principles of the circular economy.

The pressing need to mitigate climate change has led to the widespread adoption of photovoltaic (PV) solar panels as a renewable energy solution. However, the increasing disposal of end-of-life solar panels presents significant environmental challenges, as they contain valuable elements that can potentially be recycled and reused. This article reviews a novel approach to waste valorization and recycling within the circular economy framework by harnessing valuable elements from retired solar panels as alternative construction materials, thereby contributing to building climate resilience. Through case studies in China, Japan, Brazil, US, Germany, and Brazil, this study explores the feasibility and benefits of repurposing elements such as silicon, glass, and metals from decommissioned solar panels for construction applications. Key findings indicate that significant quantities of these materials can be recovered through efficient recycling processes, offering a sustainable solution to reduce waste and promote resource efficiency. Numerical assessments reveal that up to 90 % of silicon and 95 % of glass from end-of-life solar panels can be effectively recycled, thereby minimizing the environmental footprint associated with their disposal. Moreover, this approach not only diverts waste from landfills but also reduces the demand for virgin materials, thus conserving natural resources and lowering carbon emissions. The incorporation of recycled materials into construction projects enhances the circularity of the economy by closing material loops and promoting a regenerative approach to resource management. Furthermore, the utilization of recycled materials in construction enhances the resilience of built environments to climate change impacts by reducing energy consumption, mitigating greenhouse gas (GHG) emissions, and enhancing structural durability. Overall, this article underscores the potential of waste valorization and recycling from solar panels to contribute to a sustainable and resilient built environment, aligning with broader efforts to address climate change and advance circular economy in waste sector.