Mixed Plastic Waste Research Articles

Automatic and continuous separation of mixed waste plastics via magneto-Archimedes levitation

High efficiency separation is a significant process of the mechanical recycling to manage the mixed waste plastics. However, most of the extant methods can only deal with binary mixtures. In this paper, a novel automatic and continuous separation method based on magneto-Archimedes levitation is proposed to handle multi-plastics. A theoretical model on how the object is levitated above a single square magnet with the aid of paramagnetic media is established. The model revealed that object with different densities would be levitated at different heights. Lighter object would be levitated rapidly to a certain height and then be pushed away slowly. Thereby, the separated plastics could be collected automatically and the continuous separation of the mixtures can be addressed. The separation of polyurethane (PU), polyamide (PA6), and polytetrafluoroethylene (PTFE) demonstrated that the method can deal with multiple plastics with purities over 96.2%. Combined with additional advantages of low cost and no energy consumed in separation process, the method has the potential to be industrialized into an economically-viable and environmentally-friendly mass production procedure.

Production and Optimization of Energy Rich Biofuel through Co-Pyrolysis by Utilizing Mixed Agricultural Residues and Mixed Waste Plastics

Two totally waste products, agricultural residues and mixed plastic wastes collected from domestic and industrial sectors, are used in this study for the recovery of energy rich biofuel and value-added chemicals. The copyrolysis experiments using fixed bed reactor are conducted in order to analyse the synergetic effects. The experimental works are carried out with different proportion of mixed plastics blended with agricultural residues. The reaction temperature and biomass-to-waste plastics ratio on product distributions are studied and addressed. The thermogravimetric analysis conducted at different temperatures clearly distinguished the pyrolysis behaviours of biomass and plastics. The positive synergistic effects defined as higher yield of volatiles compared to predicted yield for bio-oil were identified at particular mixing ratio. Both biomass wastes and plastic wastes show optimal performance of 60.42 wt% oil yield at 60% addition of waste plastics. The oil products obtained under favourable conditions have a higher heating value compared to the oil obtained from biomass pyrolysis. The GC-MS study confirmed that the interaction between biomass and plastics during copyrolysis resulted in decreased oxygenated contents in the oil products.

Vol4 num3-6 Eco Sustainable Rail: production of sustainable railway sleepers from mixed plastics waste

Mixed plastics waste (MPW) constitute a material of extreme recycling difficulty due to their heterogeneity and contamination level. As a consequence, a large fraction of MPW is landfilled. It is imperative to find new applications for MPW that bring new value as a raw material, with application in high added-value products. The restrictions on the marketing and application of biocidal products such as the creosote treatment performed on wood railway sleepers, introduced by Directive 98/8/EC, triggered the replacement of several products traditionally produced in wood. Currently, there is a global need to find solutions for replacement of wood railway sleepers for specific railway applications. The present study investigates the application requirements and proposes a new solution based on MPW composites for the production of eco-friendly railway sleepers. The composites are mostly based on MPW and glass fibers. The prototype composite sleepers were produced by intrusion processing and tested in simulated mechanical and environmental operating conditions. Overall this new circularity approach will largely contribute to reduce the deposition of MPW in landfills, responding to a current need of the railway sector, and will contribute to implement circular economy and resource efficiency.

Towards solvothermal upcycling of mixed plastic wastes: Depolymerization pathways of waste plastics in sub- and supercritical toluene

Solvothermal liquefaction (STL) is a thermochemical conversion process, where a waste feedstock is treated with sub-and supercritical solvents. The key objective of the study was to investigate how a one-step STL using toluene as a solvent can degrade hard-to-recycle waste plastics (#5–#7). Three different plastic wastes namely, polypropylene (#5), polystyrene (#6), and polyurethane (#7), and their equal mixture (by weight, also referred here as mixed plastic wastes) were solvothermally liquefied by toluene in a 7 mL pressure bomb at 300, 350, and 400 °C for 3, 6, and 9 h in order to determine the effect of temperature and time, respectively. The liquid products were separated from the solid residue and further analyzed in terms of the STL conversion, change in elemental compositions via ultimate analysis, boiling point distribution via thermogravimetric analyzer (TGA), alteration of chemical bonds via proton nuclear magnetic resonance spectroscopy (1H NMR), and degradation products via gas chromatography mass spectroscopy (GCMS). The results showed that the STL conversion increase with the increase of reaction temperature and time. From the elemental analysis, it can be predicted that the higher heating values of the crude products are between 30 and 45 MJ/kg. Boiling point distribution showed that the production of lower hydrocarbon (C8–C20) increased significantly from about 10% at 300 °C to 80% at 400 °C. Additionally, product distribution showed that the aromaticity increased with the increase of residence time where the main products are benzene and styrene like products. Overall, it was observed that mixed plastic wastes have a synergistic effect on the degradation products.

Conversion of plastic waste into fuel oil using zeolite catalysts in a bench-scale pyrolysis reactor.

Catalytic pyrolysis of mixed plastic waste to fuel oil experiment was tested with ZSM-5 zeolite (commercial and synthesized) catalysts along with other catalysts. The ZSM-5 zeolite catalyst was effectively produced using a hydrothermal technique via metakaolin as an alumina source. The catalytic pyrolysis of different types of plastic (single and multilayer) wastes in the presence of various catalysts was tested with a bench-scale pyrolysis setup with 2 kg per batch capacity. Polyolefin based plastics (low-density polyethylene, high-density polyethylene, and polypropylene), multilayer plastics such as biaxial oriented polypropylene (BOPP), metalized biaxial oriented polypropylene layers (MET BOPP), polyethylene terephthalate (PET), metalized polyethylene terephthalate (MET/PET), polyethylene terephthalate combined polyethylene (PET/PE), and mixed plastic waste collected from the corporation sorting center were pyrolyzed in a batch pyrolysis system with 1 kg feed to determine the oil, gas and char distributions. The performances of commercial ZSM-5 and lab synthesized ZSM-5 catalysts were compared for the pyrolysis of non-recyclable plastic wastes. Other commercial catalysts including mordenite and gamma alumina were also tested for pyrolysis experiments. The gross calorific value of oil obtained from different combinations of multilayer packaging waste varied between 10 789–7156 kcal kg−1. BOPP-based plastic waste gave higher oil yield and calorific value than PET-based plastic waste. Sulfur content present in the oil from different plastic wastes was measured below the detection limit. The synthesized ZSM-5 zeolite catalyst produced a maximum oil output of 70% and corresponding gas and char of 16% and 14% for LDPE plastic. The strong acidic properties and microporous crystalline structure of the synthesized ZSM-5 catalyst enables increased cracking and isomerization, leading to an increased breakup of larger molecules to smaller molecules forming more oil yield in the pyrolysis experiments. Residual char analysis showed the maximum percentage of carbon with heavy metal concentrations (mg kg−1) in the range of viz., chromium (15.36–97.48), aluminium (1.03–2.54), cobalt (1.0–5.85), copper (115.37–213.59), lead (89.12–217.3), and nickel (21.05–175.41), respectively.

Biological Treatment of Municipal Solid Waste in Erode Corporation, Tamilanadu, India

In this article, we see the limit of utilising different city solid waste streams as feedstock for effective power energy creation. These waste streams include ordinarily degradable waste, yet are not limited to mixed burnable waste, versatile and plastic waste, clinical waste with benefits, normal biodegradable waste, biomass, and sewage grime. Current advancements such as anaerobic dealing, gasification, and pyrolysis have been investigated in close proximity to the area and waste stream sums in the chosen test region.It was seen that there are run of the mill, social and monetary benefits in the waste to energy approach for the waste streams kept an eye out for. The reachability of executing such advances is, on an exceptionally fundamental level, dependent upon the fundamental capital hypothesis and the important cost of the work space. Various factors blend the size of the waste stream, the cost of things, and deals. The quick urbanisation and change in lifestyle has increased the waste weight and, as required, ruining loads on the metropolitan environment to unmanageable and upsetting degrees. This assessment revelation embraced existing to foster waste dumping fights are fully past their end and under unsanitary conditions, impelling defiling of water sources, augmentation of vectors of communicable contamination, foul smells and aromas, the appearance of disastrous metabolites, sedative environment and imperfection, etc.

Preparation of Monocyclic Aromatic Hydrocarbons from Chlorine-Containing Mixed Waste Plastics Via Tandem Catalysis Coupled with Hydrothermal Pretreatment

Preparation of Monocyclic Aromatic Hydrocarbons from Chlorine-Containing Mixed Waste Plastics Via Tandem Catalysis Coupled with Hydrothermal Pretreatment

Study on Pyrolysis Characteristics and Kinetics of Mixed Waste Plastics Under Different Atmospheres

Study on Pyrolysis Characteristics and Kinetics of Mixed Waste Plastics Under Different Atmospheres

An overview of engineering properties and durability of glass fibre reinforced mixed plastic waste composite

In this research article a new class of epoxy- based glass fiber composite was prepared. Glass fiber was collected from the glass insulation factory. The Hand moulding method was used for the fabrication of composites. Composite fabricated with varying content ranges from 30 wt% to 50%. For a thorough characterization of GRP waste, detailed laboratory tests were performed. The results obtained from physic-chemical characteristics showed the bulk density of GRP waste as 0.84 g/cm3, specific gravity 1.39 with pH and conductivity as 6.78 and 198.33 µS. Further, the results obtained from X-ray fluorescence (XRF) showed the presence of silica and calcium in appreciable amounts. Different mechanical properties like tensile test impact test, flexural test, were carried out hence low water absorption high flexure strength shows that it is suitable for construction purpose through eco friendly process. In physical properties water absorption test was done FTIR analysis is also carried out. Which shows that the silica content is higher in the glass fiber.

Pyrolysis of plastic waste for a better environmental system

Owing to the rapid utilization of fossil fuels, the world is in need of a sustainable and renewable energy source. Surplus resources of municipal solid waste and plastic waste will act as a better biomass fuel for generating electricity and liquid fuels, which can be extracted using Pyrolysis process. The present work addresses the pyrolysis process of mixed plastic wastes. This leads to fuel oil production, which is capable to reduce the problems associated with plastic waste disposal.Plastic wastes along with municipal solid waste getting generated day to day in diversified house hold and industrial wastes are addressed to be a threat and among the major sources of environmental pollution. On other hand it’s to be noticed that theses carbonaceous plastics wastes and municipal solid waste having rich carbon content. This Biomass wastes are highly capable not only to provide a renewable source of fuel but also these technologies will act as a gate way of recycling the multidisciplinary waste getting generated in the society.

Thermal Pyrolysis of Individual and Mixed Plastic Waste of Polypropylene, Polyethylene and Polystyrene

Thermal Pyrolysis of Individual and Mixed Plastic Waste of Polypropylene, Polyethylene and Polystyrene

Experimental Study on Properties of Concrete Using Shredded Plastic Waste and M-Sand as Partial Replacement of Fine Aggregate

Disposal of large quantity of plastic causes land, water, and air pollution etc.., so a study is conducted to recycle the plastic in concrete. This work investigates about the replacement of natural aggregate with non-biodegradable plastic aggregate made up of mixed shredded plastic waste in concrete. Several tests are conducted such as compressive strength of cube, compressive strength of cylinder, flexural strength test of prism to identify the properties and behavior of concrete using shredded plastic aggregate. Replacement of fine aggregate weight by 0%, 5%, 10%, 15%, 20% with shredded plastic fine (PF) aggregate and manufactured sand (M-Sand). Totally 30 cubes, 30 cylinders and 30 prisms are casted to identify the compressive strength, cylindrical compressive strength, and flexural strength respectively. Casted specimens are tested at 7, 14 and 28 days. The identified results from concrete using shredded plastic aggregate are compared with conventional concrete. Result shows that initially there is increase in mechanical properties then there is reduction in mechanical properties due to addition of shredded plastic aggregate added concrete. This reduction in strength is mainly due to poor bond strength between cement and shredded plastic aggregate.

Waste eliminated by waste under COVID-19 pandemic: Mixed plastic waste derived N,O-rich porous carbon nano-coral reefs for chlorophenol pollutants efficient capture

Both increasing emission of chlorophenol chemicals and plastic waste pollution are severe global environmental challenges, which is worth being explored to respond with a "waste eliminated by waste" coupling treatment strategy. Herein, we propose a one-step recyclable nano-MgO template strategy to prepare in-situ N, O-doped novel porous carbon coral reefs (PCNCR) directly derived from the mixture of real waste PET and melamine formaldehyde resin. The template precursor can be conveniently recycled by facile acetic acid pickling, vacuum evaporation and drying, and the whole preparing process does not involve any toxic solvents, massive consumption of pore-forming agents, or discharge of salty wastewater. The obtained PCNCRs have hierarchical porous structures and abundant N, O-doped species, and the textural parameters can be modulation linearly by varying the mass ratio of magnesium acetate to mixed waste plastics. The optimized PCNCR-1.25 exhibited remarkable adsorption capacity for chlorophenol contaminants (777.5 mg/g for 4-Chloro-3,5-dimethylphenol, PCMX and 538.74 mg/g for 4-Chloro-3-methylphenol, PCMC) in aqueous solution. Adsorption isotherm fitting studies revealed chlorophenol contaminants tended to be rapidly adsorbed on the PCNCR surface in the form of monolayer. And the system reached adsorption equilibrium at about 15 min, which was described by linear driving force model. Reusability test verified that PCNCR-1.25 had excellent adsorption stability for chlorophenol in continuous adsorption-regeneration cycles. DFT calculation illustrated the enhancement of chlorophenol adsorption by heteroatom species, especially nitrogen dopants. This work highlighted a low-cost and sustainable approach to defuse the dual environmental threat of chlorophenol emissions and plastic waste pollution simultaneously.

Study on Performance of Wax Warm Mix Asphalt Cracked by Mixed Polyethylene Waste Plastics

In order to study the modified performance of polyethylene waste plastic cracking wax on asphalt, this paper prepared polyethylene wax (PE wax) by catalytic cracking using waste polyethylene as raw material and Ni-based zeolite as catalyst in a pressure reactor under closed conditions. 70# base asphalt was modified with PE wax, and the properties of pyrolysis wax on asphalt under different catalytic cracking time were studied by three indexes test, Brinoll rotary viscosity test, DSC test and dynamic shear rheology test. The test results show that the cracking products of mixed polyethylene waste plastic cracking wax have good viscosity reduction effect on asphalt under different cracking time. After modification, the high temperature performance of asphalt is improved, and the low temperature performance has a certain influence, but it still meets the specification requirements; In the temperature range of 0°C~60°C, the addition of pyrolysis wax can make the phase transformation of matr-ix asphalt more stable.

MIXed plastics biodegradation and UPcycling using microbial communities: the NSFC-EU 2019 project MIX-UP to help achieve "carbon neutrality"

With the transformation and revolution of the global plastics recycling system, recycling and upcycling of mixed plastics waste not only reduces the carbon emissions of plastics during its life cycle, but also addresses its potential ecological and environmental hazards. This article summarizes an international cooperation project, "MIXed plastics biodegradation and UPcycling using microbial communities" (MIX-UP) which was funded by the National Natural Science Foundation of China and the European Union (NSFC-EU) in 2019. The consortium of MIX-UP consists of 14 partners from European Union and China. Focusing on the global issue of "plastics pollution", this Sino-European MIX-UP project took the mixed waste of petroleum-based plastics (PP, PE, PUR, PET and PS) and bio-based plastics (PLA and PHA) as starting materials for biotechnological conversion into value-added, sustainable biomaterials. MIX-UP has three subprojects: 1) identification of plastics biodegradation pathway and design & engineering of key degrading elements, 2) construction and functional regulation of microbial consortia/enzyme cocktails with high-efficiency for degradation of plastics mixtures, 3) strategy of design and utilization of plastics degradation products for production of high value materials. Through NSFC-EU complementary and cross-disciplinary cooperation, MIX-UP proposes the engineering of a new-to-nature biological route for upcycling, a low carbon and sustainable bio-treatment that is different from the traditional physico-chemical treatment, which will empower the recycling industry to a new dimension. The implementation of the project will not only help to promote innovation and development in the field of biotechnology in China, but also contribute to the achievement of China's carbon neutral goal.

Using ATR-FTIR spectra and convolutional neural networks for characterizing mixed plastic waste

We present a convolutional neural network (CNN) framework for classifying different types of plastic materials that are commonly found in mixed plastic waste (MPW) streams. The CNN framework uses experimental ATR-FTIR (attenuated total reflection-Fourier transform infrared spectroscopy) spectra to classify ten different plastic types. An important aspect of this type of spectral data is that it can be collected in real-time; as such, this approach provides an avenue for enabling the high-throughput characterization of MPW. The proposed CNN architecture (which we call PlasticNet) uses a Gramian angular representation of the spectra. We show that this 2-dimensional (2D) matrix representation highlights correlations between different frequencies (wavenumber) and leads to significant improvements in classification accuracy, compared to the direct use of spectra (a 1D vector representation). We also demonstrate that PlasticNet can reach an overall classification accuracy of over 87% and can classify certain plastics with 100% accuracy. Our framework also uses saliency maps to analyze spectral features that are most informative.

Cover Feature: Synthetic Lubricants Derived from Plastic Waste and their Tribological Performance (ChemSusChem 19/2021)

The Cover Feature shows a mixed waste plastic stream being converted to synthetic motor oil lubricants. A Pt nanoparticle catalyst utilizes H2 gas to selectively break up the hydrocarbon chains via C−C scissions to produce a liquid, monodisperse product. More information can be found in the Full Paper by R. A. Hackler et al.

A new GPC/TREF/LinELSD instrument to determine the molecular weight distribution and chemical composition: application to recycled polymers

The linearized evaporative light scattering detector (LinELSD) incorporates an inverse power function facilitating the characterization of polymers in solution. To show the benefits of the LinELSD, a versatile liquid chromatograph was built by combining a high temperature gel permeation chromatograph (HT-GPC), a fast cooling/heating oven of a gas chromatograph (GC), and the LinELSD. Apart from the main GPC functionality to measure the molecular weight distribution (MWD) of polymers, the injected samples can also be eluted as a function of polymer type by applying a temperature rising elution fractionation (TREF) program on the column placed in the GC oven. The hybrid GPC/TREF/LinELSD instrument removes the limitations of the commercial GPC and TREF systems manufactured with differential refractive index (DRI) or infrared (IR) detectors, which require a sensible difference between the refractive indices of polymer and solvent, or the absence of CH2 and CH3 groups in the solvent. Thus, the new instrument qualifies to characterize the chemical structure of recycled polymers, demanding more flexible analytical conditions than those previously developed for the virgin resin analysis. Moreover, the hybrid instrument allows to investigate polyolefin solutions in xylene and toluene, which are the preferred solvents for the selective extraction of high-performance polymers from mixed plastic waste, thus qualifying as a unique analytical solution to assess the emergent solvent-based purification industrial processes.

Gasification characteristics of waste plastics (SRF) in a bubbling fluidized bed: Effects of temperature and equivalence ratio

This study investigates air gasification properties of SRF with high content of residual mixed waste plastic in a 1 kg/h lab scale bubbling fluidized bed gasifier. Gasifier internal diameter is 0.114 m and its height is 1 m. Silica sand particles with a mean diameter of 400 μm is used as the bed material. During the gasification experiments the effect of bed temperature is determined in the range of 600–900 °C and the effect of air-to-fuel equivalence ratio (ER) is investigated in the range of 0.15–0.30. Gas analysis is conducted using a non-dispersive infrared analyzer and gas chromatograph. As the operating temperature and ER increases, the gas yield increases, and tar yield decreases. The yield of CO, CH4, H2, and C2H2 in the gas product increases with temperature, whereas those of CO2, C2–C3 hydrocarbons decreases. The increase in ER decreases the concentrations of CO, CH4, H2, and C2–C3 hydrocarbons and increases the CO2 in the gas product. H2/CO ratio substantially increases with rising temperature and decreases with rising ER. Carbon conversion efficiency (CCE) and cold gas efficiency reach peak at 800 °C and ER of 0.25.

Chemical Recycling of Mixed Plastic Wastes by Pyrolysis – Pilot Scale Investigations

AbstractChemical 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.