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Composites having minimum one phase with dimensions in the nanometer range are called nanocomposites. Materials made of nanocomposite have emerged as suitable alternatives to the absurd limitations of micro composites. Nanocomposites are advanced materials with wide range of application in many fields, from biomedical applications to packaging. They also have the potential to revolutionize wastewater treatment and energy harvesting processes. This current review explores the multifaceted applications of nanocomposites, specifically tailored for addressing the complex issues associated with water purification. The many varieties of matrix nanocomposites are discussed in this article, along with their importance, composition, characteristics, methods of processing, and applications in removing heavy metal, dyes, bacteria and dissolved gas from the contaminated water. Along with limitations, environmental impact of nanocomposites and future prospects of nanocomposites were highlighted. This will ensure future researchers to find novel nanocomposites with broad-spectrum applications.

Petroleum sludge is accidentally released in oil fields and refineries, which can harm the environment because it contains emerging contaminants such as PAHs, BTEX components, heavy metals, and asphaltenes. This study developed a method to eliminate petroleum sludge-related emerging contaminants using a novel bacterium, AR-IASST (01), which can produce biosurfactants (surface tension reduced to 26.4 mN/m). The potential bacterium was Gram-negative, and molecular characterization revealed that the bacterium belongs to Enterobacter cloacae with positive oxidase, catalase, gelatin, hemolytic, and negative glucose fermentation tests. After five days of culture incubation, a degradation of 86.9% was achieved, and biosurfactant production was also observed during the sludge degradation process. The peak numbers in the GC-MS analysis were reduced from 184 to 13 in the treated sample, indicating complete degradation of PAHs in the sludge. The biosurfactant was identified as a rhamnolipid in nature. The biosurfactant was emulsified well with several oils, and an E24 of 100% was achieved against crude oil. The biosurfactant was stable across a wide temperature and salt concentration range, though it was sensitive in highly acidic conditions. Furthermore, the bacterial treatment was found to remove heavy metals viz. nickel (Ni), zinc (Zn), lead (Pb), iron (Fe), chromium (Cr), and copper (Cu) from the sludge sample. Thus, the current study demonstrates that the novel bacterium is highly potent and can be widely used to restore petroleum sludge-contaminated sites.

The recycling of Lithium-ion batteries (LIBs) waste is recognized as a viable solution for alleviating the pressure on natural resources caused by the increasing demand for materials used in LIBs production and the disposal of these hazardous wastes in landfills. Life Cycle Assessment (LCA) has been widely employed to evaluate the environmental impacts associated with LIBs recycling. However, a comprehensive synthesis of the lessons learned from these assessments, including methodological choices, findings, and implications, is lacking in the literature. Therefore, this study aims to summarize the available knowledge on the application of LCA for LIBs recycling. This study uses a systematic literature review method in combination with structured content analysis to identify and analyze 64 peer-reviewed LCA studies on LIBs recycling. The key findings reveal significant variations in potential impact results and divergent results regarding the environmental preference among the available recycling processes (hydrometallurgical, pyrometallurgical, direct recycling, and bioleaching). These discrepancies arise from different assumptions and methodological choices in LCA, including variations in system boundaries, inputs, the inclusion or exclusion of specific stages, unit process and flows, assumptions regarding the use of avoided products, functional units, impact assessment methods, and the use of secondary data due to the lack of primary data, especially on an industrial scale. While the Climate Change category receives considerable attention, other impact categories are often neglected, making it challenging to establish the environmental preference of a particular recycling technology. For direct recycling and bioleaching technologies lack assessments for all impact categories. Electricity consumption and chemical inputs are identified as hotspots for all recycling options. To enhance the sustainability of LIBs recycling, additional studies that focus on collecting primary data, particularly for the collection, pretreatment, and final disposal stages are recommended. To improve the transparency and reproducibility of future studies, this article provides recommendations and a research agenda for conducting LCA studies in the field of LIBs recycling.

Hydrogen gas is a net zero carbon emission clean fuel with an unmatched high specific energy. Water electrolysis is an important alternative method to produce hydrogen to the traditional fossil hydrocarbon reforming in industry. The main challenges of water electrolysis are the high energy consumption (ca. 5 kWh m⁻³ (H₂) at 80 ℃) and, if accidentally formed, the explosive nature of any unintended mixing of the produced hydrogen and oxygen gases. In order to solve these problems, alternate water electrolysis has been developed by, for example, decoupling of the hydrogen evolution reaction (HER) from the oxygen evolution reaction (OER) in space or time. This critical review intends to introduce the concept and recent developments of alternate water electrolysis in different schemes, including the alternate thermolysis and electrolysis of water, the alternate water electrolysis by using a liquid or solid redox intermedium and the alternate half-electrolysis of water. All the alternate water electrolysis methods solve the gas mixing problem whilst half-electrolysis and those with a solid redox medium omit the membranes. Specifically, only the alternate half-electrolysis of water can save the energy consumption without compromising the operation life and production rate.

Bioenergy with Carbon Capture and Storage (BECCS) is a key negative emission technology considered by many integrated assessment models (IAMs) to achieve the 2℃ or 1.5℃ goals in the Paris Agreement. However, the technical feasibility and economic costs of BECCS in these IAMs have been widely debated, which increases the uncertainty in the projection of climate change in the 21st century. Therefore, this paper reviews the latest understanding of BECCS. The key findings reveal the limitations of current models in projecting the capacity and costs of bioenergy with carbon capture and storage (BECCS), mainly due to insufficient consideration of ecological consequences, including availabilities of biomass and difficulties in the transportation of biomass and CO₂. To reduce uncertainties in the capacity and costs of BECCS, it is urgently needed to apply spatially explicit method for estimating the life-cycle emissions and the complete cost items when deploying BECCS, optimize the network of biomass acquisition, power plants retrofitting and transportation of biomass and CO₂, and represent the changes in the availability of biomass (for different types of bioenergy plants) under the impacts of climate change. This paper emphasizes the gap between the potential capacity of BECCS and the demand for BECCS that is needed to achieve the climate goals. Suggestion on policy interventions is provided to accelerate the application of BECCS from the aspects of economic tools, regulatory tools, and information tools. Deployment of BECCS could be accelerated to halt the rapid rise of global annual average temperature and reduce the risk of carbon lock-in from fossil-fuel supply infrastructure. As BECCS could play a key role in achieving ambitious climate targets, it is important to maintain a balance between environmental, social, and economic considerations in the Earth system under a high sustainability of development.

For the purpose of improving mechanical qualities, starch-based film hydrogel can be crosslinked. The choice of crosslinking agent is critical in adjusting hydrogel performance to fit the needs of specific applications. The present investigation examined the impact of two non-toxic crosslinking agents, namely citric acid and oxidized sucrose, on the mechanical and swelling properties of hydrogels. When compared to oxidized sucrose crosslinked hydrogels (OSH), citric acid crosslinked hydrogels (CAH) often offer a larger swelling; however, OSH without plasticizer is not included in this comparison. The OSH has the highest swelling value of 292% at pH 7, whereas the CAH has the highest swelling value of 116% at pH 7. Contrary to OSH film, which can only achieve 2.0 MPa, CAH film has a tensile strength of up to 3.75 MPa. Meanwhile, OSH film can achieve the greatest elongation of 54%.

The issue of water contamination resulting from textile dyes has garnered public attention. To address this issue, a new highly stable, greener, nontoxic composite material (ZBH.Sn) consisting of Sn²⁺ doped Zn-Bi mixed metal hydroxide (ZBH) was effectively fabricated. The adsorbent underwent a thorough investigation of its structural and morphological properties utilizing XRD, HR-TEM, FE-SEM, FTIR, XPS, Zeta, and DLS. XRD confirms the crystallinity of mixed phases of both zinc and bismuth hydroxides. The hexagonal sheet-like morphology is evident in SEM, and elemental mappings show that individual elements are evenly distributed on the external surface. The ZBH.Sn adsorbent demonstrates an adsorption efficiency in the removal of Fuschin blue (F.B.) from wastewater systems. With optimized 2.5 mg ZBH.Sn in 20 mL (0.05 mM) of F.B concentration at pH 6, the maximum adsorption capacity was 80.56 % in 180 minutes at 298 K. The detailed thermodynamic information (ΔG= −2.477 KJ/mol) including adsorption maximum capacity q_max (1472.75 mg/g), adsorption equilibrium constant (k₂= 3.7×10⁵ g.mg¹.min¹), and adsorption efficiency (80.56 %) were obtained to evaluate the different reaction performances for F.B by ZBH.Sn. Such observation suggests that these materials could serve as effective adsorbents for removing F.B. from wastewater because of their high adsorption capabilities and low cost.

Polyurethane is a useful thermoset polymer worldwide, especially for insulation characteristics, mattresses, and cushioning. Waste management of polyurethane has become a great challenge to our society. Numerous ways of waste management have been tested, and among them, pyrolysis is the most promising solution as well best way of recycling its monomers and energy recovery. A thermal analysis was performed to evaluate the best use for such waste. Gas chromatography with mass spectrometric detection and the pyrolysis method were used to analyze flexible waste polyurethane material at various pyrolytic temperatures (350, 400, and 450 °C). The results show numerous organic components with functionalities like alcohols, heterocyclic acids, alkanones, etc., compounds of nitrogen and silicone base compounds. Also, some trace amounts of chlorine compounds were observed. The results of the uncatalyzed process yield show that there is a substantial difference (P < 0.05) between values of oil products recorded at 350, 400, and 450 °C. The Neat kaolin catalyzed process indicated that there is a substantial difference (P < 0. 05) in both gas and oil products recorded at 350 °C, 400 °C, and 450 °C. For the Copper oxide nanoparticles catalyzed products, it is evident that the percentage yield of oil is significantly changed (P < 0.05) while the percentage gas formation is significantly different (P < 0.05) at 350 °C, but between 400 °C to 450 °C are not significantly different. Finally, the mixture of copper oxide nanoparticles and Kaolin makes the yield of both the oil, gas, and residue significantly different, and more oil is produced at the uncatalyzed process than the catalyze.

Rapidly increasing industrial activities and uncontrolled wastewater disposal in the different dye sectors, such as textiles, plastic, leather, cosmetics, and food industries, have severely threatened the environment and human health in recent years. Photocatalysis has emerged as an attractive ecofriendly and cost-efficient technology for environmental remediation and the development of stable and efficient photocatalysts is highly crucial. Recently, Metal-organic frameworks (MOFs) have attracted attention as a prominent class of porous materials with robust topology and excellent potential in photocatalytic water remediation applications. Numerous literatures have reviewed the photocatalytic activity of MOF-based materials for environmental and energy applications. However, only a few articles focus on the pioneering role of MOF-5, a Zn-based MOF in growing contemporary applications. Moreover, a review focused primarily on MOF-5 photocatalysts – their synthesis, application, and detailed mechanism studies for the removal of toxic organic pollutants from an aqueous medium has not been made. In this review, we summarized the recent advances in MOF-5-based photocatalysts and their application in the photocatalytic of dye pollutants from an aqueous medium. The fundamental structure and principle of MOF-5 as a photocatalytic material have been discussed. The various synthesis methods employed for the preparation of MOF-5-based photocatalysts have been discussed. This article compiles and reviews the recent advancements in utilizing MO-5-based materials for the photodegradation of dyes from water. The detailed analysis of the literature revealed that the MOF-5 photocatalysts demonstrate excellent photocatalytic performance toward the elimination of organic dye pollutants such as methylene blue, rhodamine B, congo red, and methyl orange from an aqueous medium. Furthermore, an overview of the general mechanism and pathways observed in the photodegradation of dyes using MOF-5 has also been provided. Finally, the review provides insight into the challenges and solutions in the utilization of MOF-5 as a potential photocatalyst and provides a future perspective to design and develop advanced, cost-effective, stable, and efficient MOF-5 photocatalysts for water remediation.

Electrochemical water splitting driven by renewable energy is a sustainable and environmentally friendly way to produce clean hydrogen fuel. Due to the slow reaction kinetics, the oxygen evolution reaction (OER) occurring in the anode side is regarded as the bottleneck of the overall water splitting and can only take place at a decent rate in the presence of efficient catalysts containing transition or noble metals. Given the huge demand for green hydrogen to decarbonize the energy sector and chemical industry, the global supply of metal catalysts has become a large concern. In this context, atomically dispersed catalysts (ADCs) have been proposed to be a promising alternative to the conventional nanoparticulate catalysts, enabling maximal utilization of metals and in the meantime good OER performance in the aqueous solutions of both alkali and acid. In view of huge potential application in the OER as well as water splitting, well-designed ADCs composing of transition metals (iron, cobalt or nickel) or noble metals (ruthenium or iridium) as active sites are summarized firstly in the current review. Next, the powerful tools in the investigation of structure-performance relationship and OER catalytic mechanism have been elaborated, including various in-situ characterizations and theoretical calculation. Finally, some challenges and perspectives for future development of ADCs are also listed, such as increasing the apparent activity, operation stability as well as possible device performance verification. The purpose of this review is to provide recent process in this field and our understanding in the future research of ADCs toward OER and to promote the further application in OER and water splitting.