Recycling Route Research Articles

Pathways to sound management of excavated soil and rock: A case study in Shenzhen

Due to underground infrastructure and earthworks, the excavated soil and rock (ESR) emerges as the primary construction and demolition (C&D) waste stream in numerous urban areas. The transportation and disposal of ESR entail substantial costs and adverse environmental impacts, necessitating optimized management approaches. However, the environmental and economic evaluation of various ESR disposal methods remains insufficiently explored. This study presents a comprehensive analysis of a city-scale ESR management system through a case study in Shenzhen. This rapidly expanding megacity generated an annual average of 77 million m3 of ESR. We dynamically evaluate the sustainability of ESR management by harnessing a synergistic methodology that integrates material flow cost accounting (MFCA) with life cycle thinking. The findings reveal that cross-regional transportation emerges as the prioritized ESR disposal method, accounting for 72 ± 2% of the total ESR treatment, resulting in greenhouse gas (GHG) emissions of 584 ± 35 kt CO2 eq. and economic costs of 8358 ± 64 million USD per year. Scenario analysis reveals that sound recycling routes, accompanied by policy support, can yield environmental and economic benefits by reducing GHG emissions by 574 ± 55 kt CO2 eq. and generating net profits of 248 ± 15million USD per year in the coming decade. This study exemplifies the complementary methodologies supporting sustainable ESR management in Shenzhen while offering valuable insights for other cities in China and beyond.

Operating conditions, products and sustainable recycling routes of aminolysis of polyethylene terephthalate (PET) – a review

Operating conditions, products and sustainable recycling routes of aminolysis of polyethylene terephthalate (PET) – a review

LCA of recycling aluminium incineration bottom ash, dross and shavings in a rotary furnace and environmental benefits of salt-slag valorisation

Recycling aluminium in a rotary furnace with salt-fluxes allows recovering valuable alloys from hard-to-recycle waste/side-streams such as packaging, dross and incinerator bottom ash. However, this recycling route generates large amounts of salt-slag/salt-cake hazardous wastes which can pose critical environmental risks if landfilled. To tackle this issue, the metallurgical industry has developed processes to valorise the salt-slag residues into recyclable salts and aluminium concentrates, while producing by-products such as ammonium sulphate and non-metallic compounds (NMCs), with applications in the construction or chemical industries. This study aims to assess through LCA the environmental impacts of recycling aluminium in rotary furnaces for both salt-slag management routes: valorisation or landfill. It was found that this recycling process brings forth considerable net environmental profits, which increase for all the considered impact categories if the salt-slag is valorised. The main benefits arise from the production of secondary cast aluminium alloys, which is not unexpected due to the high energy intensity of aluminium primary production. However, the LCA results also identify other hotspots which play a significant role, and which should be considered for the optimisation of the process based on its environmental performance, such as the production of by-products, the consumption of energy/fuels and the avoidance of landfilling waste. Additionally, the assessment shows that the indicators for mineral resource scarcity, human carcinogenic toxicity and terrestrial ecotoxicity are particularly benefited by the salt-slag valorisation. Finally, a sensitivity analysis illustrates the criticality of the metal yield assumptions when calculating the global warming potential of aluminium recycling routes.

The multidepot vehicle routing problem with intelligent recycling prices and transportation resource sharing

The increasing focus on environmental regulations and the economic advantages of recycling has spurred interest in the design of multidepot reverse logistics networks (MDRLNs). In these networks, the growing use of intelligent recycling bins (IRBs) has been beneficial for both product recycling and standardizing recycling product pricing. Furthermore, collaboration and resource sharing enhance the efficiency of resource utilization and recycling. This study proposes a multidepot vehicle routing problem with time windows that incorporates intelligent recycling prices (IRPs) and transportation resource sharing (MDVRPTW-IRPTRS). Initially, a linear function is developed to define the relationship between the volume of returned products and IRPs. Subsequently, the problem is expressed as a mathematical model aiming to minimize total operating costs and maximize total recycling profits. Additionally, a hybrid algorithm that combines a three-dimensional (3D) k-means clustering algorithm with a self-adapting genetic algorithm-particle swarm optimization (SGA-PSO) is devised to determine the optimal solution for MDVRPTW-IRPTRS. The 3D k-means clustering algorithm is utilized to categorize IRBs within an MDRLN. The SGA-PSO algorithm incorporates elite preservation and self-adaptive update mechanisms to enhance the solution quality and algorithm convergence. A transportation resource sharing (TRS) strategy is integrated into the SGA-PSO, facilitating the allocation of shared vehicles to alternative recycling routes. A comparative analysis of SGA-PSO against other algorithms, including a hybrid genetic algorithm, an improved particle swarm optimization algorithm, and a hybrid genetic algorithm with variable neighborhood search, demonstrates its superiority in solving the MDVRPTW-IRPTRS. The model and algorithm are applied in a real-world case study in Chongqing, China, and the study discusses the optimized results under varying TRS strategies and IRP schemes, contributing to the development of an efficient and synergistic urban reverse logistics network. Moreover, the superior performance of the proposed approach is validated through the ablation experiments. This study offers valuable decision-making support for fostering an environmentally sustainable and resource-efficient city.

Exploratory DSC investigation on the solvolytic depolymerization of PET in varied solvent systems and in the presence of model additives and contaminants

Solvolytic depolymerization of polyethylene terephthalate (PET) is a thermo-chemical recycling route that valorizes plastic waste by recovering monomers and chemicals that can be reused for the synthesis of new polymers. This study focuses on neutral hydrolysis due to the potential environmental and economic benefits of water as depolymerization agent compared to alternative organic solvents. High-pressure crucibles were used as batch reactors in differential scanning calorimetry (DSC) to perform real-time monitoring of the thermodynamic phenomena taking place during solvolytic depolymerization of PET in varied solvent systems. PET melting point depression was found to be the main identified phenomena, with PET melting point exhibiting a drop of almost 30 °C in water and 50 °C in monoalcohol solvents like methanol and ethanol. Moreover, PET only underwent significant depolymerization prior to melting in NaOH containing systems. Gas Chromatography and Mass Spectrometry were used to study the fate of model additives and contaminants under solvolytic conditions. The uncertainty concerning these foreign substances poses a challenge for the development of PET solvolytic technologies, and the methods here provided proved to be a fast-screening technique to quantify the conversion and identify potential degradation products of model additives like 2-(2-hydroxy-5-methylphenyl) benzotriazole UV-stabilizer, 1-(methylamino) anthraquinone dye, and model contaminant (R)-(+)-limonene under hydrothermal conditions.

Efficient electrocatalytic nitrate reduction using 3D copper foam-supported Co hexagonal nanoparticles in a membrane electrode assembly

Electrocatalytic nitrate reduction reaction (NO3RR) provides a promising route for nitrate recycling and ammonia production. In this work, Co nanoparticle catalyst was developed on a copper foam substrate (CoNPs/CF) by electrodeposition. The CoNPs/CF catalysis exhibits a Faradaic efficiency (FE) of 92.0% at −0.2 V vs. RHE and an NH3 yield rate of 14328.65 μg h−1 cm−2 at −0.5 V vs. RHE. In-suit Raman spectroscopy and theoretical calculations demonstrated that the 3D copper foam structure of the substrate enhances the electron exchange capacity, which promotes the adsorption of nitrate on the cobalt (Co) surface. Moreover, Membrane Electrode Assembly (MEA) is employed with CoNPs/CF, contributing to 98.43 mg h−1 with FE over 80%. Coupled with an air stripping process, this configuration has enabled the successful production of high-purity gaseous NH3 products. This work suggests a practical and viable approach for the conversion of wastewater nitrate into valuable ammonia products.

Recovery of Cerium from Automotive Catalytic Converters

Platinum group metals (PGM) and cerium as one of the rare-earth elements are considered as critical raw materials, thus their recycling and re-use is of utmost importance. Among the PGMs, platinum (Pt), palladium (Pd), and rhodium (Rh) are the basic and most valuable metals used in catalytic converters. Due to the high price of PGMs, there are already recycling routes in Europe and especially in Germany. For PGM and rare-earth elements, research is focusing on greener, plain recovery techniques, which utilize milder reagents, offer better energy efficiency, and replace the existing recycling routes. In this work, a hydrometallurgical process is proposed to add a hydrometallurgy method to the mostly pyrometallurgical industrial recycling routes, resulting in recovery rates for cerium and PGMs of 63.21% and only 1.03% with sulfuric acid, respectively. With hydrochloric acid, the leaching efficiency for cerium is even lower, and for PGM it is comparable. In the method proposed in the present paper, the main PGMs remain in monoliths and can be recycled in existing recycling routes like pyrometallurgical recycling.

Unlocking a Sustainable Future for Plastics: A Chemical-Enzymatic Pathway for Efficient Conversion of Mixed Waste to MHET and Energy-Saving PET Recycling.

The heterogeneous monomers obtained from plastic waste degradation are unfavorable for PET recondensation and high-value derivative synthesis. Herein, we developed an efficient chemical-enzymatic approach to convert mixed plastic wastes into homogeneous mono-2-hydroxyethyl terephthalate (MHET) without downstream purification, benefiting from three discovered BHETases (KbEst, KbHyd, and BrevEst) in nature. Towards the mixed plastic waste, integrating the chemical K2CO3-driven glycolysis process with the BHETase depolymerization technique resulted in an MHET yield of up to 98.26 % in 40 h. Remarkably, BrevEst accomplished the highest BHET hydrolysis (~87 % efficiency in 12 h) for yielding analytical-grade MHET compared to seven state-of-the-art PET hydrolases (18 %-40 %). In an investigation combining quantum theoretical computations and experimental validations, we established a MHET-initiated PET repolymerization pathway. This shortcut approach with MHET promises to strengthen the valorization of mixed plastics, offering a substantially more efficient and energy-saving route for PET recycling.

Towards effective recycling routes for polypropylene: Influence of a repair additive on flow characteristics and processability

Plastic recycling is a key aspect to achieve effective polymer circularity, especially for polyolefins for which usually the mechanical recycling is considered a downcycling process. This downcycling phenomenon arises from the progressive deterioration of the polymer microstructure during reprocessing, resulting in a gradual loss of processability and properties, ultimately compromising the possibility of using recycled polyolefins for applications with high engineering requirements.In this work, the effects of the thermomechanical degradation on the microstructure of polypropylene (PP) were assessed by subjecting the polymer to multiple extrusion cycles. The objective is investigating the evolution of the molecular weight and of the macromolecular architecture of PP typically occurring in a mechanical recycling process.Furthermore, a commercially available additive capable of restoring the PP molecular weight was introduced, with the purpose of proposing an effective upcycling strategy for achieving recycled PP with enhanced processability. In particular, the effects of the additive were evaluated following two different strategies that simulate pre-consumer or post-consumer mechanical recycling.The obtained results indicated that the introduction of the additive can effectively prevent the decrease of the molecular weight of reprocessed PP, also inducing some melt structuring phenomena associable with the introduction of some long chain branching and/or crosslinking. Finally, it was demonstrated that different macromolecular architectures for recycled PP can be achieved depending on the residence time during the processing in presence of the additive, opening new perspectives towards the possibility of obtaining recycled PP with modulable flow characteristics and, hence, processability.

Preparation of Li2O–Al2O3–SiO2–B2O3（LASB）glass-ceramic with low thermal expansion coefficient from spent hydrogenation catalysts and crystallization kinetics

The recovery of spent hydrogenation catalysts occupies advantages in both alleviating environmental burden and resource shortage. Whereas, the development of conventional hydrometallurgical recovery of molybdenum (Mo) and nickel (Ni) from spent MoNi/Al2O3 catalysts has been limited by the numerous processes and the accompanying generation of waste liquids and residues. Herein, A new recycling route for the preparation of spent hydrogenation catalysts with low thermal expansion coefficients (CTE) was proposed, which has the advantages of short process, green environment and high value utilization. The Li2O–Al2O3–SiO2–B2O3 (LASB) parent glass containing Mo and Ni were obtained by melting with different contents of the spent catalysts. The thermal expansion coefficient of the glass was minimized to 6.08 × 10−6/°C at an addition of 25 wt% of the spent catalysts. Moreover, according to the crystallization peak in DTA curve, glass-ceramics were prepared by one-step crystallization heat treatment at different crystallization temperatures. The main crystalline phase of the glass-ceramic precipitated by heating at 685 °C is β-quartz (Li2Al2Si3O10), which gives the glass-ceramics the lowest coefficient of thermal expansion (0.96 × 10−6/°C) of glass-ceramic as well as the maximum density (2.45 g/cm3) and Vickers hardness (705.8 Hv). Furthermore, the activation energy (354.65 ± 17.42) kJ/mol) and Avrami index (5.39) associated with crystallization were extracted from the fitting of different theoretical model, indicating the three-dimensional crystallization of the LASB glass-ceramics. This technology provides a waste-to-material strategy for hazardous waste and a clean production route for the preparation of the functional glass-ceramics.

A hybrid thermal-biological recycling route for efficient extraction of metals and metalloids from end-of-life liquid crystal displays (LCDs)

Waste liquid crystal displays (LCDs) are one of the most substantial and rapidly growing e-waste streams that contain a notable amount of critical, precious, and toxic elements. This study presented a novel thermal-biological hybrid method for resource recovery from waste LCDs. Through the design of a multistage thermal treatment process with the addition of optimized 20 wt% B2O3 to waste, the LCD's glass structure was separated into two interconnected phases, resulting in the transfer of metals from the LCD's glass phase to the B2O3 phase that can solubilize in the acid solution. Following the thermal treatment step, the biometabolites of Aspergillus niger were used for bioleaching of In, Sr, Al, and As from the obtained thermally treated product. The optimal bioleaching parameters were a pulp density of 10 g/L, temperature of 70 °C, and leaching time of 2 days, which led to the highest extraction of 82.6% Al, 70.8% As, 64.5% In, and 36.2% Sr from thermally treated LCD waste, representing a multifold increase in Al, As, and Sr extraction levels compared to untreated waste. This study demonstrated that the proposed hybrid method could successfully overcome waste complexities and ensure effective element extraction from discarded LCDs.

A novel fluidized electrode electrolysis system activated ferrate (VI) oxidation promoting sludge solubilization: Performance and mechanism

Energy and resource recovery is a viable and sustainable solution for sludge treatment and disposal, while sludge solubilization is one of the most critical issues hindering sludge conversion to valuable products. Although ferrate (VI) was considered a green sludge pretreatment approach, the poor stability of ferrate (VI) hindered the effective utilization of its oxidative potential. This study demonstrated that an innovative electrochemical system with granular activated carbon (GAC) as the fluidized electrode activated potassium ferrate (PF) oxidation could effectively catalyze the destruction of sludge structure, thereby promoting the release of organic matter and improving sludge solubilization. The results showed that the electro- granular activated carbon- potassium ferrate (E-GAC-PF) process achieved a sludge solubilization of 30.9 % within 15 min, resulting in a reduction in sludge volume by 33.9 %. In comparison, the sludge solubilization rate under PF oxidation alone was 11.5 %, with corresponding in sludge volume reduction of 13.0 %. The radical scavenging experiment and probe compound (sulfoxide) oxidation experiment revealed that the E-GAC-PF system was responsible for the production of a higher quantity of Fe (V) and Fe (IV), which significantly contributed to the sludge decomposition. Additionally, XPS and XRD analysis discovered that Fe3O4 was present as a byproduct, which opened up a new route for iron recycling during the pretreatment. Hence, E-GAC-PF system held promise as a pioneering and efficient alternative for catalytically activating PF, thereby facilitating environmentally friendly and highly efficient pretreatment of sludge.

A mechanistic approach toward understanding the mechanical and rheological properties of polyamide/reclaimed rubber blend containing silane-treated silica

The use of reclaimed tire rubber (RTR) as a rubber toughener for engineering plastics such as polyamide 6 (PA6) is a sustainable route for rubber recycling, and it is essential to determine how surface treatment of silica nanoparticles (NPs) contributes to the modification of the blend properties. Here, a comprehensive mechanistic view based on a knowledge of all the influencing factors including the dispersion state of NPs, NP localization, change in matrix crystallinity, and rheology is presented to understand the properties of PA6/RTR/Silica ternary blends. Using the long-chain silane hexamethyltrimethoxysilane, silica was surface-modified at low, medium, and high levels. The impact strength of PA/RTR exhibited an improvement level of 104 % compared to the PA6 system. The results indicate that the change in matrix crystallinity, which is by itself related to the rheological properties, is the primary factor behind the modification of the mechanical properties by the silica nanoparticles. Mechanical engagement interaction resulting from interpenetration of the silane tails significantly altered the rheology and PA6 crystallinity. A secondary role was also found for the NP state of dispersion and localization.

Standardized Method to Functionalize Plasma-Extracellular Vesicles via Copper-Free Click Chemistry for Targeted Drug Delivery Strategies.

Extracellular vesicles (EVs) have emerged as potential vehicles for targeted drug delivery and diagnostic applications. However, achieving consistent and reliable functionalization of EV membranes remains a challenge. Copper-catalyzed click chemistry, commonly used for EV surface modification, poses limitations due to cytotoxicity and interference with biological systems. To overcome these limitations, we developed a standardized method for functionalizing an EV membrane via copper-free click chemistry. EVs derived from plasma hold immense potential as diagnostic and therapeutic agents. However, the isolation and functionalization of EVs from such a complex biofluid represent considerable challenges. We compared three different EV isolation methods to obtain an EV suspension with an optimal purity/yield ratio, and we identified sucrose cushion ultracentrifugation (sUC) as the ideal protocol. We then optimized the reaction conditions to successfully functionalize the plasma-EV surface through a copper-free click chemistry strategy with a fluorescently labeled azide, used as a proof-of-principle molecule. Click-EVs maintained their identity, size, and, more importantly, capacity to be efficiently taken up by responder tumor cells. Moreover, once internalized, click EVs partially followed the endosomal recycling route. The optimized reaction conditions and characterization techniques presented in this study offer a foundation for future investigations and applications of functionalized EVs in drug delivery, diagnostics, and therapeutics.

Facile Route for Effective Separation and Full-Scale Recycling of Fly Ash and Unburned Carbon.

The synchronous production of high-quality unburned carbon concentrate and cleaned ash from high LOI (loss on ignition) fly ash without yielding secondary solid waste is a dilemma issue. In this study, a viable flotation process with one rougher and two cleaners is developed for simultaneously obtaining carbon concentrate with a yield of 18.00% and an ash content of 17.49% and cleaned ash with a yield of 82.00% and a LOI of 4.63% from fly ash, reaching 84.72% of combustible substance recovery and 80.66% of flotation perfection index. The characteristic analyses of the stage by stage releasing products using laser particle size analysis, XRF, XRD, and SEM-EDS demonstrate that the inevitable factors that lead to a remaining higher ash content in the one-step flotation carbon concentrate are the random entrainment of mineral particles in the size range of 0-20 μm, especially the quasi-colloidal parts within 0-12.5 μm and the weak selective collection of fine-grained conjoined granules in the size range of 0-40 μm. Consequently, at least two cleaning steps are required for the effective separation of unburned carbon and ash. Furthermore, batch flotation test results show that diesel is superior to kerosene in the collection of unburned carbon, with an optimum dosage of 800 g/t; no. 2 oil acts more positively than MIBC for the separation of unburned carbon and ash, with an optimal dosing amount of 600 g/t; the optimum pulp concentration and flotation time are as follows: 100 g/L and 3.5 min for the rougher, 45 g/L and 2 min for the first cleaning, and 30 g/L and 3 min for the second cleaning. This study provides an economically feasible technological solution for the full-scale recovery of high-LOI fly ash in one step and avoids the problem of secondary solid waste that would have been generated in previous studies.

A closed-loop coupling process of leaching and solvent extraction for Li2CO3 and FePO4 recovery from spent LiFePO4

To satisfy the increasing global demand for the strategic metal lithium, recycling of LiFePO4 (LFP) batteries has become an irresistible trend and poses a challenge due to the cost. A low-cost process of recovering Li and FePO4 from simulated spent LFP was investigated through a closed-loop coupling technology of isomorphic substitution leaching and solvent extraction. A total of 99.41% of Li+ can be leached, and 96% of FePO4 can be recovered with an Fe2(SO4)3:LFP molar ratio of 1:6, H2SO4:LFP molar ratio of 0.5:1, and 0.4 ml H2O2/gLFP for 30 min. An eleven-stage extraction process for Fe3+ removal from lixivium-containing extraction, stripping and regeneration processes was designed and optimized. The total removal efficiency of Fe3+ was 97.22% by the 40 vt% N235 + 15 vt% TBP + kerosene extraction system at a phase ratio O/A of 3.5/1, and the lithium concentration in raffinate was 10.074 g·L−1. The closed-coupling process was carried out on the simulated spent LFP with a total Li recovery efficiency of >99%. The low-cost leaching agent Fe2(SO4)3 was cyclically utilized. The coupling process can not only serve as a promising efficient recycling method for spent LFP batteries but also supply an inspiring route for other expensive metal recycling.

Experiment-based conceptualization of an automated disassembly process chain for the recycling of lithium-ion battery modules

As the volume of end-of-life lithium-ion batteries (LIB) used in electric vehicles increases, so does the demand for recycling to recover valuable active materials as secondary resources, reducing the need for primary raw materials and minimizing supply dependencies. In addition to pyro- and hydrometallurgy recycling processes, an increasingly examined approach is the direct recycling route, which involves disassembling battery systems into modules, modules to cells, and ultimately cells to electrodes. To minimize passive materials such as various metals from the housing, joints, arresters, plastics, foams, and adhesives in the subsequent crushed mass, the introduction of module disassembly processes into the existing LIB recycling process chain is promising for the resulting increase in recyclate purity. This study presents the conceptualization of a LIB module disassembly process chain which aims to elevate the depth of disassembly of LIB during early recycling stages. A reverse engineering approach is used to recover individual cells from two battery modules of one specific automotive manufacturer by removing their casing through milling and disconnecting the cells from the arresters. The experimental results are analyzed for influences on the disassembly possibilities for individual components as well as the interactions within the system, enabling the elaboration of a priority graph and a disassembly plan. In order to allow for scalable recycling process chains suitable for very high quantities, a concept for a fully automated and variant-compatible robot application based on the experiment is derived. Furthermore, the depth of disassembly is compared with the corresponding reduction of passive materials in the crushed mass. The findings indicate that several module components can be disassembled, resulting in cell recovery and a reduction of metal and plastic in the crushed mass by about 17 %, highlighting the importance of robotic disassembly in enhancing material separation efficiency during LIB recycling.

Process simulation and life cycle assessment of hydrometallurgical recycling routes of waste printed circuit boards

Electronic waste remains a pressing global environmental concern. Addressing the proper treatment and recycling of waste printed circuit boards (WPCBs) is imperative to mitigate environmental pollution and prevent the loss of valuable resources. In this study, a comparative analysis of acidic and alkaline leaching processes for recovering base metals (Cu, Sn, Zn, and Ni) from WPCBs was conducted by process simulation (using HSC software). Life cycle inventories were compiled accordingly. Furthermore, by incorporating an alternative method for precious metal recovery, the life cycles (using openLCA software) of both processes for recovering all metals were examined. The results revealed that while the acidic leaching process showed higher recoveries for base metals and advantages in terms of lower electricity consumption and wastewater generation, it also exhibited a more pronounced environmental impact due to the chemical input in the HNO3 leaching process. Conversely, the alkaline leaching process utilized fewer chemicals, generated less solid waste and off-gases, resulting in a lower overall environmental impact. For recycling 1 t of WPCBs, the acidic leaching process achieved recoveries of 92% for tin, 99% for copper, 79% for zinc, and 94% for nickel, whereas the alkaline leaching process yielded recoveries of 96%, 93%, 78%, and 74% for the corresponding metals. Notably, the alkaline leaching process demonstrated a lower global warming potential of 11,395 kg CO2 eq, compared to the 12,459 kg CO2 eq associated with the acidic leaching process. In the evaluation of the alkaline leaching process, most environmental impacts were found to be lower than for virgin production. As a result, while the acidic leaching process is indeed more efficient in metal recycling, the alkaline leaching process emerges as a stronger contender in terms of environmental sustainability, with great potential for further technical improvements.

Direct recycling of lithium-ion battery production scrap – Solvent-based recovery and reuse of anode and cathode coating materials

The rapid growth in the use of lithium-ion batteries is leading to an increase in the number of battery cell factories around the world associated with significant production scrap rates. Direct recycling of this scrap material has both environmental and economic benefits, such as reducing the carbon footprint of cell manufacturing, as well as reducing production costs and raw material requirements. In this work, a solvent-based direct recycling route for anode and cathode coating materials is presented that allows direct reuse of the recovered coating materials. A high yield of recovery is achieved by mechanical stress in a suitable solvent (96 % for anodes, 85 % for cathodes). The resulting suspension is used for electrode production to study the influence of direct recycled material on the resulting electrode and cell performance. It can be seen that the electrodes and cells with up to 10 % recyclate content have similar high performance in terms of electrical conductivities, initial discharge capacity (approx. 165 mAh g−1 for graphite/NMC622 coin cells) and C-rate stability. Overall, the work demonstrates that direct solvent-based recycling is an efficient method for recycling electrode scrap without compromising the performance of the cells produced when fresh material is added to the recycled suspension.

A Multistep, Multicomponent Extraction and Separation Microfluidic Route to Recycle Water-Miscible Ionic Liquid Solvents.

Recycling ionic liquid (IL) solvents can reduce the lifecycle cost of these expensive solvents. Liquid-liquid extraction is the most straightforward approach to purify IL solvents and is typically performed with an immiscible washing agent (e.g., water). Herein, we describe a recycling route for water-miscible ILs in which direct recycling is usually challenging. We use hydrophobic ILs as accommodating agents to draw the water-miscible IL from the aqueous washing stream. A biphasic slug flow of the mixed ILs and water is then separated by using a membrane. The water-miscible IL can then be drawn out from the mixed IL phase with acidified water and dried under vacuum. Both the water-miscible IL and the accommodating agent are then recycled. Here, we demonstrated a proof-of-concept of this process by recycling 1-butyl-3-methylimidazolium trifluoromethanesulfonate (BMIM-OTf) in the presence of the accommodating agent 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide (BMIM-NTf2) and acidified water. We then demonstrated the capacity to recycle 1-butyl-1-methylpyrrolidinium triflate (BMPYRR-OTf) from a realistic synthetic application: Pt nanoparticle synthesis in the water-miscible IL.