Search Results (256)

Pyrolysis of 24 samples of foliage from three U.S. regions with frequent wildland fires (Southeastern U.S., northern Utah and Southern California) was studied in a fuel-rich flat-flame burner system at 765 °C (for Southeastern U.S. samples) and 725 °C (for northern Utah and Southern California species), with a heating rate of approximately 180 °C/s. These conditions were selected to mimic the conditions of wildland fires. Individual plant samples were introduced to the high temperature zone in a flat-flame burner and pyrolysis products were collected. Tar was extracted and later analyzed by GC/MS. Light gases were collected and analyzed by GC/TCD. The estimated range for the average yields of tar and light gases were 48 to 62 wt% and 18 to 31 wt%, respectively. Apart from Eastwood’s manzanita (Arctostaphylos glandulosa Eastw.), aromatics were the major constituents of tar. The variations in the concentrations of tar compounds likely resulted from differences in biomass composition and physical characteristics of the foliage. The four major components of light gases from pyrolysis (wt% basis) were CO, CO₂, CH₄ and H₂. Tar contributed more than 82% of the high heating value of volatiles. These data can be used to improve physical-based fire propagation models. Full article

This study develops a combustible material pyrolysis model capable of numerically predicting and analyzing ultra-fast fire scenarios. The model was subsequently applied to investigate fire behavior in industrial complex facilities. Based on a propolis model and a User-Defined Function (UDF), the proposed approach simulated the mass loss of specimens due to pyrolysis and combustion, and the results were compared with experimental data. A strong correlation confirmed the reliability of the model. Using this validated framework, flame propagation patterns under various fire scenarios were analyzed, providing a quantitative characterization of the thermal behavior and propagation mechanisms of ultra-fast fires in industrial complexes. Full article

Lead (Pb(II)) contamination in water poses severe environmental and health risks due to its toxicity and persistence. This study compares almond shell-derived biochars produced by slow pyrolysis (SP) and microwave pyrolysis (MW), with and without KOH activation, focusing on structural properties and Pb(II) adsorption performance. Biochars were characterized by proximate and elemental analysis, BET surface area, FTIR spectroscopy, and adsorption experiments including pH dependence, kinetics, and equilibrium isotherms. Non-activated SP exhibited the highest surface area (S_BET = 693 m²·g⁻¹), pronounced mesoporosity (≈73% of total pore volume), and the largest observed equilibrium capacities. KOH activation increased surface hydroxyl content but degraded textural properties; in MW samples, it induced severe pore collapse. Given the very fast uptake, kinetic modeling was treated cautiously: for non-activated biochars, Elovich adequately captured the time-course trend, whereas activated samples returned non-physical kinetic constants (e.g., negative k₂) likely due to high post-adsorption pH (>11) and probable Pb(OH)₂ precipitation. Equilibrium data (fitted over 50–500 mg·L⁻¹) were better captured by the Freundlich and Redlich–Peterson models, indicating a mixed adsorption behaviour with contributions from heterogeneous site distribution and site-specific interactions. Optimal Pb(II) removal occurred at pH 4, with no measurable leaching from the biochar matrix. Overall, non-activated SP biochar is the most effective, sustainable and low-cost option among the tested materials for Pb(II) removal from water, avoiding aggressive chemical activation while maximizing adsorption performance. Full article

The thermal processing of walnut shells was investigated through pyrolysis within the range of 100–650 °C, highlighting the influence of thermal engineering parameters on biomass conversion. The resulting biochar was subjected to chemical activation with phosphoric acid, and its physicochemical properties were evaluated to determine how thermal processing enhances its performance as a cathode material for lithium–sulfur (Li–S) batteries. This approach underscores the role of thermal engineering in bridging biomass valorization with energy storage technologies. In parallel, the gaseous fraction generated during walnut shell fast pyrolysis was collected, and for the first time, volatile organic compounds (VOCs) under atmospheric conditions were identified using solid-phase microextraction (SPME) coupled with gas chromatography–mass spectrometry (GC–MS). The composition of the VOCs was characterized, quantifying aromatic compounds, hydrocarbons, furans, and oxygenated species. This study further linked the thermal decomposition pathways of these compounds to their atmospheric implications by estimating tropospheric lifetimes and evaluating their potential contributions to air quality degradation at the local, regional, and global scales. Full article

The increasing demand for renewable energy has intensified research on lignocellulosic biomass pyrolysis as a versatile route for sustainable energy and resource recovery. This study provides a comparative overview of main pyrolysis regimes (slow, intermediate, fast, and flash), emphasizing operational parameters, typical product yields, and technological readiness levels (TRLs). Reactor configurations, including fixed-bed, fluidized-bed, rotary kiln, auger, and microwave-assisted systems, are analyzed in terms of design, advantages, limitations, and TRL status. Key process parameters, such as temperature, heating rate, vapor residence time, reaction atmosphere, and catalyst type, critically influence the yields and properties of biochar, bio-oil, and syngas. Increased temperatures and fast heating rates favor liquid and gas production, whereas lower temperatures and longer residence times enhance biochar yield and carbon content. CO₂ and H₂O atmospheres modify product distribution, with CO₂ increasing gas formation and biochar surface area and steam enhancing bio-oil yield at the expense of solid carbon. Catalytic pyrolysis improves selectivity toward target products, though trade-offs exist between char and oil yields depending on feedstock and catalyst choice. These insights underscore the interdependent effects of process parameters and reactor design, highlighting opportunities for optimizing pyrolysis pathways for energy recovery, material valorization, and sustainable bioeconomy applications. Full article

Polygonum multiflorum (PM) residues represent an underutilized biomass resource, with pyrolysis offering a promising route for valorizing its biomass into valuable chemicals and biochar. This study elucidated how the intrinsic physicochemical properties of PM residue governed its pyrolysis kinetics, thermodynamics, mechanisms, and product distribution across varying thermal regimes (slow pyrolysis at 20 °C/min vs. fast pyrolysis). The primary devolatilization stage (174–680 °C) dominated the pyrolysis process. Applying three model-free kinetic approaches (FWO, KAS, Starink) over 0.1 < α < 0.7, this study observed a dramatic shift in apparent activation energy (219.7–354.7 kJ/mol). Major gaseous pyrolysis products identified included alcohols, aldehydes, ketones, acids, aromatic hydrocarbons, phenolics, CO, and CO₂. Ketones constituted the predominant fraction (23.80%), followed by acids (18.18%), phenolic derivatives (18.18%), N-containing compounds (14.28%), and furans (4.54%). The findings of this study contribute significant theoretical understanding and practical solutions for the effective pyrolysis and resource recovery from Polygonum multiflorum processing byproducts. Full article

The application of fluidized bed reactors to biomass fast pyrolysis is regarded as a promising technology for enabling high-value utilization of biomass. This work established a three-dimensional numerical model of an industrial-scale fluidized bed reactor for biomass catalytic pyrolysis, employing the multiphase particle-in-cell method (MP-PIC) and coupling catalytic pyrolysis kinetics. Primary gas flow rate and biomass–catalyst injection modes were optimized to further improve the performance of the reactor. The model received additional validation from experimental data, primarily to ensure prediction accuracy. The results revealed that an optimal primary gas flow rate of 4 kg/s achieved a peak catalytic efficiency of 71.3%. Using maximum high-quality liquid fuels and adopting a relatively dispersed inlet mode with opposite jetting for biomass and catalyst promoted uniform particle distribution and thermal homogeneity in the dense phase zone, further increasing the catalytic efficiency to 75.6%. With the integration of the multiphase particle-in-cell (MP-PIC) method with catalytic pyrolysis kinetics at the industrial-scale, this work could provide theoretical guidance for designing fluidized bed catalytic pyrolysis reactors and optimizing biomass catalytic pyrolysis processes. Full article

The world’s energy demand increases daily, fostering the search for renewable fuels to reconcile production needs with environmental sustainability. To prevent the severe atmospheric impact of fossil fuels, reducing greenhouse gas emissions is both essential and urgent, reinforcing the necessity of developing and adopting renewable fuel alternatives. Therefore, this work aimed to produce bio-oil through sugarcane bagasse fast pyrolysis. The methodology is based on fast pyrolysis operation in a fluidized bed reactor (pilot plant) as a thermochemical method for bio-oil production. This research required the conditioning of the raw material for system feeding, along with optimizing key variables, operating temperature, airflow, and sugarcane bagasse feed rate, to achieve improved yields compared to previous studies conducted in this pilot plant. The sugarcane bagasse was conditioned through drying and milling, followed by characterization using various analytical methods, including calorific value, thermogravimetric analysis (TGA), particle size analysis by laser diffraction (Mastersizer—MS), and ultimate analysis (determining carbon, hydrogen, nitrogen, sulfur, and oxygen by difference). The bio-oil produced showed promising yield results, with a maximum estimated value of 61.64%. Fourier Transform Infrared Spectroscopy (FT-IR) analysis confirmed the presence of aromatic compounds, as well as ester, ether, carboxylic acid, ketone, and alcohol functional groups. Full article

This study investigates the processing of shea nut shells (SNSs), an abundant agricultural waste, into porous activated carbon for supercapacitor electrodes through a two-stage thermal treatment involving pyrolysis and physical activation with CO₂ and steam. The aim was to develop sustainable, high-performance electrode materials while addressing waste management. Carbonization followed by activation yielded 16.5% (CO₂) and 11.3% (steam) activation yields, with total yields of 4.3% and 2.9%, respectively. CO₂ activation produced carbon (AC_CO₂) with a specific surface area (S_BET) of 1528 m² g⁻¹ and a total pore volume of 0.72 cm³ g⁻¹, a graphitization degree (I_D/I_G = 1.0), and low charge transfer resistance (9.05 Ω), delivering a specific capacitance of 47.5 F g⁻¹ at 0.5 A g⁻¹, an energy density of 9.5 Wh kg⁻¹ at 299 W kg⁻¹, and a fast discharge time of 2.10 s, ideal for power-intensive applications. Steam activation yielded carbon (AC_H₂O) with a higher specific surface area (1842 m² g⁻¹) and pore volume (1.57 cm³ g⁻¹), achieving a superior specific capacitance of 102.2 F g⁻¹ at 0.5 A g⁻¹ and a power density of 204 W kg⁻¹ at 9.2 Wh kg⁻¹, suited for energy storage. AC_CO₂ also exhibited exceptional cyclic stability (90% retention after 10,000 cycles). These findings demonstrate SNS-derived activated carbon as a versatile, eco-friendly material, with CO₂ activation optimizing power delivery and steam activation enhancing energy capacity, offering tailored solutions for supercapacitor applications and sustainable waste utilization. Full article

Addressing the urgent need to decarbonise aviation and valorise agricultural waste, this paper investigates the production of Sustainable Aviation Fuel (SAF) from corn stover. A preliminary evaluation based on a literature review indicates that among various conversion technologies, fast pyrolysis (FP) emerged as the most promising option, offering the highest fuel yield (22.5%) among various pathways, a competitive potential minimum fuel selling price (MFSP) of 1.78 USD/L, and significant greenhouse gas savings of up to 76%. Leveraging Aspen Plus simulation, SAF production via FP was rigorously designed and optimised, focusing on the heat integration strategy within the process to minimise utility consumption and ultimately the total cost. Consequently, the produced fuel exceeded the American Society for Testing and Materials (ASTM) limit for the final boiling point, rendering it unsuitable as a standalone jet fuel. Nevertheless, it achieves regulatory compliance when blended at a rate of up to 10% with conventional jet fuel, marking a practical route for early adoption. Energy optimisation through pinch analysis integrated four hot–cold stream pairs, eliminating external heating, reducing cooling needs by 55%, and improving sustainability and efficiency. Economic analysis revealed that while heat integration slashed utility costs by 84%, the MFSP only decreased slightly from 2.35 USD/L to 2.29 USD/L due to unchanging material costs. Sensitivity analysis confirmed that hydrogen, catalyst, and feedstock pricing are the most influential variables, suggesting targeted reductions could push the MFSP below 2 USD/L. In summary, this work underscores the technical and economic viability of corn stover-derived SAF, providing a promising pathway for sustainable aviation and waste valorisation. While current limitations restrict fuel quality during full substitution, the results affirm the feasibility of SAF blending and present a scalable, low-carbon pathway for future development. Full article

The Mixed Ombrophyllous Forest (MOF), inserted in the Atlantic Forest biome, is of great ecological value, with deficient management strategies. In this context, sustainable management helps to promote the regeneration and growth of individual trees and control others, while maintaining the natural forest structure. This study therefore aimed to discuss opportunities and limitations of biochar, produced from two species from the MOF, which are currently only utilized to a limited extent in the study area in southern Brazil. A slow pyrolysis process at a lab scale was designed, biochar was produced, and key properties were analyzed from Hovenia dulcis Thunb. (chosen as an invasive species) and Mimosa scabrella Benth. (chosen as a native, fast-growing species), including branches and stems. The results showed that branches of Mimosa scabrella (BMS) had the highest biochar yield (30.32 ± 0.3%) and the highest electrical conductivity (415.08 ± 24.75 mS cm⁻¹). Stems of Mimosa scabrella (SMS) showed the highest higher heating value (HHV—31.76 ± 0.01 MJ kg⁻¹), lower heating value (LHV—31.03 ± 0.01 MJ kg⁻¹), and energy yield (49.1%), while the branches of Hovenia dulcis (BHD) showed the lowest values. For the elemental analysis, SMS showed the best results, with the highest amount of fixed carbon (78.62 ± 0.22%) and carbon content (85.87 ± 0.083%), and consequently the lowest amount of ash (3.52 ± 0.08%). BHD showed a better water-holding capacity (303.26 ± 15.21%) and higher pH value (7.65 ± 0.14). The investigations conducted on the biochar from both species indicate a strong suitability of these woods for producing high-quality biochar. Full article

The CO₂ capture from flue gas using biomass-derived porous carbons presents an environmentally friendly and sustainable strategy for mitigating carbon emissions. However, the conventional fabrication of porous carbons often relies on highly corrosive activating agents like KOH and ZnCl₂, posing environmental and safety concerns. To address this challenge, in the present work sodium metaborate tetrahydrate (NaBO₂·4H₂O) has been utilized as an alternative, eco-friendly activating agent for the first time. Moreover, a water chestnut shell (WCS) is used as a sustainable precursor for boron-doped porous carbons with varied microporosity and boron concentration. It was found out that pyrolysis temperature significantly determines the textural features, elemental composition, and CO₂ adsorption capacity. With a narrow micropore volume of 0.27 cm³/g and a boron concentration of 0.79 at.% the representative adsorbent presents the maximum CO₂ adsorption (2.51 mmol/g at 25 °C, 1 bar) and a CO₂/N₂ selectivity of 18 in a 10:90 (v/v) ratio. Last but not least, the as-prepared B-doped carbon adsorbent possesses a remarkable cyclic stability over five cycles, fast kinetics (95% equilibrium in 6.5 min), a modest isosteric heat of adsorption (22–39 kJ/mol), and a dynamic capacity of 0.80 mmol/g under simulated flue gas conditions. This study serves as a valuable reference for the fabrication of B-doped carbons using an environmentally benign activating agent for CO₂ adsorption application. Full article

This study aims to investigate the oxidative pyrolysis of biomass volatiles with a particular focus on the formation of liquid products. Furfural, hydroxyacetone, and 3,4-dimethoxybenzaldehyde were chosen as volatile model compounds. The impacts of the oxygen equivalence ratio (ER, 0–15%) and temperature (400–500 °C) on the product composition and distribution were examined using a two-stage quartz-tube reactor. The results showed that volatile pyrolysis was limited at the lower temperature of 400 °C even with oxygen introduction, while it could be significantly promoted at 500 °C as illustrated by the observed great decrease in the GC-MS peak areas of the volatile compounds especially under an oxidative atmosphere. For instance, the peak area of 3,4-dimethoxybenzaldehyde at 500 °C under an ER of 4% was only ~9% of that at 400 °C. Oxygen introduction enhanced the volatile decomposition with the formation of mainly permanent gases (although not given in the study) rather than liquid products, but distinct impacts were obtained for varied volatile compounds possibly due to their different chemical structures and autoignition temperatures. From the perspective of liquid product formation, furfural would undergo the cleavage of C-C/C-O bonds to form linear intermediates and subsequent aromatization to generate aromatics (benzene and benzofuran). The presence of oxygen could enhance the oxidative destruction of the C-C/C-O bonds and the removal of O from the molecules to form simple aromatics such as benzene, phenol, and toluene. Hydroxyacetone mainly underwent C-C/C-O cleavage that was further enhanced in the presence of oxygen; the resultant intermediates would recombine to generate acetoin and 2,3-pentanedione. A higher ER would directly oxidize the alcoholic hydroxyl group (-OH) into an aldehyde group (-CHO) to form methyl glyoxal, while 3,4-dimethoxybenzaldehyde mainly underwent cleavage and recombination of bonds connected with the benzene ring including aldehyde group (-CHO), C_Ar-O, C_Methoxy-O bonds, thus forming 1,2-dimethoxybenzene, toluene, and 3-hydroxybenzadehyde. This study provides more fundamental insights into the homogeneous oxidation of volatiles during the oxidative fast pyrolysis of biomass, facilitating the deployment of this technology. Full article

With the rapid growth of the global population, increasing per capita energy demands, and waste generation, the need for innovative strategies to mitigate greenhouse gas emissions and effective waste management has become paramount. Pyrolysis, a thermochemical conversion process, facilitates the transformation of diverse biomass feedstocks, including agricultural biomass, forestry waste, and other carbonaceous wastes, into valuable biofuels such as bio-oil, biochar, and producer gas. The article reviews the benefits of pyrolysis as an effective and scalable technique for biofuel production from waste biomass. The review describes the different types of pyrolysis processes, such as slow, intermediate, fast, and catalytic, focusing on the effects of process parameters like temperature, heating rate, and residence time on biofuel yields and properties. The review also highlights the configurations and operating principles of different reactors used for pyrolysis, such as fixed bed, fluidized bed, entrained flow, plasma system, and microwaves. The review examines the factors affecting reactor performance, including energy consumption and feedstock attributes while highlighting the necessity of optimizing these systems to improve sustainability and economic feasibility in pyrolysis processes. The diverse value-added applications of biochar, bio-oil, and producer gas obtained from biomass pyrolysis are also discussed. Full article

The removal of Cr(VI) from wastewater is a crucial task due to its high toxicity. In this study, slumgum-originated biochar materials were obtained by three different methods: high-temperature pyrolysis with H₃PO₄ or CO₂ and the high-temperature treatment of CO₂-activated slumgum-originated biochar in an Ar atmosphere. The obtained materials were subjected to physicochemical characterization (nitrogen adsorption/desorption isotherms, CHN elemental analysis, Fourier transform infrared spectroscopy, and X-ray photoelectron spectroscopy) and tested for their adsorption properties towards Cr(VI) ions. The solution pH, contact time, and effects of the Cr(VI) concentration on Cr(VI) adsorption onto biochar materials were studied. The kinetics and isotherm experimental data were best fitted to the Elovich (R² = 0.848) and Freundlich (R² = 0.965) theoretical models for H₃PO₄-modified biochar. The highest adsorption capacity (45.0 mg g⁻¹) for Cr(VI) was obtained for biochar modified with H₃PO₄. It was stated that the relatively fast rate of Cr(VI) adsorption onto this biochar (equilibrium reached within 120 min) is related to its mesoporous structure. The mechanism of Cr(VI) adsorption onto H₃PO₄-modified biochar was studied in detail. The obtained biochar was successfully applied for efficient Cr(VI) removal from wastewater originating from spent bricks with a low biochar dosage (4.0 g L⁻¹). Full article