Waste Polypropylene Research Articles

Sustainable Engineered Designs and Manufacturing of Waste Derived Graphenes Reinforced Polypropylene Composite for Automotive Interior Parts.

The automotive sector is actively pursuing a lightweighting strategy as a means to urgently decrease greenhouse gas emissions, which are a significant driver of climate change. The development of lightweight composite structures has been identified as crucial for enhancing part performance while mitigating negative environmental impacts and adopting energy-efficient manufacturing methods. This comprehensive study aimed to decrease the main reinforcement content of talc in commercial compounds while integrating graphene derived from waste polypropylene (PP) grown on talc and graphene nanoplatelet obtained from waste tires by upcycling processes into the PP compound. The entire value chain of interior automotive part production, from compound development and scaling up with a high-shear mixer, to injection molding of the part and performance tests, was investigated with a focus on sustainability considerations. The successful integration of 4 wt % micron talc, together with 1 wt % graphene nanoparticles and 1 wt % hybrid additive into the blended HomoPP/CopoPP matrix resulted in a 10% weight reduction compared to the conventional part. Moreover, significant improvements in flexural and tensile strength were observed, with enhancements of 52 and 38%, respectively. The uniform dispersion of additives and improved interfacial adhesion between the PP matrix and additives facilitated efficient stress transfer, contributing to enhanced mechanical properties. Furthermore, a systematic life cycle assessment study demonstrated the positive impact of waste PP incorporation on CO2 reduction, achieving a remarkable 95% reduction compared to virgin PP. The developed compound also demonstrated favorable processability and flow properties, supporting its potential for mass production. Overall, this study presents a sustainable and effective approach for lightweight automotive interior part production using a synergistically designed PP compound meeting the requirements of the automotive industry.

An evaluation of the use of plastic waste in the manufacture of plastic bricks

An integrated analysis is performed for the present study, including an evaluation of the mechanical and durability properties of plastic brick, a cost-effectiveness analysis, and an eco-benefit analysis of recycling plastic waste into bricks. To promote sustainable construction practices, pp waste is used in plastic brick to replace waste material often discarded in landfills and burned. This study involved the preparation of 36 (230 mm × 110 mm × 90 mm) bricks. Modified fly ash containing 40, and 45% of the cement weight was incorporated into the samples. There is an increase in waste production among the Indian population. Some of these wastes pose a threat to the environment. There is also a significant amount of plastic waste in the country. Even though it is not biodegradable, it poisons trees and aquatic organisms. Thus, waste plastics were repurposed for use in the construction industry. Cement, fly ash, M sand, and plastic waste fibers are used to make plastic bricks. Polypropylene (PP) has a high deformation capacity and is a cost-effective material. Plastic waste is used in this study in the form of polypropylene fibers. To produce the bricks, different mix ratios were used in which PP waste was used in proportions of 5%, 10%, and 15% (represented as Mix1, Mix2, and Mix3), based on the total mixing of the polycarbonate substance volume of bricks. The purpose of this study is to investigate the feasibility of utilizing plastic wastes to produce a cost-effective and lightweight plastic brick for use in construction. Compressive strength, water absorption, soundness, efflorescence, and hardness tests were carried out on the bricks. The compressive strength of mix 2 at a load of 426 kg is the highest of the three plastic bricks tested. A comparison of this proportion with other mix proportions and conventional brick effectiveness.

Chromium-extracted aluminum catalyst for co-pyrolysis of cotton fabric waste and polypropylene plastic waste to bio-oil

Heterogeneous catalysts of chromium-extracted aluminum (CE) were prepared and used to produce bio-oil from the co-pyrolysis of cotton fabric waste (CFW) and polypropylene waste (PPW). The catalysts were synthesized via wet impregnation at 5–20 wt% catalyst loading and calcined at 600 °C for 5 h. The co-pyrolysis was conducted in a fixed-bed reactor at 500 °C for 1 h with 1:1 CWF/PPW ratio and 1:1 catalyst/feedstock ratio. The physical and chemical properties of the catalysts and bio-oil were characterized by several techniques such as Brunauer–Emmet–Teller, scanning electron microscopy, energy dispersive x-ray spectroscopy, x-ray diffraction, temperature-programmed desorption and gas chromatography-mass spectrometry. Investigations into the effects of metal loadings revealed that the 15CE catalyst was the most active, achieving a maximum bio-oil yield of 76.4 % and producing valuable chemical compounds like hydrocarbons, alcohols, phenols, and furans. The XRD of 15CE catalyst confirmed the presence of chromium oxide and assigned to the rhombohedral phase of the crystal lattice. BET indicated 15CE has the largest surface area (50.4 m2/g) among the CE catalysts which contributed to its high activity. The SEM revealed CE catalysts at different metal loadings contain irregular shapes and sizes with a rough surface texture. The NH3-TPD profiles indicated alterations in acid site distribution due to the interaction between the introduced Cr metal and EA. The 15CE catalyst also demonstrated significant reusability, maintaining performance after two regeneration cycles. These results confirm the potential of CE catalysts in enhancing bio-oil production from CFW and PPW.

Manufacture and Characterization of Lightweight Sand-Plastic Composites Made of Plastic Waste and Sand: Effect of Sand Types

Over the past decade, many types of waste have been exploited as feedstocks in different industries. Recycled plastics are among the waste sought for several civil engineering applications. In this work, various plastic-bonded sand composites based on polypropylene waste and silica sand were produced to serve as building materials in many construction applications. Many tests and analysis were carried out in this investigation. First of all, two initial used compounds (waste PP and various silica sand) were analyzed by using ATR-FTIR, XRF, and grain size distribution. In the second time, the different plastic-bonded sand composites were analyzed by using ATR-FTIR to assess their composition. On the other hand, mechanical, and physical tests such as three-point flexural strength, compressive strength, water absorption, and optical observation were applied on different produced composite samples, then the results were examined and analyzed. The results showed that the developed composites exhibit commendable mechanical properties, especially flexural and compression resistance, and minimal water absorption. It is worth noting that the plastic-bonded sand containing Khobana sand showed the highest flexural and compressive strength at 11.56±0.36 and 26.19±0.27 MPa, respectively, along with the lowest water absorption rate of 0.46%. This study confirms its contribution to enhancing sustainability and promoting the principles of the circular economy.

Microwave pyrolysis of polypropylene, and high-density polyethylene, and catalytic gasification of waste coffee pods to hydrogen-rich gas

Plastic waste poses a critical environmental challenge for the world. The proliferation of waste plastic coffee pods exacerbates this issue. Traditional disposal methods such as incineration and landfills are environmentally unfriendly, necessitating the exploration of alternative management strategies. One promising avenue is the pyrolysis in-line reforming process, which converts plastic waste into hydrogen. However, traditional pyrolysis methods are costly due to inefficiencies and heat losses. To address this, for the first time, our study investigates the use of microwave to enhance the pyrolysis process. We explored microwave pyrolysis for polypropylene (PP), high-density polypropylene (HDPE), and waste coffee pods, with the latter primarily comprising polypropylene. Additionally, catalytic ex-situ pyrolysis of coffee pod pyrolysis over a nickel-based catalyst was investigated to convert the evolved gas into hydrogen. The single-stage microwave pyrolysis results revealed the highest gas yield at 500 °C for HDPE, and 41 % and 58 % (by mass) for waste coffee pods and polypropylene at 700 °C, respectively. Polypropylene exhibited the highest gaseous yield, suggesting its readiness for pyrolytic degradation. Waste coffee pods uniquely produced carbon dioxide and carbon monoxide gases because of the oxygen present in their structure. Catalytic reforming of evolved gas from waste coffee pods using a 5 % nickel loaded activated carbon catalyst, yielded 76 % (by volume) hydrogen at 900 °C. These observed results were supported by elemental balance analysis. These findings highlight that two-stage microwave and catalysis assisted pyrolysis could be a promising method for the efficient management of waste coffee pods, particularly for producing clean energy.

Fused Deposition Modelling Approach in Recycled Polypropylene/Aluminum Powder Composites for Sustainable Development

Polypropylene (PP) is a versatile and widely used thermoplastic polymer that has found its way into various aspects from packaging materials and consumer products to automotive components and industrial applications. However, this widespread use of polypropylene also presents a significant challenge in the disposal of polypropylene waste and its durability aspects. So, the fused deposition modeling (FDM) technique arises as compiling outcomes for recycling discarded PP waste to create functional products. The properties of FDM components produced from recycled polypropylene (r-PP) are notably inferior to those of virgin PP FDM counterparts. Hence, it becomes imperative to comprehend the substantial alterations that r-PP undergoes during successive extrusion processes, including chain scission, alterations in viscosity, and reductions in breaking strength. The incorporation of additives has emerged as a promising solution to enhance the performance of r-PP. In this context, the present study explores the development of a novel composite material by blending r-PP with aluminum powder. The combination of these materials leverages the sustainability benefits of r-PP and the excellent thermal and mechanical properties of aluminum, making it a promising candidate for a wide range of applications. The tensile results show a significant increase in Young’s modulus for pre-heat treated composite specimen at 214 ℃ extrusion temperature. The SEM fractrographic analysis confirms the homogenized distribution after pre-heat treatments. XRD results analyzed the degree of crystallinity in the composite specimens.

An Industrial Perspective for Sustainable Polypropylene Plastic Waste Management via Catalytic Pyrolysis—A Technical Report

Recycling plastics on an industrial scale is a key approach to the circular economy. This study presents a techno-economic analysis aimed at recycling polypropylene waste, one of the main consumer plastics. Specifically, it evaluates the technical and economic feasibility of achieving a large-scale cracking process that converts polypropylene waste into an alternative fuel. Pyrolysis is considered as a promising technique to convert plastic waste into liquid oil and other value-added products, with a dual benefit of recovering resources and providing a zero-waste solution. This study concerns a fast catalytic pyrolysis in a fluidized bed reactor, with the presence of a fluid catalytic cracking catalyst of low acidity for high heat transmission, for an industrial plant with a capacity of 1 t/h of polypropylene waste provided by the Greek Petroleum Industry. From the international literature, the operational conditions were chosen pyrolysis temperature at 430 °C, pressure at 1atm, heating rate at 5 °C/min, and yields of products to 71, 14, and 15 wt.%, for liquid fuel, gas, solid product, respectively. The plant design includes a series of apparatuses, with the main one to be the pyrolyzer. The catalytic method is selected over the non-catalytic because the presence of catalyst increases the quantity and quality of the liquid product, which is the main product of the plant. The energy loops of recycling pyrolysis gas and char as a low-carbon fuel in the plant were considered. The production cost, annual revenue, for 2023, are anticipated to reach €13.7 million (115 €/t) and €15 million (15 €/t), respectively, with an estimated investment equal to €5.3 million. The Payback Time is estimated to 2.4 years to recover the cost of investment. The endeavor is rather economically sustainable. A critical parameter for large scale systems is securing feedstock with low or negligible price.

Artificial neural network for predicting the performance of waste polypropylene plastic-derived carbon nanotubes

AbstractIn this study, an artificial neural network model using function fitting neural networks was developed to describe the yield and quality of multi-walled carbon nanotubes deposited over NiMo/CaTiO3 catalyst using waste polypropylene plastics as cheap hydrocarbon feedstock using a single-stage chemical vapour deposition technique. The experimental dataset was developed using a user-specific design with four numeric factors (input variable): synthesis temperature, furnace heating rate, residence time, and carrier gas (nitrogen) flow rate to control the performance (yield and quality) of produced carbon nanotubes. Levenberg–Marquardt algorithm was utilized in training, validating, and testing the experimental dataset. The predicted model gave a considerable correlation coefficient (R) value close to 1. The presented model would be of remarkable benefit to successfully describe and predict the performance of polypropylene-derived carbon nanotubes and show how the predictive variables could affect the response variables (quality and yield) of carbon nanotubes.

Co‐reinforcing sustainable graphenes from thermoset/thermoplastic wastes for enhanced polypropylene matrix composites in automotive engineering

AbstractTalc is widely used in the automotive industry as a primary reinforcement in part manufacturing. However, its relatively high density, low impact strength, and difficulty in recycling pose challenges. The present study investigates the utilization of graphene grown on talc derived from waste polypropylene (PP) and graphene nanoplatelet obtained from waste tires by recycling and upcycling processes to be used as reinforcing agents in thermoplastic processing by keeping mechanical integrity and part performance properties the same compared to the part used in serial production. The whole value chain was examined by developing compound formulation, scaling up with a high shear mixer, and injection molding of the selected exterior part of the glass front grill with its part performance tests with the real‐case thermal and structural finite element analysis. Regarding the mechanical performance analysis, the developed compound formulation having 9 wt% micron scale talc with graphene nanoparticles and hybrid additive yielded substantial enhancements of 32% and 22% in flexural and tensile strength, respectively, in the homopolymer polypropylene (HomoPP) matrix by achieving 10% weight reduction. With a systematic life cycle assessment study, CO2 reduction was provided by 55% for the selected part by replacing virgin HomoPP with mechanically recycled waste PP originally unknown.

Catalytic pyrolysis of polypropylene waste for liquid fuels production using Ni/Al-MOF-derived catalysts

Waste plastics pose significant environmental risks due to their non-biodegradable nature and accumulation in the environment. The pandemic has exacerbated this issue by increasing the production of plastic medical waste such as surgical masks. This study developed Ni/Al-MOF-derived catalysts for pyrolysis, an effective plastic waste utilization technology. By optimizing conditions, the study successfully converted waste surgical masks, made primarily of polypropylene, into gasoline or diesel range chemicals. The oil yield from polypropylene waste reached 72.8 % using Ni/Al-MOF-derived catalysts with 5 % Ni loading at 450°C, while surgical masks yielded 58.9 % oil under the same conditions. Catalyst characterization revealed a high surface area and evenly distributed Ni particles in MOF-derived Al2O3, maximizing catalytic performance. This catalyst provides a promising solution for converting waste surgical masks into liquid fuels, reducing the environmental impact of plastic products, and promoting plastic waste recycling.

Supercritical Water Liquefaction of Mixed Waste Polystyrene, Polypropylene, and Polyethylene for Production of High Yield Oils.

Supercritical water liquefaction of different plastic wastes has been investigated under high-temperature and high-pressure conditions. The supercritical water liquefaction of commonly used plastic types, comprising polystyrene (PS), polypropylene (PP), and low-density polyethylene (LDPE) as well as their mixtures, is reported. The experiments were carried out at varying feedstock-to-water ratios with a residence time of 60 min under supercritical water reaction conditions. The process produced high oil yields of over 97 wt %, with the highest yields obtained at a plastic:water ratio of 1:3; at higher levels of input water, the yield of oil decreased slightly. The gas phase mainly consisted of light hydrocarbons such as methane, ethane, propane, and butane, with propane found to be the most abundant gas component. Aromatic hydrocarbons and alicyclic hydrocarbons were the major products in the product oil from the supercritical water liquefaction of polystyrene and polypropylene, whereas alkanes were predominant in the oil obtained from LDPE. Analysis of the oil obtained from binary (1:1) and ternary (1:1:1) plastic mixtures showed it exhibited aromatic hydrocarbons as the major constituent, indicating synergistic interaction. It was found that the incorporation of PP in the mixture facilitated the production of cyclic compounds and suppressed the production of alkanes. Supercritical water liquefaction offers an effective solution to plastic pollution, producing valuable products without the need for catalysts.

Polypropylene waste plastic fiber morphology as an influencing factor on the performance and durability of concrete: Experimental investigation, soft-computing modeling, and economic analysis

The increasing waste of plastic masses raises the danger alarm due to its adverse impacts on people and the natural environment. Hence, serious attempts should be made to manage this non-biodegradable waste for practical, sustainable, and sufficient uses, such as in construction. This research discusses experimentally the possibility of improving the behavior of concrete reinforced with waste plastic fibers (WPFs) from food trays by examining the effect of fibers morphology on concrete's mechanical properties and durability. This concept was intensively studied for steel fibers but rarely for WPFs. A 0.6 percentage of 30 mm long straight, spiral, and channel fibers were tested and compared. Compressive, tensile, and flexural strengths, impact resistance, water absorption, rapid chloride penetration tests, and microstructural analysis were conducted. The results revealed that the fibers shape influences the mechanical behavior along with the water absorption considerably, and that the spiral fibers exhibited superior performance compared to the other shapes. The mechanical properties of spiral fibers specimens have improved considerably compared to specimens of other shapes. However, the ion chloride penetration resistance did not witness any substantial improvement, and the brittle fracture of concrete did not change by using WPFs, despite the considerable increase of more than 66 % of the impact resistance of specimens with spiral fibers. According to the findings, spiral WPFs enhance concrete's behavior, making WPF implementation in concrete more efficient from an environmental and structural standpoint. Moreover, machine learning modeling and cost/benefit analysis were conducted in this work to better understand the WPF effect on concrete.

Mechanochemical preparation and performance evaluations of bitumen-used waste polypropylene modifiers

The value-added recycling of waste polypropylene (PP) as asphalt modifiers has been a popular research topic in recent years, but high blending temperatures and asphalt smoke emissions are difficult issues that have not been solved. Therefore, this study innovatively used phthalic anhydride (PA) and catalysts (NHPI or BPO) to mechanochemically turn waste PP into different reaction products as bitumen-use PP modifiers (PPM(N) & PPM(B)). To well understand the physicochemical characteristics of PPMs, thermogravimetric analysis, torque rheology, and scanning electron microscopy were adopted and analyzed. Furthermore, the penetration, softening point, viscosity, storage stability, and dynamic shear rheology (DSR) tests were also carried out to study the performance differences of their PP modified asphalt (PPMA(N) & PPMA(B)). The main results showed that the PPM(N) continues being degraded with PA, but BPO-degraded PP conversely gets chemical connections with PA. With the effects of NHPI and BPO, all PPMs can improve the deformation resistance of virgin bitumen, even at higher temperatures, but as the PA content increases, this performance will gradually deteriorate for PPMA(N) and shows a slight improvement for PPMA(B). The appropriate use of PA can decrease the mixing temperature of PPM(N) with virgin bitumen and improve the storage stability of PPMA binders, and will not significantly sacrifice the resistances of its PPMA(N) to deformation, while with the addition of PA, the mixing temperatures of PPM(B) and virgin bitumen will not be decreased as expected and the resistances of PPMA(B) to deformation remain unchanged. Overall, the proposed mechanochemical method can work out to well address the high-quality recycling and reuse issue of waste PP for its large-scale application in asphalt pavement.

Regulation of co-pyrolysis behavior of Naomaohu coal and polypropylene by controlling the cracking of polypropylene pyrolysis volatiles

Pyrolysis is one of the technologies for clean and efficient conversion and utilization of coal, however, low yield and poor quality of tar restrict its utilization. Waste polypropylene (PP) could be efficiently used to improve tar yield of low-rank coal via co-pyrolysis. To strengthen the generation and transfer of hydrogen-rich radicals, modified HZMS-5 (HZ5) catalyst was used to regulate the composition of PP pyrolysis volatiles. Results show that close contact between HZ5 catalyst and coal favors the formation of light components, which reaches the maximum value of 72.45 wt%. In the presence of zeolite catalysts modified with 0.2 mol/L NaOH (0.2Na-HZ5), light oil in tar exhibits an obvious increase of 12.78 % compared with HZ5. A synergetic effect analysis clarifies that C2-C3 produced from PP pyrolysis under the action of the catalyst participate in the formation of tar. And the reactive intermediates from secondary cracking of PP volatiles over 0.2Na-HZ5 promote the cleavage of O-containing groups in coal, leading to the increase of phenols and alcohols in tar. The co-pyrolysis behavior of benzyl phenyl ether /bibenzyl and PP is shown that the transfer of oxygenated compounds into liquid is enhanced, confirming a positive synergetic effect. Meanwhile, the clear inhibition of C2-C3 components further indicates their contribution to tar formation.

Потенциал биоразложения пластика базидиальными грибами и актинобактериями (обзор)

With the ever-increasing production and consumption of plastics, inadequate management of plastic waste and its improper disposal pose a significant threat to the environment, affecting all forms of life, natural ecosystems and economies worldwide. In the face of this threat the search for alternative environmentally friendly solutions such as biodegradation instead of traditional recycling is of paramount importance. Currently knowledge about the mechanisms and effectiveness of plastics biodegradation is focused mainly on such groups of microorganisms as Gram-negative bacteria and fungi ascomycetes. The aim of this review is to highlight the ideas available in the literature about the potential decomposition of the most common plastic waste (polyethylene, polypropylene, polyvinyl chloride, polyethylene terephthalate and polyurethane) as a result of biotic processes. Basidial fungi and actinobacteria have not yet found practical application in the technologies of processing and utilization of synthetic plastics. We discuss the ability of specific representatives of the two above taxonomic groups to decompose various synthetic polymers. The unique strategies of basidial fungi such as a powerful enzymatic system, the ability to absorb and produce natural biosurfactants – hydrophobins, allowed fungi to use plastics as a source of carbon and energy are considered. The possible contribution of mainly thermophilic actinobacteria of the genera Thermobifida, Thermoactinomyces, Thermomonospora, Saccharomonospora, Actinomadura, Microbispora and Streptomyces in improving the plastic waste disposal in order to create effective and sustainable plastic management practices has been characterized.

Tailored HZSM-5 catalyst modification via phosphorus impregnation and mesopore introduction for selective catalytic conversion of polypropylene into light olefins

The waste polyolefin composition varies regionally due to different sorting technologies, emphasizing the necessity for a robust catalyst capable of selectively converting pyrolysis vapors into valuable light olefins while maintaining stability. HZSM-5, a microporous catalyst, efficiently cracks polyethylene (PE) pyrolysis vapors rich in linear aliphatics. However, polypropylene (PP) pyrolysis typically yields branched olefins, potentially hindering effectiveness of HZSM-5 due to mass transfer constraints and coke blockage in micropores. This study modifies HZSM-5 through phosphorus impregnation, mesopore introduction, and steam treatment to evaluate the impact of acidity, pore size, and surface modifications on catalyst stability and light olefin selectivity during PP pyrolysis vapor cracking. Subsequent experiments reveal the superior stability of modified catalysts. Phosphorus-modified (P-HZSM-5ss) and mesoporous phosphorus-modified (P-mesoHZSM-5ss) catalysts retain 72 % and 80 % of their initial activity after 150 runs, respectively, while the parent HZSM-5 experiences a rapid 44 % activity loss. P-mesoHZSM-5ss demonstrates the highest light olefin selectivity (63 wt%) after 150 runs, attributed to improved accessibility of branched olefinic products to active sites within catalyst pores. Further optimization achieves exceptional light olefin selectivity of 84 wt% at 117 ms contact time and 550 °C, surpassing maximum selectivity of the parent catalyst. Comparative analyses of PP, PE, and mixed polyolefinic waste pyrolysis vapor cracking revealed the influence of polyolefin type on optimal operational conditions, stressing the need for flexibility in operating conditions to scale up the proposed polyolefin recycling method. This study highlights the potential of tailored catalyst modifications and process optimization to efficiently convert PP into valuable light olefins, advancing sustainable polyolefin recycling technologies.

Analysis of the life cycle concrete with the addition of polypropylene fibers

In accordance with the principles of sustainable construction, the results of Life Cycle Assessment (LCA) technique are useful inputs to the decision-making process when designing a building. This article presents such an analysis of a finished building product, which is a modified concrete mix. The calculations took into account the phases of the A1–A4 cycle, i.e. from the extraction of raw materials to the transport of the finished material to the construction site. Test results for concrete mixes and 28-day solid concrete are presented in tabular form. Based on all the test results obtained, it was found that the addition of waste polypropylene fibres has a positive effect on the key properties for the floor concrete. It has been found that proper processing of banding tapes or other polypropylene waste into macro-fibres can be a good example of proper waste management and can contribute to a significant reduction in residual waste. This additive is emission-free and sourced from recycling, making it an excellent alternative to commonly used dispersed reinforcement.

Rheological, mechanical, and microscopic properties of polypropylene fiber reinforced-geopolymer concrete for additive manufacturing

This study focuses on developing fiber-reinforced geopolymer concrete (GPC) for 3D printing, utilizing construction waste materials and polypropylene fibers. The GPC, reinforced with 0.8 %, 1.0 %, and 1.2 % polypropylene fibers by volume, underwent comprehensive testing, including rheological, mechanical, and microstructural analyses for lab-cast and 3D-printed samples. The results indicated that the 0.8 % polypropylene fibers enhanced flexural and tensile strengths by 8.2 % and 71.7 %, respectively, albeit decreasing compressive strength by 26.2 %. Higher polypropylene percentages led to adverse effects on material properties. Microscopic analysis revealed the formation of voids around fibers and features associated with incomplete hydration. The study emphasizes the need for optimizing water content and the use of longer polypropylene fibers. It also highlights the benefits of using GPC in the 3D printing of structural components.

Integration of Methane Reforming and Chemical Looping Technologies for Power Generation from Waste Plastic: Technical and Economic Assessment

An imperative environmental concern is escalating due to the widespread disposal of plastic waste in oceans and landfills, adversely impacting ecosystems and marine life. In this context, sustainable methods for plastic waste utilisation were evaluated, particularly for power generation. Two case studies were developed to assess the potential utilisation of waste plastic, specifically polyethylene and polypropylene, by integrating gasification with steam methane reforming (SMR) alongside two oxygen-supplying techniques for combustion including cryogenic air separation (ASU) and chemical looping combustion (CLC) for case 1 and case 2, respectively. For this, thorough process simulations of both case studies were performed to obtain detailed material and energy balances. The techno-economic analysis was performed to assess the economic performance of the processes by estimating levelized cost of electricity (LCOE). The results indicated that case 2 is more efficient (5.4%) due to the lower utility requirement of the CLC process as compared to ASU. Consequently, case 2 generated a LCOE of USD 137/MW. It was also seen from the results that the power output is directly proportional to the methane input while the increase in gasifier temperature enhances the H2 and CO content in syngas.

Dual Doping of Sulfur and Nitrogen Induces Hierarchical Porous Carbon from Wastes Medical Masks for Supercapacitor Electrodes

Demand for battery and supercapacitor materials rapidly increases as energy storage deployments accelerate. Waste-based supercapacitors have become a point of interest to accommodate growing demand and awareness of environmentally friendly products. This work aims to examine how doping with sulfur and nitrogen affects the morphology and structure of porous carbon synthesized from waste medical masks and the electrochemical performances of the prepared electrodes. Nitrogen- and sulfur-doped porous carbon (a-C:NS) is successfully obtained by solvothermal and hydrothermal processes in an autoclave followed by chemical activation using potassium hydroxide (KOH) and a carbonization procedure. Sulfur- and nitrogen-doping increase the yield compared to the directly carbonized process of the waste medical mask. The a-C:NS sample has a porous feature, showing the presence of S, N, O, and dominant C elements and the formation of C-S and C-N bonds. The supercapacitor electrode prepared from a-C:NS shows an electric double layer capacitor (EDLC)-like characteristic with a high specific capacitance (CS) of 300 F/g at the scanning rate of 5 mV/s. This study shows a possible route to transform polypropylene waste into functional materials for supercapacitor electrodes.