Pyrolysis Behavior Research Articles

Study on Pyrolysis Behavior of Avermectin Mycelial Residues and Characterization of Obtained Gas, Liquid, and Biochar

The proper disposal of antibiotic mycelial residue (AMR) is a critical concern due to the spread of antibiotics and environmental pollution. Pyrolysis emerges as a promising technology for AMR treatment. In this study, we investigated the effect of pyrolysis temperature on the thermal decomposition behavior and product characteristics of avermectin (AV) mycelial residues. Various characterization techniques were employed to analyze thoroughly the compositions and yields of the obtained gas, liquid, and biochar products. The results indicated that most of the organic matter such as protein, carbohydrate, and aliphatic compounds in AV mycelial residues decomposed intensely at 322 °C and tended to end at 700 °C, with a total weight loss of up to 72.6 wt%. As the pyrolysis temperature increased, the biochar yield decreased from 32.81 wt% to 26.39 wt% because of the enhanced degradation of volatiles and secondary reactions of the formed aromatic rings. Accordingly, more gas components were formed with the gas yield increased from 9.76 wt% to 15.42 wt%. For bio-oil, the contents were maintained in the range of 57.43–60.13 wt%. CO and CO2 dominated the gas components with a high total content of almost 62.37–97.54 vol%. At the same time, abundant acids, esters (42.99–48.85%), and nitrogen-containing compounds (32.14–38.70%) such as nitriles, amides, and nitrogenous heterocyclic compounds were detected for the obtained bio-oil. As for the obtained biochars, particle accumulation and irregular pores were presented on their bulk surface, which was primarily composed of calcium oxalate (CaC2O4) and calcium carbonate (CaCO3). This work can provide theoretical insights for the harmless disposal and resource recovery for AMR, contributing significantly to the field of solid waste reuse and management.

Effect of outdoor ageing on pyrolytic characteristics and kinetics of different organic components in waste photovoltaic panels

Pyrolysis is a potential approach for volume reduction and utilization of organic components in waste photovoltaic panels. During a usage period of 20–25 years, the physical and chemical properties of photovoltaic panels might undergo ageing and deterioration, thereby affecting their thermal decomposition characteristics. The characteristics of samples before and after ageing were studied using Fourier transform infrared spectroscopy, scanning electron microscopy, elemental analyzer, and thermogravimetry-Fourier transform infrared spectroscopy-mass spectrometry. There were certain differences in the weight loss temperature, time, residual mass, and activation energy of the samples in the pyrolysis reaction. After ageing, the production of acetic acid and methane in ethylene vinyl acetate pyrolysis products increased, while the production of CO2 decreased. After ageing, Tedlar-Polyethylene Terephalate-Tedlar mainly produced water, carbon dioxide, and fluorocarbon compounds, and the percentage of harmful fluorocarbon compounds in the human body increased. Cyclosiloxane, CO2, and hydrocarbons containing C-H bond were detected in each weight-loss stage of aged silica gel. As the heating rate changed, the amount of pyrolysis products also changed. Controlling the sample's heating rate would help to lessen the quantity of hazardous pollutants that were produced. The influence of ageing on the weight loss of mixed samples was discussed. This study seeks to give a fundamental understanding of the physicochemical properties, pyrolysis behaviour, and volatiles of samples before and after ageing, thus providing helpful insights for the final disposal or recovery of waste photovoltaic panels through pyrolysis.

Pyrolysis of multilayered plastic packets to hydrocarbon fuel feedstock: Thermal degradation behaviour, kinetics and thermodynamic analysis, and semi-batch studies

This study examines the kinetics and batch pyrolysis behavior of multilayered waste milk packets to optimize their conversion into valuable products. Using thermogravimetric analysis at heating rates of 5, 10, 15, and 20 °C/min and employing the model fitting and model-free methods such as the Kissinger-Akahira-Sunose (KAS), Flynn-Wall-Ozawa (FWO), and Kissinger methods, the process was found to follow an F1 order-based mechanism with an activation energy of 304 kJ/mol and a pre-exponential factor of 2.60 × 1012 min.−1 The maximum weight loss (97.2 %) occurs at 5 °C/min. The average changes in free energy, enthalpy, and entropy are 814.939 kJ/mol, 135.698 kJ/mol, and −903.846 × 10−3 kJK−1mol−1 respectively. At 450 °C, the maximum pyrolytic oil yield reaches 66.92 %, with FTIR analysis confirming the presence of diverse hydrocarbon components such as alkanes, alkenes, cycloalkanes, aromatic hydrocarbons etc. in the oil. Kinetic triplet and thermodynamic parameter data, alongside physical and chemical analyses, suggest that the pyrolytic oil from multilayered waste milk packets could serve as a superior substitute for petrochemical fuel oil.

Molecular structure of coal macerals and thermal response behavior of their chemical bonds obtained by structural characterizations and molecular dynamics simulations

Clarifying the microscale reaction mechanism of macerals is crucial for achieving efficient thermal utilization of coals. Herein, we analysed the chemical structures of two coals used in coking for their macerals employing 13C NMR, FTIR, and XPS to build molecules. The pyrolysis behaviours of coals and their macerals were accessed through molecular dynamics of calculating chemical bond characteristics. Results show that inertinite with higher maturity is rich in aromatic, vitrinite with stronger thermal-reactivity is rich in aliphatic, and macerals of coking and gas coal have more advantages in hydrocarbon generation and branch-chain development, respectively. Based on the validated and optimized molecules containing C, H, O, and N elements, it is found that not only the bond lengths of the longest and shortest in macerals from gas coal are greater than those from coking coal, but the thermal response of heteroatom bonds in the former is almost twice that of the later. Moreover, vitrinite and inertinite of coking coal have N–H cleavage to produce active hydrogen in the late stage of bond dissociation, while gas coal lacks this feature. These explain why the pyrolytic properties of different coals and their macerals have variability, guiding the rational selection of coal-based feedstock for industry.

Assessing bioenergy prospects of algal biomass and yard waste using an integrated hydrothermal carbonization and pyrolysis (HTC–PY): A detailed emission–to–ash characterization via diverse hyphenated analytical techniques and modelling strategies

Hydrothermal carbonization (HTC) presents a promising method for converting carbonaceous waste into renewable fuels, facilitating energy recovery. This study focuses on the HTC pretreatment of microalgae (Chlorella sorokiniana) and yard waste, examining their physicochemical structural changes, component migration, and potential for valorization via integrated HTC and pyrolysis processes. HTC notably enhances the carbon content while reducing oxygen and nitrogen levels in these feedstocks, producing a clean solid fuel with high energy density. The study investigates the pyrolytic behavior of hydrochars and their blends using different analytical techniques, kinetic modeling, and fixed–bed reactor experiments. The blends with 90% and 70% of microalgae hydrochar (CSH) exhibited the most significant synergistic effects during co–pyrolysis, evident in its devolatilization behaviors and reduced activation energies. Integrating artificial neural networks and response surface methodology models facilitated optimization of pyrolysis parameters and accurate prediction of bio–oil, biochar, and gas yields. The analytical techniques enabled characterization of pyrolysis products, revealing notable changes in bio–oil and biochar compositions, suggesting potential enhancements. The study comprehensively evaluates the HTC–pyrolysis approach’s potential for converting microalgae and lignocellulosic biomass into eco–friendly biofuels for industrial applications.

Kinetics of pyrolysis and Computational Fluid Dynamics modeling of low metamorphic coal

AbstractThis study explores the low‐temperature pyrolysis kinetic of low metamorphic grade coal from Northern Shaanxi, utilizing Fourier transform infrared (FT‐IR) spectroscopy to analyze the characteristics of various functional groups over a 293–1023 K temperature range. A kinetic model, correlating with the pyrolysis behaviors of these groups, was developed through thermal analysis kinetics. Computational fluid dynamics (CFD) technology simulated the furnace's flow dynamics, allowing an examination of the physical field alterations and functional group evolution during pyrolysis. Results showed that the pyrolysis kinetic functions for aromatic C–H, C=C, C–O, and •OH, along with temperature, pressure, and velocity fields, were successfully integrated into the simulation. This integration provided detailed insights into the temperature profile, pressure distribution, flow velocities, and functional group distribution in the furnace. Aliphatics, exhibiting the largest mass fraction and wide pyrolysis temperature range, and •OH radicals with the highest activation energy were concentrated in the furnace's pyrolysis zone center. C=C's distribution was influenced by aromatic C–H and aliphatics, showing a complementary pattern. The oxygen‐containing groups C–O and C=O had similar pyrolysis mechanisms and uniform distribution. The functional groups' mass fractions were ranked from highest to lowest as follows: aliphatics > •OH > aromatic C–H > C–O > C=C > C=O.

A quantitative investigation on pyrolysis behaviors of metal ion-exchanged coal macerals by interpretable machine learning algorithms

Generalizing the rules from complex processes such as catalytic pyrolysis to guide their process control is always a difficult but attractive task. The influences of ion-exchange of metal ions (Na+, K+, Ca2+, Mg2+, Co2+ and Ni2+) on the pyrolysis behavior of vitrinite and inertinite from Shendong coal were investigated by thermogravimetric analyzer-Fourier transform infrared spectrometer (TG-FTIR), fixed-bed reactor (FBR), gas chromatograph-mass spectrometer (GC-MS) and X-ray diffractometer (XRD). A set of machine learning models was successfully constructed based on random forest, support vector machine, and Gaussian process regression, to quantify the relationships between pyrolysis behaviors and the properties of metals and macerals. The leave-one-out-cross validation showed that there are considerable determination coefficients (R2 > 0.9) between predicted and experimental values for most responses (17 out of 29). By combining genetic programming-based symbolic regression with the black-box algorithm, 23 symbolic regression expressions with high confidence were successfully constructed. This work is a pioneering attempt of optimization in small-scale experiments. By utilizing the highly interpretable models, a demand-orientated (multi-)optimization coal pyrolysis can be achieved. The bi-objective optimization was conducted on the yield of tar and the content of light aromatics in tar, and the results show that Co is the optimal loading metal.

Chemical insight into thermal degradation, chemical kinetics, and thermodynamics behavior of sewage sludge through thermogravimetry and Fourier transform infrared analysis

Pyrolysis emerges as a promising path for sewage sludge (SS) management and value creation by producing compounds with enhanced utility. This study focuses on a comprehensive analysis of the thermal decomposition of SS using thermogravimetric analysis (TGA) and Fourier transform infrared spectrometry (FTIR). The TGA and FTIR were employed to evaluate the pyrolysis behavior, kinetics, and characteristics during pyrolysis of SS. The process revealed three distinct stages: 1st stage ranged between 30–185 °C with the removal of moisture, 2nd stage saw devolatilization of SS in the range of 185–595 °C, and the 3rd stage was mainly the formation of char in the temperature range of 595–900 °C. Pyrolysis kinetics, reaction mechanisms, and thermodynamic properties were extensively investigated at three different heating rates of 10, 20, and 30 °C /min. It was observed that with the temperature rise, the decomposition rate also increased rapidly, notably for the heating rate of 30 °C/min. Using Flynn-Wall-Ozawa, Kissinger-Akahira-Sunose, Starink, and Tang methods, activation energies for SS pyrolysis were estimated for α in the range of 0.2–0.85, and the average value for that range was found to be 84.72, 92.29, 91.99, and 91.76 kJ/mol, respectively for different iso-conversional methods. The chemical kinetics analysis through Coats-Redfern methods identified that 3-D diffusion-reaction mechanisms have the highest coefficient of determination among the other models. Criado z-master plot emphasizes the prevalence of Avrami-Erofeev (A4) as the bestsuited reaction model in combination with α, providing a detailed examination that illuminates the complex processes and mechanisms inherent in the pyrolysis of sewage sludge.

Influence of size and filler system on the pyrolysis behavior of styrene-butadiene rubber in tire wear particles

Tire wear particles (TWPs) are generated by driving vehicles and found in the environment. Model TWPs of styrene-butadiene rubber (SBR) vulcanizates with different filler systems, namely, carbon black (SBR-C), carbon black/silica (SBR-M), and silica (SBR-S), were prepared using an indoor abrasion tester, and their pyrolysis behavior was investigated in terms of particle size and filler system. Abundances of the major pyrolysis products, namely, butadiene, 4-vinylcyclohexene (4-VCH), styrene, 2-phenylpropene (2-PP), and 3-phenylcyclopentene (3-PCP), were compared. The 4-VCH/butadiene and 4-VCH/styrene ratios of vulcanized SBR were lower than those of raw SBR, whereas the 2-PP/styrene and 3-PCP/styrene ratios of vulcanizates were higher than those of raw SBR. The abundance ratios of major pyrolysis products of the vulcanized samples showed different trends, although the three vulcanizates had the same compound formulation except for the filler system. The abundance ratio decreased in the order of SBR-C > SBR-M > SBR-S, which can be explained by the sulfur crosslinks and states of the bound rubber. The 4-VCH/styrene, 2-PP/styrene, and 3-PCP/styrene ratios of TWPs increased notably with increasing the TWP size up to 200 μm and then increased slightly or almost remained constant. The pyrolysis behavior of TWPs was influenced by the filler system and particle size. Our study suggests that the differences in the pyrolysis behavior depending on the filler system and particle size should be considered for the quantification of TWPs in environmental samples.

Spontaneous ignition of corrugated cardboard under dynamic high radiant flux

Understanding the response of solid combustibles under high radiant fluxes is critical in predicting the thermal damage from extreme scenarios. Unlike the more moderate radiant fluxes in conventional hydrocarbon fires, extreme events such as strong explosion, concentrated sunlight and directed energy can generate dynamic radiant fluxes at the MW/m2 level, creating a unique threat to materials. This study investigates the pyrolysis and spontaneous ignition behaviors of corrugated cardboard by using both experimental and numerical methods, under 10-cm dynamic high radiant fluxes ranging from 0.2 to 1.25 MW/m2 for 10 s. The spontaneous ignition process at dynamic high radiant fluxes was recorded and quantified. Two ignition modes were found at the critical radiant flux of 0.4 MW/m2, namely hot-gas spontaneous ignition and hot-residue piloted ignition. The latter is not the focus of this paper due to its extremely small probability of occurrence. The research reveals that the increase in flux intensity induces shorter delay times for both pyrolysis and ignition, lower ignition energy density, along with a corresponding rise in the critical mass flux and surface temperature at ignition moment. The simulation results are generally aligned with the experimental findings, despite some divergences may be attributed to model simplifications and parameter assumptions. The work contributes to a deeper insight into material behavior under extreme radiation, with valuable implications for fire safety and hazard assessment.

Influences of the Decomposition Atmosphere and Heating Rate on the Pyrolysis Behaviors of Resin Sand

The pouring of sand casting is accompanied by severe heat conduction, and there is an urgent need to investigate the pyrolysis properties of foundry sand. The main purpose of this study was to investigate the pyrolysis behaviors of resin sand, including precoated sand (PCS), hot box sand (HBS), and warm box sand (WBS), at heating rates of 20 °C/min, 30 °C/min, and 40 °C/min in nitrogen and air atmospheres. The mass loss of the resin sand was monitored continuously with a simultaneous thermal analyzer, and the kinetic parameters of the resin sand were calculated based on the Coats–Redfern method and thermal data. The average mass loss of the resin sand during pyrolysis was 3.03%, which was much smaller than that of the other sands. The volatile release characteristic index of resin sand could not be calculated based on this concept. To solve this issue, the term Tstv/mloss was established, and its value was determined. With increasing heating rates from 20 °C/min to 30 °C/min and from 30 °C/min to 40 °C/min, the mass losses of the resin sand increased by 0.79% and 0.64%, respectively, and the volatile release characteristic indices of the resin sand increased by 3.8 × 10−10 and 1.06 × 10−9, respectively. In addition, the mass losses and volatile release characteristic indices of resin sand in an air atmosphere were greater than those in a nitrogen atmosphere. With increasing heating rate, the activation energy of the resin sand decreased in a nitrogen atmosphere. The findings concerning the thermal decomposition behaviors of resin sand provided a theoretical basis for the pouring step of the sand casting process.

Experimental and feasibility study of bio-waste valorization through pyrolysis for energy and materials production in the concept of circular economy

The pyrolysis and co-pyrolysis characteristics of large abundant bio-wastes, namely date pits (DP), peanut shells (PS), coffee grounds (CG), and tea waste (TW) were investigated in detail. The TG/DTG and pyrolysis procedures were used to examine the thermal pyrolysis behavior of these agro-wastes and their blends (50%CG/50%DP, 50%CG/50%PS, 50%DP/50%PS, 50%TW/50% DP,50%TW/50%PS and 50%CG/50% TW by weight). The characterization of these feedstock has shown their suitability for energy and material valorization. Experiments were carried out in a batch pyrolysis at a medium heating rate of 10 °C/min. The goal was to identify the best combination aiming to produce either char or hydrogen-rich gas, which can contribute to the development of the circular bio-economy. It was demonstrated that pyrolysis favored the liquid product, fluctuating from 34.31% (TW) to 50.92% (DP), while the co-pyrolysis greatly increased the gaseous product, which ranged between 42.02% (TW-DP) and 55.17% (PS-TW). The blending of CG and PS resulted in heightened reactivity, leading to an enhanced generation of H2 (34.44%). The optimal mixture was found to be CG-TW, showcasing superior performance in terms of gas quality (38.39% H2) and yield (53.74%). This outcome underscores the potential of CG and TW as a synergistic blend for efficient hydrogen-rich gas production. The FTIR findings revealed that the recovered biochars have the potential to serve as solid fuels, biofertilizers, or carbon materials. Additionally, they could be used as eco-friendly precursors for chemical and related industries. By analyzing various waste mixtures and their respective pyrolysis properties, this research aims to contribute to the development of sustainable waste management practices as well as efficient energy and material production methods.

Fire behavior and post-fire residual tensile strength prediction of carbon fiber/phthalonitrile composite laminates

Carbon fiber/phthalonitrile (Cf/PN) composite has a high potential for applications in the aerospace sector because of the outstanding heat and flame resistance of phthalonitrile resin. Here we aim to evaluate the fire behavior of Cf/PN laminate under localized one-sided flame heating as well as the residual tensile performance. The residual tensile strength after quasi-isothermal pyrolysis in an inert environment decreases linearly with the increase in the pyrolysis degree. The temperature response and pyrolysis behavior are analyzed through a combination of experiments and finite element simulations, and the damage mode of the laminate structure is concluded through morphological observation after flame exposure and the surface axial strain field using digital image correlation. Eventually, the residual tensile strength of laminates with different thicknesses after different times of flame exposure was effectively predicted based on the numerical simulated pyrolysis degree distribution. This research supplies fundamental test data on the mechanical properties of Cf/PN laminates and is expected to provide guidelines for the engineering application of Cf/PN composites in thermal protection/load-bearing all-in-one structures.

Ni/N-modulated biomass pyrolysis to make carbon-based catalysts for electrochemical CO2-to-CO conversion

There are tremendous requirements in CO2 electrolysis to produce value-added chemicals, where the functional carbon-based catalysts possess the unique superiorities for CO2 conversion. Pyrolysis kinetics as a theoretical guidance is pivotal to construct the high-activity carbon-based catalysts precisely, which is decoupled urgently. Herein, the pyrolysis behaviors of ipomea batatas leaves were well optimized by Ni/N modulators and unveiled systematically, where the residence time of biomass was prolonged during the pyrolysis process and the emerged out-of-plane orientation sp3 C–N species were increased. Additionally, the presented first-order kinetics revealed that with Ni/N modulators, the higher apparent energy barrier was determined than single biomass, corresponding to an enhanced thermostability. As a guidance, the derivative catalyst with high N content (17.22 at%) can drive electrochemical CO2-to-CO reaction efficiently. The current density was up to 200 mA cm–2 and the CO Faradaic efficiency kept over 95 % at a wide work window (–0.66 to –1.46 V versus reversible hydrogen electrode) in flow cell.

Study on combustion characteristics and pyrotechnic cutting effects of bimetal thermite Ni/Al/Fe2O3 system

AbstractNano‐thermite has become a subject of significant interest in the composite energetic materials field due to its high energy release rate. To cater to diverse engineering needs, thermite formulations are often customized to fulfill specific criteria. This study investigates the potential of metal nickel (Ni) as an additive to modify nano‐thermite formulations, selected for its optimal calorific values and chemical reactivity. The base materials, nano‐aluminum (Al) and iron oxide (Fe2O3), are blended with varying mass ratios of Ni (1 %, 3 %, 5 %, 7 %, 9 %) using the wet ball milling method. Pre‐reaction and post‐reaction morphological and compositional alterations in the resultant thermite samples are scrutinized through SEM and XRD characterization tests. Moreover, DSC analysis and combustion experiments were conducted to examine the pyrolysis and combustion behaviors of the evaluated samples. The results reveal a reduced exothermic peak on the DSC curves with the introduction of Ni, making the liquid‐solid (L‐S) phase reaction more challenging compared to the Al/Fe2O3 thermite. Intriguingly, Ni addition progressively decreases the combustion temperature of thermites as the Ni's mass ratio increases, with a peak efficiency at 7 % in the perforation tests on stainless‐steel plates. This research further reveals that the thermite reaction mechanism is a combined consequence of the “pre‐ignition‐fusion” and “fusion‐diffusion” mechanisms. These insights can provide valuable guidance for designing thermite formulations for potential applications in storage, management, and pyrotechnic cutting areas.

Study on pyrolysis behavior of municipal sludge based on TG-FTIR-MS

Sludge pyrolysis, as a new sludge disposal technology, can realize the reduction and resource utilization of municipal sludge. Based on TG-FTIR-MS technology, pyrolysis behaviors such as pyrolysis reaction kinetics, pyrolysis product composition and other pyrolysis behaviors of four common municipal sludges (SD, NJ, CS, TJ) at different pyrolysis rates were investigated in this paper, and the migration and transformation of nitrogen elements in municipal sludge were analyzed. The results showed that the pyrolysis of municipal sludge was mainly divided into three stages: dewatering (below 160 °C), volatile decomposition (160–550 °C), and carbonization stage (550–900 °C). The activation energies of the four sludge pyrolysis stages were 189.75 kJ/mol, 138.13 kJ/mol, 300.76 kJ/mol, and 237.83 kJ/mol, respectively. It was found that the sludge pyrolysis stage followed the stochastic nucleation and subsequent growth mechanism through the study of SD and CS sludge. The pyrolysis gaseous product content was affected by the rate of heating and pyrolysis temperature. Moderate temperatures (400–550 °C) favored complete sludge decomposition. Sludge is more likely to decompose in a narrow temperature range at higher heating rates, and increasing the heating rate accelerates sludge decomposition. The nitrogenous compounds in sludge are mainly pyrrole nitrogen, protein nitrogen, and pyridine nitrogen. During sludge pyrolysis, the nitrogenous compounds decompose and precipitate in the form of heterocyclic nitrogen (pyridine, pyrrole), and release small molecules of nitrogenous compounds (NH3, HCN, HCNO). The experimental results can provide a reference for the disposal of municipal sludge by pyrolysis.

Co-pyrolysis of waste tire with agricultural and forestry residues: Pyrolysis behavior, products distribution and synergistic effects

Co-utilization of waste tires (WT) and agricultural and forestry residues (AFR) provides an effective means to produce energy while simultaneously providing solution for waste treatment and environment protection. In this paper, co-pyrolysis of WT and AFR (cotton stalk, CS, peanut shell, PS, and poplar branch, PB) was performed using thermogravimetric analysis (TGA), Fourier transform infrared spectrometer (FTIR), and pyrolyzer coupled with gas chromatograph/mass spectrometer (Py-GC/MS). The synergistic effects of mass loss rate and hydrocarbon content were quantified from the results of co-pyrolysis of WT with CS, PS, or PB with the weighted average of individual pyrolysis of the feedstocks. The results showed that the mass loss rate of WT with CS, PS, or PB in co-pyrolysis increased by 3.06 %, 3.84 %, and 0.61 %, respectively, compared to the weighted average of individual pyrolysis, while the hydrocarbon content increased by 19.20 %, 18.26 % and 2.97 %, respectively. The addition of AFR to WT made the pyrolysis easier. In co-pyrolysis, the amount of O-compounds decreased while that of hydrocarbons (aromatic hydrocarbons and aliphatic hydrocarbons) increased. Co-pyrolysis of AFR and WT had an effect on reducing aromatic and nitrogen content. These results provide insights into the synergistic effects, from the products distribution and offer potential waste treatment method for these wastes via thermochemical conversion.

Study on the pyrolysis characteristics, kinetics, thermodynamics, volatile products, and chemical reactions of micron polyamide waste, a typical marine plastic microfragment

AbstractThe pollution of waste plastic microfragments to the marine ecosystems is an increasingly serious problem. Pyrolysis is widely recognized as a viable technique for the treatment of such plastic waste materials. The pyrolysis behaviors, characteristic parameters, kinetics, thermodynamics, volatiles, and possible chemical reactions during the pyrolysis of micron polyamide waste (the main component of fishing gear abandoned in the marine environment) are studied in inert atmosphere in the present work. The results show that the pyrolysis of micron polyamide may be regarded as a one‐step reaction. The peak and average reaction rates decrease significantly when the heating rate increases. The calculated kinetic parameters can effectively predict the pyrolysis behaviors of micron polyamide. The pyrolysis of micron polyamide is characterized as an endothermic reaction that occurs non‐spontaneously. Furthermore, the information of volatiles was obtained. The volatiles with higher content were –CH2 groups, CO2, and lactam, and the volatiles with smaller content were: –NH groups, NH3, HCN, H2O, CO, and amide derivatives. In addition, an analysis was conducted to explore the potential chemical reactions.Highlights The pyrolysis of micron polyamide can be considered as a one‐step reaction. The obtained kinetic parameters can well predict the pyrolysis process. Pyrolysis of micron polyamide is a non‐spontaneous and endothermic reaction. Specific volatile products are determined by Fourier transform infrared and mass spectrometry. The chemical reactions that may occur during the pyrolysis have been inferred.

Insight into the pyrolysis and gas generation behavior of silicomanganese slag and assessing its foaming abilities in foam glass ceramic

This paper proposes a novel route for the utilization of silicomanganese slag in the preparation of high-temperature foam ceramic materials, grounded in the unique characteristics of the slag. The phase evolution and gas generation mechanisms of silicomanganese slag was systematically investigated using thermogravimetric mass spectrometry (TG-MS), thermodynamic simulation, X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy-dispersive spectroscopy (EDS). Foam glass ceramic with a density of 291 ± 8 kg/m3 and a compressive strength of 2.83 ± 0.07 MPa was prepared using silicomanganese slag as a foaming agent. This research indicated that manganese and sulfur in the silicomanganese slag are critical contributors to gas generation. Manganese in the slag oxidizes to dimanganese trioxide (Mn2O3) before reaching 1000 °C, and at temperatures between 1000 and 1200 °C, trivalent manganese (Mn3+) converts to divalent manganese (Mn2+) and enters the pyroxene crystal, releasing oxygen (O2). Sulfur in the slag, captured by divalent calcium (Ca2+), forms a more stable calcium sulfate (CaSO4) during heating and enriches the slag particle surface. As the temperature exceeds 1000 °C, Ca2+ gradually integrates into the pyroxene, prompting the release of sulfate decomposition products, forming sulfur dioxide (SO2) and O2. A small fraction of unreacted CaSO4 enters the glass phase, forming fibrous crystals that enhance the compressive strength of the foam glass-ceramic through fiber reinforcement. The outcomes of this work offer new insights into the high-value utilization of silicomanganese slag and enrich the understanding of gas generation mechanisms in Mn-based and S-based foaming agents.

Pyrolysis of plasticized films based on soy protein, denatured by different substances

Polymer films based on soy protein isolate (SPI) were obtained using the thermo-pressing method. Plasticizers and denaturing agents were added to ensure better the film-forming properties and reduce the fragility of the resulting materials. Glycerol, sorbitol and their mixture were used for plasticization, while solutions of alkali (potassium hydroxide), surfactants of natural origin (sodium coco sulfate) and reducing agent (sodium sulfite) were used for denaturation. By combining different types of plasticization and denaturation, a series of samples were obtained and compared with a sample based on raw soy protein. In addition to the obvious differences in the appearance of the films, the processes of their thermal degradation, studied by pyrolysis mass spectrometry, also differed significantly. In fact, unprocessed soy protein has the highest thermal stability with the temperature of the most intensive decomposition equal to 270 °С, which can decrease to 200 °С under the conditions of denaturation and plasticization. Despite the increase in the number of film components, the amount of volatile decomposition products decreases (from 86 to 32), as well as the molecular weight of the heaviest of them (from 169 to 74). This is a sign of a change in the mechanism of soy protein degradation due to denaturation and plasticization caused by transformations in its supramolecular structure, such as unfolding and extension of macrochains with increased availability of functional groups. The pyrolytic behavior of some protein samples plasticized with sorbitol is closest to that of untreated soy protein, which may indicate a lower plasticizing efficiency of sorbitol with longer molecules than glycerol. The interpretation of the recorded mass spectra of the volatile pyrolysis products showed that the thermal degradation of protein materials is dominated by processes such as decarboxylation, dehydration, deamination and decarbonylation, while in the presence of plasticizers the splitting of their own molecules also becomes dominant. The characteristic mass spectra of protein films denatured by surfactants also contain ionic fragments of relatively high molecular weight, probably derived from sodium coco sulfate molecules.