Resource Recovery Research Articles

Circular Economy Principles and Their Integration into Global Supply Chain Strategies

The concept of circular economy has gained significant traction in recent years as a holistic approach to sustainable development and resource management. This review explores the principles of circular economy and their integration into global supply chain strategies. The transition from a linear 'take-make-dispose' model to a circular model focused on resource recovery, reuse, and regeneration is driving a paradigm shift in how businesses operate and manage their supply chains. Key principles of circular economy, including designing out waste and pollution, keeping products and materials in use, and regenerating natural systems, are examined in the context of supply chain management. Strategies for implementing circular economy principles across various stages of the supply chain, from product design and manufacturing to distribution, consumption, and end-of-life management, are discussed. The review highlights the benefits of adopting circular economy principles in supply chain strategies, including reduced resource consumption, waste reduction, cost savings, and enhanced resilience to external shocks. Case studies and examples from diverse industries illustrate successful implementation of circular economy principles in supply chain management, demonstrating tangible environmental, social, and economic benefits. Challenges and barriers to the adoption of circular economy principles in global supply chains are also addressed, including regulatory hurdles, technological limitations, and cultural barriers. Strategies for overcoming these challenges and promoting a circular mindset among stakeholders are explored, emphasizing the importance of collaboration, innovation, and cross-sector partnerships. The integration of circular economy principles into global supply chain strategies offers significant opportunities for sustainable growth, resilience, and value creation. By embracing the principles of circularity, businesses can unlock new sources of competitive advantage while contributing to the transition towards a more sustainable and regenerative economy. Keywords: Circular Economy, Supply Chain, Sustainability, Integration, Challenges, Opportunities.

Intelligent Devices Harnessing Underwater Superoleophobic and Underoil Superhydrophobic Quartz Sands for the Separation of Diverse Stratified and Emulsified Water-Oil Mixtures.

To achieve the green, sustainable, and controllable recovery of oil-water resources and to address the limited functionality of single superwet materials in oil-water separation, this study reports a multifunctional oil-water separation strategy by compositing the underwater superoleophobic and underoil superhydrophobic materials (HS). The underwater superoleophobic quartz sands with an oil contact angle of 152.68° were prepared by adjusting the particle size. This material demonstrated a water flux of 4688 L m-2 h-1 and a low-density oil and water mixture separation efficiency of 98.6%, which remained above 97.9% over 50 cycles. It was effective in separating oil-in-water emulsions with a separation efficiency of >99%. For HS, quartz sands were modified with dodecyltrimethoxysilane. The optimized HS-4 exhibited superhydrophobic properties with a water contact angle of 157.06°. It achieved an oil flux of 5775 L m-2 h-1 and a water and dichloromethane mixture separation efficiency of 98.4%. Additionally, they exhibited significant potential in the separation of water-in-oil emulsions. Furthermore, by placing the underwater superoleophobic and underoil superhydrophobic units at the bottom of the filter, we achieved cyclic separation of high-density oil and water mixtures, low-density oil and water mixtures, water-in-oil emulsions, and oil-in-water emulsions. The separation efficiency consistently exceeded 96.5% over 10 cycles. In addition, the oil-water separation mechanism of underwater oleophobic and underoil hydrophobic materials was demonstrated by the relative concentration distribution of water and oil with molecular dynamics simulations. This intelligent oil-water separation method marks a significant advancement in the sustainable separation of diverse oil-water mixtures.

Study on the influencing factors of rural residents' willingness to classify domestic waste in the context of acquaintance society: An example from Jiangsu Province in Chin.

Waste classification helps to maximize the recovery of resources, reduce environmental pollution and promote sustainable economic development. To improve the willingness of rural residents to classify waste, based on the background of a rural acquaintance society, this thesis constructed a theoretical model of waste classification cognition, willingness to classify, economic incentives, face consciousness and vernacular identity affecting the willingness of rural residents to classify waste, and put forward seven research hypotheses. With the help of 530 valid surveys of rural residents in Jiangsu Province, the seven hypotheses were verified using structural equation modeling, and the mediating effect of rural residents' willingness to classify waste was examined using the bootstrap method. The results showed that waste classification awareness, knowledge of waste classification, economic incentives, face-saving concepts and local identity all affected rural residents' willingness to classify waste, and all were significant at a 0.01 level. They also showed that face-saving concepts and local identity played partial mediating roles. Strategies to improve rural residents' willingness to classify waste have been proposed, such as multiple incentives to enhance subjective awareness, play the role of face culture in rural areas, strengthen the construction of public culture in rural areas, and improve rural residents' local identity.

Interactive effects of urine components and treatment conditions on antibiotic degradation of combined system integrating thermally activated peroxydisulfate and membrane distillation using machine learning

The antibiotic degradation in urine is gaining focus as it’s essential for resource recovery. Complex organic and inorganic substances in urine impact degradation efficiency through their involvement in radical-type chain reactions. In this study, more than 95 % of sulfamethoxazole (SMX) in urine was successfully degraded in both concurrent and sequential modes of a combined system integrating thermally activated peroxydisulfate and membrane distillation (TAP-MD), previously shown to be effective for resource recovery. Three algorithms, including random forest (RF), XGBoost, and support vector machine (SVM), were applied to model the impact of urine components and treatment conditions on SMX degradation. The XGBoot and RF models, fine-tuned by Bayesian optimization, are accurate and credible in both prediction and interpretation (R2 > 0.90). The models suggest that the improvement of SMX degradation by the MD process is due to PDS enrichment, with high PDS concentrations significantly promoting SMX degradation. Urea and HCO3− are the key factors impacting SMX degradation efficiency, followed by temperature, PDS, Cl−, and NH4+. Additionally, strong interaction effects between urine components were found on SMX degradation, contrasting with results from individual ions that were present in isolation. At high urea concentration (>100 mM), increasing concentrations of Cl−, NH4+, and HCO3− significantly inhibited SMX degradation. As the second key factor on SMX degradation, HCO3− can react with S2O82− without producing free radicals, resulting in a reduction in its yield. Furthermore, in the presence of high concentrations of HCO3−, the Cl− and NH4+ negatively affect the kobs of SMX degradation. The HCO3− competes with SMX for Cl to produce the weak oxidant CO3∙−, which reacts quickly with NH2∙ without producing other free radicals, causing a loss of free radicals.

Study on the characteristics of glass fiber‐reinforced polymers from recycled wind turbine blades as reinforcement in particleboard

AbstractGlass fiber‐reinforced polymer (GFRP), extensively employed in diverse industries, generates considerable waste, especially from decommissioned wind turbine blades. Our research group has developed a new method of mechanical recovery for GFRP from wind turbine blades. In this study, waste GFRP was processed into a mixed particle size of 0.9–6 mm using a crusher and a screening machine, and then added as reinforcement materials to particleboards. The effects of different levels of four factors (GFRP addition, hot pressing temperature, hot pressing time, and binder dosage) on the properties of GFRP particleboards were evaluated by orthogonal experiments. The study results showed that the particleboards with 30 wt% GFRP improved modulus of rupture (MOR), modulus of elasticity (MOE), and internal bonding strength (IB) by 74.94%, 42.28%, and 92.05%, respectively, compared to pure poplar particleboards. Moreover, GFRP particleboards demonstrated better water resistance and dimensional stability than commercial particleboards and excelled in thermal stability. Recycling GFRP waste from decommissioned wind turbine blades and incorporating it into particleboard production can reduce environmental pollution, increase the resource recovery utilization rate, and contribute to sustainable manufacturing practices.Highlights Low‐cost and efficient methods of recycling wind turbine blades were proposed. Recycled GFRP from wind turbine blades can be used as reinforcement for particleboard. The prepared particleboards have excellent physical and mechanical properties and are thermally stable. Determination of the optimal glass fiber‐reinforced polymer addition level in particleboard at 30 wt%.

Hazard exposure heterophily in socio-spatial networks contributes to post-disaster recovery in low-income populations

Despite recognition of the influence of socio-spatial networks on disaster recovery, limited data-driven evidence exists regarding the nature of this relationship. To address this knowledge gap, this study investigated the duration of the human mobility recovery process and its relationship with hazard-exposure heterophily (as a measure for the resourcefulness of social ties) and various other socio-demographic characteristics. We applied the concept of hazard-exposure heterophily to the possibility of resource sharing, through social-spatial networks, between communities with different hazard exposures. We used human movement patterns to measure recovery duration. To understand the disparities during recovery, we examined the correlations between recovery duration and the social demographic characteristics of race and income caused by Hurricane Harvey which made landfall in Harris County, Texas, on August 25, 2017. We discerned high/low hazard-exposure heterophily through the use of a threshold-classification method, and we got four clusters according to the flood-inundation percentage and social connectedness values. Then we applied correlation analysis to analyze the relations between hazard-exposure heterophily/income and recovery weeks among different income groups. The results revealed that hazard-exposure heterophily considerably accelerates human mobility recovery in low-income areas, as the hazard-exposure heterophily allows for the increased exchange of knowledge and resources between members of diverse groups, ultimately accelerating the recovery process. The results of this study could benefit local agents to better allocate recovery resources.

Chemical Leasing (Ch.L.) and the Sherwood Plot

Although the Circular Economy (CE) has made remarkable technological progress by offering a wide range of alternative engineering solutions, an obstacle for its large-scale commercialization is nested in the adoption of those business and financial models that accurately depict the value generated from resource recovery. Recovering a resource from a waste matrix conserves natural reserves in situ by reducing demand for virgin resources, as well as conserving environmental carrying capacities by reducing waste discharges. The standard business model for resource recovery is Industrial Symbiosis (IS), where industries organize in clusters and allocate the process of waste matrices to achieve the recovery of a valuable resource at an optimal cost. Our work develops a coherent microeconomic architecture of Chemical Leasing (Ch.L.) contracts within the analytical framework of the Sherwood Plot (SP) for recovering a Value-Added Compound (VAC) from a wastewater matrix. The SP depicts the relationship between the VAC’s dilution in the wastewater matrix and its cost of recovery. ChL is engineered on the SP as a financial contract, motivating industrial synergies for delivering the VAC at the target dilution level at the market’s minimum cost and with mutual profits. In this context, we develop a ChL market typology where information completeness on which industry is most cost-efficient in recovering a VAC at every dilution level determines market dominance via a Kullback–Leibler Divergence (DKL) metric. In turn, we model how payoffs are allocated between industries via three ChL contract pricing systems, their profitability limits, and their fitting potential by market type. Finally, we discuss the emerging applications of ChL financial engineering in relation to three vital pillars of resource recovery and natural capital conservation.

The Simultaneous Efficient Recovery of Ammonia Nitrogen and Phosphate Resources in the Form of Struvite: Optimization and Potential Applications for the Electrochemical Reduction of NO3−

In response to the need for improvement in the utilization of ammonium-rich solutions after the electrochemical reduction of nitrate (NO3−–RR), this study combined phosphorus-containing wastewater and adopted the electrochemical precipitation method for the preparation of struvite (MAP) to simultaneously recover nitrogen and phosphorus resources. At a current density of 5 mA·cm−2 and an initial solution pH of 7.0, the recovery efficiencies for nitrogen and phosphorus can reach 47.15% and 88.66%, respectively. Under various experimental conditions, the generated struvite (MgNH4PO4·6H2O) exhibits a typical long prismatic structure. In solutions containing nitrate and nitrite, the coexisting ions have no significant effect on the final product, struvite. Finally, the characterization of the precipitate product by X-ray diffraction (XRD) revealed that its main component is struvite, with a high purity reaching 93.24%. Overall, this system can effectively recover ammonium nitrogen from the NO3−–RR solution system after nitrate reduction, with certain application prospects for the recovery of ammonium nitrogen and phosphate.

Agro-industrial waste management employing benefits of artificial intelligence.

By 2050, the world's population is predicted to reach over 9 billion, which requires 70% increased production in agriculture and food industries to meet demand. This presents a significant challenge for the agri-food sector in all aspects. Agro-industrial wastes are rich in bioactive substances and other medicinal properties. They can be used as a different source for manufacturing products like biogas, biofuels, mushrooms, and tempeh, the primary ingredients in various studies and businesses. Increased importance is placed on resource recovery, recycling, and reusing (RRR) any waste using advanced technology like IoT and artificial intelligence. AI algorithms offer alternate, creative methods for managing agro-industrial waste management (AIWM). There are contradictions and a need to understand how AI technologies work regarding their application to AIWM. This research studies the application of AI-based technology for the various areas of AIWM. The current work aims to discover AI-based models for forecasting the generation and recycling of AIWM waste. Research shows that agro-industrial waste generation has increased worldwide. Infrastructure needs to be upgraded and improved by adapting AI technology to maintain a balance between socioeconomic structures. The study focused on AI's social and economic impacts and the benefits, challenges, and future work in AIWM. The present research will increase recycling and reproduction with a balance of cost, efficiency, and human resources consumption in agro-industrial waste management.

Sustainable microalgal biomass as a potential functional food and its applications in food industry: a comprehensive review.

Microalgae (MA) are the most abundant seaweeds with high nutritional properties. They are accepted as potential biocatalysts for the bioremediation of wastewater. They are widely used in food, feed, and biofuel industries and can potentially be food for future generations. MA-based purification of wastewater technology could be a universal alternative solution for the recovery of resources from wastewater for low-cost biomass feedstock for industry. They provide a wide range of functional components, viz. omega-3 fatty acids, along with a plenteous number of pigments such as ß-carotene, astaxanthin, lutein, phycocyanin, and chlorophyll, which are used extensively as food additives and nutraceuticals. Further, proteins, lipids, vitamins, and carbohydrates are described as nutritional characteristics in MA. They are investigated as single-cell protein, thickening/stabilizing agents, and pigment sources in the food industry. The review emphasizes the production and extraction of nutritional and functional components of algal biomass and the role of microalgal polysaccharides in digestion and nutritional absorption in the gastrointestinal tract. Further, the use of MA in the food industry was also investigated along with their potential therapeutic applications.

An innovative ionic liquid-aqueous biphasic system for simultaneously highly efficient dechroming and collagen recovery from chrome-tanned leather shavings at room temperature

Chrome-tanned leather shavings (CTLS) with abundant collagen of 70–90 wt% but high Cr content of 2–4 wt% are considered as hazardous wastes. Due to the stable covalent bond between Cr and collagen, current processes for collagen recovery from CTLS face challenges including low dechroming efficiency, collagen disruption, high energy and chemical consumption and secondary pollution. In this paper, an innovative IL-targeted homogeneous isolation (IL-THI) process based on the reusable ionic liquid-aqueous biphasic system (IL-ABS) was established for the simultaneous resource recovery and complete dechroming of CTLS at room temperature, with the recovery rate of collagen reached 72.4 % while Cr content in collagen is reduced from 35.65 × 103 mg/kg to 1.78 mg/kg. This IL-ABS enriched TBAH in the upper phase and potassium tartrate in the lower phase. Moreover, TBAH demonstrated excellent reproducibility across five cycles, achieving consistently low Cr content of 2.65 mg/kg in collagen, far below the 50 mg/kg limit in national standards. The triple helix conformation and the molecular weight of the collagen product were confirmed via Fourier-transform infrared spectroscopy, X-ray diffraction analyses, circular dichroism spectra analysis and SDS-PAGE. Moreover, economic calculations demonstrated the suitability of this novel process for sustainable CTLS recovery. The superior dechroming ability of IL-ABS is attributed to the formation of Cr(III)-Tartrate complexes, which preferentially migrate to the lower phase due to the solvophobic effect, while dissolved collagen is recovered from the upper phase, as disclosed by UV–Vis spectra, ICP-OES, and all-atom molecular dynamics simulations. Additionally, IL-THI process demonstrates considerable potential for the isolation of Cr(III) and collagen in solid waste, with low energy consumption, improved separation efficiency, and increased design flexibility.

Recent Advances in High-Rate Solar-Driven Interfacial Evaporation.

Recent advances in solar-driven interfacial evaporation (SDIE) have led to high evaporation rates that open promising avenues for practical utilization in freshwater production and industrial application for pollutant and nutrient concentration, and resource recovery. Breakthroughs in overcoming the theoretical limitation of 2D interfacial evaporation have allowed for developing systems with high evaporation rates. This study presents a comprehensive review of various evaporator designs that have achieved pure evaporation rates beyond 4kgm-2h-1, including structural and material designs allowing for rapid evaporation, passive 3D designs, and systems coupled with alternative energy sources of wind and joule heating. The operational mechanisms for each design are outlined together with discussion on the current benefits and areas for improvement. The overarching challenges encountered by SDIE concerning the feasibility of direct integration into contemporary practical settings are assessed, and issues relating to sustaining elevated evaporation rates under diverse environmental conditions are addressed.

Non-targeted facilitation of primary sludge anaerobic fermentation by micro-aeration and the simultaneous nutrients transformations

Anaerobic fermentation is a widely used technology for resource recovery from municipal sludge (e.g., primary sludge). Micro-aeration is an emerging strategy which can be incorporated into this technology. However, the effect of micro-aeration on the anaerobic fermentation performance and the nutrients transformations are not well known. This study investigated the impact of micro-aeration on the production of volatile fatty acids (VFAs) from primary sludge as well as the simultaneous nitrogen (N) and phosphorus (P) transformations in the system. The obtained results indicated that application of micro-aeration improved the microbial activities and facilitated all the hydrolysis, acetogenesis and methanogenesis processes. Hydrogenotrophic methanogen was enriched by micro-aeration while the acetoclastic methanogenesis was still the dominant CH4 production pathway at gene level. The concentration of VFAs was lower with micro-aeration than in the control system, which could be attributed to the enhanced consumption of VFAs. The simultaneous transformations of N and P were observed with different patterns. Micro-aeration led to removal of up to 131.6 mg/L of N, with occurrence of nitrification and denitrification found to be responsible for the N removal. In contrast, the total P content remained unchanged in the reactor. However, micro-aeration was found to inhibit both extracellular organic-P mineralization and intracellular poly-P degradation, resulting in lower soluble PO43−-P and more P distributed in the organic-P fraction in solid phase. This study provides novel insights into the microscopic mechanisms of the micro-aeration on anaerobic fermentation and the simultaneous regulation of N and P release.

Nitrogen recycling characteristics in multiphase transformation during municipal sludge pyrolysis

The nitrogen content of municipal sludge is as high as 2.5～9.0 wt%, which has become an important problem in pollution control during pyrolysis. Recycling nitrogen from municipal sludge not only enables resource utilization, but also reduces the nitrogen-related pollution. In this study, the transformation pathways of nitrogen to resource material and typical pollutants during the municipal sludge pyrolysis process were analyzed. The results showed that the nitrogen species in municipal sludge were mainly protein-N (64.41%), pyridine-N (19.47%) and inorganic-N (16.13%). After pyrolysis at 300 °C, the peptide bond of protein-N was gradually broken down, resulting in the formation of three nitrogenous intermediates (amine-N, nitrile-N and heterocyclic-N) were produced. These intermediates can be transformed to NH3 for resource recovery or to HCN pollutants. Moreover, the full nitrogen transformation pathways of municipal sludge pyrolysis were constructed by the method of Spearman's correlation coefficient and experiment analysis. It was found that NH3 and HCN were mostly generated from the cracking of three nitrogenous intermediates at 600–800 °C. In addition, there was a prominent effect on the transformation of HCN to NH3 with co-presence of calcium minerals in raw sludge. By adding inorganic calcium minerals, NH3 as a recyclable component was prominently improved by 10.30% at 700 °C, while HCN yield was decreased by 53.02% accordingly under the inhibitory effect. The results systematically provided a theoretical support to the possibility of nitrogen recycling for utilization during municipal sludge pyrolysis, as well as to control the transformation of nitrogen elements into pollutants.

Recovery of lithium and copper from anode electrode materials of spent LIBs by acidic leaching.

In view of the importance of environmental protection and resource recovery, recycling of spent lithium ion batteries (LIBs) is quite necessary. In the present study, lithium and copper are recycled to lithium carbonate and copper oxide from anode electrode material of the spent LIBs. The anode electrode material is firstly treated with hydrochloric acid to leach lithium (96.6%) and then with nitric acid to leach copper (97.6%). Furthermore, lithium and copper are recovered as lithium carbonate and copper oxide from their respective solutions using precipitation and calcinations. These synthesized products are further characterized using XRD, FE-SEM, and EDX analysis. Finally, a simple process is proposed for the recovery of lithium and copper from anode electrode material of spent LIBs.

A novel fuzzy multi-criteria decision-making for enhancing the management of medical waste generated during the coronavirus pandemic

The coronavirus pandemic significantly increased the use of essential medical supplies, resulting in a surge in medical waste generation. This surge has spurred extensive research into sustainable disposal methods for safe and environmentally responsible medical equipment management. Addressing this multifaceted issue falls within the domain of multi-criteria decision-making. This study presents a comprehensive framework for selecting optimal medical waste treatment methods, considering economic, technological, environmental, and social factors. This is the first study to address the problem of selecting a medical waste disposal technology using the Fuzzy Dombi Bonferroni. The mean operator to combine expert opinions, the fuzzy preference selection index method to evaluate the criteria and the fuzzy compromise ranking of alternatives from distance to ideal solution method to rank the alternatives. According to the weightings, the social dimension holds the highest significance at 0.3217. Disinfection efficiency ranks as the most critical criterion, weighing in at 0.0823. The autoclave is rated as the top disposal technique, with a utility function value of 5.4579. Sensitivity analyses ensured the stability and reliability of the models. The adaptability of the applied model to sustainable practices such as energy conversion, material recycling, and resource recovery represents an essential aspect of policymaking in waste management. This assessment can guide policy formulation or improvement processes for waste disposal.

Electrified Solar Zero Liquid Discharge: Exploring the Potential of PV-ZLD in the US.

Current brine management strategies are based on the disposal of brine in nearby aquifers, representing a loss in potential water and mineral resources. Zero liquid discharge (ZLD) is a possible strategy to reduce brine rejection while increasing the resource recovery from desalination plants. However, ZLD substantially increases the energy consumption and carbon footprint of a desalination plant. The predominant strategy to reduce the energy consumption and carbon footprint of ZLD is through the use of a hybrid desalination technology that integrates renewable energy. Here, we built a computational thermodynamic model of the most mature electrified hybrid technology for ZLD powered by photovoltaic (PV). We examine the potential size and cost of ZLD plants in the US. This work explores the variables (geospatial and design) that most influence the levelized cost of water and the second law efficiency. There is a negative correlation between minimizing the LCOW and maximizing the second-law. And maximizing the second-law, the states that more brine produces, Texas is the location where the studied system achieves the lowest LCOW and high second-law efficiency, while California is the state where the studied system is less favorable. A multiobjective optimization study assesses the impact of considering a carbon tax in the cost of produced water and determines the best potential size for the studied plant.

Modeling oil spill disasters using system dynamics: A case study on the MT Princess Empress oil spill in Oriental Mindoro, Philippines

Oil spill events pose potentially irreversible threats to the environment and economy of affected communities, necessitating a comprehensive analysis of their dynamics. This study employs system dynamics (SD) modeling to enhance the current understanding of the complex dynamics associated with oil spill incidents, focusing on the case of the MT Princess Empress oil spill in the Philippines last February 2023. The research integrates quantitative and qualitative data to develop a dynamic simulation model that captures the interdependencies among key variables, such as spill characteristics, environmental factors, response measures, resource allocation, and socio-economic impacts. Model validation was performed by comparing the results of the simulation with historical data from the MT Princess Empress incident. Sensitivity analysis was then conducted to identify critical factors influencing the system's behavior. Among oil spill size, initial recovery resources, resource support delay, and cash assistance to affected individuals, oil spill size was determined to have the most significant effect on the oil spill system owing to the amplification of negative consequences via reinforcing feedback loops. The research findings thus underscore the effectiveness of preventive measures as the primary strategy for mitigating the consequences of oil spills. Sustainable recovery for communities affected by such incidents also necessitates a shift towards long-term rehabilitation initiatives and proactive community engagement rather than relying on short-term solutions.

The banana tree circle as a nature-based solution for sustainable greywater management: A new design model

ABSTRACT The banana tree circle (BTC) is a low-cost system for local greywater management, using a natural treatment and disposal process, providing additional resource recovery benefits. However, there are no standard design criteria for BTC that would allow for quality control of its efficiency and sustainability, and little is currently known about the full-scale performance of BTC. Based on the scoping literature review of 31 documents in the scientific database and 8 documents from grey literature, a standard design model was proposed for the BTC technology based on the concept of water balance, greywater flows, rain, infiltration, and evapotranspiration. The first two steps of the BTC design were determining the areas required for infiltration and evapotranspiration. A cylindrical form trench, the soil percolation rate, and the hydraulic loading rate were considered for the infiltration area. The banana trees’ evapotranspiration rate was taken into consideration for the evapotranspiration area. The proposed model was applied in a case study where we used a trench with 0.8 m depth and 1.5 m diameter. This study proposes a standard design criterion for the BTC based on environmental factors, and the scoping of the literature provides the basis for future studies to evaluate its environmental sustainability.

Covalently bridged MXene/COF hybrid membrane toward efficient dye separation

Two-dimensional (2D) MXene-based membranes combine unique atomic thickness, well-arranged interlayer channel, and have received growing attention in molecular/ion separation and transport. The low permeability and instability of MXene-based membranes in water purification enable it difficult to be utilized in practical processing. Here, we present a high water-permeability and long-lived MXene membrane by assembling 2D heterostructured MXene/COF flakes on macroporous polymeric support. The intercalation of COFs into the interlayer of Ti3C2Tx nanosheets not only increases the adjacent interlayer space, but also provides abundant molecular sieving pores, thereby enhancing the permeability of MXene membrane. While being applied in removal of organic dyes, the MXene/COF hybrid membrane exhibits a superior water permeance (up to ∼ 300 L m-2h−1 bar−1), and several satisfactorily rejections for different dyes (98.2 % for congo red, 98.7 % for chrome black T, 96.4 % for methyl blue, and 97.2 % for methyl orange) are simultaneously achieved. Additionally, the covalent anchoring of COFs on MXene surface can greatly improve the stability. The reduction of hydrophilicity of MXene surface mitigates water molecular absorption on the fluid channel wall and endow the membrane with well swell tolerance in aqueous environment. Such high performance MXene/COF hybrid membrane is mainly caused by the physical sieving mechanism supported by the repulsive interaction, as well as adsorption capability originating from porous COFs. This work provides an alternative approach for the fabrication of high performance MXene-based membranes used for highly effective dye wastewater treatment, and extends the application of 2D membranes in desalination, pollutant treatments, and resource recovery.