Sustainable Materials and Technologies最新文献

Underwater wearable sensors utilizing conductive hydrogels have garnered significant attention in recent years. However, the response sensitivity to the mechanical strain, quantified by the gauge factor (GF), of most hydrogels is noticeably diminished when submerged in water, and little consideration has been given to the GF value of sensors operating both in air and underwater. Consequently, the development of underwater sensors with high sensitivity in aquatic environments remains a challenge. In this study, we propose a “soaking-in-water” strategy to enhance the sensitivity of the wearable sensor based on starch/poly(vinyl alcohol)/graphene oxide/ionic liquid hydrogel. Through this approach, the maximum GF of the hydrogel underwater was improved to 9.71, representing an 86.7% increase compared to the unsoaked hydrogel (GF of 5.20). Furthermore, the hydrogel demonstrated adjustable conductivity (from 0.26 to 1.82 S·m⁻¹) and tensile properties (from 0.05 MPa at 244% to 0.21 MPa at 527%). The hydrogel underwent the processes of water-absorbing swelling, exudation of ionic liquid and water-repelling shrinkage. The enhancement in sensitivity and swelling mechanism of the hydrogel were closely linked to the movement of ions and water between the hydrogel and soaking water. Leveraging these properties, we further developed an underwater strain sensor capable of monitoring human motions underwater, offering quick, effective, and stable signal transmission. The proposed soaking method represents a promising avenue for improving the sensitivity of hydrogel sensors, providing a facile strategy for achieving accurate and efficient underwater monitoring applications.

The development of energy generation without greenhouse gas emissions is necessary due to climate change, there are different technologies to replace fossil fuels, including the photovoltaic (PV) modules. However, up to 8 million tons of waste PV modules are estimated by 2030 and 78 million tons by 2050. Therefore, developing recycling processes for PV modules is crucial for the recovery and reuse of their components. This investigation presents a simplified recycling process, encompassing characterization as well as dismantling, comminution, and sieving separation stages. During the dismantling phase, 100% of metallic aluminum was separated. Subsequently, the PV structure was reduced to particles smaller than 6.35 mm and strategically classified into fractions. A polymeric fraction (>4.00 mm) containing 33.71% polymers was obtained. The 0.5 mm to 2.00 mm fraction mainly comprised glass (76.85%), and also concentrated 99.37% of Cu. However, it still contained 64.04% polymers. Metals such as Ag were concentrated at 94.12% in fine fractions (<0.25 mm). Additionally, this fraction was also enriched with crystalline silicon.

Zinc dross is highly zinc-rich industrial waste produced during galvanization of steel. It is a byproduct of the reaction between molten zinc and loose iron particles in a molten zinc bath. Generally, 10–20% of galvanized zinc is converted into zinc dross. This work proposes a unique way of recycling of dross into a high value sustainable resource material leading to development of sacrificial anode used in cathodic protection of steel. The electrochemical behavior was studied in 3.5 wt% NaCl solution. The anode performance test was performed as per the standard DNV-RP-B401 in an artificial seawater solution. The performance parameters, (closed circuit potential (CCP), anode efficiency, and consumption rate) of the recovered zinc anode from dross, are close to the commercial zinc anodes. It satisfies the required anode criteria. Hence, the recovered zinc anode from dross could be used as a sacrificial anode for the cathodic protection of steel structures.

Wood is an important renewable resource for a future sustainable bioeconomy. Ion-mediated response in wood is considered a major factor in sap-flow regulation. This study examined the influence of sap replacement with KCl solution and deionised water on drying collapse, wood permeability, and streaming potential of never-dried wood. Volumetric and tangential collapse in KCl-treated Eucalyptus nitens logs decreased significantly by 42%–62% and by 51%, respectively. Improvement in shrinkage properties was concentration-dependent, with a maximum at a concentration (20 mM) in the range of total ionic strength found in living trees. Logs treated with deionised water showed higher normal shrinkage, without affecting collapse. Consistent with reduced collapse in KCl-treated logs, eucalyptus stem cores showing low collapse contained significantly more inorganic cations than the high-collapsed wood. The decrease in collapse when treated with KCl solution coincided with increased green wood permeability. Sap conductivity affected the streaming potential, with the polarity of the induced electric potential varying between concentrations and matching literature reports of electric potential measurements in living trees and laboratory experiments.

This study confirmed that drying collapse was negatively correlated to sap conductivity, and potential technological solutions to drying collapse in E. nitens could include sap replacement as a pre-drying treatment, and/or nutrient management of the plantations.

This study presents a new environmentally favorable hydrometallurgical approach to the recycling of nickel–metal hydride (Ni–MH) battery anodes into new materials based on mixed oxides of Ni, Co, Mn, and lanthanides, which were applied as photocatalysts and electrodes in alkaline media. The starting material was characterized by X-ray diffraction (XRD) and inductively coupled plasma optical emission spectroscopy (ICP-OES). Tartaric acid was used as leaching agent for anode metals, and the resulting tartrate salts were converted to oxides via thermal treatment. Characterization of the synthesized materials was performed by XRD, scanning electron microscopy (SEM), and energy-dispersive X-ray spectroscopy (EDS). Cyclic voltammetry and electrochemical impedance spectroscopy were used to analyze the electrochemical properties of oxides, which were found to behave as electric double-layer capacitors. The recycled materials were used as catalysts in the decolorization of methylene blue in the presence of H₂O₂ under UV radiation. A decolorization efficiency greater than 90% was achieved in a shorter time than that taken for the non-catalyzed reaction to achieve 80% color removal (maximum decolorization). The results showed that methylene blue photocatalysis and photolysis differ in optimal pH conditions and that the catalyzed reaction follows pseudo-first-order kinetics.

Among various energy storage materials, Zinc-based metal-organic frameworks (Zn-MOFs used as precursors, templates, and shape controllers) act as potential candidates for supercapacitor (SC) applications due to their remarkable properties, such as facile preparation methods, high specific surface area (SSA), large porosity, outstanding power (P_den) & energy density (E_den), astonishing crystallinity, adjustable sizes, exceptional chemical & thermal stability, elongated life-cycle, framework diversity, and tunable structures. The present review focuses on the most recent progress on pristine Zn-MOFs, nanocomposites (with graphene (Gr), carbon nanotubes (CNTs), and polyaniline (PANI)), and their derivatives (metal oxides (MOs) & hydroxides (MHOs), porous carbon (PC) & activated carbon (AC), and metal sulfides (MSs)) as electrode materials to present the most up-to-date overview in this specific field. We first discuss the fundamental charging mechanisms (electric double-layer capacitance and pseudocapacitance) and the electrochemical techniques (cyclic voltammetry, galvanostatic charge-discharge, and electrochemical impedance spectroscopy) of SCs. We then analyzed different methods with advantages and disadvantages of Zn-based MOF synthesis, such as solvothermal, hydrothermal, sonochemical, microwave heat-assisted, simple stirring, slow evaporation, mechanochemical, and electrochemical. Furthermore, structural, morphological, and electrochemical assessment techniques of reported Zn-based MOFs were examined in detail in three- and two- electrode configurations (asymmetric/symmetric devices with power and energy density). Finally, the ongoing issues and future developments in this field for architecturing supercapacitive devices are also discussed.

The requirements for new materials are increasing, as multidimensional criteria should be included in the material design process. A comprehensive approach for designing new steels is presented, where the environmental dimension for each alloying element is considered, besides the technological and economic aspects. A case study focuses on increasing the hardenability of air-hardening steel. Economic and environmental figures expand the technical perspective. It is demonstrated within this study that standard alloying elements used to increase the hardenability significantly influence further selection criteria. It is exemplified that alloying elements like boron provide higher hardenability at lower costs and a lower carbon footprint than, for example, nickel or chromium. This comprehensive design approach can be transferred to other technological optimization phenomena. It might help design future generations of steel by considering further objectives and disclosing possible trade-offs.

An evaluation of neodymium‑iron‑boron permanent magnets (NdFeB PMs) from different end-of-life products, as a secondary resource of rare-earth elements (REEs), is presented. De-coating of PM was investigate as pre-treatment to facilitate efficient direct magnet recycling. Thus, critical aspects from disassembling to the de-coating of the magnets were addressed. A challenge for the de-coating process is that the magnets have different sizes, weights, and their coating compositions are not known beforehand. It was shown that ammonia-based solutions was thermodynamically suitable to dissolve nickel and zinc coatings selectively, while keeping the bulk magnet stable. Nevertheless, the dissolution of Zn was much faster than the Ni one, and more efficient.

The electroreduction of CO₂ into formic acid (HCOOH) holds economic value and industrialization potential. Despite that Bi-based materials are effective for producing formic acid, challenges remain due to the insufficient understanding the actual active sites and the lack of facile synthesis of simple materials. We synthesized four bismuth-based catalysts using hydrothermal method (with water as the solvent), which exhibit high selectivity for the reduction of CO₂ to formate. Through comprehensive physical and electrochemical characterizations, we demonstrated that these Bi-based materials underwent reduction and maintained their metallic Bi state at the potentials where CO₂ electroreduction took place. Bulk-Bi displayed the Faradaic efficiency of HCOO⁻ higher than 94.3% from −0.90 V to −1.15 V. Moreover, the Faradaic efficiency of HCOO⁻ remained above 98.1% over 10 h electrolysis at −1.05 V. This finding suggests that metallic Bi serves as the primary active site for the electroreduction of CO₂ to formate. Leveraging this insight, we effectively enhanced the atomic utilization of Bi metal by directly synthesizing metallic Bi nanoparticles. Our results further indicate that these nanoscale Bi particles maintained a high Faradaic efficiency for HCOO⁻ production.

Ultra-High-Performance Concrete (UHPC), a unique cementitious composite that exhibits an ideal solution for structural reclamation. The significant objective is to develop UHPC with binary nanomaterials (nanosilica and nano clay) using Modified Andreasen and Andersen particle packing theory and examine effect of nano hybridization in flexural and shear behaviour of reinforced UHPC beams. In addition, findings such as load-deflection behaviour and crack pattern are validated with Finite Element Analysis (ANSYS). The synergistic effect of hybrid nanomaterials enhances formation of hydration products that accounts for 27%, 30.7%, and 49% improvement in compressive, splitting tensile, and flexural strength in 2% nanosilica and nano clay (D2 mix Id). Moreover, flexural UHPC beam (D2 F) and shear UHPC beam (D2 S) withstand 9.5% and 10% higher ultimate load than control (A0 F and A0 S mix). The Finite Element Analysis predicts ultimate load in very minimum discrepancy percentage that ranges from 1 to 3%.