Waste Polyethylene Research Articles

Parameter study of waste shiitake substrate/waste polyethylene Co-gasification using Aspen Plus kinetic modeling

Waste Shiitake Substrate, a major agricultural waste in Taiwan, is typically packaged in plastic bags (Waste Polyethylene, PE) during mushroom cultivation process. Consequently, these plastic bags become additional waste that requires proper disposal. In recent years, Taiwan has produced over 150,000 tons of waste shiitake substrate annually, with approximately 1580 tons of plastic bags used for mushroom cultivation. Up to now, there has not been an effective method for handling this waste. This study aims to develop a co-gasification process using the complementary characteristics of WSS and PE. Unlike traditional direct combustion, the co-gasification approach can convert these wastes into cleaner bioenergy. This study aims to develop an Aspen Plus model for a laboratory-scale 1 kWth bubbling fluidized bed gasifier. This model incorporates kinetic reactions and tar formation during co-gasification. The model accurately predicted the experimental results. Different variables were investigated, including gasifier temperature, blending ratio (BR) of the two fuels, mixing ratio (MR) of the gasifying agent, and equivalence ratio (ER). The results showed that hydrogen production correlated positively with the steam-to-carbon ratio in the gasification medium, whereas carbon monoxide (CO) was more affected by the feedstock type and equivalence ratio, with CO reaching its peak at an equivalence ratio of 0.2. When gasifying using only waste shiitake substrate (BR = 0%), at an ER of 0.2, a gasification furnace temperature of 950 °C, and an MR of 100% (pure CO2), the maximum CO mass flow rate in the syngas is obtained. Waste plastics contain significant amounts of volatile matter and no oxygen, leading to increased production of CH4, CO, and H2 during co-gasification with the addition of waste plastic. For plastics, high temperature and low ER conditions promote the production of CO, H2, and CH4 because of the significant tar content, thereby enhancing the Cold gas efficiency (CGE). When the gasification temperature is 950 °C, with 80% polyethylene (BR = 80%) and an ER of 0.1, the highest HHV is achieved. These results can serve as a reference for determining the operational conditions for the scale-up of gasification systems.

Recovering Low-Density Polyethylene Waste for Gypsum Board Production: A Mechanical and Hygrothermal Study.

In recent decades, plastic waste management has become one of the main environmental challenges for today's society. The excessive consumption of so-called single-use plastics causes continuous damage to ecosystems, and it is necessary to find alternatives to recycle these products. In this work, a mechanical and hygrothermal characterisation of novel plaster composites incorporating LDPE waste in their interior was carried out. Thus, prefabricated plasterboards have been designed with a partial replacement of the original raw material with recycled LDPE in percentages of 5-10-15% by volume. The results show how these new composites exceeded the 0.18 kN minimum breaking load in panels in all cases, while decreases in density and thermal conductivity of up to 15% and 21%, respectively, were obtained. In addition, an increase of 3.8%in thermal resistance was obtained by incorporating these new gypsum boards in lightweight façade walls through simulations. In this way, a new pathway was explored for the recovery of these wastes and their subsequent application in the construction sector.

Upcycling waste polyethylene terephthalate (PET) bottles into high-performance activated carbon for electrochemical desalination

Upcycling waste polyethylene terephthalate (PET) bottles has attracted intensive research interests. This simultaneously alleviates plastic pollution and achieves a waste-to-resource strategy. Waste PET water bottles were used to fabricate value-added activated carbon (AC) electrodes for capacitive deionization (CDI). The KOH activation temperature (greater than 700 °C) prominently affected the physi-chemical properties and desalination performance of PET-derived activated carbons (PET-AC). Profiting from a large Brunauer–Emmet–Teller specific surface area (1448 m2 g−1) with a good mesoporous structure (the ratio of the mesopore volume to the total pore volume was 41.3%), PET-AC-1000 (activated at 1000 °C) possessed a huge specific capacitance of 108 F g−1 for capacitive ion storage. Moreover, when utilized as the electrode material in single-pass CDI, PET-AC-1000 exhibited a maximum electrosorption capacity of 10.82 ± 0.11 mg g−1 and a low level of energy consumption (0.07 kWh mol−1), associated with good electrochemical charging-discharging cyclic stability. The results provide a promising facile approach to tackle the challenge of plastic pollution and promote the advancement of electrode materials for economic affordable and energy-efficient electrochemical desalination process, which meets the United Nations (UN) sustainable development goals (SDGs).

Ammonia-Borane Dependent Transfer Hydrogenation of Carboxylic Esters to Primary Alcohols.

Here, we present a user-friendly protocol that uses bench-stable NH3·BH3 (AB) as the hydrogen transfer agent for the reduction of both aromatic and aliphatic esters without an external catalyst and base, delivering a structurally diverse array of primary alcohols (80-98% yields). The broad functional-group tolerance (halogen, boronic ester, -NO2, -OH, etc.) under environmentally acceptable conditions implies high practical utility. Further, a tandem catalytic conversion of a plastic waste polyethylene terephthalate (PET) bottle to 1,4-benzenedimethanol including fatty esters into respective fatty alcohols was shown.

Production of paver blocks from polyethylene terephthalate solid waste as partial replacement of sand

Plastic waste management is an international concern. Polyethylene terephthalate (PET) plastic waste is present everywhere in Addis Ababa relative to other types of plastic waste and it is an international concern regarding environmental problems. The amount of plastic trash produced globally is increasing at a rapid rate, and this pollution is caused by improper disposal, the waste’s non-biodegradability, and the harmful gases released during incineration pose a hazard to human health. Because it’s used in so many commonplace items, such as bottles and containers for the food and beverage sectors, polyethylene terephthalate, or PET, is one of the most widely used consumer polymers. Because of its many characteristics, including its inability to biodegrade and the gasses it releases when burned, it has grown to be a significant environmental problem. Waste made of polyethylene terephthalate (PET) must therefore be recycled and used efficiently. The purpose of this study was to produce paver blocks by partially replacing sand with waste Polyethylene Terephthalate (PET) material. Preparing the raw materials, mixing, vibrating, molding, curing, testing the flexural and compressive strengths, and curing are the steps in the production process. . The mixing proportion of paver blocks implemented for this study was 1:2:3, which is a predictable volume basis-mixing ratio of cement, aggregate, and sand correspondingly. Design-Expert 13.0.0 Three-level three factor Box–Behnken design was used for experimental design and statistical analysis of results based on the outcome and discussion. A total of 17 trials were carried out with the following parameters: 10, 20, and 30% of polyethylene terephthalate; 0.52, 0.55, and 0.58 as the water-to-cement ratio; and 7, 14, and 28 days for the curing period. The interaction effects were examined based on the examination of the experimental data. The physio-mechanical properties of Paver Blocks, including water absorption, compressive strength, and flexural strength, were examined. At a water-to-cement ratio of 0.55, obtained maximum flexural and compressive strength which is 4.92 MPa, and 29.74 MP respectively, and when PET plastic waste percentage increased, both flexural and compressive strength decreased but we got a good flexural and compressive strength value at 10% PET. And also water absorption rates were increased as PET plastic waste increased. The ideal process variables for polyethylene terephthalate percentage were 10 and 28. The paver blocks average and maximum water absorption rates were 3.39% and 3.95%, respectively. Compared to regular blocks, the resultant Paver Blocks are lighter and have superior physical and mechanical qualities. These are excellent illustrations of planned paver applications that can make use of prefabricated paver blocks.

Sustainable and Renewable Microcross-Linked Polyurethane Pressure-Sensitive Adhesive from Waste Polyethylene Terephthalate

Sustainable and Renewable Microcross-Linked Polyurethane Pressure-Sensitive Adhesive from Waste Polyethylene Terephthalate

Parameter selection for the hydroconversion of waste polyethylene plastic under mild conditions: A comprehensive evaluation

Parameter selection for the hydroconversion of waste polyethylene plastic under mild conditions: A comprehensive evaluation

Effect of Using Alkoxy - Silane (ethoxy silane) Coupling Agent to Enhance the Mechanical Properties of Bio-Composites

This research work investigated the effect of alkoxy silane (ethoxy silane) on the mechanical properties of polyethylene/ dried powdered pine apple peels composite. The pine apple peels was washed in distilled water, sun dried for about eight hours and later oven dried at a temperature of 60oC for about three hours. The dried pine apple peels was pulverized and sieved using a mechanical sieve arranged in descending order of fineness. The alkoxy-silane (ethoxy-silane) coupling agent (2%) was first hydrolyzed in ethanol to deliver the alkoxy functional silane to the interior of the pineapple peels and ion-free water at room temperature for 6 hours. This was followed by addition of the dried powdered pineapple peels into the hydrolyzed coupling agent solution in a reactor at a temperature of about 80 ◦C for 20 minutes. The formed product was oven dried at 110 ◦C for 3 hours and pulverized using a locally made grinding machine and sieved using a set of sieves arranged in descending order of fineness in accordance with BS1377:1990 standard as was reported by Rajan et al., (2007) to obtain pineapple peels coated with the coupling agent (150mμ). The recycled polyethylene waste was washed using distilled water, sun-dried and shredded in a shredding machine. The pineapple peels powder coated with alkoxy silane and the shredded recycled polyethylene waste were blended using a two-roll rheo-mixer at 50°C and a rotor speed of 60 rpm. The percentage of the powdered pineapple peels coated with coupling agent in the recycled polyethylene matrix was varied from 10% to 40% to produce four different compositions. A hydraulic pressing machine was used to compress the produced composites for about ten minutes applying a pressure of about 25 tons at 130°C. The produced composite samples were allowed to cool to room temperature under sustained pressure before being removed from the hydraulic press for various mechanical tests. The impact tests were performed according to ASTM D256 standard using Impact testing machine model EXT94064/6705CE, 300 J. Flexural test was performed using Universal Testing Machine model TUE-C-100, according to ASTM D790. The hardness tests were performed according to ASTM D785 standard using Rockwell Scale K hardness testing machine. The results showed that maximum flexural strength of 10.8MPa and 384Hv were recorded at 40wt.% reinforcement. The developed composite can be used applications where moderate strength will be required.

Preparation and Characterization of Paving Blocks from Polyethylene-Based Plastic Waste and Natural Fibre

The current methods of managing plastic waste especially in developing countries have become an issue of environmental and public health concern globally. This has led environmentalists and scientists to work on finding day-to-day activities that can help to reduce the plastic waste disposal problem. Recycling and reuse of plastic waste into construction materials is a valid way to reduce the effect of this improper disposal of plastic waste. This will help to reduce the negative impact of the high cost of cement in the construction industry. In this research, polyethylene waste (table water sachet) was used as a replacement for cement in the construction of paving blocks. The sample with a 1:4 mixing ratio was found to have the highest compressive strength among the different mix ratio examined. Paving blocks were then produced with this mixing ratio from plastic-aggregates and plastic-aggregate-fibre and compared with the standard cement-aggregate paving blocks for their compressive and tensile strengths, water absorption, thickness swelling, density, and thermal properties (thermogravimetric analysis (TGA) and horizontal burning rate). Scanning Electron Microscopy (SEM) with Energy Dispersive X-ray (EDX) was also conducted on the paving blocks to determine the distribution of the particles of the blocks, the compatibility of the matrix, and their elemental composition. The results of the compressive strength test showed 18.1667 Nmm<sup>-2</sup> for plastic-aggregate block, though lower when compared with the cement-aggregate block with a compressive strength of 21.6667 Nmm<sup>-2</sup>. The plastic-aggregate block has the least water absorption value among the three samples. The 0.1350% and 1.8861% water absorption values obtained for the plastic-aggregate and plastic-aggregate-fibre bricks respectively showed an impressive water absorption which falls within the maximum of 5% water absorption for quality paving blocks. The plastic-aggregate and plastic-aggregate-fibre both also recorded lower density when compared with the cement-aggregate block, which gives them a logistic advantage over the cement-aggregate block in the case of transporting them from one location to another. The blocks were found to be stable at low temperatures. The SEM images of the plastic-aggregate and plastic-fibre-aggregate paving blocks clearly showed a consistent dispersion of the plastic waste particles within the aggregate matrix over that of the cement-aggregate paving block. Therefore, plastic-aggregate brick can be recommended for use as paving bricks for low-traffic roads, walkways, parks, and gardens, although there is need to carry out further studies on other material properties of the plastic-based paving block.

Evaluating the impact of variability in the source of waste polyethylene on the design of plastic modified asphalt mixtures

Use of waste plastics in asphalt mixtures suffers from a serious problem of significant variability with global sources; preventing proper guidelines for field applications. The aim of this study is to address the variability in source of waste plastic and its impact on asphalt mixture design. Polyethylene (PE) obtained from 5 different sources was used as a replacement for asphalt binder through dry mixing at dosage levels of 3 %, 6 %, and 9 % by weight of binder. Two mixing temperatures (151°C, 165°C) with respective compaction temperatures (140°C, 156°C) were utilized during mix production to account for the increase in binder stiffness due to plastic modification. The changes in asphalt mixture volumetrics were correlated to plastic properties such as density(ρ), viscosity (η), melting point (Tm), and Degree of Crystallinity (Xc), apart from plastic source. Construction Densification Index (CDI) and Traffic Densification Index (TDI) values were also calculated for further understanding the workability of PE modified asphalt mixtures. Even though five plastics irrespective of sources could be categorized as PE, the Xc (<65 %) and η (<5594 Pa.sec at 165°C) played a prominent role in ensuring mixtures met volumetric requirements; after increasing the mixing and compaction temperatures. PE with Xc value (> 65 %) and η value (>5594 Pa.sec at 165°C) resulted in reduced workability with increased tendency of PE to behave as a filler. The study further recommends addressing PE in terms of core properties such as Xc and η rather than source or supplier to reduce variability and better understand its suitability in asphalt mixtures.

Tandem Integration of Biological and Electrochemical Catalysis for Efficient Polyester Upcycling under Ambient Conditions.

Excessive production of waste polyethylene terephthalate (PET) poses an ecological challenge, which necessitates developing technologies to extract the values from end-of-life PET. Upcycling has proven effective in addressing the low profitability of current recycling strategies, yet existing upcycling technologies operate under energy-intensive conditions. Here we report a cascade strategy to steer the transformation of PET waste into glycolate in an overall yield of 92.6% under ambient conditions. The cascade approach involves setting up a robust hydrolase with 95.6% PET depolymerization into ethylene glycol (EG) monomer within 12 h, followed by an electrochemical process initiated by a CO-tolerant Pd/Ni(OH)2 catalyst to convert the EG intermediate into glycolate with high Faradaic efficiency of 97.5%. Techno-economic analysis and life cycle assessment indicate that, compared with the widely adopted electrochemical technology that heavily relies on alkaline pretreatment for PET depolymerization, our designed enzymatic-electrochemical approach offers a cost-effective and low-carbon pathway to upgrade PET.

Innovative solutions for potential use of waste polyethylene terephthalate bottle cap as aggregates in concrete

Innovative solutions for potential use of waste polyethylene terephthalate bottle cap as aggregates in concrete

Development of modifying additives for epoxy oligomers based on household waste polyethylene terephtalate

A method for synthesis of oligoester polyols (OEP) and modified resins is presented, the effect of the OEP content on the dynamic viscosity, reactivity of resins, physicochemical and mechanical properties of structural materials is studied. Materials based on epoxy-diane resin modified with glycolyzed products were obtained. It was found that the use of the developed oligomers with optimal content of epoxy-diane resin as modifier leads to an increase in some characteristics of the resulting materials: elasticity, tensile strength and elastic modulus at static bending, viability of the composition. The use of glycolysis products is advisable because it is a promising method for recycling of household waste polyethylene terephthalate. It is characterized by ease of synthesis, as well as low cost and availability of initial components, and makes it possible to increase the physical and mechanical properties of structural materials based on epoxy resins, as well as contribute to solving environmental problems.

Fabrication of Fe-Zr, Co-Zr, and Ni-Zr Catalysts to Boost CNTs Synthesis from Plastic Wastes and the Electrocatalytic Oxygen Evolution Reaction.

The efficient conversion of plastic wastes to high-value carbon materials like carbon nanotubes (CNTs) is one important issue about the rational recycling, reduction, and reuse of solid wastes. Herein, Fe-, Co-, and Ni-Zr catalysts were prepared and used for CNTs synthesis from polyethylene (PE) waste via a two-stage reaction system. At the same time, the effects of the PE/catalyst ratio and reaction temperature on CNTs synthesis have been studied. Compared with Co-Zr and Ni-Zr, Fe-Zr exhibited the best activity in CNTs synthesis from PE, and it achieved the highest CNTs yield of 806.3 mg/g (per gram of Fe-Zr) at 800 °C with a PE/catalyst ratio of 4. Furthermore, the obtained Fe-Zr/CNTs composite exhibited a low overpotential of 267 mV for the electrocatalytic oxygen evolution reaction (OER) at 20 mA/cm2 in 1 M KOH electrolyte solution, which was 21 mV lower than commercial RuO2 (288 mV) and 50 mV lower than Fe-Zr (317 mV). It was deduced that the in situ growth of CNTs reduced the charge transfer resistance and improved the electron transport efficiency of the Fe-Zr/CNTs composite, leading to superior activity in the electrocatalytic OER. This work provided detailed information for the preparation of the metal/CNTs composite from plastic wastes, which contributed positively to alleviate the environment and energy crisis.

Ir(triNHC)-Catalyzed Upcycling of Waste PET for Lactic Acid Production with Sustainable Isolation via Bipolar Membrane Electrodialysis.

For the upcycling of waste polyethylene terephthalate (PET), encompassing both colored and fabric PET materials, we investigated the Ir(triNHC)-catalyzed dehydrogenative coupling of PET and methanol, leading to the production of sodium lactate with good yields. We proposed a sustainable method for isolating lactic acid from the catalytic reaction mixture of sodium lactate and regenerating the base using bipolar membrane electrodialysis (BMED). This isolation method demonstrated high effectiveness, achieving isolation of lactic acid while maintaining economic feasibility at $ 0.10 per kg of lactic acid, and enabling sustainable NaOH regeneration with complete resource circulation. We assessed the recyclability of the catalyst and elucidated the mechanism involving base-mediated depolymerization and catalyst-promoted dehydrogenation, highlighting the importance of triNHC ligands in enhancing catalytic activity.

Ir(triNHC)‐Catalyzed Upcycling of Waste PET for Lactic Acid Production with Sustainable Isolation via Bipolar Membrane Electrodialysis

AbstractFor the upcycling of waste polyethylene terephthalate (PET), encompassing both colored and fabric PET materials, we investigated the Ir(triNHC)‐catalyzed dehydrogenative coupling of PET and methanol, leading to the production of sodium lactate with good yields. We proposed a sustainable method for isolating lactic acid from the catalytic reaction mixture of sodium lactate and regenerating the base using bipolar membrane electrodialysis (BMED). This isolation method demonstrated high effectiveness, achieving isolation of lactic acid while maintaining economic feasibility at $ 0.10 per kg of lactic acid, and enabling sustainable NaOH regeneration with complete resource circulation. We assessed the recyclability of the catalyst and elucidated the mechanism involving base‐mediated depolymerization and catalyst‐promoted dehydrogenation, highlighting the importance of triNHC ligands in enhancing catalytic activity.

Selective and Controllable Cracking of Polyethylene Waste by Beta Zeolites with Different Mesoporosity and Crystallinity.

Waste plastics bring about increasingly serious environmental challenges, which can be partly addressed by their interconversion into valuable compounds. It is hypothesized that the porosity and acidity of a zeolite-based catalyst will affect the selectivity and effectiveness, enabling a controllable and selective conversion of polyethylene (PE) into gas-diesel or lubricating base oil. A series of embryonic, partial- and well-crystalline zeolites beta with adjustable porosity and acidity are prepared from mesoporous SBA-15. The catalysts and catalytic systems are studied with nuclear magnetic resonance (NMR), X-ray diffraction (XRD), and adsorption kinetics and catalytic reactions. The adjustable porosity and acidity of zeolite-beta-based catalysts achieve a controllable selectivity toward gas-diesel or lubricating base oil for PE cracking. With a catalyst with mesopores and appropriate acid sites, a fast escape and reduced production of cracking of intermediates are observed, leading to a significant fraction (88.7%) of lubricating base oil. With more micropores, a high acid density, and strong acid strength, PE is multiply cracked into low carbon number hydrocarbons. The strong acid center of the zeolite is confirmed to facilitate significantly the activation of hydrogen (H2),and, an in situ ammonia poisoning strategy can significantly inhibit hydrogen transfer and effectively regulate the product distribution.

Correction: Tsai et al. Polyethylene (PE) Waste Minimization Study of Cement Mortar with Adding PE Content under Different W/B Ratios. Buildings 2022, 12, 2117

Following publication [...]

Assessing the impact of discarded plastic bottles on the resistance to rutting in hot mix asphalt

Undoubtedly, the damage to the upper layer of road pavement caused by the tremendous load of vehicles and climate factors is alarming and challenging to both the government and researchers in the respective field. Addressing these challenges requires innovative solutions to enhance pavement durability and sustainability. In this context, the authors seek to assess the impact of incorporating waste polyethylene terephthalate (PET) as a modifier on asphalt mixture properties. This study investigates the potential of PET, a commonly discarded plastic, to improve the performance of asphalt pavements. The authors conducted evaluations on the rutting performance of asphalt blends containing different PET percentages (0%, 0.2%, 0.6%, 0.8%, 1%) and diverse PET sizes (12 × 3 mm, 20 × 3 mm, and 30 × 4 mm). The experimental approach included dynamic creep tests and the use of a Hamburg wheel tracking device to simulate real-world traffic conditions and measure the mixtures' resistance to deformation. The findings revealed that incorporating PET into asphalt mixtures significantly enhances rutting resistance. Specifically, the addition of PET content improved the viscoelastic properties of the asphalt, making it more resistant to permanent deformation under load. However, the size of PET particles was found to play a crucial role in performance. Larger PET sizes were associated with a decrease in rutting resistance, suggesting an optimal particle size must be determined to maximize benefits. These results support the idea that the careful selection of PET content and size can significantly improve the performance and longevity of asphalt pavements. This approach not only addresses the issue of plastic waste but also contributes to the development of more sustainable infrastructure. By incorporating PET, the research highlights a viable method for enhancing road durability and supporting environmental sustainability, offering a promising solution for future road construction projects.

Process Parameter Optimization of Waste Polyethylene Terephthalate Bottle Neutral Hydrolysis Depolymerisation Using Process Simulation and Response Surface Methodology

The global surge in plastic production has led to a concerning accumulation of durable plastic waste in landfills and the environment. To address this issue, the depolymerization of waste polyethylene terephthalate (PET) through neutral hydrolysis has been proposed as a chemical recycling solution. Despite its potential environmental benefits, the endothermic nature of this process at high temperatures has raised doubts about its commercial feasibility. In response, this study was conducted to assess optimal conditions for waste PET depolymerization using neutral hydrolysis in a continuous stirred tank reactor with zinc acetate as a catalyst. Process simulation, aimed to manufacture pure terephthalic acid (TPA) and ethylene glycol from pelletized post-consumer PET bottles, was conducted with Aspen Plus Version 11. Sensitivity analysis explored the impact of factors such as reaction temperature, reaction time, PET flake size, and catalyst to PET ratio on both PET conversion and TPA yield. The study found that PET depolymerization increased with decreasing particle size, longer reaction times, increasing catalyst to PET ratio and reaction temperatures within the range of 200–240°C. Optimizing the process through response surface modelling revealed that key parameters for neutral hydrolysis considering a mean particle size of 20 mm were the ratio of water to PET, temperature, pressure, and reaction time with optimal values of 5:1, 225°C, 30 bar, and 67.5 min respectively. The model's reliability was confirmed through variance analysis, emphasizing the significance of main and interaction effects in the regression model.