ABSTRACT
A treatment method producing solid fuel from surgical face masks was developed to address the high cost of medical waste management and the environmental concerns of large-scale, hazardous waste dumping during the coronavirus 19 (COVID-19) pandemic. The fuel properties were investigated of solid fuel produced from surgical face masks (polypropylene material (PP)) and from PP mixed with biomass (composite PP-biomass) using a hydrothermal carbonization process (HTC), followed by pyrolysis using thermogravimetric analysis (TGA). The Coats-Redfern (CR) method was used to analyze the pyrolysis kinetics and thermodynamic parameters. The results demonstrated that the thermal decomposition of raw PP material was less stable than for its hydrochar and the fuel properties of hydrochar obtained from the PP material were substantially improved using an increased HTC temperature. The activation energy value of the raw composite PP-biomass material was higher than for its hydrochar. This research identified an option for a potentially environmental-friendly treatment method for PP-material and its utilization as solid fuel.
ABSTRACT
This research aims to develop a new strategy to valorize wasted COVID-19 masks based on pyrolysis to convert them into useful products. First, surgical and FFP2 masks were thermally pyrolyzed at temperatures of 450–550 ºC with the purpose of determining gas, liquid (oil) and solid (char) yields. At low temperatures, solid yield was high, while at high temperatures the gas product was enhanced. The highest yield of liquid was found at an operating temperature of 500 ºC in both surgical and FPP2 masks pyrolysis. The liquid product yields were 59.08% and 58.86%, respectively. Then, the volatiles generated during thermal pyrolysis of residual masks were cracked over sepiolite as catalyst at a temperature of 500 ºC. The catalytic pyrolysis increased the yield of gas product (43.89% against 39.52% for surgical masks and 50.53% against 39.41% for FFP2 masks) and decreased the viscosity of the liquid product. Finally, the effect of sepiolite regeneration and reuse in consecutive pyrolysis tests was examined. Results showed that, with the higher regeneration-reuse of sepiolite, the catalyst was degraded obtaining a liquid product with higher molecular mass. This effect was hardly noticeable in the case of FFP2 masks. © 2022 International Multidisciplinary Scientific Geoconference. All rights reserved.
ABSTRACT
The Association of Southeast Asian Nations is blessed with agricultural resources, and with the growing population, it will continue to prosper, which follows the abundance of agricultural biomass. Lignocellulosic biomass attracted researchers' interest in extracting bio-oil from these wastes. However, the resulting bio-oil has low heating values and undesirable physical properties. Hence, co-pyrolysis with plastic or polymer wastes is adopted to improve the yield and quality of the bio-oil. Furthermore, with the spread of the novel coronavirus, the surge of single-use plastic waste such as disposable medical face mask, can potentially set back the previous plastic waste reduction measures. Therefore, studies of existing technologies and techniques are referred in exploring the potential of disposable medical face mask waste as a candidate for co-pyrolysis with biomass. Process parameters, utilisation of catalysts and technologies are key factors in improving and optimising the process to achieve commercial standard of liquid fuel. Catalytic co-pyrolysis involves a series of complex mechanisms, which cannot be explained using simple iso-conversional models. Hence, advanced conversional models are introduced, followed by the evolutionary models and predictive models, which can solve the non-linear catalytic co-pyrolysis reaction kinetics. The outlook and challenges for the topic are discussed in detail.
ABSTRACT
Plastic waste pollution has grown exponentially since the 1950s. This situation was exacerbated when the volume of personal protective equipment (PPE)-based plastic waste surged after the COVID-19 pandemic. Plastic waste management such as landfills and incineration have adverse effects on the environment and human health due to the leaching of hazardous chemicals and the emission of toxic gases. Modern solutions such as biodegradable plastics and green brick technology are expensive and not well developed to valorize the current accumulation of plastic waste. This has led to the emergence of thermal degradation processes, which is faster and more realistic to solve the PPE-based plastic waste buildup. Pyrolysis and gasification systems to valorize plastic waste into hydrocarbons and fuels are discussed and compared with examples respectively. Scoping review approach is employed to conduct this study. To further increase the value of the final product of plastic waste management, the integrated pyrolysis system to upcycle plastic waste to carbon nanomaterials (CNMs) and the factors affecting the production of non-condensable gases are critically reviewed. The importance of feedstock composition, catalyst type, pyrolysis operating condition (including gas condition and temperature profiles) based on various studies is discussed. The potential and limitation of an integrated pyrolysis system are assessed from kinetic analysis, economic analysis and life-cycle assessment. This review is expected to contribute to the industrial-scale development of sustainable upcycling of plastic waste and enhance the production of desirable gas components for CNM synthesis for environmental sustainability.
ABSTRACT
The COVID-19 pandemic has created a new type of waste (surgical mask waste "WMs") that presents a major challenge now and in the future, given the strong possibilities of similar epidemics to reoccur. In order to find an effective industrial solution to the millions of WMs produced daily, this research aims to develop a new eco-friendly strategy to convert WMs into H-2-CH4-rich syngas, carbon nanoparticles (CNPs), and benzene-rich tar using an updraft gasifier system. The experiments started with the preparation of WM granules using shredding followed by granulation processes. Subsequently, the granules were processed in a lab-scale reactor with a capacity of 0.9-1 kg/h and consisted of a continuous WM feed system, a gasifier, a sampling system for syngas and tar, a ceramic filtration unit for separating the CNPs against the synthesis gas, and a burner. The gasification experiments were performed in ambient air with different air-fuel equivalence ratios (ER: 0.21, 0.25, and 0.29) and temperatures (700 degrees C, 800 degrees C, and 900 degrees C) to determine the optimal conditions that yield the maximum amount of H-2-CH4-rich syngas and CNPs with less impurities. The chemical composition and morphology of the obtained gasification products (syngas, tar, and CNPs) were observed using GC-FID, FTIR, and SEM. The results showed that the maximum production of syngas (4.29 +/- 0.16 kg/h with HHV of 3804 kJ/kg) and CNPs (0.14 +/- 0.011 kg/h) accompanied by a moderate tar rate (0.123 +/- 0.009 kg/h with HHV of 41,139.88 kJ/kg) could be obtained at 900 degrees C and ER = 0.29, while the highest H-2 (16.93 +/- 1.7 vol.%) and CH4 (10.44 +/- 0.85 vol.%) contents in syngas product were synthesized at 900 degrees C and ER = 0.19. Benzene and toluene were the major GC-FID compounds in the formulated tar product with abundance up to 25.6% and 11%, respectively. Meanwhile, gasification conditions of 900 degrees C and ER = 0.24 allowed the best morphology to be formulated for spherical-shaped CNPs with a diameter of less than 200 nm.
ABSTRACT
During the COVID-19 pandemic, more than 24 billion pieces of surgical mask waste (WM) were generated in the EU region, with an acute shortage of their management and recycling. Pyrolysis and gasification are among the most promising treatments that were proposed to dispose of WMs and convert them into pyrolysis oil and hydrogen-rich syngas. This work aimed to investigate the techno-economic analysis (TEA) of both treatments in order to assess the feasibility of scaling up. The TEA was carried out using a discounted cash flow model and its data were collected from practical experiments conducted using a fluidised bed pyrolysis reactor and bubbling fluidised bed gasifier system with a capacity of 0.2 kg/h and 1 kg/h, respectively, then upscaling to one tonne/h. The technological evaluation was made based on the optimal conditions that could produce the maximum amount of pyrolysis oil (42.3%) and hydrogen-rich syngas (89.7%). These treatments were also compared to the incineration of WMs as a commercial solution. The discounted payback, simple payback, net present value (NPV), production cost, and internal rate of return (IRR) were the main indicators used in the economic feasibility analysis. Sensitivity analysis was performed using SimLab software with the help of Monte Carlo simulations. The results showed that the production cost of the main variables was estimated at 45.4 EUR/t (gate fee), 71.7 EUR/MWh (electricity), 30.5 EUR/MWh (heat), 356 EUR/t (oil), 221 EUR/t (gaseous), 237 EUR/t (char), and 257 EUR/t (syngas). Meanwhile, the IRR results showed that gasification (12.51%) and incineration (7.56%) have better economic performance, while pyrolysis can produce less revenue (1.73%). Based on the TEA results, it is highly recommended to use the gasification process to treat WMs, yielding higher revenue. [ FROM AUTHOR] Copyright of Energies (19961073) is the property of MDPI and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full . (Copyright applies to all s.)
ABSTRACT
Plastic is one of the most widely used materials in industries including packaging, building, and construction due to its lightweight, low cost, durability, and versatility. However, the mass production of plastics has exacerbated plastic pollution. Globally, plastic waste is predominantly incinerated, landfilled, or released into the environment;only 5-6% is recycled in the United States. Although conventional management protocols such as incineration and landfilling are evidently effective for plastic waste disposal, they are associated with significant environmental and societal challenges. In addition, most recycled plastic is downcycled, and thus does not provide sufficient incentive to use recycled materials instead of virgin materials. This review discusses thermo-chemical upcycling processes such as (catalytic) pyrolysis and heterogeneous catalysis. Furthermore, we present the recent progress in the thermo-chemical upgrading of single-type plastic waste, heterogeneous plastic mixtures, and post-consumer plastic waste obtained from different locations and, finally, suggest future research directions.
ABSTRACT
Pyrolysis of medical waste components combined via a novel systematic combination approach (sequentially binary, ternary, and quaternary copyrolysis) was conducted at 400°C to investigate the synergy between medical waste components in improving chemical characteristics and yields of pyrolytic oil. Pyrolysis of hydrocarbon-polymer-containing materials such as medical gloves and rubber bands produced more than 30% of liquid products with substantial compositions of saturated aliphatic hydrocarbon polymers. On the other hand, moisture- and carbonyl-rich pyrolytic liquid products with low selectivity were obtained from pyrolysis of lignocellulosic biomass waste such as HVS paper (houtvrij schrijfpapier, meaning "writing paper made from wood pulp”) and garden waste. Binary copyrolysis of lignocellulosic biomass and medical gloves exhibited improvement on pyrolytic liquid yield and selectivity toward saturated aliphatic hydrocarbon polymers due to hydrogen donor as the medical glove fraction became dominant. The addition of rubber band to the mixture of HVS paper and medical face masks enhanced the pyrolytic liquid yield. The pyrolysis of the mixture of HVS paper, medical face masks, medical gloves, and either rubber bands or cotton fabrics with mixture ratio of 60:20:10:10 yielded the most optimum pyrolytic liquid yield with significant distribution of alkanes in the pyrolytic liquid products. © 2023 Taylor & Francis Group, LLC.
ABSTRACT
Millions of face mask has been converted to waste since the onset of COVID-19 virus. Hence, present study explores the feasibility of converting disposable face masks to energy through catalytic pyrolysis process using a low-cost waste (spent aluminum hydroxide/oxide nanoparticle adsorbent) derived catalyst. Thermogravimetric analysis of the non-catalytic and catalytic pyrolysis of disposable face mask was conducted at varied heating rates of 10 °C/min, 20 °C/min, 30 °C/min, 40 °C/min, and 50 °C/min, respectively. Iso-conversional methods, Kissinger Akahira Sunose (KAS) and Ozawa Flynn Wall (OFW) were used for the kinetic study. The reaction mechanism was analyzed using Criado's z-master plot (CZMP) method along with the determination of thermodynamic parameters of the process. Results found that the addition of a catalyst to the process benefits the overall efficacy of the process by reducing the activation energy (Ea) (without catalyst;OFW-Ea: 188.7 kJ/mol, KAS-Ea: 186.2 kJ/mol) as well as lowering the disordered state of the process. Metal doped catalyst (Ni/ γ-Al2O3) (OFW-Ea: 168.4 kJ/mol, KAS-Ea: 167.8 kJ/mol) shows a larger reduction in activation energy in comparison to bare alumina (γ-Al2O3) (OFW-Ea: 183.2 kJ/mol, KAS-Ea: 180.4 kJ/mol). The current study presented disposable face masks as reclaimable in terms of energy and waste-derived catalyst as a potent solution to be explored in place of high-cost commercial catalysts. © 2023 Energy Institute
ABSTRACT
The ongoing global pandemic of COVID-19 has devastatingly influenced the environment, society, and economy around the world. Numerous medical resources are used to inhibit the infectious transmission of the virus, resulting in massive medical waste. This study proposes a sustainable and environment-friendly method to convert hazardous medical waste into valuable fuel products through pyrolysis. Medical protective clothing (MPC), a typical medical waste from COVID-19, was utilized for co-pyrolysis with oil palm wastes (OPWs). The utilization of MPC improved the bio-oil properties in OPWs pyrolysis. The addition of catalysts further ameliorated the bio-oil quality. HZSM-5 was more effective in producing hydrocarbons in bio-oil, and the relevant reaction pathway was proposed. Meanwhile, a project was simulated to co-produce bio-oil and electricity from the co-pyrolysis of OPWs and MPC from application perspectives. The techno-economic analysis indicated that the project was economically feasible, and the payback period was 6.30-8.75 years. Moreover, it was also environmentally benign as its global warming potential varied from -211.13 to -90.76 kg CO2-eq/t. Therefore, converting MPC and OPWs into biofuel and electricity through co-pyrolysis is a green, economic, and sustainable method that can decrease waste, produce valuable fuel products, and achieve remarkable economic and environmental benefits.
ABSTRACT
Waste management and mitigation is the primary necessity across the globe. The daily use of plastic materials in different forms emergence the plastic pollutions, and it has been significantly increased during the COVID-19 pandemic. Thus, mitigation of waste plastics generation is one of the major challenges in the present situation. The present study addressed the conversion of waste plastics into value-added products such as liquid hydrocarbon fuels and their application in reducing greenhouse gas emissions. A comprehensive investigation has been performed on engine performance and combustion characteristics at various compression ratios and PO blending. The effect of liquid fuel blending with commercial diesel was investigated at three different compression ratios (15.1, 16.2, and 16.7) under various BMEP conditions. The results revealed that blending of liquid fuel produced from waste plastic can improve the BTE significantly, and the highest 35.77% of BTE was observed for 10% blending at 15.1 CR. While the lowest BSFC of 5.77 × 10-5 kg/kW-s was estimated for 20% PO blending at 16.7 CR under optimum BMEP (4.0 bar) conditions. The investigation of combustion parameters such as cylinder pressure, net heat release rate, rate of pressure rise, and cumulative heat release showed that it increases with the compression ratio from 15.1 to 16.7. At the same time, the emissions of CO, CO2, and unburnt hydrocarbon was decreased significantly. The economic analysis for the present lab-scale study estimated that approximately â¹12.17 ($0.15) profit per liter is possible in the 1st year, while the significant profit starts from the 2nd year onward, which is in the range of â¹59.78-â¹84.48 ($0.75-$1.07) when the PO is blended with CD within the permissible limits as per the norms.
Subject(s)
COVID-19 , Gasoline , Humans , Pandemics , Vehicle Emissions , Biofuels , Carbon Monoxide/analysis , Hydrocarbons , PlasticsABSTRACT
This research aims to develop a new strategy to valorize wasted COVID-19 masks based on chemical recycling by pyrolysis to convert them into useful products. First, surgical and filtering face piece masks, as defined in Europe by the EN 149 standard (FFP2), were thermally pyrolyzed at temperatures of 450, 500, and 550 °C, and the yields of valuable solid (biochar), liquid (biooil), and syngas products and their characteristics were determined. At low temperatures, biochar formation was favored over biooil and syngas production, while at high temperatures the syngas product yield was enhanced. The highest yield of biooil was found at a pyrolysis temperature of 500 °C, with both surgical and FFP2 masks achieving biooil yields of 59.08% and 58.86%, respectively. Then, the pyrolysis experiments were performed at 500 °C in a two-stage pyrolysis catalytic reactor using sepiolite as a catalyst. Sepiolite was characterized using nitrogen adsorption–desorption isotherms and Fourier-transform infrared spectroscopy. Results showed that the two-stage process increased the final yield of syngas product (43.89% against 39.52% for surgical masks and 50.53% against 39.41% for FFP2 masks). Furthermore, the composition of the biooils significantly changed, increasing the amount of 2,4-Dimethyl-1-heptene and other olefins, such as 3-Eicosene, (E)-, and 5-Eicosene, (E)-. Additionally, the methane and carbon dioxide content of the syngas product also increased in the two-stage experiments. Ultimately, the effect of sepiolite regeneration for its use in consecutive pyrolysis tests was examined. Characterization data showed that, the higher the use-regeneration of sepiolite, the higher the modification of textural properties, with mainly higher changes in its pore volume. The results indicated that the pyrolysis of face masks can be a good source of valuable products (especially from biooil and syngas products). © 2023 by the authors.
ABSTRACT
The current study aims to investigate and compare the effects of waste plastic oil blended with n-butanol on the characteristics of diesel engines and exhaust gas emissions. Waste plastic oil produced by the pyrolysis process was blended with n-butanol at 5%, 10%, and 15% by volume. Experiments were conducted on a four-stroke, four-cylinder, water-cooled, direct injection diesel engine with a variation of five engine loads, while the engine's speed was fixed at 2500 rpm. The experimental results showed that the main hydrocarbons present in WPO were within the range of diesel fuel (C13–C18, approximately 74.39%), while its specific gravity and flash point were out of the limit prescribed by the diesel fuel specification. The addition of n-butanol to WPO was found to reduce the engine's thermal efficiency and increase HC and CO emissions, especially when the engine operated at low-load conditions. In order to find the suitable ratio of n-butanol blends when the engine operated at the tested engine load, the optimization process was carried out by considering the engine's load and ratio of the n-butanol blend as input factors and the engine's performance and emissions as output factors. It was found that the multi-objective function produced by the general regression neural network (GRNN) can be modeled as the multi-objective function with high predictive performances. The coefficient of determination (R2), mean absolute percentage error (MAPE), and root mean square error (RSME) of the optimization model proposed in the study were 0.999, 2.606%, and 0.663, respectively, when brake thermal efficiency was considered, while nitrogen oxide values were 0.998, 6.915%, and 0.600, respectively. As for the results of the optimization using NSGA-II, a single optimum value may not be attained as with the other methods, but the optimization's boundary was obtained, which was established by making a trade-off between brake thermal efficiency and nitrogen oxide emissions. According to the Pareto frontier, the engine load and ratio of the n-butanol blend that caused the trade-off between maximum brake thermal efficiency and minimum nitrogen oxides are within the approximate range of 37 N.m to 104 N.m and 9% to 14%, respectively.
ABSTRACT
The Russia-Ukraine conflict and the COVID-19 pandemic have made fossil energy more urgent, and the catalytic pyrolysis of biomass is conducive to energy transformation to achieve global sustainable development. In this paper, the influence mechanisms of different metal ions on biomass pyrolysis under conventional heating and microwave heating conditions were studied. Through thermogravimetric analysis, it was found that the existence of metal ions could change the pyrolysis behaviors of biomass, leading to different degrees of changes in the main pyrolysis temperature and range. Compared with conventional heating conditions, metal ion-loaded biomass samples exhibited higher heating rates under microwave heating conditions due to the possible hotspot phenomenon, resulting in increased gas yields and decreased bio-oil yields. Among them, the trivalent iron ion exhibited excellent catalytic properties for gas generation, with a high gas yield of 57.9% and a bio-oil yield of 12.1%. The components in bio-oil were greatly simplified by microwave irradiation, the number of the bio-oil compounds from the pyrolysis of Fe-loading pine sawdust was reduced to 77, and the GC-MS area of light compounds with carbon number less than 10 was increased to 84.4%. Phenol and furan in bio-oil are also catalytically converted into aromatic hydrocarbons, which are ideal chemical raw materials. © 2023 Elsevier Ltd
ABSTRACT
Elevated medical waste has urged the improvement of sustainable medical waste treatments. A bibliometric analysis is initially conducted to investigate scientific development of medical waste management to pinpoint the publication trends, influential articles, journals and countries and study hotspots. Publications on medical waste and its management sharply increased since 2020. The most influential article was written by Klemeš et al., and "Waste Management and Research” is the most productive journal. India, China, the United Kingdom, Iran and Italy have published the most works. The research spotlights have switched from "human” and "sustainable development” in 2019 to "COVID-19” and "circular economy” in 2021. Since government acts essentially in handling medical waste and controlling disease transmission, rule implementations among the abovementioned countries are summarized to seek gaps between scientific advancement and regulatory frameworks. For accomplishing a circular economy, waste-to-energy technologies (incineration, gasification, pyrolysis, plasma-based treatments, carbonization, hydrogenation, liquefaction, biomethanation, fermentation and esterification) are comprehensively reviewed. Incineration, gasification, pyrolysis and carbonization are relatively feasible methods, their characteristics and limitations are further compared. By holistically reviewing current status of medical waste research, the focal points involved in management at the policy and technical level have been highlighted to find proper routes for medical waste valorization. © 2023 by the authors.
ABSTRACT
The outbreak of COVID virus resulted not only in massive human deaths but also created huge waste disposal issues. Proper disposal of COVID waste is necessary. The conversion of these wastes into value‐added products such as syngas is beneficial to overcome energy scarcity issues. The Indian high ash coal (HAC) is nonreactive, and the co‐utilisation of HAC with these plastic wastes is advantageous to produce high‐quality syngas. In the present study, thermal treatment of overall gowns (OG) used during COVID by pyrolysis and gasification process was carried out under inert and reactive conditions with and without HAC at various operating temperatures. During pyrolysis, oil with a yield of 17% was produced under N2 conditions at 900°C, whereas a reduced oxygen content in the oil was observed (absence of C–O) under CO2 conditions. The co‐gasification of OG with high ash coal in the fuel mixture resulted in the heating value of syngas as high as 8.56 MJ nm−3. The calorific value of the syngas increases by 51.8% when OG content in the fuel mixture is increased to 20% because hydrocarbon content in syngas increases by 8.73 times. Thermogravimetric analysis showed that by adding OG, gasification initiated 35°C earlier as compared to HAC. The solid residue obtained by co‐gasification contains calcium in the form of CaO and CaCO3 due to COVID‐19 waste. The global warming potential of the syngas generated is reduced by 32% with the addition of OG to 20%. [ABSTRACT FROM AUTHOR] Copyright of Asia-Pacific Journal of Chemical Engineering is the property of John Wiley & Sons, Inc. and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)
ABSTRACT
During the COVID-19 pandemic, the world saw an exponential surge in the production of Personal Protective Equipment (PPE) kits, which eventually got discarded in the biomedical waste stream. In this study, thirteen different polymer samples from the PPE kit were collected and characterized using Fourier transform infrared spectrometer, thermogravimetric analysis, and analytical pyrolysis-gas chromatograph/mass spectrometry. The characterization data showed that about 94 % by mass of components were made of only three polymers, viz. polypropylene (PP, 75.6 wt %), polyethylene terephthalate (PET, 12.5 wt %), and polycarbonate (PC, 6 wt %). The analytical pyrolysis of the PPE coverall suit (PP) yielded mainly alkenes containing 2,4-dimethyl-1-heptene as the major compound with 17 wt % yield at 600 °C. The pyrolysates from face shield (PET) were rich in benzoic acid (5.8 wt %) and acetophenone (4.8 wt %), while those from safety goggles (PC) were rich in phenol (17.6 wt %) and p-cresol (12.4 wt %) at 600 °C. HZSM-5 and HY zeolites were used for the catalytic upgradation of pyrolysates especially from PP, PET and PC. The temperature and feed-to-catalyst ratio were optimized by performing catalytic fast pyrolysis experiments at 500 °C, 600 °C and 700 °C with different feed-to-catalyst ratios 1:2, 1:4, and 1:6 (w/w). The yield of aromatic hydrocarbons, viz., BTEX (benzene, toluene, ethylbenzene, xylenes) and naphthalene, was maximum (â¼25.7 wt %) from PP coverall when HY catalyst was used at 600 °C and 1:6 (w/w) loading. In the case of PET face shield, the total yield of BTEX, naphthalene and biphenyl was maximum (27.9 wt %) at 600 °C and 1:4 (w/w) of HZSM-5, while in the case of PC goggles, it was maximum (18.6 wt %) at 700 °C and 1:4 (w/w) of HY. This study shows that the entire PPE kit can be valorized via catalytic fast pyrolysis to generate petrochemical products and platform molecules like monoaromatic hydrocarbons at high selectivities.
ABSTRACT
Bamboo, the fastest-growing plant, has several unique characteristics that make it appropriate for diverse applications. It is low-cost, high-tensile, lightweight, flexible, durable, and capable of proliferating even in ineffectual areas (e.g., incline). This review discusses the unique properties of bamboo for making charcoal and biochar for diverse applications. To produce bamboo charcoal and biochar, this study reports on the pyrolysis process for the thermal degradation of organic materials in an oxygen-depleted atmosphere under a specific temperature. This is an alternative method for turning waste biomass into products with additional value, such as biochar. Due to various advantages, bamboo charcoal is preferred over regular charcoal as it has four times the absorption rate and ten times more surface area reported. According to the reports, the charcoal yield ranges from 24.60 to 74.27%. Bamboo chopsticks were the most useful source for producing charcoal, with a high yield of 74.27% at 300 °C in nitrogen, but the thorny bamboo species have a tremendous amount of minimal charcoal, i.e., 24.60%. The reported biochar from bamboo yield ranges from 32 to 80%. The most extensive biochar production is produced by the bamboo D. giganteus, which yields 80% biochar at 300 °C. Dry bamboo stalks at 400 °C produced 32% biochar. One of the sections highlights biochar as a sustainable solution for plastic trash management produced during the COVID-19 pandemic. Another section is dedicated to the knowledge enhancement about the broad application spectrum of the charcoal and biochar. The last section highlights the conclusions, future perspectives, and recommendations on the charcoal and biochar derived from bamboo.
ABSTRACT
Inexpensive iron-based catalysts are the most promising catalysts for microwave pyrolysis of waste plastics, especially a large number of disposable medical masks (DMMs) with biological hazards produced by spread of COVID-19. However, most synthesized iron-based catalysts have very low microwave heating efficiency due to the enrichment state of iron. Here, we prepared FeAlOx catalysts using the microwave heating method and found that the microwave heating efficiency of amorphous iron and hematite is very low, indeed, these materials can hardly initiate pyrolysis at room temperature, which limits the application of iron-based catalysts in microwave pyrolysis. By contrast, a mixture of DMMs and low-valent iron oxides produced by hydrogen reduction at 500 °C can be heated by microwaves to temperatures above 900 °C under the same conditions. When the hydrogen reduction temperature was incerased to 800 °C, the content of metallic iron in the catalyst gradually increased from 0.34 to 21.43%, which enhanced the microwave response ability of the catalyst, and decreased the gas content in the pyrolysis product from 78.91 to 70.93 wt%;corresponding hydrogen yield also decreased from 29.03 to 25.02 mmolH2·g-1DMMs. Moreover, the morphology of the deposited solid carbon gradually changed from multi-walled CNTs to bamboo-like CNTs. This study clarifies the pyrolysis mechanism of microwave-assisted iron catalysts and lays a theoretical foundation for their application in microwave pyrolysis. © 2022 Elsevier Ltd
ABSTRACT
The COVID-19 pandemic has resulted in an alarming accumulation of plastic waste. Herein, an integrated hydropyrolysis and hydrocracking process was performed to upcycle disposable masks into fuel-range iso-alkanes over carbon supported ruthenium (Ru/C). Experimental results indicated that catalyst type significantly affected product distribution during the hydropyrolysis and vapor-phase hydrocracking of disposable masks. Compared with zeolites-induced catalytic cascade process where up to ∼25.9 wt% yield of aromatic hydrocarbons such as toluene and xylenes were generated, a ∼82.7 wt% yield of desirable iso-alkanes with a high C5–C12 gasoline selectivity of 95.5% was obtained over Ru/C under 550 °C hydropyrolysis temperature and 300 °C hydrocracking temperature at 0.2 MPa H2. The cascade hydropyrolysis and hydrocracking process also exhibited high adaptability and flexibility in upcycling single-use syringes, food packaging, and plastic bags, generating 79.1, 81.6, and 80.3 wt% yields of fuel range iso/n-alkanes, respectively. This catalytic cascade hydrotreating process provides an efficient and effective approach to convert pandemic-derived plastic waste into gasoline-range fuel products. © 2022 Elsevier Ltd