Mixed Plastics Research Articles

Photooxidation of Polyolefins to Produce Materials with In-chain Ketones and Improved Materials Properties.

Herein, we report a selective photooxidation of commodity postconsumer polyolefins to produce polymers with in-chain ketones. The reaction does not involve the use of catalyst, metals, or expensive oxidants, and selectively introduces ketone functional groups. Under mild and operationally simple conditions, yields up to 1.23 mol% of in-chain ketones were achieved. Installation of in-chain ketones resulted in materials with improved adhesion of the materials and miscibility of mixed plastics relative to the unfunctionalized plastics. The introduction of ketone groups into the polymer backbone allows these materials to react with diamines, forming dynamic covalent polyolefin networks. This strategy allows for the upcycling of mixed plastic waste into reprocessable materials with enhanced performance properties compared to polyolefin blends. Mechanistic studies support the involvement of photoexcited nitroaromatics in consecutive hydrogen and oxygen atom transfer reactions.

Microwave-assisted pyrolysis of plastic waste for liquid oil production

In this work, the article presents the results of the production of fuel oil from plastic waste using microwave-assisted pyrolysis. Under the influence of microwave power, microwave absorption material, time, catalyst, polyethylene (PE), polypropylene (PP), polystyrene (PS) and mixture (34% PE + 33% PP + 33 wt% PS) were pyrolyzed to liquid oil. The results showed that with 500 g of raw plastic, 500 W microwave power, and 120 minutes, the carbon absorber accounted for 10 wt% (compared to plastic), catalysts accounted for 20 wt%, fuel efficiency reached 84% with PS and PP, 83% with PE, and 83.5% with mixed plastics. The oil obtained qualified the standards of FO No. 1 TCVN 6239:2019. The gas chromatography/mass spectroscopy GC/MS analysis (GC-MS) showed that the composition of the pyrolysis oil is mainly hydrocarbon from C7-C12.

Applications of H2-Enriched syngas and slag products from plastic wastes via novel plasma dual-stage-arc pyrolysis

Sustainable plastic waste management in the prevailing ‘new-normal’ post-pandemic scenario calls for calorific waste plastic up-cycling into high-end product recovery pathways. The present work employed a novel dual-stage arc plasma pyrolysis reactor to recover syngas and slag products from mixed plastics and Low-Density Polyethylene and Polyethylene Terephthalate (LDPE-PET) plastic waste feeds. Syngas product yield decreased while the solid slag yield increased with rising arc current, attaining 75% and 25% for mixed plastic waste feed and 59% and 41% for LDPE-PET wastes, respectively, at 200A arc current. The resultant syngas composition showed 83% and 77% H2 while 1.7% and 2.7% CO for mixed plastic waste-feed and LDPE-PET wastes, respectively, with no significant presence of CO2. Slag characterization studies revealed the presence of scattered pores on the slag surface, graphitic nanostructures due to scraped carbon depositions from electrode tips and the absence of aromatic groups due to complete conversion. High carbon content was observed in the slag due to the dissociation of lighter hydrocarbon and carbon dioxide on dual-arc exposure in two stages, underscoring the higher efficiency. For holistic integrated circular onsite ‘plastic waste-to-resource’ recovery-cum-application, electricity was generated from the resultant syngas and the slag was used for the manufacture of tiles in the community platform. Techno-economic evaluation of an up-scaled plasma pyrolysis facility shows the power recovery of 3.5 kWh/kg of waste plastic, with a net annual profit of $2800 and a payback period of 1.7 years. The findings of the present work suggest that the proposed integrated dual-arc plasma pyrolysis based plastic waste-to-resource recovery in circular-economy model has a viable outcome.

Navigating the depths of refuse-derived fuel in Canada: From heterogeneity to insightful analysis

ABSTRACT Refuse-derived fuel (RDF) presents inherent heterogeneity, encompassing diverse physical and chemical compositions. This study aims to comprehensively investigate the thermogravimetric characteristics of key RDF fractions and compare them with RDF compositions from Canada and other countries. A representative RDF sample was obtained using three ASTM standard procedures, including the quartering technique, manual sorting, and laboratory preparation. Five major RDF fractions – cardboard (46%), mixed papers (17%), mixed plastics (19%), other organics (3%), and fines (13%) – were manually separated and subjected to cryogenic grinding for characterization analysis. Thermogravimetric characterization at 20°C/min in a nitrogen atmosphere, along with proximate/ultimate analysis and heating value measurements, revealed significant variability in decomposition behavior. DTG analysis showed that LDPE exhibited the highest thermal stability, which peaks at 483.6°C, whereas cardboard and mixed paper underwent single-step decomposition, peaks at 361.4°C, and 359.3°C, respectively. In contrast, mixed plastics, other organics, fines, and raw RDF displayed complex, multi-step decomposition behaviors, underscoring the heterogeneous nature of RDF and informing thermal processing optimization. The Canadian RDF sample showed notably higher cardboard 45% and fines content 13% compared to other studies from different countries averaged 25% cardboard, and 8% fines. Additionally, sorting a 2 kg representative sample required 5 man-hours per kilogram, highlighting the labor-intensive nature of the process.

Co-pyrolysis of furniture wood with mixed plastics and waste tyres: assessment of synergistic effect on biofuel yield and product characterization under different blend ratio

Pyrolysis of waste furniture wood, mixed plastics and waste tyres was examined separately and in different combinations from the perspective of improved value products and energy production. The effect of different combinations of furniture wood, plastics and tyres on the product distribution during co-pyrolysis was analyzed. The experimental work throughout this study was performed at a temperature of 500 °C. Prior to the pyrolysis experiments, thermogravimetric analysis was done to assess the thermal degradation behavior of all selected feedstocks. During individual pyrolysis, mixed plastic wastes produced 70.6 wt% of pyrolysis liquid, which is 37.9% and 33.4% more than furniture wood and waste tyres. During co-pyrolysis, a binary blend of mixed plastics and waste tyres produced 63.3 wt% of pyrolysis liquid, which is 7.65% more than the logarithmic mean value, indicating a positive synergistic interaction on liquid production. The liquid yield of the ternary blend was observed to be as low as 54.4 wt% due to the lower volatiles present in the blend. The presence of volatiles in the feedstock is correlated with the production of liquids by individual and co-pyrolysis. For feed-flexible, more efficient, and cleaner operating systems, the increased liquid production offers crucial information. With the use of Fourier transform infrared spectroscopy (FT-IR) and gas chromatography/mass spectroscopy (GC–MS), the impact of different combinations on product characterization was investigated. The characterization study of the pyrolysis liquid obtained from mixed plastics showed the presence of different aromatic and aliphatic compounds. The findings offered viable options for efficiently utilizing waste materials, particularly plastics and tyres to improve the quality and substance of products.

Total separation of multi-plastic wastes using magnetic levitation with adjustable sensitivity

Novel separation method with high efficiency is of great significance for mechanical recycling mixed waste plastics plays. However, the efficiency of most extant methods is restricted by their shortage that the methods can only deal with binary mixtures. In this paper, a novel magnetic levitation (MagLev) separation method based on scaled-up MagLev device is proposed to handle multi-plastics. A theoretical model on distribution of magnetic flux intensity and levitation conditions is established to guide the design of separation process. Based on the theoretical analysis, different processes for separation of multi-plastics with different purpose can be realized. The high sensitivity allows the separation of plastics with similar appearances (e.g. transparent plastics like polycarbonate and polymethyl methacrylate) and densities (difference with 0.01 g/cm3). The adjustable distribution of magnetic field changes the levitation condition of the waste plastics. Thus, the sequential separation of multi-plastics and extraction of target material from multi-plastics mixture are successfully addressed. The experiments demonstrate that the purities of separated multiple plastics reach to approx. 100 %. Furthermore, additional advantages of low cost and no energy consumed in separation process make the method a promising solution for economically-viable and environmentally-friendly mass production procedure.

Tailoring the Properties of Chemically Recyclable Polyethylene‐Like Multiblock Polymers by Modulating the Branch Structure

Developing plastics that fill the need of polyolefins yet are more easily recyclable is a critical need to address the plastic waste crisis. However, most efforts in this vein have focused on high‐density polyethylene (PE), while many different types of PE exist. To create broadly sustainable PE with modular properties, we present the synthesis, characterization, and demonstration of materials applications for chemically recyclable PE‐like multiblock polymers prepared from distinct hard and soft blocks using ruthenium‐catalyzed dehydrogenative polymerization. By altering the branching pattern within the soft blocks, a series of PE‐like multiblock polymers were synthesized with tunable glass transition temperatures (Tg) while maintaining consistent high melting temperatures (Tm). A clear U‐shape trend between Tg and mechanical properties was found, showcasing their potential as sustainable materials with tailored properties spanning commercial linear low‐density polyethylene (LLDPE) and low‐density polyethylene (LDPE). These materials offer adjustable adhesive strength to metal and demonstrate chemical recyclability and selective depolymerization in mixed plastic streams, promoting circularity and separation.

An experimental investigation on performance, emission and combustion characteristics of IC engine using liquid fuel produced through catalytic co-pyrolysis of pressed oil cake and mixed plastics with the addition of nanoparticles

The study focuses on using a combination of diesel and a liquid fuel derived from the co-pyrolysis of pressed neem cake (PNC) and mixed waste plastics (MWP) containing waste polyethylene terephthalate (PET) and low density polyethylene (LDPE) in equal amounts with the help of cupric oxide (CuO) catalyst. The engine analysis was carried out using diesel and five different blends of co-pyrolysis oil with diesel in proportions of 20 % (20 % pyrolysis oil + 80 % diesel = PD20), 40 % (PD40), 50 % (PD50) and 100 % pyrolysis oil (PD100), respectively. Initially, the co-pyrolysis oil was produced using PNC and MWP in a ratio of 1:2 under different operating temperatures between 350 °C and 650 °C. The process temperature was optimized to yield maximum liquid oil, and the characterization study was performed. In addition to that, CeO2 nanoadditives were used to improve the properties of PD20 fuel. Different dosages of nanoadditives were blended with PD20 to prepare PD20@25 (PD20 + 25 ppm CeO2), PD20@50, PD20@75, and PD20@100. The objective of the study is to assess the performance, emission, and combustion characteristics of a diesel engine utilizing co-pyrolysis oil-diesel blend by including the nanoadditives. The analysis was carried out on a single-cylinder water-cooled diesel engine mounted with an eddy current dynamometer. The experiments demonstrated that the combination of PD20 and 50 ppm CeO2 resulted in a 6 % increase in thermal efficiency when compared to other blended fuels and diesel. When compared to all fuels, the PD20@50 produced a higher decrease in CO and HC emissions by roughly 30 and 6.2 %, respectively. The combustion analysis showed that the heat release rate (HRR) and maximum cylinder pressure were also found to have improved by adding nanoparticles.

Simple catalysts recycle mixed plastics

Simple catalysts recycle mixed plastics

Upcycling of recycled polyethylene for rotomolding applications via dicumyl peroxide crosslinking

AbstractPolyethylene (PE), including high‐density polyethylene (HDPE) and low‐density polyethylene (LDPE), makes up a significant part of post‐consumer plastics in municipal solid waste, presenting challenges for traditional recycling methods due to a wide range of melt flow properties and poor interfacial adhesion between the different resin, which often leads to low quality products (downcycling). In this study, a method is proposed to modify the molecular structure of post‐consumer PE (rHDPE and rLDPE) and their blends by using a straightforward organic peroxide crosslinking technique with 1 phr of dicumyl peroxide (DCP). Different rHDPE/rLDPE blend weight ratios (0/100, 20/80, 40/60, 50/50, 60/40, 80/20, and 100/0) were prepared using a combination of co‐rotating twin‐screw extrusion and pulverization. The final parts were produced via rotomolding where both the forming and crosslinking processes occurred concurrently. Subsequently, the materials were characterized in terms of chemical, thermal, and mechanical properties. It was found that the tensile strength (228%), tensile modulus (345%), flexural strength (145%), and flexural modulus (251%) increased by crosslinking the 80% wt. rHDPE (x‐rHDPE). Conversely, the gel content increased by 17%, thermal resistance by 37.2%, and the impact strength by 93% with 80% wt. rLDPE (x‐rLDPE). It can be concluded that a balance between the properties occurs as the addition of DCP improved both the interfacial adhesion and melt properties of rHDPE/rLDPE blends. This innovative approach represents a simple and straightforward method to upcycle mixed plastics (PE) streams, especially for rotomolding applications. It also offers promising avenues for sustainable waste management and material reuse.

High‐Performance Dynamic Photo‐Responsive Polymers With Superior Closed‐Loop Recyclability

AbstractChemical recycling to monomer (CRM) provides an ideal solution for reducing plastic waste and achieving a circular polymer economy. Cyclopentene (CP) and its derivatives are representative molecules that exemplify an efficient CRM process under mild conditions. However, most CP‐based polymers possess limited thermal and mechanical properties, constraining their potential applications. Herein, new CP‐based polymers with superior thermo‐mechanical properties and autonomous functions are proposed by integrating anthracene as a dynamic functional motif. Anthracenes not only serve as supramolecular cross‐linkages through strong π–π interactions but also form stronger chemical ones under UVA light irradiation, enhancing thermo‐mechanical properties. Furthermore, damage‐reporting, self‐healing, and local shape reprogramming capabilities are accomplished by utilizing the reversible nature of photodimerized anthracene. A mild and orthogonal depolymerization condition for the CP‐based polymers facilitates efficient monomer recovery even from mixed plastic wastes. This work presents a simple yet effective strategy to expand the usability of chemically recyclable polymers and contribute to a closed‐loop polymer economy.

Environmental impact of waste plastic oil and hydrogen-enriched diesel engines: A comprehensive review on performance, combustion, and emissions

This review focuses on the sustainable use of waste plastic by converting it into waste plastic oil (WPO) through catalytic pyrolysis. The primary objective is to explore the potential of WPO, derived from used polyethylene terephthalate bottles, as an alternative fuel for diesel engines. This review also evaluates WPO's physical and chemical properties, revealing that it possesses fuel attributes similar to those of petroleum-based fuels. Catalytic pyrolysis is employed on a laboratory scale, using catalysts such as silica, Zeolite Socony Mobil-5 (ZSM-5), alumina, and kaolin to extract WPO from mixed waste plastics. However, direct use of WPO in diesel engines has shown drawbacks, including significant combustion delays and increased emissions. To address these issues, this review suggests blending WPO with diesel fuel rather than using it as a standalone fuel. Furthermore, the review explores hydrogen enrichment in WPO blends to improve combustion efficiency. Hydrogen enrichment enhances thermal efficiency and reduces environmental emissions, showing potential for improved performance and lower brake-specific fuel consumption. This review presents a comparative analysis of various WPO blends with hydrogen enrichment, highlighting the benefits of incorporating hydrogen to boost combustion and performance. Although promising, further research is needed to ensure the sustainability and effectiveness of WPO blends as a long-term energy source.

Advances in Nonreactive Polymer Compatibilizers for Commodity Polyolefin Blends.

Recycling mixed polyolefin plastics is a significant challenge due to the limitations in sorting and degraded mechanical properties of blends. Nonreactive compatibilization by adding a small amount of polymeric additive is a widespread approach to restoring the performance and value of recycled plastics. Over the past several decades, synthetic advances have enabled access to low-cost copolymers and precision architectures for deepening the understanding of compatibilization mechanisms in semicrystalline polyolefins. This review covers the design parameters of a polymeric compatibilizer, the testing of blends, the synthetic methods of producing economically viable additives, and surveys the literature of blends of compatibilized HDPE, LLDPE, LDPE, and iPP. From this, readers should gain a comprehension of the polymer mechanics, synthesis, and macromolecular engineering of processable polyolefin blends, along with the field's future directions.

Developing hybrid C-sections from waste and recycled composite materials

This paper investigates the performance of hybrid composites made from mixed waste plastics (wMP), recycled carbon fibre (rCF), and waste glass fibre (wGF). Two lay-up configurations with varying wGF and rCF contents were considered: one with approximately 7 vol% rCF (25 vol% wGF) and another with approximately 15 vol% rCF (9.4 vol% wGF). The tensile, compressive, and flexural performance of standard coupon specimens for both configurations were assessed, revealing that specimens with increased rCF content exhibited superior performance. Additionally, three hybrid C-sections, containing 15 vol% rCF, were thermoformed and subjected to axial compression. All three C-sections failed due to bearing failure, accompanied by some interlaminar delamination and material crushing at the loading ends. Their weight-specific load capacity surpassed that of similar sections published in the literature, such as ultra-thin-walled steel C-sections, by almost 95 %. A finite element model (FEM) of the C-section was developed and was able to predict reasonably well the stress versus strain response. These findings demonstrate that waste and recycled composite materials could serve as sustainable alternatives to ultra-thin-walled steel C-sections and other conventional materials commonly used in construction.

Production of cycloalkane-rich fuel by vacuum pyrolysis of mixed waste plastics using combined titanium and aluminum oxide: a preliminary investigation

The mitigation of plastic pollution constitutes one of the major challenges worldwide. Innovative research approaches have been solicited to improve the properties of fuel derived from plastic pyrolysis. The present study looks at the effect on the chemical composition of pyrolysis oil of the application in situ of a mixed metal oxide of titanium and aluminum in vacuum pyrolysis of mixed waste polyethylene, polypropylene, and polyethylene terephthalate. The experiment was performed at process parameters of 250 °C temperature, 79.9 Kpa vacuum pressure, and 1:10 catalyst-to-feedstock ratio, first without the mixed metal oxide (parent reaction) and then with the mixed metal oxide (modified reaction). The results showed that the presence of combined titanium and aluminum oxides in the reaction medium accounted for the presence of alkyl-substituted cycloalkanes at an area% of 33.97% in the liquid product, and a calorific value of 11,950 cal/gm was reported for the modified reaction. The parent reaction produced higher liquid and gaseous yields of 28.3% and 43.1% respectively while the modified reaction produced a greater percentage of char (23.8%) and residual wax(36.0%). The fuel properties of the liquid products obtained were equally determined.

Revolutionizing waste from household plastics to eco-friendly diesel alternatives through catalytic degradation with biogas utilization

The study tackled the pressing environmental issue of managing both biodegradable and non-biodegradable household plastic waste, aiming to convert this waste into valuable hydrocarbons, thus addressing critical concerns over plastic pollution and the quest for renewable energy sources. In the context of escalating environmental degradation and the urgent need for sustainable alternatives to fossil fuels, the ability to transform various forms of waste into energy presents a significant stride towards ecological and energy sustainability. Utilizing an innovative methodology, the research employed catalytic degradation of mixed plastic waste, leveraging fly ash as a catalyst and biogas produced from a combination of cow dung and kitchen waste as a renewable and sustainable heat source. This process was fine-tuned across several catalyst-to-polymer (cat/pol) ratios, specifically 0.10, 0.15, and 0.20, with detailed documentation of the degradation temperatures and yields of liquid and gaseous hydrocarbons for each 1 kg batch of plastic waste. Notably, at a cat/pol ratio of 0.20, a remarkable 100% conversion rate was achieved, highlighting the efficiency of this method. Following this, the resultant oil was segmented based on boiling points for further analysis and evaluation of its utility as a diesel fuel substitute. Significant findings include the highest liquid hydrocarbon yield of 65.1% at 378 °C, achieved with the 0.20 cat/pol ratio. Moreover, fractions boiling above 100 °C were identified to possess superior heating values and cetane numbers compared to conventional diesel, particularly the fraction boiling at 100 °C–150 °C (C2), which demonstrated optimal performance and combustion qualities. This fraction achieved a maximum brake thermal efficiency of 32.92%, exhibited low smoke density and hydrocarbon emissions of 48 HSU and 32ppm, but it also resulted in a significant increase in NOx emission. Among all the fractions, diesel C2 was observed to be the best in terms of performance & combustion and was lower in emission. The conclusions drawn underscore the method’s potential to mitigate plastic pollution and reduce fossil fuel reliance by converting both biodegradable and non-biodegradable waste into useful energy. This study’s novelty lies in its comprehensive approach to waste management and energy recovery, significantly advancing over previous literature by achieving a 100% conversion rate at a specific cat/pol ratio and optimizing the output for use as a diesel alternative. It stands out by producing a fraction with both high efficiency and lower emissions, offering a scalable, sustainable solution to waste management challenges and paving the way for future innovations in sustainable energy production.

Material Recycling of Plastics—A Challenge for Sustainability

The complexity of plastic polymers and even more so of additives has increased enormously in recent years. This makes the material recycling of plastic waste considerably more difficult, especially in the case of mixed plastic waste. Some additives have now been strictly regulated or even completely banned for good reasons (‘legacy additives’). Material or mechanical recycling generally uses old plastics that still contain these substances. Consequently, products that are manufactured using such recyclates are contaminated with these harmful substances. This poses a major challenge for sustainability, as there is a conflict of objectives between protecting the health of consumers, especially vulnerable groups, conserving resources and recycling, keeping material cycles ‘clean’ and destroying pollutants, and transporting them to a safe final sink. With regard to the first objective, we recommend avoiding the use of contaminated recyclates for products with intensive contact with consumers (‘contact-sensitive products’) until further notice. We also show that the climate policy challenges for the plastics (and chemical) industry necessitate defossilization (‘feedstock change’). This turnaround can only succeed if solely closed-loop recycling takes place in the future; recyclates should primarily replace virgin plastics. For material or mechanical recycling, this means that this can only work if used plastics with a high degree of homogeneity and known formulation are collected separately, as is already the case today with PET bottles. The objective of this article is to illustrate the increasing complexity of plastic polymers and additives, especially legacy additives, which will force a legislative readjustment of todays’ material recycling.

Characterization of municipal solid waste in Kuwait: Sector-specific composition analysis and implications

ABSTRACT Municipal solid waste (MSW) characterization plays a pivotal role in devising effective waste management strategies conducive to fostering a circular economy. This study presents composition analysis across twenty-four subcategories sourced from residential, commercial, and industrial sectors in Kuwait. The study is conducted in accordance with the Standard Test Method for Determination of the Composition of Unprocessed Municipal Solid Waste (ASTM D5231). The results indicate that organic waste comprises 45.3%, followed by paper waste (19.9%) and plastics (19.8%). The remaining waste comprises glass waste (3.5%), diapers (2.7%), textiles (2.6%) and other waste. Paper waste (19.9%) consists mainly of mixed paper (12.1%), cardboard (3.7%), newspaper (3.3%), printer printouts (0.6%) and other office paper (0.2%). Plastic waste (19.8%) consists mainly of film (11.2%), PET (3.1%), HDPE (1.1%) and other mixed plastics (4.4%). Residential and mixed areas have the highest proportion of organic waste. Commercial areas produce the highest proportion of wastepaper (22.4%) and textiles (3.7%). Industrial areas produce the highest proportion of plastic waste (29.1%), most of which is film (17.3%). The study also provides an overview of the MSW management system in the country, an overview over the legislative framework, and forecasts of future waste generation rates with comparison to historical baselines. Implications: The precise and up-to-date characterization of municipal solid waste is imperative for scholarly journal submissions, as it establishes a foundational understanding of waste composition, aiding researchers and policymakers in the development of effective waste management strategies, resource recovery initiatives, and sustainable solutions to address the evolving challenges in waste management systems. This study provides detailed composition analysis for twenty-four municipal solid waste (MSW) subcategories collected across different sources: residential, commercial, industrial, and mixed areas. Time series forecasting is applied to predict MSW generation based on historical data obtained through the local municipality over the past decade. Factorial analysis is applied to investigate changes across source areas, and a hypothesis test is used to compare the current MSW composition against previous baselines. The results demonstrated significant variation across most waste categories. The plastic waste proportion has increased by 48.5% compared to 2013 data, despite awareness campaigns. Paper waste has also increased in proportion from 6.8% to 16.2%; this increase is associated with the mixed paper subcategory, which is mostly used for packaging. The composition data provided in this study are necessary for long-term monitoring, strategy assessment, and legislation associated with waste reduction and remediation.

Life cycle assessment of recycling metallised food packaging plastics using mechanical, thermal and chemical processes

Single treatment of metallised food packaging plastics waste (MFPW) has shown disappointing results with recycling rate <20 % due to its complex structure consisting of 10 % aluminium (Al) and 90 % mixed plastic films made of PE, PP, PS, PET, etc. Besides, it is generating many emissions and residues that must be landfilled making it difficult to integrate them into the circular economy. Therefore, a multi-stage recycling (MSR) approach has recently been developed using several sequential mechanical, thermal and chemical processes to recover energy and Al from MFPW with additional revenue for recycling plant operators. The thermal treatment helps to decompose the plastic fraction into wax or oil, gaseous, and solid residue (SR) composed of Al and coal, while the mechanical process can be used as a pre-treatment of MFPW feedstock and SR. Finally, the chemical treatment (leaching and functionalization) can be used to extract Al from SR and to refine coal into carbon microparticles (CPs), respectively. In order to investigate the environmental performance of the proposed MSR system, this research was developed. The investigation was performed using SimaPro life cycle analysis (LCA) tool according to ISO 14040/44 Standards and the impact assessment method is ReCiPe 2016. Five different scenarios were proposed in the constructed LCA layout, namely, conversion of MFPW to a) wax and gas (pyrolysis), b) wax, gas, and aluminium chloride (AlCl₃) (pyrolysis and leaching), c) wax, gas, AlCl₃, and CPs (pyrolysis, leaching, and functionalization), and d) oil, gas, AlCl₃, and CPs (catalytic pyrolysis, leaching, and functionalization). Besides, the oil produced from catalytic pyrolysis is used for generation of electricity (scenario e). The results showed that wax and gas recovery scenario (a) has better environmental potential and environmental benefits compared to incineration practice. The results did not change much after extraction of Al and CPs (scenario b, c), with a few increasing by 2–4% in the total score. While a lot of environmental burdens from upgrading and utilization (Scenario d, e) were recorded, reaching 79 % due to the huge amount of the catalyst was used. Thus, MSR systems have bigger environmental benefits, however, the chemical and catalytic processes still need to be further improved to reduce the effect of terrestrial acidification.

Biological Upcycling of Plastics Waste.

Plastic wastes accumulate in the environment, impacting wildlife and human health and representing a significant pool of inexpensive waste carbon that could form feedstock for the sustainable production of commodity chemicals, monomers, and specialty chemicals. Current mechanical recycling technologies are not economically attractive due to the lower-quality plastics that are produced in each iteration. Thus, the development of a plastics economy requires a solution that can deconstruct plastics and generate value from the deconstruction products. Biological systems can provide such value by allowing for the processing of mixed plastics waste streams via enzymatic specificity and using engineered metabolic pathways to produce upcycling targets. We focus on the use of biological systems for waste plastics deconstruction and upcycling. We highlight documented and predicted mechanisms through which plastics are biologically deconstructed and assimilated and provide examples of upcycled products from biological systems. Additionally, we detail current challenges in the field, including the discovery and development of microorganisms and enzymes for deconstructing non-polyethylene terephthalate plastics, the selection of appropriate target molecules to incentivize development of a plastic bioeconomy, and the selection of microbial chassis for the valorization of deconstruction products.