Recycling Methods Research Articles

Structure-Guided Engineering of a Versatile Urethanase Improves Its Polyurethane Depolymerization Activity.

Polyurethane (PUR), the fifth most prevalent synthetic polymer, substantially contributes to the global plastic waste problem. Biotechnology-based recycling methods have recently emerged as innovative solutions to plastic waste disposal and sparked interest among scientific communities and industrial stakeholders in discovering and designing highly active plastic-degrading enzymes. Here, the ligand-free crystal structure of UMG-SP2, a metagenome-derived urethanase with depolymerization activities, at 2.59 Å resolution, as well as its (co-)structures bound to a suicide hydrolase inhibitor and a short-chain carbamate substrate at 2.16 and 2.40 Å resolutions, respectively, is reported. Structural analysis and molecular dynamics simulations reveal that the flexible loop L3 consisting of residues 219-226 is crucial for regulating the hydrolytic activity of UMG-SP2. The semi-rational redesign of UMG-SP2 reveals superior variants, A141G and Q399A, exhibiting over 30.7- and 7.4-fold increased activities on polyester-PUR and a methylene diamine derivative of PUR, respectively, compared to the wild-type enzyme. These findings advance the understanding of the structure-function relationship of PUR-hydrolyzing enzymes, which hold great promise for developing effective industrial PUR recycling processes and mitigating the environmental footprint of plastic waste.

Impact of recyclability on the tensile and Impact properties of coated plastic materials for the automotive and electronic sectors

This research focuses on the study of the tensile modulus and impact resistance) of acrylonitrile-butadiene-styrene (ABS) and its blends with polycarbonate (ABS/PC) including recycled and painted material. A comprehensive assessment was done to determine the impact of reprocessing cycles, remaining coating and their combined effect in the final properties of the recycled polymer. Post-consumer materials are in an already-aged state, lowering their initial properties. Mechanical recycling methods showed that the reprocessing cycles have a higher impact on the mechanical performance than the amount of recycling material content. Also, the material is often coated when they are about to be recycled. The remaining coating impurities play a major role in the recycling process, losing up to 42% of the impact resistance for ABS and 28% for ABS/PC. It was demonstrated that below a 10% of remaining paint, both materials retained is performance as a neat product. Impurities was declared to be the most pernicious element on the recycling process and their elimination must be a priority regarding this objective. These results provide a better knowledge of the recycling effect and can be used to decide the potential recyclability of plastic. The ascribed project of this study (DECOAT) aims to develop efficient systems to remove coatings at the end-of-life of the part, to reduce the damage and promote the use of recycled material in high-tech applications.

Evaluating the Environmental and Energy Implications of Solar Panel Recycling in India: A Sustainability Assessment

Solar panel recycling is crucial for resource conservation, economic opportunities, and environmental impact reduction. Among different recycling methods, this study finds mechanical recycling to be most suitable for India, efficiently recovering valuable materials like silicon, silver, and cadmium/tellurium. Various recycling methods used globally were reviewed, however we specifically explore India’s context , where by 2030, solar panel waste is projected to reach 340,000 tons, highlighting the urgent need for effective recycling strategies. Our study shows that mechanical recycling can recover 85% of silicon, 70% of silver, and 60% of cadmium/tellurium, with estimated costs of ₹22/kg for silicon, ₹90,000/kg for silver, and ₹150,000/kg for cadmium/tellurium. Embracing these methods could reduce imports, benefitting both the economy and the environment.

Mechanical properties and micro-mechanisms of polyurethane foam treatment of construction waste

ABSTRACT The generation of construction and demolition waste (CDW) has been rising rapidly in recent years. However, the recycling rate of CDW remains low due to inherent challenges such as easy fragmentation, inadequate strength, and poor engineering properties of CDW particles. To address these issues, this study investigates the application of polyurethane foam adhesive (PFA) as a strengthening agent to enhance the mechanical and structural properties of CDW for use in civil engineering infrastructure. Unconfined compressive strength (UCS) tests and consolidated undrained triaxial compression (CU) tests were performed to evaluate the mechanical performance of PFA-modified CDW, while the microstructure was analyzed using Scanning Electron Microscopy (SEM). The results indicate a substantial increase in UCS with varying PFA content after 24 h of gelling. Specifically, UCS values increased by 123.7, 263.93, 497.78, and 737.18 kPa with successive increments in PFA content. Moreover, PFA exhibited a more pronounced enhancement of shear strength compared to UCS. At a PFA content of 6%, cohesion increased dramatically from 5.29 kPa to 868.96 kPa, while the internal friction angle rose from 35.83° to 39.53°. SEM analysis revealed that PFA improves the internal structure of CDW by cementing particles, filling voids, and forming cohesive aggregates. These findings propose a novel method for CDW recycling, offering significant potential for the broader adoption of PFA-enhanced CDW in engineering applications.

Magnetically recyclable CoFe2O4 nanocatalysts for efficient glycolysis of polyethylene terephthalate

Efficient and sustainable recycling of polyethylene terephthalate (PET) is essential in mitigating its environmental impacts on climate, human health, and global ecosystems. Glycolysis, a closed-loop recycling method that converts PET into bis(2-hydroxyethyl) terephthalate (BHET), stands out as one of the most promising methods due to its mild operating conditions and environmentally friendly nature. However, the complete convert PET into BHET with a high stability are still challenging. In this study, magnetically recyclable CoFe2O4 nanocatalysts were synthesized by the solvothermal method and surface-modulated with Na3Cit·2H2O as a modifier. When utilizing an optimized CoFe2O4 catalyst, conversion of PET achieved 100 %, with a BHET yield of 91.7 % at 210 °C for 1 h. The excellent catalytic performance of CoFe2O4 is attributed to its smaller particle size, improved dispersion, higher surface Co/Fe ratio, and increased oxygen vacancies, all of which can be achieved through straightforward surface modulation. DFT calculations of M−O distance (M = Co or Fe), adsorption energy, and Bader charges confirm that a higher surface Co/Fe ratio enhanced PET glycolysis, consistent with experimental results. Additionally, a modified energy economy coefficient (εm) was proposed to characterize the catalytic efficiency. The εm value of CoFe2O4-60 % was 0.624, indicating promising applications in efficient PET glycolysis. This work presents a versatile approach for easily manipulating the surface properties of magnetic catalysts and identifies key factors for achieving high performance in PET-to-BHET conversion. It offers valuable guidelines for the future design of nanoparticle catalysts with magnetic properties for chemocatalytic reactions.

Efficient Recycling Processes for Lithium-Ion Batteries

Lithium-ion batteries (LIBs) are an indispensable power source for electric vehicles, portable electronics, and renewable energy storage systems due to their high energy density and long cycle life. However, the exponential growth in production and usage has necessitated highly effective recycling of end-of-life LIBs to recover valuable resources and minimize the environmental impact. Pyrometallurgical and hydrometallurgical processes are the most common recycling methods but pose considerable difficulties. The energy-intensive pyrometallurgical recycling process results in the loss of critical materials such as lithium and suffers from substantial emissions and high costs. Solvent extraction, a hydrometallurgical method, offers energy-efficient recovery for lithium, cobalt, and nickel but requires hazardous chemicals and careful waste management. Direct recycling is an alternative to traditional methods as it preserves the cathode active material (CAM) structure for quicker and cheaper regeneration. It also offers environmental advantages of lower energy intensity and chemical use. Hybrid pathways, combining hydrometallurgical and direct recycling methods, provide a cost-effective, scalable solution for LIB recycling, maximizing material recovery with minimal waste and environmental risk. The success of recycling methods depends on factors such as battery chemistry, the scalability of recovery processes, and the cost-effectiveness of waste material recovery. Though pyrometallurgical and hydrometallurgical processes have secured their position in LIB recycling, research is proceeding toward newer approaches, such as direct and hybrid methods. These alternatives are more efficient both environmentally and in terms of cost with a broader perspective into the future. In this review, we describe the current state of direct recycling as an alternative to traditional pyrometallurgical and hydrometallurgical methods for recuperating these critical materials, particularly lithium. We also highlight some significant advancements that make these objectives possible. As research progresses, direct recycling and its variations hold great potential to reshape the way LIBs are recycled, providing a sustainable pathway for battery material recovery and reuse.

Shipping Logistics Network Optimization with Stochastic Demands for Construction Waste Recycling: A Case Study in Shanghai, China

In this paper, we introduce a shipping logistics network optimization method for construction waste recycling. In our case, construction waste is transported by a relay mode integrating land transportation, shipping transportation, and land transportation. Under the influence of urban economic life, the quantity (demand) of construction waste is uncertain and stochastic. Considering the randomness of construction waste generation, a two-stage stochastic integer programming model for the design of a shipping logistics network for construction waste recycling is proposed, and an accurate algorithm based on Benders decomposition is presented. Based on an actual case in Shanghai, numerical experiments are carried out to evaluate the efficacy of the proposed model and algorithm. Based on an actual case study in Shanghai, numerical experiments demonstrate that the proposed model can help to reduce transportation costs of construction waste. Sensitivity analysis highlights that factors like the penalty for untransported waste and capacity constraints play a crucial role in network optimization decisions. The findings provide valuable theoretical support for developing more efficient and sustainable logistics networks for construction waste recycling.

Water-Induced Integrated Regeneration of Cathode Materials from Spent Sodium-Ion Batteries.

The increasingly accumulated end-of-life batteries require high-efficiency regeneration technology for sustainable development. However, the existing recycling methods are highly restricted in a direct additive process due to the inconsistent content of alkaline ions within various spent materials and then failure to recover them together. Here, a subtractive process is introduced for the integrated regeneration of spent cathode materials, which successfully transforms the cathode materials with an unknown Na+ content to the desodiation phase together via water only. Because water and Na salt in NaOH solution are reused together after enough CO2 is absorbed, the regeneration process exhibits net zero emission and ∼100% recovery efficiency. Meanwhile, the regenerated materials display a similar cyclability to the pristine ones, while the former reserves 50.2% of production costs and half of the production time compared to the coprecipitation method. Furthermore, the integrated regeneration of single and polycrystals at various states as well as their mixtures is also verified following the same route. Accordingly, the water-induced subtractive process achieves the integrated recycling of end-of-life sodium-ion batteries and promotes the scale-up application and sustainable development of green energies.

Polymer Structural Composites Reinforced with Hemp Fibres—Impact Tests of Composites After Long-Term Storage in Representative Aqueous Environments and Fire Tests in the Context of Their Disposal by Energy Recycling Methods

This paper presents the potential for an alternative use of structural polymer composite reinforcement, made from natural industrial hemp (Cannabis sativa L.) fibres, in the manufacture of selected products in the shipbuilding industry. This research used fabrics made from unmodified and chemically modified industrial hemp fibres. The primary research focus was on determining the impact strength of the new eco-friendly structural composites produced after long-term storage in representative aqueous environments. Also presented are the results of fire response tests of these composites in the context of their disposal by energy recycling. The tests carried out also referred to a well-defined glass fibre-reinforced polymer composite, from which a control slab of the actual product was realistically produced in the form of a representative section of a 34-foot boat hull plate below the waterline. The results of this basic research into these structural composites confirmed the validity of continuing, respectively, application and implementation research, aimed at producing composites dedicated to selected products of the shipbuilding industry.

Waste Management of Wind Turbine Blades—A Review of Recycling Methods and Applications in Cementitious Composites

Waste Management of Wind Turbine Blades—A Review of Recycling Methods and Applications in Cementitious Composites

Impact of electric vehicle battery recycling on reducing raw material demand and battery life-cycle carbon emissions in China

The rapid growth of electric vehicles (EVs) in China challenges raw material demand. This study evaluates the impact of recycling and reusing EV batteries on reducing material demand and carbon emissions. Integrating a national-level vehicle stock turnover model with life-cycle carbon emission assessment, we found that replacing nickel-cobalt-manganese batteries with lithium iron phosphate batteries with battery recycling can reduce lithium, cobalt, and nickel demand between 2021 and 2060 by up to 7.8 million tons (Mt) (67%), 12.4 Mt (96%), and 37.2 Mt (93%), respectively, significantly decreasing reliance on import. Moreover, battery recycling coupled with reuse can reduce carbon emissions by up to 6,532-6,864 Mt (36.0-37.9%), depending on four recycling methods employed. However, this reuse strategy delays battery recycling and risks lithium supply shortage, necessitating trade-offs between carbon reduction and material supply. Future technologies, such as lithium-sulfur and all-solid-state batteries, despite their energy efficiency, might exacerbate lithium shortage, underscoring the crucial need for increased lithium supply.

Large-Scale Compatible Roll-to-Roll Coating of Paper Electrodes and Their Compatibility as Lithium-Ion Battery Anodes.

A recyclability perspective is essential in the sustainable development of energy storage devices, such as lithium-ion batteries (LIBs), but the development of LIBs prioritizes battery capacity and energy density over recyclability, and hence, the recycling methods are complex and the recycling rate is low compared to other technologies. To improve this situation, the underlying battery design must be changed and the material choices need to be made with a sustainable mindset. A suitable and effective approach is to utilize bio-materials, such as paper and electrode composites made from graphite and cellulose, and adopt already existing recycling methods connected to the paper industry. To address this, we have developed a concept for fabricating fully disposable and resource-efficient paper-based electrodes with a large-scale roll-to-roll coating operation in which the conductive material is a nanographite and microcrystalline cellulose mixture coated on a paper separator. The overall best result was achieved with coated roll 08 with a coat weight of 12.83(22) g/m2 and after calendering, the highest density of 1.117(97) g/cm3, as well as the highest electrical conductivity with a resistivity of 0.1293(17) mΩ·m. We also verified the use of this concept as an anode in LIB half-cell coin cells, showing a specific capacity of 147 mAh/g, i.e., 40% of graphite's theoretical performance, and a good long-term stability of battery capacity over extended cycling. This concept highlights the potential of using paper as a separator and strengthens the outlook of a new design concept wherein paper can both act as a separator and a substrate for coating the anode material.

Advances in the Recovery of Critical Rare Dispersed Metals (Gallium, Germanium, Indium) from Urban Mineral Resources.

Urban mineral resources, with their significant recycling potential, have increasingly accumulated worldwide and become an important source for extracting valuable metals, particularly critical rare dispersed metals (CRDMs) such as gallium, germanium, and indium. As the electronics industry continues to grow rapidly, the demand for CRDMs is rising. However, CRDMs in primary mineral resources are often found in small, dispersed concentrations, making extraction challenging. In contrast, urban mineral resources contain relatively higher concentrations of CRDMs, making their comprehensive exploitation more advantageous than that of primary minerals. This paper underscores the importance of metal recycling by examining the current state of e-waste recycling from urban mineral resources in China. It outlines the general process of e-waste recycling, briefly compares the advantages and disadvantages of common metal recycling methods, and summarizes the current status of CRDMs recycling from various electronic wastes. Finally, this paper discusses the development trends and future prospects of metal recycling technology in urban minerals.

Efficient and Scalable Direct Regeneration of Spent Layered Cathode Materials via Advanced Oxidation.

Among direct recycling methods for spent lithium-ion batteries, solid-state regeneration is the route with minimal bottlenecks for industrial application and is highly compatible with the current industrial cathode materials production processes. However, surface structure degradation and interfacial impurities of spent cathodes significantly hinder Li+ replenishment during restoration. Herein, we propose a unique advanced oxidation strategy that leverages the inherent catalytic activity of spent layered cathode materials to address these challenges. This strategy decomposes H2O2 to generate •OH and •O2 - free radicals, facilitating oxidation reactions with the surface of the spent cathode. As a result, this approach effectively elevates the Ni valence state, modifies the surface microstructure, and eliminates fluorine-containing interface impurities, thereby promoting the solid-state regeneration process. The regenerated LiNi0.83Co0.12Mn0.05O2 cathodes demonstrate a specific capacity of 206mAhg-1 at 0.1 C, comparable to commercially available cathodes. Meanwhile, this advanced oxidation strategy proves adaptable and scalable for treating industrial dismantled LiNi0.5Co0.2Mn0.3O2 black mass. A 3.1Ah pouch cell assembled with the regenerated LiNi0.5Co0.2Mn0.3O2 exhibits impressive capacity retention of 74% after 500 cycles. Additionally, a techno-economic analysis reveals that this strategy possesses low energy consumption, minimal environmental footprint, and high economic viability, suggesting its suitability for the battery recycling industry.

Emerging Trends and Future Opportunities for Battery Recycling.

The global lithium-ion battery recycling capacity needs to increase by a factor of 50 in the next decade to meet the projected adoption of electric vehicles. During this expansion of recycling capacity, it is unclear which technologies are most appropriate to reduce costs and environmental impacts. Here, we describe the current and future recycling capacity situation and summarize methods for quantifying costs and environmental impacts of battery recycling methods with a focus on cathode active materials. Second use, electrification of pyrometallurgy and hydrometallurgy, direct recycling, and electrochemical recycling methods are discussed as leading-edge methods for overcoming state of the art battery recycling challenges. The paper ends with a discussion of future issues and considerations regarding solid-state batteries and co-optimization of battery design for recycling.

Sustainable Management of Photovoltaic Waste Through Recycling and Material Use in the Construction Industry.

The rapid expansion of photovoltaic (PV) technology as a source of renewable energy has resulted in a significant increase in PV panel waste, creating environmental and economic challenges. A promising strategy to address these challenges is the reuse of glass waste from decommissioned PV panels as a component of cementitious materials. This review explores the potential of integrating glass waste from PV panels into cementitious materials, focusing on its impact on their mechanical, thermal, and durability properties. This analysis includes various methods of processing PV glass waste, such as crushing and grinding, to obtain the desired particle size for cementitious applications. It goes on to analyze how advances in cementitious materials can facilitate the incorporation of PV glass waste, helping to improve properties such as compressive strength, workability, and setting time. In addition, this review makes a detailed analysis of the long-term sustainability and environmental benefits of PV glass waste, highlighting its potential to reduce the carbon footprint of cementitious materials. Incorporating PV glass waste can improve certain properties of cementitious materials, resulting in increased durability and improved thermal insulation, while contributing to waste reduction and resource conservation. This review highlights the importance of developing standardized recycling methods and integration processes and identifies areas for further research to optimize the use of PV glass waste in cement formulations. Ultimately, the sustainable integration of PV glass panel waste into cementitious materials is a viable approach to promote green building practices and support a circular economy in the construction industry.

Large Language Modeling to Assist Natural Polyphenols as Green Precipitants for Recycling Spent Batteries.

The growing demand for energy storage batteries, driven by the need to alleviate global warming and reduce fossil fuel dependency, has led to environmental concerns surrounding spent batteries. Efficient recycling of these batteries is essential to prevent pollution and recover valuable metal ions such as nickel (Ni2+), cobalt (Co2+), and manganese (Mn2+). Conventional hydrometallurgical methods for battery recycling, while effective, often involve harmful chemicals and processes. Natural polyphenols offer a greener alternative due to their ability to coordinate with metal ions. However, optimizing polyphenol selection for efficient recovery remains a labor-intensive challenge. This study presents a strategy combining natural polyphenols as green precipitants with the power of GPT-4, a large language model (LLM), to enhance the precipitation and recovery of metal ions from spent batteries. By leveraging the capabilities of GPT-4 in natural language processing, we enable a dynamic, iterative collaboration between human researchers and the LLM, optimizing polyphenol selection for different experimental conditions. The results show that tannic acid achieved precipitation rates of 94.8, 96.7, and 96.7% for Ni2+, Co2+, and Mn2+, respectively, outperforming conventional methods. The integration of GPT-4 enhances both the efficiency and accuracy of the process, ensuring environmental sustainability by minimizing secondary pollution and utilizing biodegradable materials. This innovative strategy demonstrates the potential of combining artificial intelligence-driven analysis with green chemistry to address battery recycling challenges, paving the way for more sustainable and efficient methods.

Design Principles for Efficient Hydrothermal Relithiation of Spent Lithium Iron Phosphate.

Direct regeneration, which involves replenishing lithium in spent cathode materials, is emerging as a promising recycling technique for spent lithium iron phosphate (s-LFP) cathodes. Unlike solid-state regeneration, the aqueous relithiation method consumes less energy, ensures even lithium replenishment, and significantly recovers the capacity of s-LFP. However, liquid-phase lithium replenishment formulations are generally less standardized. In this study, we propose designing principles for hydrothermal relithiation recipes to achieve efficient relithiation while ensuring a high yield of relithiated LFP products, assisted by various electrochemical techniques. This led to the discovery of an economical hydrothermal relithiation approach. Specifically, using sulfurous acid (H2SO3) as the reducing agent and LiOH as the lithium source in the hydrothermal precursor, we achieved complete relithiation at a mild hydrothermal temperature of 90 °C with a high yield (only 3.1% mass loss) of relithiated LFP products. The regenerated LFP recovers approximately 29% of its capacity and exhibits remarkable capacity retention (98.9%). This research highlights a significant advancement in the efficient hydrothermal regeneration of s-LFP, presenting a green and economically viable method for LFP recycling and setting a benchmark for sustainable battery recycling technologies.

Synthesis of photocatalyst composite films from recycled plastics via hot pressing for dye wastewater treatment

Recycled plastic-derived photocatalyst films efficiently degrade dye wastewater, offering a sustainable method for waste recycling and environmental protection.

Heterogeneous catalysis strategies for polyolefin plastic upcycling: co-reactant-assisted and direct transformation under mild conditions.

The large-scale production and inadequate disposal of polyolefin (PO) plastics pose significant environmental challenges. Traditional recycling methods are energy-intensive and often ineffective, prompting a need for more sustainable approaches. In recent years, catalytic upcycling under mild conditions has emerged as a promising strategy to transform PO plastics into valuable products. Co-reactants such as hydrogen, short-chain alkanes or alkenes, oxygen, and CO2 play a crucial role in driving these transformations, influencing reaction mechanisms and broadening the range of possible products. This review categorizes recent advancements in PO plastic upcycling based on the type of co-reactant employed and compares these with direct, co-reactant-free processes. Despite these advances, challenges remain in improving catalytic stability, product selectivity, and overcoming diffusion limitations in viscous plastic feedstocks. This review underscores the catalytic chemistry underpinning the development of efficient PO plastic upcycling processes with co-reactants, offering insights into future directions for sustainable plastic chemical management.