RSC sustainability最新文献

Food wastes, municipal solid wastes, sewage sludge, plant materials, animal biomasses, aquatic and terrestrial wastes, agricultural and forestry wastes, industrial and domestic wastes and many other lignocellulosic biomasses are grouped under the category of organic wastes or bio-wastes. Various techniques, mainly mechanical (high-pressure homogenization and ultra-sonication), thermal (temperature-based), microwave-assisted, chemical, and biological pretreatments, have been found to be effective in organic waste valorization. Fungal pretreatment of organic wastes is a promising biological technology because of its excellent efficiency in the decomposition of various types of organic wastes, such as food wastes, ligno-cellulosic biomasses, hemicellulose, agricultural wastes, hardwoods, softwoods, switchgrass, spent coffee grounds, park wastes, cattle dung, and solid digestate, which are specifically reviewed. Fungal pretreatment of organic waste materials can generate advantageous products such as biogas, alternative energy sources, monomeric or oligomeric sugar products, and different types of acids. However, the major challenge associated with fungal pretreatment technology is the requirement of a longer time to achieve a greater degree of biomass valorization, which increases the cost and vulnerability to contamination. However, the use of fungal pretreatment with other pretreatment techniques may shorten the time and enhance the functionality of the method with a higher rate of biomass valorization. Heat generation in the fungal pretreatment process and need for feedstock sterilization before fungal pretreatment are some other challenges that need to be properly addressed for its efficient application on an industrial scale. In this review, the use of different fungal pretreatment methods for the valorization of different types of biomasses and production of valuable products is evaluated and discussed. We performed a comprehensive assessment of the fungal pre-treatment of various types of organic wastes together with a concise but effective discussion on organic solid wastes and different pretreatment techniques involved in bio-waste digestion processes. Furthermore, techno-economic analysis, challenges and future perspectives are discussed.

To ensure carbon negativity, processes that achieve carbon dioxide removal (CDR) from the atmosphere must consider lifecycle emissions and energy requirements across the entire system. We conduct a harmonized lifecycle greenhouse gas assessment to compare the carbon removal efficiency and total energy required for twelve engineered carbon removal technologies. The goal of this comparison is to enable the assessment of diverse engineered carbon removal approaches on a consistent basis. Biomass-based CDR approaches generally maintain higher carbon removal efficiency than direct air capture (DAC) and, to a lesser extent, enhanced rock weathering (ERW) due to the high concentration of carbon within the biomass and the relatively low energy requirements for processing the biomass for removal. Nevertheless, there is high variance in CDR approaches, as some biomass conversion processes (e.g., pyrolysis for biochar or gasification for fuels) exhibit high, yet variable, carbon losses, while DAC and ERW can utilize low-carbon energy inputs for more efficient removal. Regarding energy use, ERW and biomass-based approaches generally require less energy than DAC today, but biomass approaches again exhibit more variation. Displacement of products, when included, increases the total climate benefits of biomass used for bioenergy with carbon capture and storage (BECCS) and biochar. These two measures are intuitive metrics to guide allocation of scarce resources amongst potentially competing uses of biomass and low-carbon energy.

The flexibility of hybrid silicon-oxide cellulose aerogels was achieved through the formation of thin, uniform silica coatings on cellulose fibres, or local regions of a classical spherical aerogel (Kistler aerogel) combined with areas of less coated cellulose fibres, making use of the flexible properties of the cellulose nanofibres. Furthermore, the inclusion of cellulose during the sol–gel formation allowed the use of traditional freeze-drying instead of CO₂ critical point drying as a method for the removal of the liquid phase. The silicon oxide morphologies revealed the possibility of fine-tuning the coating's structure by the choice of the silicon-oxide precursors. Using methyltrimethoxysilane (MTMS) resulted in the formation of classical aerogel or spherical particles, while the use of tetraethyl orthosilicate (TEOS) yielded “pearl-necklace” fibres, and the mix of (3-aminopropyl)triethoxysilane (APTES) with MTMS yielded smooth uniform coatings. The prepared coating morphologies markedly influenced the aerogel's properties (mechanical stiffness/flexibility, flame resistance and hydrophilicity). The silica coatings endured high-temperature exposure and the thermal removal of the cellulose template without substantial morphological changes was confirmed, showing the possibility to use cellulose as an effective template for the synthesis of silicon-oxide nanofibres. The possibility to selectively control aerogel properties already at the synthesis stage, using abundant and renewable materials together with the possibility of using more energy-conservative freeze-drying (rather than critical point drying), is a promising method for more sustainable aerogel preparation towards high-end commercial applications such as electrical fuel cell insulation.

Nitrogen-containing fertilizers are key chemicals for our population, ensuring the constantly growing demands in food production. Fertilizers promote vegetative growth, specifically through the formation of amino acids, the building blocks of proteins. However, the current synthesis method relies on the Haber–Bosch process for ammonia synthesis, one of the largest-volume chemicals made globally, having a significant environmental impact. The need for a sustainable and green industry with low CO₂ emission triggers the demand to reconsider the current fertilizer production approach. In this context, electrified, local, small-scale production emerges as a promising option to address current environmental and economic challenges. This approach allows production to be consumer-oriented while adhering to environmental regulations. In light of this, non-equilibrium plasma technology has gained a wave of attention. Plasma-based nitrogen fixation has a long history, starting more than a century ago. It was one of the first nitrogen fixation methods invented and later replaced by more energy-efficient technologies. In the current paradigm, this approach can fulfill all industrial and social demands: it perfectly aligns with non-stable renewable energy, is carbon-neutral, relatively simple to maintain, and can provide a valuable source of fixed nitrogen on a small-scale, on-farm production with complete control over land processing. The plethora of existing publications on plasma-based nitrogen fixation addresses the concept of synthesizing nitrogen-containing fertilizers. However, despite significant advancements in the field and the availability of numerous reviews, they tend to focus on specific aspects, such as plasma physics (e.g., the role of vibration excitation), plasma-initiated chemistry (e.g., nitrogen oxidation or reduction), or reactor design. This tutorial review aims to bridge these gaps by presenting an integrated and accessible explanation of the interconnections between different aspects affecting plasma-based nitrogen fixation. It is designed both for newcomers to the field and those who want to broaden their knowledge, highlighting the current state-of-the-art and offering insights into future research directions and implementations.

Massive amounts of plastic and biomass waste are mismanaged worldwide, causing detrimental consequences to human health and the environment. In fact, the disposal of residues through landfills without further processing and burning for household heating and cooking are common practices. Thermochemical processing, such as pyrolysis, chemical depolymerization and bioprocessing, has proven feasible for recovering valuable building block molecules from plastic residues. The main goal of pyrolysis is to obtain aliphatic hydrocarbons useful as fuel, while chemical processing generates constitutive molecules of plastic (i.e., monomers and polyols) that can be repolymerized and reintroduced in the market. Alternatively, the bioprocessing of plastic waste requires prior chemical depolymerization in order to unleash the building blocks. Chemo-enzymatic treatment of waste plastic-biomass mixtures is an open challenge due to the diverse composition of their residues, along with the presence of additives and contaminants. The few reports found in the literature regarding the bioprocessing of plastic residues with lignocellulosic biomass and paper indicate that chemical pretreatment cannot be avoided and that some substances present in the residues can act as fermentation inhibitors that affect waste bioprocessing.

Marble dust (MD) is a significant landfill waste generated as a byproduct of mining and construction industries. Methylene blue (MB) is a widely used hazardous dye responsible for serious ecological and health risks, and its treatment has become increasingly alarming. This investigation scrutinizes the facile preparation of a non-complex, low-cost, sustainable, and industrially feasible adsorbent along with conducting its mechanistic studies, including XRD, TEM, WD-XRF, FE-SEM, FTIR, BET, TGA, and XPS, followed by its implementation in the removal of MB dye. To examine the relative influence of different variables, namely, time, temperature, pH, activated marble dust (AMD) amount and MB concentration, a central composite design (CCD) model of response surface methodology (RSM) was employed with approved R² = 0.9914, supporting the credibility of the model. The additional verification was provided by ANOVA results, including the lack of fit and p-values, endorsing a quadratic model. The 3D response plots clarified the influence of variables on the removal yield; the pH had a dominant influence on the system at its higher value, while at lower pH values, the concentration played a more significant role. The removal process followed a pseudo-second-order kinetics (R² = 0.999) and adhered to the Langmuir isotherm model (R² = 0.9735), representing monolayer adsorption with q_max = 1.16 mg g⁻¹. The thermodynamic study of the process fell under Henry's law region and unveiled that the removal of MB is exothermic, spontaneous, and feasible and has appreciable reproducibility up to five cycles. The overall process of adsorption followed physisorption, which was confirmed by the adhesion probability and activation energy calculations. The adsorption process followed pore diffusion and bond formation mechanisms.

The discharge of waste organic solvents, various oil/water mixtures and the frequent infiltration of oil into water bodies have created significant threats to the ecological environment. As a result, the separation and recovery of oil/water mixtures have been increasingly investigated by scholars. Many researchers have developed numerous separation materials with excellent separation efficiency and high separation flux, including filter materials, adsorption materials and smart materials with switchable wettability. Among them, natural cotton fabric has been widely studied as a separation material substrate due to its three-dimensional surface structure, porosity, excellent fiber adsorption capacity, recyclability, low cost, and biodegradability. As an oil/water separation material, it is essential for the substrate surface to have a micro–nano structure. Researchers typically use various methods to modify the surface of cotton fabrics with various kinds of micro–nano particles, which create a certain roughness on the fabric surface. These methods include dip-coating, spray-coating, and grafting reactions, followed by further modifications to obtain separation materials for various purposes. In this work, we review the technology of creating rough textures on the surface of cotton fabrics for oil/water separation.

Metallic oxides show great potential in achieving high specific capacity as electrodes for lithium-ion batteries (LIBs). However, their inherent poor conductivity and significant volume expansion often result in inferior rate performance and reduced stability in electrochemical cycles. Here, we report a composite of ZnO and Co₃O₄ wrapped in carbon nanotubes (denoted as ZnO/Co₃O₄@CNTs) with hierarchically porous architecture via pyrolysis–oxidation of a Zn/Co-zeolitic imidazolate framework (ZIF) precursor. The dual-transition metal oxides can undergo abundant redox and alloying reactions with enhanced redox kinetics, while the CNT layers facilitate electron transfer and mitigate volume expansion. As a result, ZnO/Co₃O₄@CNTs exhibits high electrochemical performance with excellent lithium storage capability and high electronic and ionic diffusion kinetics, making it a promising anode material for LIBs. It achieves a high reversible capacity of 1156 mA h g⁻¹ at a current density of 200 mA g⁻¹ after 200 cycles, with an extremely low capacity degradation rate of about 0.54‰ per cycle.

This study evaluated the effectiveness of low-cost eucalyptus biochar (EUBC) as a precursor for activated carbon (EUAC), for methyl orange (MO) removal and supercapacitor applications. The surface charge was made positive by impregnating EUAC with a 10% weight polyethyleneimine (PEI) solution, improving anionic MO adsorption. The impregnation was verified by SEM and XPS, showing a nitrogen content of 9.39%. The adsorption capacity of the 10% wt PEI/EUAC is 142 mg g⁻¹, significantly surpassing previous reports. The adsorption mechanisms were described using the Sips isotherm and Elovich kinetics, indicating heterogeneous adsorption, physisorption and electrostatic interactions. In electrochemical tests, EUAC (263 F g⁻¹) and 10% wt PEI/EUAC (244 F g⁻¹) exhibited similar specific capacitances, six times higher than that of EUBC (40 F g⁻¹) at a current density of 1 A g⁻¹. However, EUBC electrodes exhibited nearly double the internal resistivity of those from EUAC and 10% wt PEI/EUAC, attributed to particle size, pore size, and surface area differences.

Meeting global sustainable development and climate goals requires a rapid transition to renewable energy technologies. However, these emerging technologies rely on critical elements whose sourcing presents geopolitical and environmental challenges. In this study, we explore ferromanganese nodules from the Oacoma site in South Dakota as a viable feedstock for sourcing manganese, a critical element used in the production of battery cathodes, consumer electronics, and steel. The nodules are readily accessible from the surface site and primarily consist of rhombohedral metal carbonates, including manganese at 3.5–5.4 at% (9.2–14.1 wt%) relative to all the elements present in the nodules. Based on titration experiments and an equilibrium speciation model, we developed a strategy for extracting the manganese by selectively dissolving carbonate phases in acidic conditions, followed by selectively re-precipitating manganese oxide in alkaline conditions. Specifically, exposing the samples to pH 1.5–2 dissolved almost all the calcium and manganese ions, while retaining a significant portion of the iron and magnesium in the residual nodule powders. Subsequently, increasing the pH of the leachate to 5.7 resulted in the selective re-precipitation of predominantly iron hydroxide. Further increasing the pH of the leachate solution to 10.9 finally produced a relatively pure manganese oxide product. Our pH cycling approach recovered 65.7–74.2% of the manganese in the nodules at 70.3–85.4 at% (81.5–91.0 wt%) purity relative to the other metals, without the need for specialty chemicals, membranes, ligands, or resins, and without generating highly acidic wastes. We further performed a preliminary assessment of the scalability and industrial relevance of this process to explore these nodules as a feedstock for sustainable sourcing of manganese.