Plastic Economy Research Articles

Developing a prediction model in a lightweight packaging waste sorting plant using sensor-based sorting data combined with data of external near-infrared and LiDAR sensors.

Sensor-based material flow monitoring allows for continuously high output qualities, through quality management and process control. The implementation in the waste management sector, however, is inhibited by the heterogeneity of waste and throughput fluctuations. In this study, challenges and possibilities of using different types of sensors in a lightweight packaging waste sorting plant are investigated. Three external sensors have been mounted on different positions in an Austrian sorting plant: one Light Detection and Ranging (LiDAR) sensor for monitoring the volume flow and two near-infrared (NIR) sensors for measuring the pixel-based material composition and occupation density. Additionally, the data of an existing sensor-based sorter (SBS) were evaluated. To predict the newly introduced parameter material-specific occupation density (MSOD) of multi-coloured polyethylene terephthalate (PET) preconcentrate, different machine learning models were evaluated. The results indicate that using SBS data for both monitoring of throughput fluctuations caused by different bag opener settings as well as monitoring the material composition is feasible, if the pre-set teach-in is suitable. The ridge regression model based on SBS was comparable (RMSE = 3.59 px%, R² = 0.57) to the one based on NIR and LiDAR (RMSE = 3.1 px%, R² = 0.68). The demonstrated feasibility of the implementation at plant scale highlights the opportunities of sensor-based material flow monitoring for the waste management sector and paves the way towards a more circular plastics economy.

Addressing Plastic Concern: Behavioral Insights into Recycled Plastic Products and Packaging in a Circular Economy

The excessive production and use of new plastic materials pose a critical environmental challenge, and reducing its consumption has emerged as a major global hurdle. Understanding human behavior is thus essential for creating a circular economy for plastics. The study aims to gain insights into consumers' buying habits concerning recycled plastic, which has received relatively little attention in prior research on the subject of environmentally friendly consumer behavior. This study draws on the Theory of Planned Behavior to analyze the factors influencing consumer behavior regarding products and packaging made from recycled plastic. To this end, we employed a questionnaire, which was administered to 511 consumers in Italy. Results support that concerns about plastics and perceived efficacy exert a direct influence on attitudes. Additionally, our findings demonstrate that social norms, attitudes, and perceived behavioral control significantly shape purchasing behaviors concerning recycled plastic. The research contributes to extending the Theory of Planned Behavior model in predicting environmental-friendly behavior by adding new empirical evidence and provides valuable suggestions for companies to develop effective communication strategies and policies to redirect plastic consumption behavior towards less-impacting use of plastic.

Bridged Bicyclic Lactam Enables Chemically Recyclable Nylon

AbstractNylon, a widely‐used high‐performance thermoplastic, boasts exceptional durability and resistance to various solvents and weak acids, making it indispensable across diverse applications. However, its nonbiodegradable nature has led to alarming environmental pollution in land and oceans. Chemical recycling to monomers (CRM) stands as a crucial strategy for establishing a circular plastic economy, but the CRM of nylon remains largely unexplored. Herein, we introduce the bridged bicyclic lactam 5‐azabicyclo[2.2.1]octan‐6‐one (5/6‐LM), evolved from δ‐valerolactam and pyrrolidone, to solve the trade‐off in depolymerizability and performance. Notably, 5/6‐LM exhibits nearly 95 % conversion in mild polymerization conditions and efficient depolymerization catalyzed by lewis acids. This compound is synthetically accessible from commercially available chemicals in a single step at room temperature, demonstrating high efficiency and scalability up to 50 g in laboratory. Furthermore, the resulting polyamide displays remarkable attributes including high crystallinity and thermostability up to 283 °C, significantly broadening the scope of chemically recyclable nylons.

Bridged Bicyclic Lactam Enables Chemically Recyclable Nylon.

Nylon, a widely-used high-performance thermoplastic, boasts exceptional durability and resistance to various solvents and weak acids, making it indispensable across diverse applications. However, its nonbiodegradable nature has led to alarming environmental pollution in land and oceans. Chemical recycling to monomers (CRM) stands as a crucial strategy for establishing a circular plastic economy, but the CRM of nylon remains largely unexplored. Herein, we introduce the bridged bicyclic lactam 5-azabicyclo[2.2.1]octan-6-one (5/6-LM), evolved from δ-valerolactam and pyrrolidone, to solve the trade-off in depolymerizability and performance. Notably, 5/6-LM exhibits nearly 95 % conversion in mild polymerization conditions and efficient depolymerization catalyzed by lewis acids. This compound is synthetically accessible from commercially available chemicals in a single step at room temperature, demonstrating high efficiency and scalability up to 50 g in laboratory. Furthermore, the resulting polyamide displays remarkable attributes including high crystallinity and thermostability up to 283 °C, significantly broadening the scope of chemically recyclable nylons.

Magnetic resonance insights into the heterogeneous, fractal-like kinetics of chemically recyclable polymers.

Moving toward a circular plastics economy is a vital aspect of global resource management. Chemical recycling of plastics ensures that high-value monomers can be recovered from depolymerized plastic waste, thus enabling circular manufacturing. However, to increase chemical recycling throughput in materials recovery facilities, the present understanding of polymer transport, diffusion, swelling, and heterogeneous deconstruction kinetics must be systematized to allow industrial-scale process design, spanning molecular to macroscopic regimes. To develop a framework for designing depolymerization processes, we examined acidolysis of circular polydiketoenamine elastomers. We used magnetic resonance to monitor spatially resolved observables in situ and then evaluated these data with a fractal method that treats nonlinear depolymerization kinetics. This approach delineated the roles played by network architecture and reaction medium on depolymerization outcomes, yielding parameters that facilitate comparisons between bulk processes. These streamlined methods to investigate polymer hydrolysis kinetics portend a general strategy for implementing chemical recycling on an industrial scale.

Corrosion Engineering of Part-Per-Million Single Atom Pt1/Ni(OH)2 Electrocatalyst for PET Upcycling at Ampere-Level Current Density.

The plastic waste issue has posed a series of formidable challenges for the ecological environment and human health. While conventional recycling strategies often lead to plastic down-cycling, the electrochemical strategy of recovering valuable monomers enables an ideal, circular plastic economy. Here a corrosion synthesized single atom Pt1/Ni(OH)2 electrocatalyst with part-per-million noble Pt loading for highly efficient and selective upcycling of polyethylene terephthalate (PET) into valuable chemicals (potassium diformate and terephthalic acid) and green hydrogen is reported. Electro-oxidation of PET hydrolysate, ethylene glycol (EG), to formate is processed with high Faraday efficiency (FE) and selectivity (>90%) at the current density close to 1000mAcm-2 (1.444V vs RHE). The in situ spectroscopy and density functional theory calculations provide insights into the mechanism and the understanding of the high efficiency. Remarkably, the electro-oxidation of EG at the ampere-level current density is also successfully illustrated by using a membrane-electrode assembly with high FEs to formate integrated with hydrogen production for 500h of continuous operation. This process allows valuable chemical production at high space-time yield and is highly profitable (588-700$ton-1 PET), showing an industrial perspective on single-atom catalysis of electrochemical plastic upcycling.

Recyclable and (Bio)degradable Polyesters in a Circular Plastics Economy.

Polyesters carrying polar main-chain ester linkages exhibit distinct material properties for diverse applications and thus play an important role in today's plastics economy. It is anticipated that they will play an even greater role in tomorrow's circular plastics economy that focuses on sustainability, thanks to the abundant availability of their biosourced building blocks and the presence of the main-chain ester bonds that can be chemically or biologically cleaved on demand by multiple methods and thus bring about more desired end-of-life plastic waste management options. Because of this potential and promise, there have been intense research activities directed at addressing recycling, upcycling or biodegradation of existing legacy polyesters, designing their biorenewable alternatives, and redesigning future polyesters with intrinsic chemical recyclability and tailored performance that can rival today's commodity plastics that are either petroleum based and/or hard to recycle. This review captures these exciting recent developments and outlines future challenges and opportunities. Case studies on the legacy polyesters, poly(lactic acid), poly(3-hydroxyalkanoate)s, poly(ethylene terephthalate), poly(butylene succinate), and poly(butylene-adipate terephthalate), are presented, and emerging chemically recyclable polyesters are comprehensively reviewed.

Unveiling the environmental gains of biodegradable plastics in the waste treatment phase: A cradle-to-crave life cycle assessment

Biodegradable plastics have emerged as promising and sustainable solutions for addressing the environmental challenges caused by plastic wastes. In this study, we present a comprehensive cradle-to-grave life cycle assessment (LCA) of two prominent biodegradable plastics, polyhydroxybutyrate (PHB) and polylactic acid (PLA), to quantitatively evaluate their environmental impact. In cradle-to-gate analysis, production processes of biodegradable plastics from their respective raw materials were analyzed. The global warming potentials (GWPs) for 1 kg of PHB and PLA plastics were 3.09 CO2 equivalent (kg CO2 eq.) and 5.79 kg CO2 eq., respectively, which were higher than those of fossil-based plastics. However, gate-to-grave LCA demonstrated that the superior end-of-life (EOL) options for biodegradable plastics, such as anaerobic digestion and incineration, result in an overall reduction in GWP under well-controlled waste management scenarios. These findings underscore the importance of developing technology and infrastructure for the effective treatment of biodegradable plastic waste, in addition to expanding its market share. Furthermore, the comprehensive cradle-to-grave LCA provides valuable guidance for policymakers to incentivize emission reductions throughout the entire product life cycle, rather than focusing on localized scopes. We believe that the insights from this study will encourage extensive discussions on both technical and regulatory aspects, facilitating efforts towards a more sustainable plastic economy.

CO2 and Lignin‐Based Sustainable Polymers with Closed‐Loop Chemical Recycling

AbstractThis work highlights the conversion method of chaining up greenhouse gas CO2 with biomass lignin to develop new sustainable, recyclable polymers from abundant and non‐food based renewable resources. A cyclic carbonate monomer has synthesized using a cost‐effective, non‐phosgene‐based, and greener approach under atmospheric pressure and room temperature. The fully programable ring‐opening polymerization is accomplished by varying the catalyst (DBU and TBD), catalyst loading (0.5–5.0%) and reaction time (2–40 min). The best polymer is obtained in 1% TBD with a 30‐min reaction. The precise characterization of the synthesized cyclic carbonate monomer and polymers' structure are established using spectroscopic analyses including 1H, 13C, and 2D HSQC NMR, FT‐IR, and GPC. The new polymers exhibit high molecular weights (Mn: 120.34–154.58 kDa) and adequate thermal stabilities (Td5%: 244–277 °C from TGA and Tg: 33–52 °C from DSC), rendering them advantageous for practical applications. Significantly, the CO2 and lignin‐based polymers have successfully recycled to the monomer for a circular plastic economy by heating at 90 °C for 12 h in the presence of DBU. This process yields original monomers for another polymerization without unwanted changes in chemical structures, presenting an ultimate sustainable solution.

Interface-engineering of the Catalysts for Efficient Electrocatalytic Upcycling of Polyethylene Terephthalate Waste

Plastics have become an essential component of our daily lives, but their widespread use has resulted in significant environmental and ecological pollution. Conventional methods for plastic waste treatment are both environmentally unfriendly and energy-intensive. In recent years, the emergence of electrocatalytic degradation technology for plastic waste has opened up new possibilities for converting waste plastics into valuable chemicals, thus promoting the realization of a circular economy for plastics. This review aims to provide an in-depth overview of the fundamental principles and characteristics of interfaces, focusing on the electrocatalytic degradation of ethylene glycol (EG) derived from polyethylene terephthalate (PET). This review primarily examines the two primary methods of electrocatalytic oxidation reactions of PET-derived EG, along with the advancements in interface engineering technology. It delves into the research progress made in interface catalysts for the electrocatalysis of PET-derived EG, while also discussing future research directions. The objective is to delve deeper into the development of effective electrocatalytic degradation catalysts, to address the pressing challenges posed by the ecological environmental crisis and the imperative need for transforming and upgrading PET plastic waste.

The global governance of marine plastic pollution: rethinking the extended producer responsibility system

The harm caused by marine plastic pollution to the wider environment highlights its importance as a governance issue. The Fifth United Nations Environment Assembly (UNEA) adopted a resolution, “End Plastic Pollution: Towards an International Legally Binding Instrument”, which represents a shift towards globalism in the governance of marine plastic pollution. This resolution focuses on the circular economy of plastics and highlights the role of corporations in contributing to a more socially responsible society, thereby increasing emphasis has been placed on the Extended Producer Responsibility (EPR) system that integrates the two factors referred to above. This paper provides a full technical explanation of the EPR system and its implementation in entities such as the European Union, the United States, and China. The challenges faced when integrating the EPR system into international legal instruments for plastic governance were identified, including the different national perspectives, the absence of a supervisor in the public domain, the obscurity of its application, and the lack of supporting measures for the implementation of the system. Therefore, new standards and requirements in the governance of marine plastic pollution and the advantages associated with implementing the full-life-cycle obligations under the EPR system on plastic producers should be fully considered. On this basis, the positioning and implications of the EPR system should be clarified by obligation-oriented regulation and extension-based interpretation. Moreover, the extended and prolonged applicability of the system, including the original sources of marine plastic wastes and considerations of the full-life-cycle of plastics, should be achieved in pursuit of improvements and upgrades in application and complementary policies. If this can be achieved, it is hoped that the goals of protecting human health and controlling plastic pollution can be achieved, contributing to the development of an ocean-based economy and a better world.

Science-based evidence on pathways and effects of human exposure to micro- and nanoplastics.

Human exposure to plastic particles has raised great concern among all relevant stakeholders involved in the protection of human health due to the contamination of the food chain, surface waters, and even drinking water as well as due to their persistence and bioaccumulation. Now more than ever, it is critical that we understand the biological fate of plastics and their interaction with different biological systems. Because of the ubiquity of plastic materials in the environment and their toxic potential, it is imperative to gain reliable, regulatory-relevant, science-based data on the effects of plastic micro- and nanoparticles (PMNPs) on human health in order to implement reliable risk assessment and management strategies in the circular economy of plastics. This review presents current knowledge of human-relevant PMNP exposure doses, pathways, and toxic effects. It addresses difficulties in properly assessing plastic exposure and current knowledge gaps and proposes steps that can be taken to underpin health risk perception, assessment, and mitigation through rigorous science-based evidence. Based on the existing scientific data on PMNP adverse health effects, this review brings recommendations on the development of PMNP-specific adverse outcome pathways (AOPs) following the AOP Users' Handbook of the Organisation for Economic Cooperation and Development (OECD).

Integrated analytical hierarchy process-grey relational analysis approach for mechanical recycling scenarios of plastics waste in India.

Mechanical recycling is an indispensable tool for plastic waste (PW) recycling and has the highest share in the PW recycling sector in India. The transition to the circular economy of plastics (CEoP) needs a systemic perspective on the mechanical recycling processes. Nevertheless, the assessment of multiple parameters influencing the mechanical recycling of PW is a complex decision-making problem for the development of triple-bottom-line mechanical recycling. A systemic perspective of various mechanical recycling scenarios was performed by employing a multi-criteria decision-making approach to examine the complexity of interlinked factors in the present investigation. Analytical hierarchy process (AHP) integrated with grey relational analysis (GRA) was used to evaluate the criteria that directly influence quality-oriented mechanical recycling. Data were collected by conducting semi-structured interviews using a framed questionnaire in stakeholder engagement with mechanical recyclers of PW. The first level hierarchy included economy, technical, resource consumption and environmental criteria. These criteria were further categorized into various significant indices such as quality of recyclate, recyclability, water and energy consumption during recycling. The results of the integrated grey relational analysis indicated that the technical parameters including quality of recyclate, resource efficiency, PW processing rate and recyclability have a significant influence on mechanical recycling. Based on AHP-GRA, scenario MR6, i.e. manufacturing of PET strap from recycled PET flakes, was ranked the optimal mechanical process amongst the various scenarios. MR6 was followed by Straps and Films at the second and third rank. The lowest ranking was observed for polymer blend recycling. These processes with higher ranks produced good quality recyclate with better efficiency and recyclability. Moreover, these processes consumed optimal resources during manufacturing. These processes also exhibited less maintenance cost, high production rate, low chemical consumption and waste generation as well as implemented pollution control practices.

Global Plastic Pollution and the Transition Towards a Circular Economy: Lessons from the EU’s Legal Framework on Plastics

Since the 1950s, billions of tons of primary plastic waste have been generated around the globe to date. Instead of the current linear make-use-dispose plastic economy, a circular plastics economy is said to be able to reduce plastic pollution in the environment. Recently, the United Nations Environment Assembly adopted a resolution to forge a globally binding treaty addressing plastic pollution by addressing the full life cycle of plastics and by taking such a circular approach. A circular approach for plastics has already been adopted by the EU. Therefore, this contribution sets out some lessons that the UN Treaty can learn from the implementation of the EU’s circular approach for plastics. These relate to the restriction on placing on the market of certain plastic products, the introduction of ecodesign requirements and the establishment of EPR schemes. The EU legal framework on plastics shows that it is important to take into account the inherent interlinkage between not only plastic life cycle stages, but also between the different provisions and obligations, in order to maximize the contribution to and unlock synergies in tackling plastic pollution.

Technological Advances in Mechanical Recycling Innovations and Corresponding Impacts on the Circular Economy of Plastics

The impact of plastic pollution on the world and its inhabitants is yet to be fully measured. Significant quantities of microplastics and nanoplastics have been found in human organs, and many diseases have been traced to their presence. Even human placentas have been found to contain microplastics. This study examines the recycling landscape, advanced reprocessing techniques, and technical challenges in this industry. It points out the top recyclable types of plastics (such as high-density polyethylene, polyethylene terephthalate, and thermoplastic elastomers) by analyzing their different recycling capacities globally. It highlights the most advisable recycling techniques by identifying those most successful, least environmentally damaging, and easiest. Mechanical recycling is arguably the easiest and most common recycling technique. This study examines mechanical reprocessing technologies for construction materials, composite boards, additive manufacturing, and other applications. It also points out prevailing setbacks of these approaches and analyzes different solutions. Promising recycling processes are suggested for further investigation.

Photocatalytic Upgrading of Polylactic Acid Waste into Alanine under Mild Conditions

AbstractPolylactic acid (PLA) has attracted increasing interest as a sustainable plastic because it can be degraded into CO2 and H2O in nature. However, this process is sluggish, and even worse, it is a CO2‐emitting and carbon resource waste process. Therefore, it is highly urgent to develop a novel strategy for recycling post‐consumer PLA to achieve a circular plastic economy. Herein, we report a one‐pot photoreforming route for the efficient and selective amination of PLA waste into value‐added alanine using CoP/CdS catalysts under mild conditions. Results show the alanine production rate can reach up to 2.4 mmol gcat−1 h−1, with a high selectivity (>75 %) and excellent stability. Time‐resolved transient absorption spectra (TAS) reveal that CoP can rapidly extract photogenerated electrons from CdS to accelerate proton reduction, favoring hole‐dominated PLA oxidation to coproduce alanine. This study offers an appealing way for upcycling PLA waste and creates new opportunities for green synthesis of amino acids.

Photocatalytic Upgrading of Polylactic Acid Waste into Alanine under Mild Conditions.

Polylactic acid (PLA) has attracted increasing interest as a sustainable plastic because it can be degraded into CO2 and H2O in nature. However, this process is sluggish, and even worse, it is a CO2-emitting and carbon resource waste process. Therefore, it is highly urgent to develop a novel strategy for recycling post-consumer PLA to achieve a circular plastic economy. Herein, we report a one-pot photoreforming route for the efficient and selective amination of PLA waste into value-added alanine using CoP/CdS catalysts under mild conditions. Results show the alanine production rate can reach up to 2.4 mmol gcat -1 h-1, with a high selectivity (>75 %) and excellent stability. Time-resolved transient absorption spectra (TAS) reveal that CoP can rapidly extract photogenerated electrons from CdS to accelerate proton reduction, favoring hole-dominated PLA oxidation to coproduce alanine. This study offers an appealing way for upcycling PLA waste and creates new opportunities for green synthesis of amino acids.

Designing a circular carbon and plastics economy for a sustainable future.

The linear production and consumption of plastics today is unsustainable. It creates large amounts of unnecessary and mismanaged waste, pollution and carbon dioxide emissions, undermining global climate targets and theSustainable Development Goals. This Perspective provides an integrated technological, economic and legal view on how to deliver a circular carbon and plastics economy that minimizes carbon dioxide emissions. Different pathways that maximize recirculation of carbon (dioxide) between plastics waste and feedstocks are outlined, including mechanical, chemical and biological recycling, and those involving the use of biomass and carbon dioxide. Four future scenarios are described, only one of which achieves sufficient greenhouse gas savings in line with global climate targets. Such a bold system change requires 50% reduction in future plastic demand, complete phase-out of fossil-derived plastics, 95% recycling rates of retrievable plastics and use of renewable energy. It is hard to overstate the challenge of achieving this goal. We therefore present a roadmap outlining the scale and timing of the economic and legal interventions that could possibly support this. Assessing the service lifespan and recoverability of plastic products, along with considerations of sufficiency and smart design, canmoreoverprovide design principles to guide future manufacturing, use and disposal of plastics.

Valorising Cassava Peel Waste Into Plasticized Polyhydroxyalkanoates Blended with Polycaprolactone with Controllable Thermal and Mechanical Properties

Approximately 99% of plastics produced worldwide were produced by the petrochemical industry in 2019 and it is predicted that plastic consumption may double between 2023 and 2050. The use of biodegradable bioplastics represents an alternative solution to petroleum-based plastics. However, the production cost of biopolymers hinders their real-world use. The use of waste biomass as a primary carbon source for biopolymers may enable a cost-effective production of bioplastics whilst providing a solution to waste management towards a carbon–neutral and circular plastics economy. Here, we report for the first time the production of poly(hydroxybutyrate-co-hydroxyvalerate) (PHBV) with a controlled molar ratio of 2:1 3-hydroxybutyrate:3-hydroxvalerate (3HB:3HV) through an integrated pre-treatment and fermentation process followed by alkaline digestion of cassava peel waste, a renewable low-cost substrate, through Cupriavidus necator biotransformation. PHBV was subsequently melt blended with a biodegradable polymer, polycaprolactone (PCL), whereby the 30:70 (mol%) PHBV:PCL blend exhibited an excellent balance of mechanical properties and higher degradation temperatures than PHBV alone, thus providing enhanced stability and controllable properties. This work represents a potential environmental solution to waste management that can benefit cassava processing industries (or other crop processing industries) whilst developing new bioplastic materials that can be applied, for example, to packaging and biomedical engineering.Graphical

Polyurethane with β‐Selenocarbonyl Structure Enabling the Combination of Plastic Degradation and Waste Upcycling

AbstractDegradable polymers offer a promising solution to mitigate global plastic pollution, but the degraded products often suffer from diminished value. Upcycling is a more sustainable approach to upgrade polymer waste into value‐added products. Herein, we report a β‐selenocarbonyl‐containing polyurethane (SePU), which can be directly degraded under mild conditions into valuable selenium fertilizers for selenium‐rich vegetable cultivation globally, enabling both plastic degradation and waste upcycling. Under oxidation condition, this polymer can be easily and selectively degraded via selenoxide elimination reaction from mixed plastic waste. The degraded product can serve as effective selenium fertilizers to increase selenium content in radish and pak choi. The SePU exhibits excellent mechanical properties. Additionally, we observed the formation of spherulites‐like selenium particles within the materials during degradation for the first time. Our research offers a successful application of selenoxide elimination reaction in the field of plastic degradation for the first time, endowing plastics with both degradability and high reusable value. This strategy provides a promising solution to reduce pollution and improve economy and sustainability of plastics.