Predicting gas evolution during steam gasification of chars derived from biomass pyrolysis

Low temperature pyrolysis of centralized and decentralized sewage sludges: Biochar production, per-and polyfluoroalkyl substances (PFAS) reduction and release.

Biomass-derived biochar as a precursor for graphene-like carbon materials via slow pyrolysis: A review

Optimization of liquid smoke production from coconut shell waste via slow pyrolysis in a fixed-bed reactor using FCCD-RSM

Feasibility study of co-mixing biomass with additive waste materials for biochar high calorific value of co-firing applications

Biomass is recognized as a renewable energy source with high potential. Its pyrolysis produces biogas, a storable bio-oil and char. Although bio-oil also contains a variety of C, H, O components; it also contains value-added chemicals such as levoglucosan. Pyrolysis proceeds at moderate temperatures (300 to 400 °C) temperatures in a slow mode, or at >> 500 °C is a fast mode. At low temperatures and long residence times, slow pyrolysis fosters the production of pyrolysis gas and biochar. At a very fast heating rate and a short residence time in the reactor, the pyrolysis mode changes to the so-called fast mode, where liquid pyrolysis products are higher than in slow pyrolysis mode. After condensation, a brown, acid, and low viscosity bio-oil is obtained. The research will assess the slow pyrolysis system, through its conversions, product distribution and process economics in view of a maximum gas and char production, both considered advantageous toward for energy-carrier storage and peak-time electricity generation.

A replacement of the non-renewable type of peat with circular ones entails the resolution of the so-called nutrient-salinity conflict of pyrolyzed agro-wastes. This study aims to assess physicochemical profiles, toxicity mechanisms, and critical safety levels of biochars obtained from shrimp shells (SS), pineapple peels (PP), and eggshells (ES). Biochars were produced through slow pyrolysis at 500°C and characterized for macronutrients, electrical conductivity (EC), pH, and elemental composition. Agronomic validation was conducted using three indicator crops (Capsicum annuum, Solanum lycopersicum, and Cucumis sativus) to determine safe substitution levels in peat-reduced substrates. Slow pyrolysis concentrated essential macronutrients (SS: 15.5% P₂O₅; PP: 15.2% K₂O) but also produced very high EC (39.5 and 31.9 dS m⁻1) and highly alkaline matrices (pH 10.0-12.0). Elemental profiling described a marine salinity complex in SS biochar with extreme salinity coupled with cadmium (4.35mgkg⁻1) exceeding international safety limits. Salinity-induced osmotic stress was the main physiological limitation on plant survival. A maximum substitution rate of 10% (v/v) was identified for high-salinity biochars (SS, PP). Although biomass remained lower than the peat control due to nitrogen dilution and residual osmotic stress, this level prevented plant mortality and moderated alkalinity through natural buffering capacity. Low-salinity ES biochar functioned as a calcitic buffer at 30% (v/v). These results provide practical safety thresholds for using agro-waste biochars in peat-reduced substrates, balancing nutrient supply, salinity stress, and buffering capacity for sustainable plant growth.

PAHs formation and distribution: Mechanistic insights from pyrolysis of chlorine-rich waste polyvinyl dichloride.

The production ofbiochar through slow pyrolysis undercontrolledconditions represents a promising strategy for converting agro-industrialresidues into functional materials for environmental remediation.This approach contributes to sustainability by providing an alternativeto the disposal of waste with no specific application. In this context,the present study aimed to evaluate the interaction of cassava peel-derivedbiochars, produced at different pyrolysis temperatures (350 °C,450 °C, 500 °C, and 550 °C), with lead (PbII) ionsand to investigate their efficiency in removing this contaminant underenvironmentally relevant conditions. The biochars were characterizedby elemental analysis. To assess their performance in Pb­(II) removal,adsorption isotherms, equilibrium time, complexation capacity, andin situ application tests were conducted. Elemental analysis revealeda clear influence of the pyrolysis temperature on the physicochemicalproperties of the biochars. Among the adsorption isotherm models tested,the Langmuir model provided the best fit to the experimental data,indicating that Pb­(II) adsorption occurs on a homogeneous monolayersurface without interactions between adsorbed ions. The maximum adsorptioncapacity for Pb­(II) reached 37.27 mg g–1, a relativelyhigh value compared to similar studies, and was obtained with biocharproduced at the highest pyrolysis temperature (550 °C). The complexationcapacity ranged from 37.60 to 39.11 mg g–1. In thein situ application, the biochar produced at 550 °C using 200mg exhibited the highest Pb­(II) retention (15.56 mg g–1). Overall, cassava peel-derived biochars demonstrate considerablepotential as low-cost, environmentally friendly materials for mitigatingPb­(II) contamination in aquatic environments.

Biomass pyrolysis has emerged as a flexible platform for converting low-value residues into higher-value energy carriers (bio-oil, biochar and gas) and carbon-rich materials, with realistic potential for negative emissions when biochar is deployed in long-lived sinks. Over the last decade, three developments have driven the field forward: first, a finer mechanistic understanding of devolatilization and secondary reactions; second, major improvements in analytical techniques for characterising feedstocks and products; and third, more rigorous techno-economic and life-cycle assessments that place pyrolysis in a broader energy-system context. Recent experimental work on forestry and agro-industrial residues has clarified how biomass composition, ash chemistry and operating conditions jointly govern product yields, energy content and stability. Parallel advances in GC×GC–MS, high-resolution mass spectrometry, NMR and thermogravimetric methods have shifted the discussion from bulk “bio-oil” and “char” to families of molecules and well-defined structural domains, which can be deliberately targeted by reactor and catalyst design. Data-driven models, ranging from support vector machines applied to TGA curves to ANFIS and random forests for yield prediction, are now accurate enough to support process screening and multi-objective optimisation. At the system level, commercial fast pyrolysis biorefineries report overall useful energy efficiencies on the order of 80–86%, while slow pyrolysis configurations centred on biochar can be economically viable when carbon storage and co-products are appropriately valued. Thermodynamic analyses confirm that indirect gasification via fast-pyrolysis oil sacrifices some energy and exergy efficiency relative to direct solid-biomass gasification but may offer logistical and integration advantages. This review synthesises recent work on (i) feedstock and process characterisation; (ii) state-of-the-art analytical methods for bio-oil, biochar and gas; (iii) modelling and machine-learning tools; and (iv) energy-system deployment of pyrolysis products. Throughout, the emphasis is on how characterisation and modelling inform concrete design choices and on the trade-offs that arise when pyrolysis is considered as part of a wider decarbonisation portfolio. By integrating laboratory-scale characterisation with system-level modelling, this review aligns biomass pyrolysis with several United Nations Sustainable Development Goals (SDGs). The optimisation of thermochemical conversion pathways for forestry and agro-industrial residues directly supports SDG 7 (Affordable and Clean Energy) by enhancing the efficiency of bio-oil and syngas production. Furthermore, the deployment of biochar as a stable carbon sink for negative emissions and soil amendment addresses SDG 13 (Climate Action) and SDG 15 (Life on Land). By converting low-value waste streams into high-value energy carriers and chemicals within a circular bioeconomy framework, the research further contributes to SDG 12 (Responsible Consumption and Production) and SDG 9 (Industry, Innovation and Infrastructure).

Biochar production represents a sustainable approach to biomass management and soil fertility improvement. This study synthesised biochar from corn cob residue through slow pyrolysis using a low-cost, custom-designed metallic kiln and evaluated its key physico-chemical properties. The produced biochar exhibited an alkaline pH (7.53), moderate electrical conductivity (1.35 dS m-1) and a high total organic carbon content (70.1 %). Nutrient analysis revealed appreciable levels of macro- and micronutrients (N: 1.48 %, P: 0.42 %, K: 2.30 %, S: 0.27 %, Zn: 5.3 ppm and Cu: 5.3 ppm), along with a favorable C:N ratio (47:36). Its high porosity (73 %) and substantial surface area (926 m² g-1) suggest strong potential for improving soil structure, nutrient retention and long-term carbon sequestration. The pyrolysis process achieved a biochar recovery of 47 %, indicating efficient carbon retention and minimal biomass loss. The study hypothesised that controlled slow pyrolysis of corn cob residue using an affordable, decentralised kiln could produce biochar with desirable agronomic properties and economic viability. This is particularly important because corn cob waste is abundant and often burned, contributing to pollution, while escalating fertiliser costs demand cost-effective nutrient alternatives. The results confirm that simple, low-cost reactor systems can convert agricultural waste into high-quality biochar with physicochemical properties comparable to those produced using advanced technologies. The findings highlight opportunities for decentralised biochar production, low-cost fertiliser substitution and carbon-credit generation. With the global biochar market valued at USD 0.76–2.2 billion, corn cob-based biochar holds strong commercial potential. Future work should include field-scale evaluation, quality standardisation and techno-economic assessments utilising digital twins and AI-based modeling to optimise its agricultural and environmental applications.

The improper disposal of end-of-life tires poses significant environmental challenges due to their petroleum-based composition and slow degradation, while simultaneously representing an underutilized energy resource. This study investigates the slow pyrolysis of shredded waste tires in a fixed-bed electrically heated reactor to evaluate the production and fuel properties of gaseous, liquid, and solid fractions. Experiments were conducted with 100 g samples under nitrogen at final temperatures of 400, 500, and 600 °C, with residence times of 40, 25, and 10 min, respectively. Higher temperatures promoted gas formation, increasing yields from 27% to 32% and achieving a maximum lower heating value of 30.54 MJ m−3 at 600 °C, with enhanced H2 and CH4 contents. Solid yields decreased slightly (41% to 37%), while char maintained stable heating values (~29 MJ kg−1). Liquid yields remained near 33% and showed high calorific values (~41 MJ kg−1), densities of 700–770 kg m−3, low acidity, low ash content, and increased viscosity at higher temperatures. Energy conversion efficiency reached 74.4% at 500 °C. The integrated evaluation of all fractions under identical conditions highlights fixed-bed pyrolysis as a promising pathway for waste-tire valorization and decentralized fuel production.

The valorization of anaerobic digestates through slow pyrolysis offers a sustainable pathway for agricultural systems. This study assessed the effects of digestate type (swine, cattle, and dairy) and pyrolysis temperature (400, 500, and 600°C) on biochar properties and evaluated their impact on maize (Zea mays) fodder grown under hydroponic-like soilless conditions. Thirty-six treatments were evaluated in a factorial design combining digestate source, temperature, and application rate (0-6.25g per container). Biochar from dairy digestate (BDST) pyrolyzed at 500°C exhibited the most favorable characteristics, with high carbon content (60.4%), low electrical conductivity (≈ 916 µS cm-1), and improved water and nutrient retention. At an application rate of 6.25g per container, BDST-500 also achieved the highest SPAD and dry mass values. In contrast, swine- and cattle-derived biochars presented higher ash and salinity, reducing their agronomic performance. Multivariate analysis indicated that digestate type was the main determinant of plant physiological performance, beyond the individual effects of pyrolysis temperature and application rate. Overall, dairy-derived biochar demonstrates strong potential as a functional amendment for hydroponic fodder systems and as a tool to advance circular bioeconomy practices.

Activation entropy of degradation of cross-linked polymer in catalyzed and uncatalyzed slow pyrolysis

This work explores the influence of two preparation methods, solvent casting and melt mixing, on the structure-property relationships of poly-L-lactic acid (PLLA) composites reinforced with char derived from different waste feedstocks. Three types of char were produced by slow pyrolysis at 550 °C: olive pruning waste biochar (OC), tyre-derived char (TC), and a 1:1 hybrid co-pyrolyzed char (OTC). Each filler was incorporated into PLLA at 1 and 2 wt.% loadings, and the resulting composites were characterized through physicochemical, thermal, mechanical, and electrical analyses. Raman, FTIR, and SEM analyses revealed distinct structural characteristics for each char, with the hybrid OTC exhibiting the highest structural order due to synergistic interactions during co-pyrolysis. The preparation method affected filler dispersion. Solvent-cast films displayed micrometric agglomerates and interfacial voids, whereas melt mixing ensured a more homogeneous distribution. Thermal characterization showed that char addition did not significantly alter the crystallization or melting behavior of PLLA, although melt-mixed samples exhibited restricted chain mobility. Mechanical tests revealed opposing effects of filler loading depending on processing: in solvent-cast materials, stiffness increased while strength remained nearly unaffected, whereas melt-mixed composites exhibited reduced modulus and strength, attributed to the disruption of the denser amorphous structure generated during melt processing. Electrical resistivity depended on the preparation method. Solvent-cast composites remained insulating, while melt mixing, with OTC at 2 wt.%, led to a resistivity drop (down to 0.02 × 1015 Ω·cm from 20 × 1015 Ω·cm for unfilled PLLA), although all materials remained within the insulating regime. Overall, this work provides insight into the role of sustainable char fillers in improving the performance of PLLA composites and highlights the interplay between processing method and material properties. The developed PLLA/char composites are promising candidates for applications in flexible electronics, sensors, and antistatic components, as well as in lightweight structural materials and energy devices.

A comprehensive characterization of tender coconut waste biochar produced through slow pyrolysis at different temperatures and heating rates

As the global population continues to rise, the generation of organic waste has significantly increased, despite low recycling rates. Among these wastes, fruit peels are commonly produced in large quantities. When fruit peels end up in landfills, they decompose, releasing emissions that can harm the environment. This study investigates the incorporation of banana peel biochar into concrete at varying sand replacements (5%, 10%, and 15%) and its effects on blended concrete composites' mechanical, physicochemical, and microstructural properties. The banana peel biochar was prepared through slow pyrolysis over six hours. Various analytical techniques were employed to characterise the biochar and its incorporation into concrete composites, including X-ray fluorescence, laser diffraction particle size analysis, X-ray diffraction, scanning electron microscopy, Carbon, Hydrogen, Nitrogen, and Sulphur analysis, and compressive-strength tests. The results indicate a 24.7% increase in the 7-day compressive strength of concrete incorporating 15% banana peel biochar as a sand replacement, compared to the control mix. This improvement suggests an accelerated hydration process and enhanced early-age strength. By 28 days, the compressive strength of all biochar-blended mixes was comparable to that of the control sample. This suggests that the main advantage of adding biochar is its ability to promote early strength gain. Additionally, the increase in normalised actual calcium hydroxide observed in the thermogravimetric analysis (TGA) at 28 days confirms accelerated cement hydration as the biochar content increases. • Banana peel biochar used as a sustainable sand replacement material in concrete production • Biochar accelerates cement hydration improving early strength • 24.7% early-age strength enhancement achieved at 15% biochar sand replacement

Waste crosslinked polyethylene (XLPE) can be a source of valuable hydrocarbons for further use. XLPE is widely used material which – unlike polyethylene – is very stable both chemically and mechanically. There-fore, its waste is difficult to process. A very promising way is slow pyrolysis catalyzed by ruthenium (Ru/Al2O3) which allows the conversion of waste into hydrocarbons via degradation of rigid chemical structure of cross-linked material. High hydrocarbon yields (91–92 wt.%) were achieved by slow pyrolysis without or with cata-lyst, but significant changes in the composition of resulting gas and oil were found with the Ru/Al₂O₃ catalyst. To reveal the possibilities of using this catalyst for processing of XLPE at a relatively lower final temperature (max. 480 °C, mostly 450–470 °C), an effect of the catalyst on degradation of XLPE structure and related rheological properties of XLPE melt was investigated. It was found that the activation energy of degradation decreases significantly in the presence of the catalyst and the degradation is greatly facilitated by Ru/Al2O3 at the defect sites of the XLPE structure (the tertiary carbons). By the catalyst, the torque for XLPE melt and the its shear viscosity are significantly reduced already at 250 °C. Thus, Ru/Al2O3 catalyst, even in very small amounts (1 wt.% Ru), significantly promotes the degradation of XLPE structure and reduces the solid pyrolysis residue. This finding greatly facilitates the processing of waste XLPE. The catalytic mechanism of action of Ru is outlined and the equations for the XLPE cleavage are given. The main product of processing, pyrolysis oil, can be used as a clean heating fuel, or oil for further use, or a source of solvents, liquid and solid hydrocarbons, especially paraffin.

Abstract. Hassan MAM, El-Sayed MEA, Abdallah MH, Gahlan AA. 2026. Characterization of acid-modified corn cob biochar for potential alkaline soil remediation. Asian J Agric 10 (1): g100125. https://doi.org/10.13057/asianjagric/g100125. Biochar (BC), derived from agricultural residues, is increasingly recognized for its capacity to enhance soil quality and contribute to the reduction of greenhouse gas emissions. Conversely, the typically high pH of BC limits its effectiveness in alkaline soils, such as those prevalent in Egypt. In order to overcome this difficulty, this study produced BC from corncobs via slow pyrolysis at 350°C for an hour at a heating rate of 10°C min-1. Its surface was modified with phosphoric acid, sulfuric acid, and humic acid, resulting in PBC, SBC, and HBC, respectively. Biochar and its modified forms were characterized by elemental analysis, Fourier Transform Infrared (FTIR) spectroscopy, X-Ray Diffraction (XRD), Brunauer-Emmett-Teller (BET) surface area, and Field-Emission Scanning Electron Microscopy (FE-SEM). The findings revealed that the pH of MBCs has decreased from 7.87 to 7.13 compared to 8.32 for BC. This adjustment can improve the compatibility of BC with alkaline soils. In addition, all Modified Biochars (MBCs) have higher surface areas of 83.73, 79.60, and 75.23 m²/g for HBC, SBC, and PBC, respectively, compared to 73.41 m²/g for unmodified BC. Pores of MBCs were microporous, while BC is composed of mesopores. The elemental analysis demonstrated that the MBCs have more functional groups than BC, which improves BC properties and applications. Overall, the MBCs demonstrated enhanced specific physicochemical properties, particularly in pH adjustment, functional groups, surface areas, and pore size distribution following the order: HBC>SBC>PBC>BC, suggesting their potential as effective ameliorants for alkaline soils. These results highlight the benefits of agricultural waste and tailoring BC properties to address the specific needs of alkaline soils, while also contributing incidentally to carbon sequestration as a beneficial secondary outcome.

For the efficient utilization of pharmaceutical waste resources, tuber biochar (TB) and herbal biochar (HB) were prepared via oxygen-limited slow pyrolysis at 500 °C for 3 h, using residues from tuber-type Xinsuning capsule and herbal-type Changyanning pill as the raw materials, respectively. The biochars were characterized by FESEM, BET, XRD and FTIR, and the feedstock physico-chemical properties were measured by common agricultural chemical analysis methods. The results revealed that both biochars possessed a high percentage of elemental O, a honeycomb-like porous structure, and surfaces enriched with functional groups such as hydroxyl, carboxyl, and carbonyl. HB exhibited a larger specific surface area and pore volume than TB, making it a more recommended carbon material. The chemical compositions of the pyrolysis by-products were systematically analyzed. The bio-oils were rich in ketones, alkanes, alcohols, olefins, fatty acids, phenols, and heterocyclic compounds, identifying them as potential sources of liquid fuels and chemical feedstocks. The most abundant components in bio-oils from tuber and herbal biomass were "Ethanol, 2,2-diethoxy-" (7.25%) and "Phosphonic acid, (p-hydroxyphenyl)-" (10.52%), respectively. The syngas has a low hydrogen content, is mainly pyrolysis off-gas and therefore has a limited application potential. Furthermore, the environmental application for Cd²⁺ removal was critically evaluated. Adsorption isotherms demonstrated high adsorption capacities, well-described by the Freundlich model (R² ≥ 0.99), indicating multilayer adsorption. The maximum adsorption capacities for TB and HB were 188.89 and 186.67 mg·g⁻¹, respectively. Kinetic studies revealed that the adsorption process followed the Elovich model (R² ≥ 0.98), suggesting heterogeneous diffusion, with HB achieving a higher equilibrium capacity (85.67 mg·g⁻¹) than TB (73.70 mg·g⁻¹). In conclusion, pyrolysis, particularly using herbal biomass, presents a promising strategy for the comprehensive and high-value utilization of waste pharmaceutical residues, simultaneously producing effective adsorbents for heavy metal remediation and valuable bio-energy products.