Pyrolysis of the waste organic fraction is expected to be a central element to meet the primary energy demand in future: it increases the impact of renewable energy sources on the power generation ...sector and allows the amount of waste to be reduced, putting an end to landfills. In the present study, kinetic studies on the pyrolysis of biomass wastes are carried out. Two kinds of industrial organic waste are investigated: brewery spent grain (BSG) and medium-density fiberboard (MDF). The main target of this work is to provide a global equation for the one-step pyrolysis reaction of the investigated materials in an argon atmosphere using isoconversional methods. The conducted analysis allowed to estimate the activation energy as 225.4–253.6 kJ/mol for BSG and 197.9–216.7 kJ/mol for MDF. For both materials nth order reaction was proposed with reaction order of 7.69–8.70 for BSG and 6.32–6.55 for MDF. The developed equation allowed to simulate the theoretical curves of thermal conversion. These curves indicated the highest conversion at the temperature of the degradation of dominant component, which was experimentally verified. By this method, a one-step kinetic model is derived, which can be applied for the reaction kinetics in the CFD modelling of, e.g., pyrolysis and gasification processes.
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•The kinetic triplets of BSG and MDF pyrolysis in argon were determined.•Friedman, Flyn-Wall-Ozawa, and Kissinger-Akahira-Sunose methods were compared.•The calculated reaction order of pyrolysis of BSG and MDF was 8.70 and 6.55, respectively.•The single-step reaction of BSG and MDF pyrolysis was simulated using the Runge-Kutta method.•The modelled pyrolysis curves were successfully verified via experimental results.
Environmental concerns associated with the rapid rising plastic consumption have led to the search for better waste utilization and management. Pyrolysis has emerged as an ideal and promising waste ...management technique for energy extraction from plastic waste. The aim of this work is to explore the effects of operation temperature and heating rate on the pyrolysis behavior under non-isothermal heating conditions. The decomposition characteristics, reaction mechanism, kinetics and thermodynamics of a typical widely used thermosetting plastic, acrylonitrile butadiene styrene (ABS), were studied via coupled thermogravimetry, Fourier transform infrared spectrometry and gas chromatography-mass spectrometry analysis (TG-FTIR-GC/MS). Kinetic analysis showed the average Eα values are estimated to be 187.02, 188.55, 187.04 and 185.67 kJ/mol via advanced Vyazovkin, Flynn-Wall-Ozawa (FWO), Tang and Starink model-free method, respectively. Model-fitting CR and master-plots methods indicated that f(α)=(1-α)n is the most probable reaction mechanism. The equation of kinetic compensation effect was further developed as lnA = −3.1955 + 0.1736 Eα. Furthermore based on these initial inferences, a new reaction scheme coupled with Particle Swarm Optimization (PSO) was put forward for modeling ABS pyrolysis. The optimized values for E, A and n were 198.07 kJ/mol, 7.61 × 1012 s−1 and 1.56, respectively. The predicted results showed that the experimental data can be well characterized by the optimized parameters from PSO, validating the effectiveness and accuracy of the inverse modeling procedure. Moreover, it is found that the volatile products are mainly composed of aromatic compounds, ketones, amines, esters, nitrile compounds, alkenes and amines. Based on the FT-IR and GC-MS results, the possible chemical reactions for ABS pyrolysis from molecular structure were proposed. Finally, thermodynamic analysis were carried out, the calculated values of enthalpy ΔH, Gibb's free energy ΔG and entropy ΔS indicated that non-spontaneous reactions with low favorability exists during ABS decomposition, the process is complex therefore extra energy is needed to promote the reaction. The above obtained results should offer as an important reference for future disposal and thermochemical management of plastic waste.
•ABS pyrolysis kinetics is studied by combined model-free and model-fitting methods.•GC-MS suggested the main volatile products released are aromatic compounds.•n-th order reaction model is identified to best describe ABS pyrolysis mechanism.•Kinetic parameters characterizing the pyrolysis process are optimized by PSO.•Possible chemical reactions pathway for ABS thermal degradation is given.
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•Nano-ZnO (0.47 wt%)/MPP doping imparts geopolymer coatings enhanced flame retardancy.•The ceramic-like ZnP4O11 makes pyrolysis Eα rise from 204.30 to 255.61 kJ·mol−1 at ...800 ∼ 1000 °C.•The interpenetrating Si/C/P residues exert 56% formaldehyde-adsorption capacity.
Herein the nano-ZnO/melamine polyphosphate (MPP) co-doped silica fume-based geopolymer composite coatings is fabricated for flame-retarding plywood. Its flame-retarding mechanism is investigated by microstructural characterizations and pyrolysis kinetics. The results show that an appropriate dosage of nano-ZnO (0.47 wt%) enhances flame retardancy, evidenced by the fire performance index increased to 2.98 s·m2·kW−1 from 1.10, the fire growth index (FGI) decreased from 0.48 to 0.23 kW·m−2·s−1, the flame retardant index (FRI) climbs from 1 to 2.79. Because the doped ZnO initiates the formation of ceramic-like Si/C/P residues, the as-formed ZnP4O11 is determined through the reactions between MPP and nano-ZnO. The ceramic-like reactions make the pyrolysis Eα rise from 204.30 to 255.61 kJ·mol−1 at 800 ∼ 1000 °C, according to the as-identified three-stage deceleration function (F3) of pyrolysis kinetics, resulting in the resilient and interpenetrating residues with a formaldehyde adsorption rate of 56%. It seeks effective recycling of metallurgical solid waste for preparing ecological flame-retarding coatings, proposing an efficient approach for quantitatively probing the Si/C/P residues.
•Compensation effect is minimized using Gauss multi-peak fitting method.•Ea of cellulose and hemicellulose vary in range of 140–220 kJ mol−1.•Ea of lignin varies in range of 30–200 kJ mol−1.•Linear ...dependency of lnA on Ea also exists for high-order reactions.•High-order reaction is more suitable for lignin pyrolysis.
Compensation effect is an unsolved issue when determining pyrolysis kinetics of biomass using inverse modelling and optimization algorithms, implying no unique solution can be obtained. To address this problem, a new method coupling Gauss multi-peak fitting method, Kissinger method, a numerical model, and Shuffled Complex Evolution (SCE) optimization algorithm is proposed to extract kinetics from microscale thermogravimetric analysis (TGA) experiments and avoid attainment of unreasonable good-fit solutions. TGA tests of beech wood at nitrogen atmosphere were conducted at three heating rates. Gauss multi-peak fitting method was employed to separate the overlapped peaks in TGA curves and identify the contribution of each elemental component reaction. The kinetics of individual reactions were estimated by Kissinger method to provide an initial solution for SCE optimization. Then, narrow initial search ranges were determined to further refine the kinetics by SCE. By compiling previous data in literature and our optimization results, it was found compensation effect exists for individual basic components, hemicellulose, cellulose and lignin, following a linear correlation between lnA andEa, and among multiple components. Pyrolysis of hemicellulose can be modelled by either first-order or high-order reactions, while cellulose pyrolysis is more likely a first-order reaction. Nevertheless, the long tail in DTG curves associated with decomposition of lignin can only be captured by a high-order reaction. Although the Kissinger solution of lignin cannot be used in selecting an appropriate search range for SCE optimization, the narrow search ranges of the remaining kinetic parameters can ensure the accuracy and convergency efficiency of optimization.
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•Devolatilization kinetics is coupled with the heat and mass transfer processes.•Evolution of pore structure in coal pyrolysis with solid heat carrier is included.•Multi-physical ...fields inside a lignite particle during pyrolysis is elaborated.•The intraparticle mass transfer mechanism influences the secondary reaction.
The study of mesoscale solid fuel pyrolysis behavior is a key bridge between the microscopic reaction kinetics and macroscopic multiphase reaction flow in a reactor. In this work, a one-dimensional nonstationary model was developed in spherical coordinate system for the pyrolysis of millimeter-scale lignite particles with solid heat carriers, in which a modified multistep kinetic model (MSM) was coupled with a series of correlative transient heat and mass conservation equations in conjunction with the dusty gas model (DGM). The MSM for coal pyrolysis was modified by adding a set of kinetic equations of pseudo-elementary secondary reactions, making the kinetic model comparable to the Chemical Percolation Devolatilization model in terms of accuracy. In addition, a semiempirical submodel for the evolution of pore structure parameters (porosity, pore size, and permeability) was incorporated to obtain the precise mechanism of volatile species transport in the porous coal matrix. The modified MSM and pore evolution submodel were validated against literature data. The coupling effects between intraparticle transport processes and transient devolatilization kinetics were investigated. It was concluded that notable multiphysical fields (pressure, concentration, and velocity) emerged within lignite particles during pyrolysis, governed by the heating history. In addition, it should be noted that the direction and mechanism of volatiles transfer within porous lignite particles varied during pyrolysis, which can significantly affect secondary reactions. Flow reversal and shifts in the dominant mass transfer mode influenced the secondary reaction pathway, in addition to the impact of volatiles flow velocity on the reaction degree.
•Biomass pyrolysis behavior was estimated from its main constituents and heating rate.•The kinetic constants of lignocellulose pyrolysis were predicted by ANFIS–PSO model.•The developed framework ...could accurately estimate the biomass pyrolysis behavior.•A practical and handy software was designed for predicting biomass pyrolysis kinetics.
In-depth knowledge on pyrolysis behavior of lignocellulosic biomass is pivotal for efficient design, optimization, and control of thermochemical biofuel production processes. Experimental thermogravimetric analysis (TGA) is usually employed to peruse the pyrolysis kinetics of biomass samples. In addition to that, the main constituents of biomass (i.e., cellulose, hemicellulose, lignin) as well as the process heating rate can excellently reflect its pyrolysis characteristics through modeling techniques. However, the application of statistical and phenomenological models for extremely complex and highly nonlinear phenomena like lignocellulose pyrolysis is challenging. To address this challenge, adaptive network-based fuzzy inference system (ANFIS) was consolidated with particle swarm optimization (PSO) algorithm to prognosticate the kinetic constants of lignocellulose pyrolysis. More specifically, the PSO algorithm was applied to tune membership function parameters of the ANFIS model. Three ANFIS−PSO topologies were designed and trained to estimate the kinetic constants of lignocellulose pyrolysis, i.e., energy of activation, pre-exponential coefficient, and order of reaction. The input variables of the developed models were biomass main constituents and the process heating rate. The developed models could predict the kinetic constants of lignocellulosic biomass pyrolysis with an R2 > 0.970, an MAPE < 3.270%, and an RMSE < 5.006. The pyrolysis behaviors of three different biomass feedstocks (unseen data to the developed models) were adequately prognosticated with an R2 > 0.91 using the developed models, further confirming their fidelity. Overall, the lignocellulose pyrolysis behavior could be reliably and accurately estimated using the trained ANFIS–PSO approaches as an alternative to the TGA measurements. In order to make practical use of the trained models, a handy freely-accessible software platform was designed using the selected ANFIS−PSO models for approximating biomass pyrolysis kinetics.
Herein, the synthesis of β-cyclodextrin (β-CD) modified aliphatic waterborne polyurethane (AWP)-based coatings via the sol-gel method. The investigation aims to determine the appropriate dosage of ...surface-modified ammonium polyphosphate (APP) by using β-CD and the Di(dioctyl pyrophosphate) ethylene titanate (KR-238S). The flame retardancy of β-CD modified APP on AWP-based coatings is evaluated by quantitative analysis. Results show that adding 2 wt% β-CD enhances the flame retardancy of AWP-based coatings, as evidenced by an increase in the flame retardancy index (FRI) and a decrease in the peak of heat release rate (p-HRR). The FRI increases from 1.00 to 3.26, while p-HRR decreases from 133.30 kW·m−2 to 75.21 kW·m−2. Then, the modified APP improves the resilience and compatibility of AWP-based coatings using microscopic analysis. Moreover, the pyrolysis kinetics is modeled using the 3D Jander model, revealing an increase in Eα from 165.74 kJ·mol−1∼197.44 kJ·mol−1 in the stage of 352 °C∼394 °C. The superior flame retardancy benefits from the dispersed β-CD and KR-238S co-modified APP: hydrogen bonding, inclusion complex, and electrostatic interaction. Generally, it prepares a non-toxic and cleaner coating and provides a new strategy to solve the problem of coating performance degradation caused by excessive flame retardants.
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Flexible polyurethane foam is widely used in furniture upholstery, car seats, and other products. Its safety has attracted increasing attention, especially fire safety in luxury cruise ship. ...Thermogravimetry-Fourier Transform Infrared Spectroscopy-Gas Chromatography-Mass Spectrometry (TG-FTIR-GC-MS) is used to explore the pyrolysis characteristics of flexible polyurethane foam. The experimental results show that three weight loss peaks can be observed in the pyrolysis of flexible polyurethane foam under nitrogen atmosphere, which implies that the pyrolysis behaviors of isocyanate, polyol and catalyst are responsible for the peaks. The pyrolysis process of flexible polyurethane foam can be divided into two regions: the fifth-order reaction (F5) model and the one-dimensional diffusion (D1) model corresponding to regions I and II, respectively. The main pyrolysis intermediate function groups includes CO2, gaseous H2O, C-O, CO, C-H and other functional group stretching products. The amount of intermediate function groups generated in order of most to least is C-O > C-H > CO2 > CO > H2O. Six main products are generated under the N2 atmosphere, including Ethane, 2-Octen-1-ol, 3,7-dimethyl-isobutyrate, Diisopropyl ether, 1-Propoxypropan-2-yl acetate, Z-8-Methyl-9-tetradecenoic acid, Methyl 7,9-tridecadienyl ether and N-(2-Methylbutyl) undeca-(2E,4E)-diene-8,10-diynamide. The Shuffled Complex Evolution (SCE) algorithm is used to optimize the experimental pyrolysis kinetic parameters, and the optimized data show good agreement with the experimental data.
•TG-FTIR-GC-MS was used to analysis the pyrolysis of flexible polyurethane foam.•SCE algorithm was used to optimize pyrolysis parameters of flexible polyurethane foam.•The pyrolysis of flexible polyurethane foam can be described by a three-step reaction.•The GC-MS data of flexible polyurethane foam are well agreeable with the FTIR data.•The mount of intermediate function groups is C-O > C-H > CO2 > CO > H2O.
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•1 wt% modified β-CD imparts an enhanced flame retardancy to the geopolymeric coating.•The crosslinking makes the Eα rise from 132.1 to 185.5 kJ·mol−1 at 1000–689 °C.•The ...flame-retarding mechanism in modified β-CD doped geopolymeric coating is elaborated.
A novel β-cyclodextrin (β-CD)/silica fume-based coating is prepared by sol-gel method to seek ecological and environmentally friendly flame retardants, which is employed for flame-retarding plywood extensively used as the decorative materials. The flame-retarding mechanism is elaborated through microstructure characterizations and pyrolysis kinetics. The results show that an appropriate dosage of γ-aminopropyl triethoxysilane modified β-CD (1 wt%) enhances the flame retardancy of the geopolymeric coating, the peak of heat release rate decreases from 125.95 kW·m−2 to 59.65 kW·m−2, the flame retardancy index climbs from 1 to 4.06. Because of the hydrogen-bonding crosslinking, filling, and subsequent adsorption, the coating transforms into an interpenetrating network, compact, and non-combustible layer during firing, thus blocking the transfer of heat or mass, leading to an increase in the pyrolysis Eα (it rises from 132.1 to 185.5 kJ·mol−1 at 1000–689 °C) according to the three-level chemical reaction model (F3). It explores an efficient approach for designing Si/C hybrid fireproof coatings with biomaterials and metallurgical solid waste, promoting the development of green flame retardant technologies.
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•0.5 wt% Zn-PA endows the geopolymer coating with better flame retardancy.•The Si-C-P structure provides better physical adsorption capacity.•The flame retardant mechanism and ...cross-linking mechanism of Zn2+ chelated Si-C-P geopolymer coating are described.
Zinc phytate (ZnPA) chelated geopolymer and in-situ polymerized chitosan oligosaccharide (COS)/DOPO explored a challenging and exciting flame retardant organic–inorganic hybrid coating via sol–gel method to find halogenated high-efficiency bio-flame retardants are widely used as decorative materials for flame-retardant plywood. Herein, the results show that the appropriated ZnPA (0.5 wt%) enhances the flame retardancy of the geopolymer coating, the peak of heat release rate (p-HRR) decreases from 136.09 to 99.39 kW·m−2, the fire growth index (FGI) dropped from 0.47 to 0.28 kW m−2 s−1, the fire performance index (FPI) climbs from 1.00 to 2.52 s·m2·kW−1, and the flame retardancy index (FRI) climbs from 1.00 to 2.52. Meanwhile, through the microstructural analysis of the residual layer, a strong, compact and non-flammable resilient residues is obtained after combustion; Moreover, the pyrolysis kinetics show that the Z.-L.-T. three-dimensional diffusion reaction model governs the pyrolysis of hybrid coatings. Appropriated ZnPA increases the pyrolysis Eα from 138.95 kJ·mol−1 to 160.75 kJ·mol−1 at 741 ∼ 890 ℃ and improves the thermal stability of the coating. The Si-C-P structure improves the formaldehyde adsorption rate by 46.5%. Therefore, this study, by preparing COS-pretreated ZnPA and DOPO to co-construct alkali-excited cenospheres-based Si-C-P coating, reveals the sustainable development of modified bio-based geopolymer flame-retardant coatings in the construction industry.
