RSC sustainability最新文献

Vegetable oil-based lubricants have attracted increased research attention in recent decades as sustainable alternatives to conventional petroleum-based lubricants in metal machining. However, more studies are required to fully elucidate the thermo-rheological and tribological properties. This study presents an investigation of the thermo-rheological and tribological properties of different vegetable oils, including low- and high-oleic soybean oil, high-oleic sunflower, safflower, and canola oils. The lubricity, and evolution of viscosity and thermodynamic properties as a function of temperature were investigated to obtain important parameters including the viscosity index, flow behavior index, flow activation energy, specific heat capacity, thermal conductivity, coefficient of friction, contact angle, and thermal-oxidative decomposition profile. The properties were compared with those obtained with mineral oil, conventional emulsion coolant (CEC), and a commercial bio-based lubricant, Acculube LB-2000, commonly used for metal cutting applications. The vegetable oils displayed comparable properties to the commercial LB-2000 lubricant and pure mineral oil, featuring Newtonian fluid characteristics, high viscosity indices, high flow activation energy, low specific heat capacity and thermal conductivity, and high thermal-oxidative stability. Generally, vegetable oils with high oleic acid content featured higher rheo-thermal stability, higher contact angle, and better performance in reducing the coefficient of friction. On the other hand, CEC displayed non-Newtonian fluid behavior with lower initial viscosity and flow activation energy, and lower thermal-oxidative stability, but comparatively higher specific heat capacity and thermal conductivity compared to the vegetable oils. Compared to pure mineral oil, the vegetable oils show higher oxidative-thermal stability, thermal conductivity and specific heat capacity, and better lubrication performance in the mixed and hydrodynamic lubrication regimes of the Stribeck curve. The results provide important datasets that will contribute to improving the database on the properties of vegetable oils to guide their utilization in designing sustainable vegetable-oil-based biodegradable lubricants.

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It is well known that tin oxides and oxyhydroxides show high selectivity for the electrochemical CO₂ reduction reaction (CO₂RR) to form HCOOH in aqueous solutions. Tin oxides and oxyhydroxides are reduced to form metallic Sn during the CO₂RR, and the formed interface between the oxide and metallic Sn plays important roles in the CO₂RR. In this study, reduction behaviors of tin oxides and oxyhydroxide during the CO₂RR were investigated. SnO, SnO₂ and tin oxyhydroxide containing both amorphous and crystalline phases were formed using solvothermal, sol–gel and precipitation methods, respectively. Reduction current densities of SnO₂ and the oxyhydroxide for the CO₂RR and hydrogen evolution reaction at −0.8 V vs. RHE were higher than that of SnO, and the faradaic efficiency of the oxyhydroxides for formation of HCOOH and CO was >90%. Based on high-resolution TEM observation and EDS mappings, it was revealed that metallic Sn nanoparticles with a ∼40 nm diameter were formed from SnO₂ and tin oxyhydroxides during the CO₂RR via a dissolution and reductive deposition process. Aggregates of SnO₂ and the oxyhydroxide were dissolved in a neutral electrolyte solution during the CO₂RR, and subsequently, metallic Sn nanoparticles with highly effective surface areas were formed on carbon electrodes via reductive deposition from dissolved Sn cations, leading to a higher reduction current. The thickness of native oxide layers formed on the surface of the metallic Sn particles in air after the CO₂RR from the oxyhydroxide was greater than those of SnO and SnO₂. Therefore, it is speculated that metallic surfaces of the former ones were more easily formed at the interface between SnO_x and metallic Sn than those of the latter ones, leading to high selectivity for the CO₂RR.

This study explores the development of non-isocyanate polyurethane (NIPU) composites incorporating bio-based soybean oil and TiO₂ nanoparticles (TNPs) with enhanced functional properties. Epoxidized soybean oil (ESBO) was converted to 5-membered cyclic carbonated soybean oil (CSBO) through CO₂ insertion under high temperature and pressure. TNPs (0%, 0.25%, 0.5%, and 1%) were incorporated into CSBO and cured with ethylenediamine (EDA). ATR-FTIR analysis confirmed the formation of urethane linkages in the NIPU films. The impact of TNPs on the physiochemical properties of the NIPU films was evaluated, including mechanical, thermal, surface wetting, and antimicrobial performance. Thermogravimetric analysis (TGA) indicated that TNPs did not significantly alter the degradation temperature of the NIPU films, whereas Differential Scanning Calorimetry (DSC) revealed that the glass transition temperature (T_g) of the NIPU films increased from 24 °C to 27 °C with TNP loading. Mechanical properties showed increased tensile strength with higher TNP content, while elongation at break decreased. Surface wettability measurements demonstrated that all composite films exhibited hydrophobic behavior, with contact angles ranging from 97° to 105°, higher than those of the bare NIPU films. Antimicrobial testing against Escherichia coli and Staphylococcus aureus demonstrated that TNP-loaded NIPU films exhibited significant antimicrobial activity against E. coli and antifouling properties against S. aureus. These bio-based NIPU composites offer a sustainable alternative to petroleum-based polyurethanes, with potential applications in eco-friendly adhesives, antimicrobial coatings, and protective surfaces, thereby contributing to greener solutions in materials science.

The most efficient and stable perovskite solar cells typically contain lead compounds as a key component in the light-absorbing layer. To advance the commercialization of perovskite photovoltaics, it is crucial to address sustainability concerns regarding the use of toxic lead. In this work, we have developed a straightforward lead recycling pathway that converts lead compounds from lead–acid batteries into lead iodide. Purity analyses of the resulting lead iodide and the direct fabrication of perovskite solar cells demonstrate that the recycled lead iodide matches the quality of commercially available products. Most importantly, establishing this efficient lead recycling process not only supports sustainable recycling and resource utilization in a circular materials flow but also promotes the future development of perovskite photovoltaics.

Incorporation of nanoparticles into the membrane matrix plays a pivotal role in water purification and treatment. In this review, the recent advances in coupling green nanoparticles, encompassing diverse materials, such as metallic-, metal oxide-, and carbon-based nanoparticles, for tailoring NPs for specific membrane applications are elucidated. The green approach involves the synthesis of nanoparticles using plant extracts, enabling precise control over the size, shape, and surface properties of NPs. The incorporation of NPs improves the underlying hydrophilicity, antifouling properties, mechanical strength, and selectivity of the membrane matrix for various separations, including water purification, desalination, and wastewater treatment. This review also addresses the potential challenges in utilizing green-synthesized nanoparticles in membrane technology for targeted applications. Factors such as scalability, stability, and long-term environmental impact are assessed to ensure the practical viability and sustainability of this approach. In conclusion, the integration of green-synthesized nanoparticles in membrane applications represents a sustainable and innovative paradigm in the field of membrane technology. This approach not only augments the performance of membranes but also aligns with global efforts towards eco-friendly and sustainable practices in synthesis of materials and environmental remediation. This review encourages further research and development in this area, paving the way for greener and more efficient membrane-based separation processes.

Noble gas plasma-collisional splitting (NgPCS) is an emerging hydrogen production technology. Conventional methods, such as fossil fuel-based decomposition and water electrolysis (the latter requiring large amounts of electrolytes), have been widely used, but NgPCS eliminates the need for electrolytes, offering an eco-friendly and cost-effective alternative for producing hydrogen.

This work investigates the non-equilibrium regeneration of one scalable sorbent material for carbon capture, calcium oxide, in a customized flow reactor coupled to a low-temperature atmospheric-pressure plasma source. The results show that such a plasma is capable of desorbing CO₂ from CaCO₃, with an operating temperature far below the thermal decomposition temperature of carbonate. The desorbed CO₂ is further converted to CO in situ. The energy cost is 1.90 × 10³ kWh per tCO₂, as the same order of magnitude as the state-of-the-art high temperature regeneration technology. A non-equilibrium kinetic mechanism is proposed in which CO₂ desorption is coupled into air plasma chemistry. Electron-impact reactions in air lead to the generation of vibrationally excited nitrogen and ozone. Subsequent quenching of atomic oxygen on the carbonate surface can regenerate CaO, while NO_x will pollute the surface. Compared with the previous methods used in sorbent regeneration, plasma-based technologies offer an electrified, sustainable, and low-temperature solution based on the non-equilibrium plasma chemistry. Possible scaling strategies include fluidization, flow pulsation, and plasma catalysis. This work demonstrates the feasibility of non-equilibrium plasma processing of the sorbent material for cyclic capture and regeneration in atmospheric air using thermally low-intensity processes.

Increased human activity due to the ever-increasing global population has necessitated the urgent need for a sustainable environment, food, and energy. Cyanobacteria, classically known as blue-green algae, are oxygen-producing photosynthetic organisms that are emerging as an option to achieve sustainable development goals. These Gram-negative prokaryotes can efficiently sequester atmospheric CO₂ due to an efficient carbon concentrating mechanism and divert it to the production of energy-rich compounds, i.e., biofuel, and other valuable chemicals, using their flexible metabolic chassis. Additionally, cyanobacteria also minimize the emission of methane, which is another greenhouse gas, by providing oxygen to methane-oxidizing bacteria. In recent years, several genetically engineered strains of cyanobacteria have been developed that can produce biofuels and several other valuable chemicals. Strains have also been engineered for bioplastic production and bioremediation purposes. These organisms have gained attention as biofertilizers and can increase the quality and fertility of soil. Thus, cyanobacteria are promising CO₂ sinks that can contribute to global efforts in carbon capture and storage initiatives while producing bioenergy, cosmetics, pharmaceuticals, and several other valuable chemicals. Therefore, these blue-green cells can be used for green chemistry while minimizing the atmospheric CO₂ concentration. In this review, we present various applications of cyanobacterial biomass to achieve sustainable development goals. We also discuss challenges associated with the wide application of cyanobacteria and the future direction to make full use of these robust organisms to fulfill our future demands in an environment-friendly manner.

As the science of transformation of matter, chemistry provides knowledge, innovation and practice that are fundamental to the current efforts to achieve sustainability in the face of challenges that include multiple environmental crises (including pollution, climate change and biodiversity loss) and looming shortages of ‘critical’ materials. This article presents the case for chemistry and the chemical sciences adopting material stewardship as a central mission, whose aim is to transform and use the Earth's available stock of material resources in ways consistent with ensuring sustainability for people and for the physical and biological systems of the planet on which all life depends. The implications of this mission are examined, including for chemistry's contributions to extending knowledge, processes and products required for stewarding the Earth's physical and biological materials and systems. The mission includes supporting energy transitions necessary to stabilise Earth systems that are increasingly perturbed by anthropogenic effects. An overview is presented of how chemistry's mission of material stewardship interconnects with sustainability frameworks providing broad principles and goals, including the UN's Sustainable Development Goals and the Planetary Boundaries and Human Security frameworks, as well as with specific chemistry movements and orientations (including green, sustainable, circular and one-world chemistry) and enabling tools (e.g. systems thinking, material circularity and life cycle assessment) that provide guiding concepts, pathways and capacities for chemistry's contributions towards sustainability. The utility of the material stewardship mission is exemplified through three case studies, related to a product type, a sustainability tool, and a sustainability movement. The need is emphasised for the chemistry profession to work across disciplines to help shape policy and practice towards a sustainable future. This includes engaging with others in the processes of negotiation that shape global agreements on goals, policies and programmes that impact on sustainability. Critical ones currently in progress include the efforts to find mechanisms to reduce greenhouse gas emissions to limit global warming to the UN's target of not more than 1.5 °C above pre-industrial levels by 2050, and to establish a UN Science-Policy Panel on chemicals.