Waste Plastic Mixture Research Articles

Transformative and sustainable approach to waste plastic mixture valorization

The development of innovative methods for waste plastic valorization can benefit the environment and economy. In this study, the full spectrum of products (gas, oil, and solid products) resulting from the pyrolysis–reforming of a plastic mixture functioned as precursors of value-added products: 1) ethylene–propylene copolymers, 2) polyacrylonitrile (PAN)-based carbon nanofibers (CNFs), and 3) carbon quantum dots (CQDs). The CNFs were subsequently applied as supercapacitor electrodes, whereasthe CQDs acted as co-sensitizers for the primary sensitizer, N3, in dye-sensitized solar cells (DSSCs). Adding oil to PAN increased the specific capacitance of the CNFs by 46.12% to 226.64F/g, compared with that of pure PAN CNFs. With the aid of CQDs, the short-circuit current density and photo-conversion efficiency of DSSCs increased by 25.89% and 17.08%, respectively. Mechanisms associated with the integrated valorization pathway were proposed.

Strategic conversion of plastic containers with food waste into energy through thermochemical processes

Plastic valorization has received particular attention as an environmentally benign approach to achieve carbon neutrality and reduce greenhouse gas emissions. However, contaminated plastic and biomass waste mixtures suffer from single-stream recycling. Waste mixtures are currently discarded through landfilling and incineration. As a sustainable disposal and valorization method for converting plastic and biomass waste mixtures into energy-intensive products, especially syngas (H2 and CO), this study utilizes catalytic pyrolysis and a CO2 flow gas. A plastic container contaminated with a food waste mixture (PFW) was used as the model waste. The major products of the pyrolysis of PFW were liquid hydrocarbons (HC) (C7–30) and wax-like HCs with negligible formation of oxygen-containing HCs. However, the high production of wax-like HCs becomes a problem. Catalytic pyrolysis was employed to convert HCs into simpler product streams such as syngas. Although syngas formation tripled with the Ni catalyst, catalyst deactivation was observed. To suppress catalyst deactivation and promote CO formation, CO2 was introduced instead of N2. During the CO2-assisted catalytic pyrolysis, the syngas yield from PFW increased to 95.5 % because the chemical reactions between CO2 and liquid/wax-like HCs produced additional H2 and CO. The catalytic reaction with CO2 suppressed carbon deposition because long-chain HCs were converted to CO rather than coke.

Catalytic Approaches to Tackle Mixed Plastic Waste Challenges: A Review.

Plastics are widely used materials in our daily lives and various industries due to their affordability and versatility. The massive production of plastic waste, however, has recently emerged as a pressing environmental concern across all media. To address this, emerging technologies are being explored for the sustainable valorization of postconsumer plastic wastes including thermochemical, physical, and catalytic processes aimed at transforming them into higher value-added products. However, the chemical recycling of mixed plastic wastes poses a formidable challenge due to the diverse array of monomers and catalyst systems involved, each employing distinct mechanisms. Complicating matters further is that contaminants reduce catalytic efficacy, requiring rigorous and labor-intensive separation and purification processes to extract individual plastic streams from practical plastic waste mixtures. Consequently, the majority of such mixtures often end up in incineration and landfills, perpetuating environmental and societal challenges, such as leachate, carbon dioxide emissions, and other air pollutants. This review will introduce current technical developments available for recycling practical plastic waste mixtures through catalytic processes. The current challenges in process performance, low selectivity of the desired products, and catalyst deactivation from the catalysis of plastic waste mixtures are also discussed. Promising approaches to overcome the problems are suggested in future research directions.

Transforming a mixture of real post-consumer plastic waste into activated carbon for biogas upgrading

Plastic waste management is a current environmental issue that demands potential solutions since complete mechanical recycling is limited to the complexity and feasibility regarding the quality and purity of plastic waste. Pyrolysis has emerged as a reasonable solution for the recycling of those fractions that are not further suitable for recycling. Although the implementation of this technology is mature, the generated solid fraction or char has not been completely inserted in the closed loop of plastic recycling. This work explores the possibility of using the carbonaceous char as a precursor for the preparation of porous activated carbons for environmental application as CO2 adsorbent and biogas upgrading. The effect of the pyrolysis temperature (450 or 500 ºC) on the obtained chars has been assessed for the benefits in the second stage of chemical activation, exploring the possibility of the use of diverse chemical agents. The composition, textural, and surface properties of the porous materials were characterized. N2 isotherms showed that the char prepared at 500 ºC provided the best textural properties with a performance of K2CO3 ∼ KOH > Na2CO3 > NaOH > ZnCl2 > FeCl3. Isotherms of CO2 adsorption showed that the activation with K2CO3 displayed the best uptake (130.2 mg g−1 at 273 K), closely followed by KOH (125.0 mg g−1 at 273 K), also confirmed by dynamic tests in a fixed bed column configuration. The uptake was well correlated with the ultramicropore volume and the oxygenated functional groups. The CO2 and CH4 adsorption were studied either in static or dynamic assays. The behavior of the sample activated with K2CO3 was studied in detail in column tests, suggesting that the activated material exhibits promising behavior for biogas upgrading.

Transformation of biomass and waste plastic mixtures into hydrocarbon oils and gases by pyrolysis using different reactor temperatures and pressures

In this work the laboratory scale pyrolysis and gasification of biomass and plastic waste mixtures were investigated at different temperatures (450°C and 750°C) and reactor pressures (0.1 bar and 1.0 bar). The main decomposition reactions and the effect of the process parameters were followed through the product yields and compositions of gases and pyrolysis oils. Less residue and significantly more gases had been found at higher temperature, which phenomena was more notable in case of higher proportion of plastic waste in the raw material mixtures. The concentration of hydrogen in gases changed by opposite trend at 450°C and 750°C as function of biomass ratios. The hydrogen and CO ratio can also increase by the increasing in plastic proportion of raw materials at both temperatures and pressures. Regarding the pressure, it can increase the pyrolysis and gasification reactions resulted higher yields of gases and lower oil/water ratios. More hydrogen and less C2-C6 compounds were found using 0.1 bar reactor pressure. Pyrolysis-oil contained aliphatic and aromatic hydrocarbons; n-paraffin, n-olefin, aldehyde, ketones, alcohols, phenols, carboxylic acids, etc. Due to deoxygenation reactions, hydrocarbons with less oxygen-containing compounds were found at 0.1 bar pressure.

Factors influencing synergistic pyrolysis of biomass and polypropylene for alcohols and hydrocarbon production

Results are presented on the co-pyrolysis of different blends of rapeseed stalk and plastic polypropylene (100:0, 75:25, 50:50, 25:75 and 0:100) using thermogravimetric analysis (TGA), Fourier transform infrared (FTIR) spectroscopy and pyrolyzer-gas chromatography/mass spectrometry (Py-GC/MS), independently. The effect of temperature (450, 550 and 650 °C) on the synergistic effect between rapeseed stalk and polypropylene at different blend ratios as well as on the yield and amounts of alcohols and hydrocarbons produced are presented. The thermogravimetric analysis results showed that at the same temperature, increase of polypropylene in the mixture, gradually increased the intensity and rate of pyrolysis reaction. The weight loss data revealed improved pyrolysis during the process. The Fourier transform infrared spectroscopy results showed that the transmittance of ketones, esters and acids increased while the content of ketones, esters and acids decreased with increased polypropylene in the mixture. The pyrolyzer-gas chromatography/mass spectrometry results showed that temperature and feedstock mixture ratio had an impact on the yield and amounts of alcohols and hydrocarbons. The pyrolysis effect was most favorable at 550 °C temperature and rapeseed stalk/polypropylene mixture ratio of 1:3. These results provide some practical insights on clean energy recovery from mixtures of agricultural residues and waste plastics using thermochemical conversion.

Exploring the Influence of Plastic Powder Incorporation on Geotechnical Properties of Expansive Soil Stabilized with Granite Powder for Building Applications

An experimental study was undertaken to investigate the effect of plastic and granite waste powder on the geotechnical performance of expansive soil, using different mix ratios. The soil studied is Hachem, in the northwestof Algeria. In this context, first reinforcing the plastic powder with granite powder, then add the mixture to the expansive soil. The percentage of plastic powder is (0%, 1%, 2%, 3%, 4%) and reinforced at 2%, 4%, 6% and 8% with granite powder. The experimental results showed a gradual decrease in liquid limits, swell potentials, and swelling pressure as the proportions of plastic and granite powder increase. In terms of the results obtained by reducing swelling and swelling pressure values and increasing unconfined compressive strength (UCS) tests and ductility values, this mixture of waste plastics and granite can be of great importance in improving the mechanical properties of samples.

Investigation of waste LDPE with Pongamia pinnata seed for sustainable resource recovery: Thermodynamics, Kinetics and artificial neural network modeling for co-pyrolysis potential

Pyrolysis conversion offers the advantages of significant waste reduction and potential energy recovery. This work examined the potential of combining plastic and agricultural wastes as pyrolysis feedstocks. The mixture of waste low-density polyethylene and Pongamia pinnata seeds was analysed using differential and thermogravimetric methods. In addition to the Coats-Redfern (CR) method, Kissinger-Akahira-Sunose (KAS), Flynn-Wall-Ozawa (FWO), Friedman (FRM), and Kissinger (KN) model-free methods were also applied to calculate the kinetic parameters. The apparent activation energy (Ea) calculation demonstrated that the co-pyrolysis conversion required Ea values of 125–154 kJ mol−1. The artificial neural network (ANN) model was considered to validate thermogravimetric data. The R2 values were near unity in training, validation, and testing conditions, with the minimum possible value for mean square error obtained for the considered heating rates. The Pongamia pinnata seeds and waste plastic mixture could surely be utilized to lessen environmental degradation, add value to leftover seeds and waste low-density polyethylene by extracting fuel for transportation and other commercial activities, and produce industrial chemicals, as found through the kinetic modelling, thermodynamic parameters, and ANN modelling.

Effect of metal powder and coil on microwave pyrolysis of mixed plastic

Plastic is used in a wide range of application, thus generating a huge amount of plastic waste which is difficult to manage. Real life waste streams often consist of a complex mixture of plastic waste. Mixed plastic waste is a challenge for the recycling industry since different type of plastics tend to be incompatible when recycled together. Hence, microwave pyrolysis of mixed plastic is conducted to efficiently recover oil product and achieve the required plastics recycling rates. In this study, the interaction of iron metal of different shapes (powder and coil) was investigated. Three type of plastics that was, polystyrene (PS), polypropylene (PP) and low-density polyethylene (LDPE) were mixed together at a constant ratio of 1:1:1. The ratio of mass of iron powder (g) with the quantity of iron coil was varied as followed: 5:5, 10:5, 5:10 and 10:10. The pyrolysis of mixed plastic (PS, PP and LDPE) with iron powder and coil ratio at 10:5 yielded the highest oil product at 70.24 wt% followed by 65.19, 52.72 and 40.38 wt% for 5:10, 10:10 and 5:5 ratio. The heating mechanism of the different shapes of metal differed such that the metal powder absorbed the microwave radiation whereas the metal coil concentrated the microwave at its surface and reflected it. Synergistic effect between microwave absorption and reflection may result in higher rate of plastic degradation and higher oil yield.

Investigation of gasoline-like transportation fuel obtained by plastic waste pyrolysis and distillation

Gasoline-like hydrocarbon products obtained from the distillation of different pyrolysis oils produced from solid wastes of polypropylene (PP), polystyrene (PS), polyethylene (PE), and their blends were investigated as these materials together form a good candidate for providing gasoline with properties approaching or fulfilling standard requirements in various countries. A laboratory-scale batch reactor equipped with reflux was used in this research, while the gasoline fractions of pyrolysis oils processed by distillation were further analyzed by GC-MS. Fuel density, volatility, distillation curves, olefin content, aromatics (including benzene) content, and oxygenates were analyzed, and various scenarios were proposed for reaching standard quality. The results were compared to a commercial gasoline sample from Hungary. It was found that the gasoline-like product of low-density PE (LDPE) and high-density PE (HDPE) showed the most similarities to standard requirements regarding molecular distribution. The PS produced mainly aromatics, while the gasoline yield of PP contained 53.5 vol% 2,4-dimethyl-1-heptene, which severely affects the distillation requirements presented by gasoline fuel standards. The results show that the mass ratio of plastic materials used in the pyrolysis process can heavily influence the oil products’ applicability as a transportation fuel. The optimal plastic waste mixture combined with the saturation of the olefin content by catalytic hydrogenation can provide standard-quality gasoline.

Impact of Metal Impregnation of Commercial Zeolites in the Catalytic Pyrolysis of Real Mixture of Post-Consumer Plastic Waste

This work reports the study of the catalytic pyrolysis of rejected plastic fractions collected from municipal solid waste whose mechanical recovery is not plausible due to technical or poor conservation issues. The chemical recycling using catalytic pyrolysis was carried out over commercial zeolites formulas, i.e., HY and HZSM-5, in which Ni or Co metals were deposited at two different loadings (1 and 5%, wt.). The presence of these transition metals on the zeolitic supports impacted the total production of compounds existing in the liquid oil. The samples were characterized in terms of structural, chemical, and morphologic properties, and the production of different fuel fractions (gasoline, light cycle oil, and heavy cycle oil) was correlated with a combined parameter defined as a ratio of Acidity/BET area.

Improving Performance in Mixture Porous Asphalt: Application Polyethylene-Terephthalate (PET) and Lawele Granular Asphalt (LGA)

Plastic has various types, one of which is PET (Polyethylene Terephthalate) plastic, which is often used as a raw material for plastic bottles. One type of asbuton that is often used for road pavement is LGA (Lawele Granular Asphalt) asphalt. Repairs by adding asbuton to the porous asphalt mixture need to be done. This is because porous asphalt has several weaknesses, namely low strength or stability compared to other asphalt mixtures. The addition of PET and LGA waste to porous asphalt is a topic in this article. This research design uses a quantitative design with a type of experimental research. The results of the study concluded that: (1) The results of testing the characteristics of the constituent ingredients of the porous asphalt mixture meet the specifications of SNI, and (2) The test results of the addition of PET (Polyethylene Terephthalate) plastic and LGA (Lawele Granular Asphalt) to porous asphalt mixture meet the specifications by RSNI 2 Design and Implementation of Porous Asphalt Mixture 2012. It is hoped that this research can be an alternative to the mixture of PET plastic waste and LGA asbuton in a porous asphalt mixture. In addition, the newness of this material is expected to also help the construction of roads.

Pyrolysis study of a waste plastic mixture through different kinetic models using isothermal and nonisothermal mechanism.

Pyrolysis can be a convenient way to produce oils and gases simultaneously, as well as hydrocarbons and even crude petrochemicals. It can also be used to produce energy from a waste plastic mixture (WPM). To ascertain the kinetics parameters at the heating rates of 5, 10, 20, and 50 °C min-1, various kinetic models, including (a) model-fitting and (b) model-free, which are further separated into isothermal and non-isothermal categories, have been selected. The apparent activation energy (E a) and pre-exponential factor (A a) were calculated using the Friedman (model-free isothermal), KAS, FWO (model-free non-isothermal), and Coats-Redfern (model-fitting non-isothermal) approaches. The activation energy (E a), pre-exponential component (A a), and overall reaction order (n) were also calculated using a multi-linear regression methodology. In addition, the solid fuel characterization of WPM has been compared with previous literature results, as have the physico-chemical characteristics of pyrolytic oil. Finally, a brief mention of WPM's kinetic process has been included in this work. However, the results indicated two stages of thermal degradation and volatilization of the WPM zone during pyrolysis (410-510 °C, 510-770 °C). In the temperature range of 410-510 °C, 510-770 °C, two-stage thermal degradation zones are used to analyze the kinetic parameters for WPM. The result showed the average activation values obtained by the KAS, FWO, and Friedmam methods were 297.61, 295.25, and 267.26 kJ mol-1. In the case of the Coats-Redfern methods, the lowest activation energy was obtained by the PT1 kinetic model at 22.56 kJ mol-1, and the highest activation energy was found in the D3 kinetic model at 418.80 kJ mol-1 in the temperature zone of 410-510 °C. The temperature zone with the lowest activation energy was found to be between 510 °C and 770 °C.

Analysis of the thermal behavior of a fixed bed reactor during the pyrolysis process

Pyrolysis is a thermochemical process of degradation of organic compounds where the reaction takes place in an inert atmosphere. The process scale varies between industrial, semi-industrial or laboratory. During the pyrolysis process temperature has to be controlled, but, most of pyrolysis studies do not clearly state where the temperature is measured and weather the temperature field is uniform. In this paper thermal behavior of a laboratory scale fixed-bed reactor and energy consumption during pyrolysis processes were analyzed. Three different samples were used: mixture of plastic waste (sample 1), biomass (sample 2) and mixture of plastic waste and biomass (sample 3). The analysis of the thermal behavior of the reactor indicates that with careful regulation or temperature control of the process, one can obtain diagrams that can be used for the purpose of recording thermally intensive processes, similar to more complex thermogravimetric (TG) and derivative thermogravimetric (DTG) analyses. It has been shown that it is possible to change the heating rate and the overall energy efficiency of the process by simply choosing the appropriate raw material mixture.

A Comparative Study Between Conventional Concrete and Concrete Made from Plastic Waste by Using SolidWorks Software

Production of conventional concrete leads to several negative impacts on the environment while the plastic waste concrete can effectively overcome the environmental issues and having better performance than conventional concrete. Therefore, this research presents the works in producing new concrete by replacing the fine aggregates in concrete by using a mixture of soft and hard plastic waste with different ratios density. In addition, this research also aims to evaluate the mechanical and physical properties of different ratios of fine aggregate plastic waste in producing a concrete. At the end of this research, a comparison is made between the optimum composition of plastic waste concrete and conventional concrete. This study is conducted by using SolidWorks software version 2021. The tests conducted include compressive strength test, drop test, and failure analysis. The results from the compressive strength test revealed that a force at 100kN with 20% plastic waste (Sample B) showed the highest stress (18.91 MPa). Meanwhile, from the drop height of 2.0m, the impact strength of Sample B showed the highest result with a value of 7.830 x106 N/m2. However, failure analysis results revealed that Sample B has more cracking than Sample A. From the study carried out, it can be summarised that an optimum replacement of 20% plastic waste as fine aggregates in a concrete gives the best performance is the most suitable option to be used as a replacement concrete in lightweight construction.

Thermogravimetric and Kinetic Analysis of Waste Biomass and Plastic Mixtures

Thermogravimetric and Kinetic Analysis of Waste Biomass and Plastic Mixtures

Valorization of Agricultural Polyolefin Plastic Waste in the Kingdom of Morocco through Thermal Pyrolysis: Influence of Thermal Parameters on Pyrolytic Oil Yields

This article focuses on exploring the recycling of agricultural plastic waste mixtures through the route of thermal cracking. In an experimental setting within a pilot-scale batch reactor, the impact of temperatures and heating rates on the yields obtained in the pyrolysis process have been meticulously examined. The temperatures of the pyrolysis process were varied between 360°C and 480°C, while the heating rates underwent changes, including 10, 15, and 30°C/min. The response parameters were the liquid, solid, and gas fractions. This research indicates that moderate temperatures and slower heating rates, resulting in extended reaction times, promote the generation of liquid fuel from pyrolysis. We achieved an optimal liquid fuel yield of 79% at 380°C, employing a temperature ramp of 10°C/min. Characterization of pyrolysis fuel resulting from the pyrolysis process revealed an extensive variety of hydrocarbons, requiring prior fractionation for optimal use in internal combustion engines. This step led to the separation into three distinct fractions: a light fraction (analogous to gasoline), accounting for 22.62% of the total weight, a middle fraction (similar to diesel), weighing 53.67% of the weight, and a heavy fraction (comparable to heavy diesel), totaling 23.71% of the weight. The light fraction presents an octane rating in line with conventional gasoline values, while the middle fraction meets the required cetane criteria for diesel.

Three-stage pyrolysis–steam reforming–water gas shift processing of household, commercial and industrial waste plastics for hydrogen production

Five common single plastics and nine different household, commercial and industrial waste plastics were processed using a three-stage (i) pyrolysis, (ii) catalytic steam reforming and (iii) water gas shift reaction system to produce hydrogen. Pyrolysis of plastics produces a range of different hydrocarbon species which are subsequently catalytically steam reformed to produce H2 and CO and then undergo water gas shift reaction to produce further H2. The process mimics the commercial process for hydrogen production from natural gas. Processing of the single polyalkene plastics (high-density polyethylene (HDPE), low-density polyethylene (LDPE), and polypropylene (PP)) produced similar H2 yields between 115 mmol and 120 mmol per gram plastic. Even though PS produced an aromatic product slate from the pyrolysis stage, further stages of reforming and water gas shift reaction produced a gas yield and composition similar to that of the polyalkene plastics (115 mmol H2 per gram plastic). PET gave significantly lower H2 yield (41 mmol per gram plastic) due to the formation of mainly CO, CO2 and organic acids from the pyrolysis stage which were not conducive to further reforming and water gas shift reaction. A mixture of the single plastics typical of that found in municipal solid waste produced a H2 yield of 102 mmol per gram plastic. Knowing the gas yields and composition from the single plastics enabled an estimation of the yields from a simulated waste plastic mixture and a ‘real-world’ waste plastic mixture to be determined. The different household, commercial and industrial waste plastic mixtures produced H2 yields between 70 mmol and 107 mmol per gram plastic. The H2 yield and gas composition from the single waste plastics gave an indication of the type of plastics in the mixed waste plastic samples.Graphical abstract

A multifunctional SiC@HZSM-5@CoFe2O4 catalyst for synergistic co-pyrolysis of biomass and waste plastics by microwave irradiation

Improving the yield of the target product of monocyclic aromatic hydrocarbons plays an important role in increasing the economic competitiveness of biomass and waste plastics. In this study, a 3D SiC@HZSM-5@CoFe2O4 multifunctional catalyst with high microwave absorptivity and excellent catalysis was successfully fabricated by a “coating-coating” method. Results showed that the obtained SiC@HZSM-5@CoFe2O4 catalyst had a stable porous structure, abundant oxygen vacancy defects, high specific surface area, good dielectric loss performance, and magnetic loss performance. Encouragingly, co-pyrolysis of corncob (CC) and polystyrene (PS) revealed that the catalyst significantly promoted the synergistic effect and improved the selectivity of renewable gasoline-range aromatics (47.2 area %). In addition, finite element simulations indicated that the prepared catalyst with high microwave absorptivity could effectively accelerate the mass and heat transfer, thereby facilitating the cracking and conversion of pyrolysis vapors. This work provides an efficient method for the production of renewable gasoline-range aromatics from the mixture of biomass and waste plastics by microwave-assisted co-pyrolysis (MACP).

Modeling and simulation of microwave assisted catalytic pyrolysis system of waste plastics polymer for fuel production

Pyrolysis is a promising method of chemically recycling plastic waste, as it allows for the recovery of both energy and materials. In this work, a comprehensive mathematical model has been developed to predict the pyrolysis of plastic wastes over ZSM-5 catalyst in microwave-assisted pyrolysis (MAP) system for fuel production. To conduct a transient numerical analysis of the underlying processes, a lumped kinetic model that takes into account three lumped pyrolysis products (olefins, paraffins, and aromatics) is coupled with the equations that govern the microwave field, heat transfer, mass transfer, and fluid flow (Darcy's law). The distributions of electric field, temperature, and pyrolysis products within MAP are presented. The study investigated the effects of several factors on the rate of production and consumption in the pyrolysis reactions of a waste plastic mixture when using MAP. These factors include the microwave power input, the inlet velocity of the fluidizing gas, as well as the mass and particle size of the catalyst used. Increasing the input power leads to a higher intensity of the electric field, which causes a greater increase in temperature within the same time frame. The mass and particle size of the catalyst used also have a significant impact on the yield of olefins, paraffins, and aromatics. Reducing the particle size of the catalyst generally increases the reaction rate, but particle sizes smaller than 50 μm are not ideal for fluidization due to increased intermolecular forces. Increasing the inlet velocity of the fluidizing gas may result in an incomplete consumption of intermediates and a low yield of products. All in all, The MAP system is a highly efficient and effective design for using plastic waste as a source of energy, due to its superior energy efficiency and lower processing temperature compared to traditional fluidized-bed reactors.