Sustainable Materials and Technologies最新文献

Harvesting energy from vibrations using piezoelectric mechanism has attracted much attention for powering wireless sensors over the past decade. This paper proposes a tunable pendulum-like piezoelectric energy harvester for multidirectional vibration (TP-PVEH) to enhance the power generation characteristic, durability, and environmental adaptability of energy harvester. Unlike traditional cantilevered piezoelectric vibration energy harvesters (PVEHs), which typically lowered working frequencies by adding the weight of proof mass at the end of beam or reshaping beam, TP-PVEH employed a pendulum to harness low-frequency vibrations. Moreover, in contrast to typical pendulum-like PVEHs, the pendulum in this design was not mounted at the end of beam but was attached to a radial spherical plain bearing (RSPB) structure, which avoided the irreversible beam damage caused by gravitational force. TP-PVEH utilized simple-pendulum-induced RSPB motion to smoothly pluck piezoelectric beams, subjecting the piezoelectric beams to unidirectional compressive stress only. Meanwhile, the RSPB structure's capability to facilitate multidirectional rotation enabled TP-PVEH to efficiently capture energy from various directions. Theoretical analysis, numerical analysis and experiment tests were conducted to validate the design and examine how excitation and structural parameters influenced on the output performance of TP-PVEH. The results demonstrated that the excitation amplitude, excitation angle, proof mass, and mass distance brought significant effects on the output characteristic of TP-PVEH. The working frequency, output voltage and power could be efficiently tuned by the abovementioned parameters. With an excitation amplitude of 3 mm, TP-PVEH achieved an optimal output power of 9.81 mW and an output power density of 11.37 μW/mm³, operating with a load resistance of 200 kΩ at a frequency of 12.5 Hz.TP-PVEH could power 100 blue LEDs and a calculator. Additionally, the ability of TP-PVEH to charge capacitors further demonstrated its practical power supply capabilities.

Graphene oxide (GO) exhibits great potential in various fields such as catalysis, wastewater treatment, and energy storage. However, traditional top-down GO preparation methods based on graphite exfoliation often suffer from high energy consumption and inevitably environmental pollution. In this work, an environmentally benign and low-voltage electrochemical exfoliation approach to fabricate nanoscale GO employing carbon fiber-based materials as the precursor using phosphate was proposed. Under neutral phosphate electrolyte, bilayer graphene oxide with a lateral size of ∼500 nm, thickness of ∼1.5 nm, and C/O ratio of 2.96 could be obtained via a constant potential process. By adjusting the pH to 12 to intensify the exfoliation reaction, the lateral size of the graphene oxide was controllable, decreasing to ∼50 nm, while the C/O ratio decreased to 0.9. Due to the further decrease in C/O ratio, the thickness increased slightly to 2–3 nm. The exfoliation potential (1.6–2.5 V vs. Ag/AgCl) and electrolyte concentration (50–500 mM) had an obvious impact on the yield of graphene oxide. Through electrochemical analysis such as linear sweep voltammetry, as well as density functional theory calculations, the exfoliation mechanism of phosphate is elucidated in detail, demonstrating that the stepwise ionized phosphate anions possess more robust intercalation capability than sulfate, thus enabling efficient exfoliation to the intertwined nanocrystalline graphite structure of carbon fibers. The DFT results revealed the bilayer-favored intercalation of phosphate, which accords well with experiments. This work provides a new controllable and green approach for GO synthesis, demonstrated by life cycle assessment. It could assist subsequent studies exploring the size effects of GO and its applications in environmental remediation and energy storage.

The production of aerospace-grade aluminum alloy sheet is characterized by stringent demands, resulting in a low yield rate. The processing of this material generates considerable amounts of highly alloyed scrap, complicating its recycling due to the challenge of maintaining melt cleanliness. This study employed an aerospace-grade melt refining system to purify the recycled 7075 alloy melt obtained from comprehensive scrap remelting. The melt's cleanliness was assessed using Porous Disc Filtration Analysis (PoDFA) and Liquid Metal Cleanliness Analyzer (LiMCA) and Alscan. The microstructure of the ingots and sheets was examined through Scanning Electron Microscopy (SEM) and Electron Backscatter Diffraction (EBSD), whereas the mechanical properties of recycled sheets were evaluated and benchmarked against those of primary sheet at an aerospace-certified testing facility. The findings indicate that the recycled 7075 sheet meets aviation standards, with no significant differences in microstructure or performance when compared to primary sheet. Furthermore, the study highlights the economic benefits of recycling scrap, revealing a potential cost saving of $4210.8 per ton of recycled sheet. The findings presented herein offer a theoretical framework and empirical evidence supporting the development of a recycling system for aerospace scraps and the certification of airworthiness for recycled aerospace aluminum alloy.

Poly(lactic acid) (PLA) and poly(butylene adipate-co-terephthalate) (PBAT) blends provide sustainable packaging solutions renowned for their robustness and biodegradability. Herein, we used a commercial PLA/PBAT blend (Ecovio® - E) to develop films by thermo-pressing, incorporating polylimonene (PLM) and comparing them with limonene (LIM) at 5% and 10% additive concentrations. Remarkably, E/PLM10% film exhibited an 84.9% reduction in Staphylococcus aureus count and a 62% decrease in Aspergillus niger count, surpassing LIM and PLA/PBAT. Additionally, PLM substantially improved the antioxidant activity of the films, achieving more than 40% DPPH scavenging and providing light-blocking capability, with E/PLM5% virtually halting UV-A transmission. Mechanical assessments showed that, although higher PLM levels reduced tensile strength, E/PLM5% matched control performance. FT-IR analysis confirmed PLM presence without chemical alterations, and minimal changes in crystallinity were observed via DSC and XRD, while TGA confirmed the attractive thermal stability of the films. Expanding on these findings, we evaluated film efficacy in cherry tomato preservation, including unpackaged controls. E/PLM5%-packaged tomatoes exhibited superior visual quality and fungal inhibition, proving a promising option for active food packaging due to their antimicrobial effectiveness, antioxidant activity, and UV-light protection. Therefore, this study represents significant progress in advanced packaging development, providing prolonged food preservation, sustainability, and retained performance even when prepared in simulated industrial conditions.

The present global energy shortage and climate crisis can be addressed by embracing recycling, reuse, and recovery; for example, this can be achieved by methodically utilizing the problematic wastes for energy harvesting. This research describes a novel approach for recovery and reutilization of waste material by incorporating dog fur waste into a triboelectric energy harvester; this was accomplished via a simple, inexpensive, and eco-friendly chemical processing to turn this problematic waste into a high-performance tribolayer. Due to the complications of operating practical devices with dog fur in its natural form, the dog fur waste was transformed for the first time into a uniform thin-film-based high-performance positive tribolayer. The optimization of the fabrication of the dog fur film featured hexagonal pyramid nanostructures, and a novel tribopair was selected and consisted of the dog fur-based film and a Teflon film; these films have very large differences in electron affinities. Based on this optimization and selection, we achieved an outstanding output voltage, current, and power density of 2021.46 V, 109.84 μA and 24,669.957 μWcm⁻², respectively, along with appreciable mechanical stability during continuous operation up to 10,000 cycles. Our research demonstrates the potential for integration of green electronics and self-powered human-pet interaction systems while providing a sustainable approach to a circular bioeconomy.

Developing sustainable energy storage devices is challenging for the progress of energy storage applications. Here, nanotechnology represents a strategic route to reduce the amount of used critical materials, while continuing to take advantage of their properties, thanks to the high surface to volume ratio which characterizes nanostructures. WO₃ nanostructures represent a promising active material for energy storage applications, thanks to their wide capability of small positive ions (H⁺ and Li⁺) intercalation and their high stability in acidic conditions. The coupling between WO₃ nanorods and carbon black powder is studied to realize a highly efficient coin cell supercapacitor. The morphology of WO₃ nanorods and carbon black is investigated by using a scanning electron microscope, and the energy storage performances were evaluated by performing cycling voltammetry and galvanostatic charge and discharge analysis, thus obtaining promising specific capacitance results (79 and 70 F/g at 5 mV/s and 0.5 A/g respectively). Moreover, the stability of the obtained coin cell was investigated, thus getting good capacity retention over 250 charge-discharge cycles. Energy and power densities were also calculated, obtaining the highest energy density of 39 Wh/kg at a power density of 500 W/kg. The WO₃‑carbon black coin cells are used to power a red LED, so demonstrating the viability for practical applications.

The demand for eco-friendly and natural food packaging materials has sparked considerable interest in the research and development of sustainable active packaging materials. In this study, a chitosan-based film was developed using glycerol as a plasticiser, chitooligosaccharide (COS) as an additive, and gallic acid as a cross-linking agent. The physical, barrier, mechanical, morphological, thermal, and functional properties of fabricated films were measured. The bio-composite film showed significantly lower moisture content (from 24.28 to 17.01%), water solubility (from 41.56% to 31.03%), water vapour permeability (14.63 to 9.79 × 10⁻⁹ gm⁻¹s⁻¹Pa⁻¹), and light transmittance (from 63.67% to 21.71%) compared to neat chitosan film. Furthermore, the bio-composite film exhibited higher tensile strength (57.66 MPa) and elongation at break (88.76%), smooth microstructure, strong DPPH and ABTS radicals scavenging capacity, and good antimicrobial activity towards E. coli, L. innocua, and S. cerevisiae, and non-toxic to HaCaT cells indicating promising potential for use in sustainable active food packaging.

Climate change and carbon emissions attributed to anthropogenic activities is getting alarming dimensions. On the other hand, the overwhelming progress of industrialization and urbanization contributed to an explosion in the municipal solid waste (MSW), as one of the other global challenges. However, developing a cost-effective adsorbent with appealing textural properties for CO₂ capture is still one of the main challenges. Lately, carbon-based solid waste materials of biogenic origin have received a major interest to this end, owing to the renewability, availability and low-cost. Routinely, academic research mainly focuses on lab-scale development of activated carbons derived from waste materials. However, there is a significant gap concerning the industrial production of activated carbon from such materials. Accordingly, in this work, an industrial plant has been designed for producing activated carbon derived from digestate of MSWs in the industrial scale by presenting all scale-up details, engineering assumptions and process specifications. The results indicated that the plant has a potential to process 90,273 ton MSW annually, which consumes 1367.8 MWh net electricity and 20,134.4 GJ net heat, also produces 4788.10 ton CO₂ adsorbent, per year. The economic assessment specified that the plant capital cost is around $14.112 million with the net price of 0.61 $/kg for produced activated carbon. Further, the sensitivity analysis and parametric study determined that the sample level in the drum is the determinative parameter on the energy consumption and net price of adsorbent. Finally, Response Surface Methodology was employed to maximize the plant profitability concerning the designing factors.

Red dragon fruit (RDF, Hylocereus polyrhizus) is high in betacyanins content but is understudied for its antioxidant mechanisms in liver cells. The present study aimed to investigate the antioxidant mechanisms of the stabilised betacyanins in a novel RDF functional drink, Improved-FRDFD-dH₂O (produced from mild, sustainable approaches) using HepG2 cell line. Results revealed the betacyanins of Improved-FRDFD-dH₂O (12.5% and 25%, v/v) showed the highest direct scavenging effect on intracellular ROS from 75.39% to <31%. The antioxidant enzymes (SOD, CAT and GPx) activities in HepG2 cells were remarkably increased, with 12.5% and 25% Improved-FRDFD-dH₂O demonstrating the greatest enhancing effects. RT-qPCR proved the betacyanins of Improved-FRDFD-dH₂O possessed indirect antioxidant mechanisms, where the gene expressions associated with Nrf2-ARE pathway were upregulated by all the tested sample concentrations (highest fold: 6.82). Overall, the present findings highlighted the RDF's potential in functional product development with betacyanins as the prominent bioactive compound to provide direct and indirect antioxidative and hepatoprotective activities.

The layered double hydroxides (LDHs) emerged as a class of low-cost potential adsorbents for organic pollutant separation, whereas the deep study of organic dye separation regulated by LDH hollow morphology under ambient conditions is still lacking. To address this gap, ZIF-67, Bulk-CoNi-LDH, and HPS-CoNi-LDH materials of different morphology and porosity were synthesized and investigated in the dye separation process. Methyl orange (MO), congo-red (CR), methylene blue (MB), and rhodamine B (Rhb) dyes were selected as model dye pollutants. The spectroscopic and structural analysis reveals the HPS-CoNi-LDH exhibits less-aggregated 2D nanosheets, high BET surface area of 163.2 m²/g, large pore size of 12.29 nm, greater positive surface charges (27.5 mV), superior optical (2.18 eV), and charge-separation capabilities as compared to Bulk-CoNi-LDH, Which provides potential sites for adsorptive and photo-degradation for anionic dyes under natural sunlight. Therefore, it achieves a remarkable removal efficiency of 92.6% for methyl orange (15 ppm) with a superior kinetic rate of 3.0$\times$10⁻² min⁻¹ within 90 min, outperforming Bulk-CoNi-LDH and ZIF-67 having removal efficiency of 71.7% and 40.8%, and kinetic rate of 1.35$\times$10⁻² and 0.5$\times$10⁻² min⁻¹, respectively. Poor removal efficiency and kinetic by ZIF-67 was mainly due to its smaller pore size (1.16 nm) and surface-confined charges (6.13 mV). Additionally, HPS-CoNi-LDH exhibits superb selectivity (at a ppm level) and excellent recyclability under ambient conditions. The mechanism of photo-catalytic reaction is discussed. These results delineate the hollow morphological LDH structure could be a worthy candidate for selective wastewater treatment and useful for sustainable conditions, which points the way to other crucial anionic micropollutant remediation.