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In this study, the catalytic (co‐)pyrolysis of low‐density polyethylene (LDPE) and polyethylene terephthalate (PET) with HZSM‐5 and HY zeolite catalysts was conducted in a micro‐pyrolysis reactor coupled to a two‐dimensional gas chromatography system. Pyrolysis operating conditions, such as the pyrolysis temperature, the catalyst to feedstock (CF) ratio, and the LDPE:PET ratio, were varied. It was found that for the co‐pyrolysis of LDPE and PET, HZSM‐5 led to higher yields of C2‐C4 olefins and monoaromatic products. Lower CF ratios increased the yield of C2‐C4 olefins for LDPE pyrolysis, but decreased benzene yield for PET pyrolysis, concomitant with an increased yield in benzoic acid. A lower temperature of 400°C which was sufficient for the pyrolysis of LDPE, led to incomplete conversion of PET. Surface response diagrams were used to visualize the impact of the various pyrolysis operating conditions on the yield of C2‐C4 olefins and BTEX, which serve as target products for the circular economy. [ABSTRACT FROM AUTHOR]

Mixed plastic packaging waste sorting residue (MPO323) was treated by thermal pyrolysis to utilize pyrolysis oil and char. The pyrolysis oil was found to contain aromatic and aliphatic hydrocarbons. The chlorine and bromine contents were as high as 40,000 mg/kg and 200 mg/kg, respectively. Additionally, other elements like sulfur, phosphorous, iron, aluminum, and lead were detected, which can be interpreted as impurities relating to the utilization of oils for chemical recycling. The pyrolysis char showed high contents of potentially active species like silicon, calcium, aluminum, iron, and others. To enhance the content of aromatic hydrocarbons and to reduce the level of contaminants, pyrolysis oil was reformed with the corresponding pyrolysis char to act as an active material in a fixed bed. The temperature of the reactor and the flow rate of the pyrolysis oil feed were varied to gain insights on the cracking and reforming reactions, as well as on performance with regard to decontamination. [ABSTRACT FROM AUTHOR]

This article introduces three mixed integer programming (MIP) models to address a network design problem for mixed plastic waste (MPW) supply chains. By tracking waste compositions throughout the supply chain, the models optimize the technologies needed to process MPW. The three models adopt different approaches to preserve composition information in the supply chain. We also remark on how to improve solution times with additional constraints, and how the models can be easily modified to handle larger‐scale problems. The proposed models provide an approach for examining emerging MPW recycling technologies that may be more sensitive to input composition, as well as determining the extent to which advanced sorting is useful. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

This research demonstrates the co-pyrolysis of real-world plastic polystyrene (PSW), polypropylene (PPW) and low-density polyethylene (LDPEW) leads to synergistic effects. Combination of these plastics produce valuable products, good product selectivity and conversion efficiency. It also identifies specific product ratios, complex interaction and transformation, leads to distinct product outcomes. The aim was to analyse the production of high-quality oil by varying the blend ratios of the plastics, as well as the reaction temperature and time. The maximum oil yield achieved was 83.18 wt.% using a blend ratio of 1:1:0.5 (PSW: PPW: LDPEW), a reaction temperature of 446 °C, and a reaction time of 81 min, respectively. The presence of PSW in the mixture have contributed to more oil yield. To determine the kinetic parameters of the pyrolysis reaction, two models were used: the Kissinger model and the Kissinger Akhira Sunose (KAS) model. The activation energies for the different plastic blends were: 115 kJ mol−1 for PSW: PPW, 28 kJ mol−1 for PSW: LDPEW, 371 kJ mol−1 for PPW: LDPEW and 51 kJ mol−1 for PSW: PPW: LDPEW according to the Kissinger model. The KAS model yielded activation energies of 83 kJ mol−1 for PSW: PPW, 44 kJ mol−1 for PSW: LDPEW, 386 kJ mol−1 for PPW: LDPEW and 27 kJ mol−1 for PSW: PPW: LDPEW. The composition of the oil obtained from the pyrolysis process was analysed using gas chromatography–mass spectrometry (GC–MS). It was found that the oil derived from the pyrolysis of PSW contained 85.26 wt.% of aromatic content. Furthermore, the properties of the oil were compared to those of Bharat stage-IV gasoline and diesel, which are the Indian national standards for fuels. The oil exhibited favourable properties for fuel production, including good cold flow properties and an energy yield of 86.08 wt.%. This study demonstrates the potential of co-pyrolysis of plastic blends, specifically PSW, PPW and LDPEW, to produce high oil yields with desirable properties for fuel production. [ABSTRACT FROM AUTHOR]

Plastic recycling is a critical aspect of achieving a circular economy, aiming to reduce fossil fuel dependency, greenhouse gas emissions, and biodiversity impacts from uncontrolled disposal routes. The study outlines the evolving landscape of plastic recycling in the European Union (EU), addresses challenges, and emphasizes the need for innovative approaches to achieve circular economy goals. This paper delves into the innovative approaches and strategies employed by the PHOENIX project, a multidisciplinary project funded by the Cariplo Foundation, which focuses on plasmix – a complex mixture of plastics often excluded from recycling due to its heterogeneous composition. The authors utilize a systemic design approach, integrating survey results, interviews, literature reviews, and case studies to provide a comprehensive understanding of plasmix and propose novel solutions. Key findings include the application of design from recycling, systemic design strategies, and the utilization of plasmix in new product developments. It presents survey insights and stakeholder perspectives, and introduces systemic strategies applied in the project. The study concludes with valuable considerations for future research and underscores the significance of such initiatives in reshaping the plastic recycling paradigm.

Developing low-cost and high-activity catalysts is one of the keys to promoting the catalytic pyrolysis of waste plastics to fuels for plastic recycling. This work studied the effect of clay as the catalyst on mixed plastic pyrolysis for fuel and energy recovery. Four kinds of clay, including nanoclay, montmorillonite, kaolin, and hydrotalcite, were used as catalysts for the pyrolysis of mixed plastic consisted of polyethylene terephthalate, polystyrene, polypropylene, low-density polyethylene, and high-density polyethylene. The product yield and distribution varied with different clay in pyrolysis. The highest yield of oil was 71.0 % when using montmorillonite as the catalyst. While the highest contents of gasoline range hydrocarbons and diesel range hydrocarbons in the oil were achieved when using kaolin and nanoclay, respectively as catalysts. For the gas products, the CO, C2H4, C2H6, C3H6, and C4H10 increased with decreased CO2 in the gaseous products when using clay as catalysts. In general, the mild acidity of clay catalyst was essential to improve the oil yields and the proportion of the gasoline or diesel range fuels in the catalytic pyrolysis of mixed plastic waste.

Indian Railways (IR) is the third largest in the world and an economic transportation mode in India. A recent report by the Central Pollution Control Board, Government of India revealed that most of the IR stations were unable to comply with the norms of solid waste management especially on treatment of plastic waste. Hence, this study is aimed to explore potential plastic waste resources/generation across Indian Railway Units (IRUs) and to recommend eco-smart energy solutions to improve plastic waste management at IRUs. Significant problems related to collection, segregation, and treatment of railway mixed plastic waste were addressed. Recent initiatives by IR to eradicate the plastic pollution in IRUs were highlighted in the study. Eco-smart solutions such as financial rewarding system, concession in railway ticket price, priority reservation during booking of railway tickets, converting the unsegregated waste into valuable products of railway platform tiles, pavements, and bricks were recommended. Finally, the study provides a comprehensive perspective of plastic waste to energy conversion in terms of plasto-oil, plasto-char, and plasto-gas products. [ABSTRACT FROM AUTHOR]

Catalytic pyrolysis of post‐industrial and post‐consumer waste is studied in an auger‐type reactor at pilot scale by applying two different zeolites and an amorphous silica‐alumina catalyst in‐situ at 400–550 °C. Contrary to thermal pyrolysis, of polyolefin‐rich waste, high gaseous pyrolysis product yields of approx. 85 wt % are achieved with C2–C4 olefin contents of up to 67 wt %. After deactivation by coke deposition catalyst regeneration is proved feasible for maintaining the gaseous product yield and composition. Waste feedstocks with significant nitrogen and halogen heteroatom content are not suitable for in‐situ catalytic pyrolysis. [ABSTRACT FROM AUTHOR]

The application of paper–aluminum–plastic packaging has been widely adopted in various fields such as the food and medical industries, owing to its exceptional preservation and obstruction properties. Nonetheless, the recycling process for paper and aluminum from this packaging type typically involves water pulping and solvent separation. The resulting residual waste, commonly known as multi-plastic waste (PMW), poses significant challenges in terms of separation and recycling. In this research article, we propose a solution for the recycling of PMW using solid-state shear milling (S3M). This process utilizes powerful three-dimensional shear force to achieve pulverization and excellent dispersion of multicomponent polymers, all while maintaining ambient temperature conditions. The thermoplastic processability of milled PMW powder was improved. The results indicate that a significant reduction in the the average particle size of PMW from 700 μm to 226 μm after 10 milling cycles, as evidenced by both a particle size analyzer and SEM. Furthermore, S3M processing leads to a good dispersion of PMW domains, as confirmed by the reduction in domain size from 9.64 μm to 2.65 μm. DSC and DMA reveal excellent compatibility between the components of the composite, resulting in improved mechanical properties such as tensile stress (from 14.03 MPa to 22.02 MPa) and unnotched impact strength (from 3.26 KJ/m2 to 4.82 KJ/m2). The findings suggest that S3M technology could be an effective and sustainable method for recycling PMW without any separation process, with promising industrial application. [ABSTRACT FROM AUTHOR]

Plastic materials are recalcitrant in the open environment, surviving for longer without complete remediation. The current disposal methods of used plastic material are inefficient; consequently, plastic wastes are infiltrating the natural resources of the biosphere. The mixed composition of urban domestic waste with different plastic types makes them unfavorable for recycling; however, natural assimilation in situ is still an option to explore. In this research work, we have utilized previously published reports on the biodegradation of various plastics types and analyzed the pattern of microbial degradation. Our results demonstrate that the biodegradation of plastic material follows the chemical classification of plastic types based on their main molecular backbone. The clustering analysis of various plastic types based on their biodegradation reports has grouped them into two broad categories of C-C (non-hydrolyzable) and C-X (hydrolyzable). The C-C and C-X groups show a statistically significant difference in their biodegradation pattern at the genus level. The Bacilli class of bacteria is found to be reported more often in the C-C category, which is challenging to degrade compared to C-X. Genus enrichment analysis suggests that Pseudomonas and Bacillus from bacteria and Aspergillus and Penicillium from fungi are potential genera for the bioremediation of mixed plastic waste. The lack of uniformity in reporting the results of microbial degradation of plastic also needs to be addressed to enable productive growth in the field. Overall, the result points towards the feasibility of a microbial-based biodegradation solution for mixed plastic waste. [ABSTRACT FROM AUTHOR]

• Oil/wax yields from pyrolysis of mixed plastics can be predicted to a good extent. • The presence of PET in mixed plastic favors solid formation beyond predicted values. • The model can consistently predict the aliphatic carbon fraction in the oil/wax product. The predictability of pyrolysis yields and product composition of mixed plastics has been studied. To do so, pyrolysis of virgin polymers (HDPE, LDPE, PP, PS and PET) and eight individual sorting categories from a real waste DKR-350 stream (PE rigid/film, PP rigid/film, PET, PS, multilayer flexibles, and clogged materials) was performed in a batch reactor at 500 °C at laboratory scale. The obtained oil/wax, gas, and solid yields and the composition of oil/wax of those individual feedstocks were used as input of a superposition model to predict the corresponding pyrolysis yields and oil/wax composition of mixed feeds, which were later compared with the experimentally measured product yields from the pyrolysis of those mixed streams. This linear model predicts the oil/wax yield of the mixed streams to a reasonable extent, with a maximum yield deviation (overestimation) of 8 percentage points. However, the presence of significant amounts of PET (above 33 wt%) in the mixed plastic streams negatively impacts the production of the condensable product and promotes the formation of solid products beyond the expected predicted values. Quantification of the type of carbon (aliphatic, aromatic and carbonyl) present in all the oil/wax products was done using 13C NMR spectroscopy. A linear model could also predict the aliphatic carbon yield in the condensable product from plastic waste streams with high accuracy (maximum yield difference of 6 percentage points). However, the aromatic carbon yield could not be predicted, probably due to the observed behavior of PET, which interacts with other polymers to promote solid product formation. [ABSTRACT FROM AUTHOR]

The EU legislation put the focus on the material recovery of waste while energy recovery is not elaborate enough and all thermochemical conversion technologies are classified in the same category regardless of the final products, which can hamper overall sustainability. Therefore, this research analyses technologies for recovery of plastic waste to review the existing EU legislation and technology classifications. Most important LCA impact categories from the legislation point of view were identified and used in the analysis. As alternative thermochemical recovery technologies are not widely used, their inventories were modelled based on an extensive literature review. Results show that pyrolysis of plastic waste has 46%, 90%, and 55%, while gasification up to 24%, 8%, and 91%, lower global warming, abiotic depletion, and cumulative energy demand-related impacts, respectively, compared to incineration with CHP generation. Incineration-based scenarios show lower impacts only in the acidification potential category which is dependent on energy mixes of substituted energy vectors which are quickly changing due to the energy transition. Thus, alternative thermochemical recovery technologies can help in reaching sustainable development goals by lowering environmental impacts and import dependence. But, before considering new investments, the substitution of less environmentally sustainable fuels in facilities like cement kilns needs to be looked upon. Results of this analysis provide levelized results for environmental and resource sustainability based on which current legislative views on individual thermochemical recovery technologies may be re-examined. [ABSTRACT FROM AUTHOR]

Plastic recycling is gaining traction to reduce the demand for fossil resources for plastic production. Poly(ethylene terephthalate) (PET), mainly used in the packaging and textile sectors, is often isolated in the sinking fraction during the density-based separation of mixed plastic waste streams. The heterogeneity of the sinking fraction makes direct mechanical recycling of PET impossible. Therefore, neutral hydrolysis of PET was investigated in the presence of other polymer contaminants to study their impact on the neutral hydrolysis of PET. PA6, PC, POM, and PVC were found to decompose during hydrolysis, whereas ABS, PMMA and a mixture of PE, PP and PS was chemically inert during the hydrolysis treatment. The subsequent BHET synthesis with excess ethylene glycol was performed directly on a mix of the polymer contaminated hydrolysis products or a hydrolyzed post-consumer plastic waste fraction. BHET was successfully formed in the plethora of decomposition products in the synthesis, and a subsequent recrystallization recovered the BHET in high purity with only water being used as solvent. This demonstrated a robust method to handle PET fractions in mixed plastic waste that can be applied without purification prior to BHET synthesis - enabling chemical recycling of PET. Abbreviations: ABS, Poly(acetonitrile-butadiene-styrene); ATR-FTIR, Attenuated Total Reflectance Fourier Transformed Infrared Spectroscopy; BC, Bis(2-Hydroxyethyl) terephthalate crystals; BHET, Bis(2-Hydroxyethyl) terephthalate; DMSO, Deuterated dimethyl sulfoxide; DSC, Differential Scanning Calorimetry; EG, Ethylene glycol; 1 H NMR, Proton Nuclear Magnetic Resonance; H m , Melting enthalpy; Oligo, Oligomers; PA6, Polyamide 6; PC, Polycarbonate; PE, Polyethylene; PET, Poly(ethylene terephthalate); PMMA, Poly(methyl methacrylate); POM, Polyoxymethylene; PP, Polypropylene; PS, Polystyrene; P, Purity; PVC, Poly(vinyl chloride); rpm, Revolutions per minute; SPHP, Solid Phase Hydrolysis Product; Ti(IV)OBu, Titanium(IV) butoxide; T m , Melting temperature; TPA, Terephthalic acid; Wt, Weight; Y, Solid Phase Hydrolysis Product yield; Y t , Bis(2-Hydroxyethyl) terephthalate yield; ν, IR stretching mode; δ, IR bending mode; ω, IR wagging mode., Competing Interests: Declaration of competing interest The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: [Mogens Hinge reports financial support was provided by Innovation Fund Denmark]., (Copyright © 2024 The Author(s). Published by Elsevier Ltd.. All rights reserved.)

Chemical recycling of plastic wastes can be a useful complement to mechanical recycling to achieve the required plastics recycling rates and to establish a circular economy that is climate neutral and resource‐efficient. Different mixed plastic wastes that are subject to future recycling efforts are studied under uniform conditions of intermediate pyrolysis characterized by a medium heating rate and pyrolysis temperature. Product distributions and selected product properties are determined, and process mass and energy balances are derived. Product yields and compositions are highly dependent on the waste pyrolyzed. The results show that pyrolysis is a suitable process to recover chemical feedstock from various complex mixed plastic wastes. [ABSTRACT FROM AUTHOR]

In this study, microwave pyrolysis was experimented with mixed types of plastic waste. Two different plastic wastes polystyrene waste (PSW) and polypropylene waste (PPW) were used as feedstock. Carbon and activated carbon were synthesized from different biomass; rice husk (RH), corn husk (CH) and coconut sheath (CS) respectively which are used as microwave susceptors. The effect of impregnation on product yields was studied. Microwave pyrolysis at 900 W and with a polymer to an absorbent ratio of 10:1, produced the highest oil yield of 84.30 wt% when coconut sheath activated carbon (CSAC) was used as an absorbent. The reaction time was 10 min for the complete decomposition of polymer mixtures. Oil properties were determined and a high calorific value of 46.87 MJ kg−1 was obtained. These properties were compared to conventional fuel properties and the product oil has a density of 0.76 g ml−1 and viscosity of 2.4 cSt which is an equivalent fraction obtained to that of gasoline. Product oil has a styrene recovery of 67.58% from microwave pyrolysis. The results demonstrate that, microwave pyrolysis has a great potential for energy recovery from mixed plastic waste and the use of agricultural residues as absorbents enhanced the production efficiency of the process. Image 1 • Microwave pyrolysis treats polypropylene and polystyrene simultaneously. • It demonstrates the use of different activated carbon in microwave heating. • Product oil was equivalent to gasoline-range hydrocarbons. • 91.06 wt% of energy yield was obtained. • Reaction time of 10 min for complete decomposition of plastic waste. [ABSTRACT FROM AUTHOR]

The climate crisis is brewing up worldwide and there is an urgent need to develop and adopt products with low carbon footprint. Although the drivers of pollution are numerous, the lack of solid waste management is a key contributor. To tackle this menace of increasing solid waste in the environment three R's of waste management are proposed which includes reduce, recycle, and reuse. In this research, an attempt has been made to reuse solid waste from different sources to fabricate a brick that conforms to the standards laid by international and local building codes. Plastic waste comprising of Polyethylene Terephthalate (PET), High Density Polyethylene (HDPE) and Low Density Polyethylene (LDPE) were utilized along with waste foundry sand from steel industry. Waste plastic brick with different dosages of PET, HDPE, and LDPE as well as waste foundry sand were manufactured. Its properties were later investigated and compared with control clay fired brick samples. Test results revealed that waste plastic brick formulation 50:50 i.e. (waste plastic: foundry sand) exhibited the optimal mechanical performance. Its compressive strength was 8.23 MPa which was comparable to second class clay fired brick. Its splitting tensile strength was 1.35 times and flexural strength was twice compared to second class clay fired brick. From durability perspective, waste plastic brick does not show any sign of efflorescence and has water absorption ten times less than conventional clay fired bricks. Waste plastic brick is a better thermal and electrical insulator than second class clay fired brick and also possesses adequate bond strength with mortar. From the test results it is evident that waste plastic brick formulation 50:50 has adequate structural performance and can serve as replacement of conventional clay fired bricks in masonry structures. Utilizing waste plastic brick in masonry structures would be a giant leap forward towards a sustainable construction sector while addressing environmental concerns simultaneously. [Display omitted] • Waste plastic brick is fabricated from waste plastic and foundry sand. • Waste plastic brick formulation 50:50 has optimal physico-mechanical properties. • Flexural Strength of waste plastic brick is twice the conventional clay fired brick. • Waste plastic brick has better insulation properties than clay fired brick. [ABSTRACT FROM AUTHOR]

• We optimise a supply chain for mixed plastic waste in Northern Italy. • We compare incineration and pyrolysis treatment technologies. • A multi-objective framework maximises gross profit and minimises GHG emissions. • Incineration gives the best economic performance. • Pyrolysis is chosen for minimum GHG emissions. In the quest for sustainable plastic waste management, understanding economic and environmental implications enables optimal selection of treatment technologies. This study presents a multi-objective mixed integer linear programming framework to optimise the supply chain for mixed plastic waste in Northern Italy. Two technologies are considered: incineration and pyrolysis. Results offer quantitative insights into economic and environmental performance, balancing trade-offs between maximising gross profit and minimising greenhouse gas (GHG) emissions. Economic optimisation favours incineration for treating mixed plastic waste, resulting in the highest gross profit of 115 M€ per year, and the highest net GHG emissions of about 680 kt CO 2 eq per year. When the aim is environmental optimisation, pyrolysis is preferred due to its lower GHG emissions of 387 kt of CO 2 eq per year and yielding a gross profit of 54 M€ per year. Trade-off Pareto optimal solutions were analysed to identify reasonable trade-off configurations between the two objectives. [ABSTRACT FROM AUTHOR]

Garbage and waste became lately one of the biggest problem in Lebanon since the population increased to 6 million in 2019. This project aim is to develop an efficient method to reuse plastic packages that are used in our daily life. A machine is designed to recycle and mix the Polypropylene (PP) and the Polyethylene (PE), commonly used in packages. Different specimens of these polymers were prepared by varying the percentage of each component. The propylene diene monomer (EPDM) was used as a compatiblizer in the blends preparation. Mechanical properties were selected to estimate the compatibilization efficiency of EPDM. Addition of EPDM to PE/PP blends improved mechanical properties, especially the elongation at break. [ABSTRACT FROM AUTHOR]

Developing low-cost and high-activity catalysts is one of the keys to promoting the catalytic pyrolysis of waste plastics to fuels for plastic recycling. This work studied the effect of clay as the catalyst on mixed plastic pyrolysis for fuel and energy recovery. Four kinds of clay, including nanoclay, montmorillonite, kaolin, and hydrotalcite, were used as catalysts for the pyrolysis of mixed plastic consisted of polyethylene terephthalate, polystyrene, polypropylene, low-density polyethylene, and high-density polyethylene. The product yield and distribution varied with different clay in pyrolysis. The highest yield of oil was 71.0 % when using montmorillonite as the catalyst. While the highest contents of gasoline range hydrocarbons and diesel range hydrocarbons in the oil were achieved when using kaolin and nanoclay, respectively as catalysts. For the gas products, the CO, C 2 H 4 , C 2 H 6 , C 3 H 6 , and C 4 H 10 increased with decreased CO 2 in the gaseous products when using clay as catalysts. In general, the mild acidity of clay catalyst was essential to improve the oil yields and the proportion of the gasoline or diesel range fuels in the catalytic pyrolysis of mixed plastic waste., Competing Interests: The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (© 2023 The Author(s).)

Conversion of mixed–plastic waste into carbon nanotubes (CNTs) and hydrogen–rich hydrocarbon gases was carried out in a multi–core reactor using Ni/Mo/MgO catalyst. The mixed plastic waste consisted of HDPE (67.2 wt%), PP (11.2 wt%), PS (6.2 wt%), PVC (5.2 wt%) and PET (10.2 wt%). Optimization of process parameters such as pyrolysis temperature, CNT synthesis temperature, reaction time and recycle ratio were carried out using Box–Behnken 3–level and 4–factorial design method. The result shows that CNTs of 6.63 g and hydrocarbon gases containing 78% hydrogen would yield using 60 g plastic waste and 1 g of catalyst. Recycle ratio and pyrolysis temperature have shown the considerable effect over the yield of CNTs and product gases. The HRTEM analysis indicates that CNTs with aligned graphene walls can be produced at 50% recycle ratio, while 70% recycle ratio produces CNTs with bamboo like structure. High recycle ratio results in an increase of CO/CO 2 concentration with reduction of CNTs and hydrogen yield. [ABSTRACT FROM AUTHOR]

This paper studies the recyclability of construction and household plastic waste collected from local landfills. Samples were processed from mixed plastic waste by injection moulding. In addition, blends of pure plastics, polypropylene and polyethylene were processed as a reference set. Reference samples with known plastic ratio were used as the calibration set for quantitative analysis of plastic fractions in recycled blends. The samples were tested for the tensile properties; scanning electron microscope–energy-dispersive X-ray spectroscopy was used for elemental analysis of the blend surfaces and Fourier transform infrared (FTIR) analysis was used for the quantification of plastics contents. [ABSTRACT FROM AUTHOR]

• Mixed plastic waste is converted into substitute natural gas and carbon black. • TEA and LCA obtain high IRR of 56.9% and low carbon emission of −449 kg CO2-eq. • APP for gas and carbon have better economy and lower emission than liquid fuels. The mass production, consumption, and disposal of plastics pose a considerable threat to the environment and human life; however, the recycling of plastic waste remains challenging. This study converted mixed plastic waste into gas and solid without generating a liquid product. The pyrolysis gas had a high CH 4 content and a high heat value. The solid product comprised 2–8 μm carbon spheres with a semicrystalline graphitic structure. The techno-economic and carbon footprint analyses revealed that the upcycling of mixed plastic waste into carbon black and natural gas substitutes produced a high internal rate of return (56.9%), a short payout period (3.46 years), and negative carbon emissions (−449 kg CO2-eq per t plastic waste). The product price and plant capacity are the main factors influencing the profitability of the project. Compared with autogenic pressure pyrolysis for the production of liquid fuels, this method showed considerably higher economic and environmental benefits. [Display omitted] [ABSTRACT FROM AUTHOR]

Pyrolysis of a post-consumer plastic waste stream (DKR-350) has been performed at a laboratory scale in a fixed-bed reactor at 500 °C. DKR-350 is a complex mixture of post-consumer plastics comprising polyethylene, polypropylene, polystyrene, polyethylene terephthalate, clogged materials, multilayer flexibles, together with considerable amounts of biogenic and inorganic residues and halogens. The influence of different washing procedures on feedstock composition and pyrolysis product yields was investigated. Washing effectively lowers the biogenic, inorganic and halogen contents in DKR-350, though does not affect the yield of the desired oil/wax (66 to 69 wt%). 27% of the oil/wax lies in the boiling point range of naphtha and gasoline (< 200 °C). During pyrolysis, the oxygen content of the oil/wax is reduced to 8–14 wt%, compared to 10–16 wt% in the feed. Chlorine analysis revealed that most of the chlorine present in the feed is removed by washing. Nevertheless, the concentration of chlorine in the oil/wax is still high (>150 ppm), showing the presence of recalcitrant organochlorides in the feed. Thus, post-treatment is still required to upgrade it to feedstock for the production of fuels and/or chemicals. • Pyrolysis condensable yields of ~70 wt% were obtained from a plastic waste stream. • Washing pretreatments do not affect the pyrolysis condensable yield. • A reduction of molecular weight of ~125 times (feed to condensable product) is achieved. • Chlorine concentration is reduced up to ~92% (feed to condensable product). [ABSTRACT FROM AUTHOR]

The first step consisted in a field investigation carried out in Waste Electric and Electronic Equipment (WEEE) treatment plants coupled with a bibliographic product analysis and FT-IR spectroscopy polymers identification. Three main polymers of the thermoplastic fraction of small appliances were identified: in the external cases it was possible to find acrylonitrile-butadiene-styrene (ABS) and high impact polystyrene (HIPS), while polybutadiene terephthalate (PBT) was contained in the printed circuit boards (PCBs). Taking into account this identification, a ternary polymer mixture of ABS-HIPS-PBT was prepared as a representative sample of the thermoplastic fraction contained in WEEE (real WEEE sample). From the thermal characterization (proximate and ultimate analysis, high heating value (HHV) direct measurement and Energy-Dispersive-X-Ray-Fluorescence analysis (ED-XRF)) the only polymer whose properties sensibly differ from the analogous virgin polymer is the one contained in PCBs. A kinetic analysis of pyrolysis occurring on the three components and on their ternary mixture was performed using a thermogravimetry (TG) apparatus in argon atmosphere under non isothermal conditions. Triplicates of TG experiments at four heating rates of 2, 5, 10 and 15 K min −1 were carried out and two different model-free approaches were adopted, namely the Kissinger and Ozawa-Flynn-Wall methods in order to determine the activation energy E (as a single mean value or as a function of the degree of conversion α ). The conversion dependencies of both activation energy and pre-exponential factors were determined as well as the reaction model, representing the reaction mechanism. The suitability of the models selected was tested using the Akaike's Information Criteria (AIC) score, being the geometric model R3 the best found for pyrolysis of ABS, HIPS and real WEEE samples, while PBT sample showed an uncertainty between the R3 and the diffusion D2 model. The reaction time values to achieve the maximum pyrolysis rate in the three main components and in the real WEEE sample were also calculated. [ABSTRACT FROM AUTHOR]

The detailed compositional characterization of plastic waste pyrolysis oil was performed with comprehensive two-dimensional GC (GC × GC) coupled to four different detectors: a flame ionization detector (FID), a sulfur chemiluminescence detector (SCD), a nitrogen chemiluminescence detector (NCD) and a time of flight mass spectrometer (TOF-MS). The performances of different column combinations were assessed in normal i.e. apolar/mid-polar and reversed configurations for the GC × GC–NCD and GC × GC–SCD analyses. The information obtained from the four detectors and the use of internal standards, i.e. 3-chlorothiophene for the FID and the SCD and 2-chloropyridine for the NCD analysis, enabled the identification and quantification of the pyrolysis oil in terms of both group type and carbon number: hydrocarbon groups (n-paraffins, iso-paraffins, olefins and naphthenes, monoaromatics, naphthenoaromatics, diaromatics, naphthenodiaromatics, triaromatics, naphthenotriaromatics and tetra-aromatics), nitrogen (nitriles, pyridines, quinolines, indole, caprolactam, etc.), sulfur (thiols/sulfides, thiophenes/disulfides, benzothiophenes, dibenzothiophenes, etc.) and oxygen containing compounds (ketones, phenols, aldehydes, ethers, etc.). Quantification of trace impurities is illustrated for indole and caprolactam. The analyzed pyrolysis oil included a significant amount of nitrogen containing compounds (6.4 wt%) and to a lesser extent sulfur containing compounds (0.6 wt%). These nitrogen and sulfur containing compounds described approximately 80% of the total peak volume for respectively the NCD and SCD analysis. TOF-MS indicated the presence of the oxygen containing compounds. However only a part of the oxygen containing compounds (2.5 wt%) was identified because of their low concentrations and possible overlap with the complex hydrocarbon matrix as no selective detector or preparative separation for oxygen compounds was used. [ABSTRACT FROM AUTHOR]

Abstract: Air gasification of mixed plastic waste was conducted in a two-stage gasifier. The effects of the combination of olivine as the fluidized bed material and activated carbon with or without other additives for tar cracking, as well as a Ni-plated distributor, the use of steam as a gasifying agent, and the calcination of olivine on the producer gas compositions and tar production, were also investigated. The maximum H2 concentration (27.3 vol%) was obtained with 900 g of activated carbon in the tar-cracking zone, and through the use of calcined olivine as the bed material. In the experiments, the maximum tar removal efficiency calculated using a base case reached 98.2%. The LHVs of the producer gases were in the range of 6.1–9.0 MJ/Nm3. The increase in the activated carbon amount led to an enhanced H2 production, as well as a decrease in tar production. The Ni-plated distributor was found to be effective for tar removal. In the application of dolomite in the tar-cracking zone and the use of steam as a fluidizing medium resulted in a high rate of HCl removal. The minimum HCl concentration in the producer gases was under 1 ppm. [Copyright &y& Elsevier]

Abstract: The glycolysis of postconsumer polyethylene terephthalate (PET) waste was evaluated with catalysts of zinc acetate, zinc stearate and zinc sulfate, showing that zinc acetate was the most soluble and effective. The chemical recycling by solvolysis of polylactic acid (PLA) and PET waste in either methanol or ethanol was investigated. Zinc acetate as a catalyst was found to be necessary to yield an effective depolymerization of waste PLA giving lactate esters, while with the same reaction conditions PET remains as an unconverted solid. This provides a strategy to selectively recycle mixed plastic waste by converting one plastic to a liquid and recovering the unreacted solid plastic by filtration. [Copyright &y& Elsevier]

Abstract: The effect of the degree of degradation of the components of a model municipal plastic waste (a mixture of low-density polyethylene, high-density polyethylene, polypropylene and high-impact polystyrene) on the toughness and stability of recyclates compatibilised with a cooperative compatibilisation system (a mixture of ethylene–propylene statistical and styrene–butadiene block copolymers with a secondary amine-based stabiliser) was studied. It was shown that good impact strength was achieved for recyclates having components with a low or medium degree of degradation. Mechanical properties of recyclates having the components with a high degree of degradation are deteriorated. The addition of the cooperative compatibilisation system leads to a higher thermo-oxidative stability of recyclates irrespective of the degree of degradation of their components. Photo-oxidative stability of the recyclates is low but it can be improved to a satisfactory level by the addition of carbon black or a commercial photo-stabiliser. [Copyright &y& Elsevier]

Abstract: The thermal cracking is one of the possible ways to obtain petrochemical feedstock from polymer wastes. The properties of the cracking products depend mainly on the type of the raw material. In this study the degradation of different mixtures of polymer wastes (polypropylene and polystyrene) were investigated in a horizontal tube reactor. Temperature of 510–520°C and residence time of 15–30min were used. The effects of the concentration of polystyrene on the yields and structure of products were also studied. Moreover, the interaction between the polymers during the pyrolysis was investigated. The products of the thermal cracking were analyzed by gas-chromatography, infrared spectroscopy and different standardized and non-standardized methods. It was found, that the concentration of polystyrene significantly affected both the quantity and quality of degradation products. It was also observed that the presence of the polystyrene in the raw material increased the reaction rate coefficient, and enhanced the degradation rate of polypropylene. By higher concentration of polystyrene in raw materials, the yield of light products considerably increased, furthermore, in the naphtha-like fraction the concentration of aromatics also increased. The characteristics of the products were changed with the polystyrene content in the raw materials. The liquid products had advantageous properties for further utilization as fuel like or petrochemical feedstock applications. [Copyright &y& Elsevier]

High surface area varieties of graphene have captured significant attention, allowing for improved performance in a variety of applications. However, there are challenges facing the use of graphene in these applications since it is expensive and difficult to synthesize in bulk. Here, we leverage the capabilities of flash Joule heating to synthesize holey and wrinkled flash graphene (HWFG) in seconds from mixed plastic waste feedstocks, using in situ salt decomposition to produce and stabilize pore formation during the reaction. Surface areas as high as 874 m 2 g -1 are obtained, with characteristics of micro-, meso-, and macroporosities. Raman spectroscopy confirms the wrinkled and turbostratic nature of the HWFG. We demonstrate HWFG applications in its use as a metal-free hydrogen evolution reaction electrocatalyst, with excellent stability, competitive overpotential, and Tafel slope; in a Li-metal battery anode allowing for stable and high discharge rates; and in a material with high gas adsorption. This represents an upcycle of mixed plastic waste, thereby affording a valuable route to address this pressing environmental pollutant concern.

Plastic wastes have become one of the biggest global environmental issues and thus recycling such massive quantities is targeted. Low-density polyethylene (LDPE), high-density polyethylene (HDPE), polypropylene (PP), and polystyrene (PS) are considered among the main types of plastic wastes. Since pyrolysis is one of the most promising recycling techniques, this work aims to build knowledge on the co-pyrolysis of mixed polymers using two model-fitting (Criado and Coats–Redfern) methods. Seventeen co-pyrolysis tests using a thermogravimetric analyzer (TGA) at 60 K/min for different mixed compositions of LDPE, HDPE, PP, and PS were conducted. It was observed that the pyrolysis of the pure polymer samples occurs at different temperature ranges in the following order: PS < PP < LDPE < HDPE. However, compared to pure polymer samples, the co-pyrolysis of all-polymer mixtures was delayed. In addition, the synergistic effect on the co-pyrolysis of polymer blends was reported. The Master plot of the Criado model was used to determine the most suitable reaction mechanism. Then, the Coats–Redfern model was used to efficiently obtain the kinetic parameters (R2 ≥ 97.83%) and the obtained values of the activation energy of different polymer blends were ranging from 104 to 260 kJ/mol. Furthermore, the most controlling reaction mechanisms were in the following orders: First order reaction (F1), Contracting sphere (R3), and then Contracting cylinder (R2). [ABSTRACT FROM AUTHOR]

Wastes containing short-chain chlorinated paraffins (SCCPs) at concentrations above the Basel Convention low persistent organic pollutant content (LPC) values must be destroyed or irreversibly transformed in an environmentally-sound manner. Here, we developed a novel liquid chromatography–electrospray ionization-tandem mass spectrometry (LC–ESI-MSMS) method for determining the concentrations of SCCPs in mixed plastic wastes. Major SCCP homologues were identified with good separation and peak width by using a low-hydrophobicity cyano-propyl column and a mobile phase consisting of water and methanol containing ammonium acetate. Precursor ion peaks corresponding to the formation of stable SCCP homologue–adducts were observed, followed by two intense product ion peaks corresponding to separation of the adduct into acetate and the homologue. The formulation of a novel calibration standard with known SCCP homologue percentage composition supported the development of our novel mass spectrometric technique. The results obtained with the LC–ESI-MSMS system were quantitatively and qualitatively comparable with those obtained with a high-resolution mass spectrometry (HRMS) coupled to gas chromatography (GC) system. Homologue concentrations determined by LC–ESI-MSMS were significantly correlated with those determined by GC–HRMS in samples of commercial chlorinated paraffin mixture and mixed plastic waste, respectively. As a complementary technique to the highly accurate, but less versatile GC–HRMS approaches, the SCCP analysis by LC–ESI-MSMS is a practical way to identify mixed plastic wastes containing SCCPs at concentrations higher than the Basel Convention's LPC value. • Novel mass spectrometric method to quantify SCCPs in plastic wastes was developed. • Major SCCP homologues were identified with good separation and peak width. • Present data were in good agreement with high-resolution mass spectrometry data. • Plastic wastes containing SCCPs above Basel Convention limits can be identified. [ABSTRACT FROM AUTHOR]

• Design from Recycling was applied to bring a complex plastic waste stream (sink fraction) from incineration to recycling. • This Greentile product passed mechanical load simulations, outdoor testing, LCA and an exploratory market study. • PVC content remains a challenge for the complex sink fraction. • The composition of the sink fraction may shift over the coming years, depending on changes in policy, state of technology and waste management systems. With today's continued drive to increase recycling rates of plastics, the low-hanging fruit of clean mono-streams of plastic waste has long since been picked. If Europe's ambitious recycling targets are to be met, plastics waste streams that have until now been labeled 'problematic' and have consistently been sent to incineration, must be considered as well. One such stream is the sink fraction obtained from float-sink sorting of mixed post-consumer packaging waste. It is a very complex stream in terms of composition. Moreover, it contains a sizeable amount of PVC, which is considered detrimental to further mechanical recycling of any mixed plastic waste. Within the current research, the sink fraction was extensively analyzed for composition and mechanical properties, as well as treated for removal of PVC and non-ferrous metals. Subsequently, the Design from Recycling strategy was applied to successfully develop a new product with this material, called the Greentile. The Greentile was effectively manufactured and found to be a useful construction element for slanted green roofs. [ABSTRACT FROM AUTHOR]

Resource stewardship and sustainable use of natural resources is mandatory for a circular plastic economy. The discovery of microbes and enzymes that can selectively degrade mixed-plastic waste enables to recycle plastics. Knowledge on how to achieve efficient and selective enzymatic plastic degradation is a key prerequisite for biocatalytic recycling of plastics. Wild-type natural polymer degrading enzymes such as cellulases pose often selective non-catalytic binding domains that facilitate a targeting and efficient degradation of polymeric substrates. Recently identified polyester hydrolases with synthetic polymer degrading activities, however, lack in general such selective domains. Inspired by nature, we herein report a protocol for the identification and engineering of anchor peptides which serve as non-catalytic binding domains specifically toward synthetic plastics. The identified anchor peptides hold the promise to be fused to known plastic degrading enzymes and thereby enhance the efficiency of biocatalytic plastic recycling processes., (© 2021 Elsevier Inc. All rights reserved.)