Biochar Properties Research Articles

Impact of carbonization reactor compartment size on groundnut (Arachis hypogaea) shell biochar properties

Abstract This study investigates the impact of low-temperature top-lit updraft reactor chamber size on GNSBC yield and properties. For this study, the volumes of carbonization chamber (2,364, 2,013, 1,468, and 970 cm3) in a biomass-fueled TLUD biomass gasifier were varied, and the resulting biochar was analyzed using SEM, EDX, and FTIR. The novelty of this work lies in its investigation of the unexplored impact of carbonization reactor compartment size on groundnut shell biochar properties and yield, driven by the need to optimize biochar production efficiency and support sustainable waste management practices. The results showed that carbonization chamber size variation significantly affected GNSBC yield, with an initial increase followed by diminishing returns. An increase in the carbonization compartment size led to decreased carbonization duration, increased carbonization temperature, increased porosity, and decreased oxygen content. SEM analysis revealed consistent amorphous and multi-layered morphological features across BC samples, while EDX analysis confirmed high carbon content in the samples. FTIR spectroscopy confirmed the presence of oxygenated functional groups suitable for pollutant adsorption, supporting GNSBC’s role in environmental remediation and industrial processes. This research contributes to optimizing biochar production efficiency, advancing circular economy goals, and sustainable waste management practices.

The electrochemical mechanism of biochar for mediating the product ratio of N2O/(N2O + N2) in the denitrification process

The biochar electrochemical properties and surface functional groups significantly impact N2O production and reduction during denitrification process. However, its effects on N2O emissions during the denitrification process and its electrochemical mechanisms remain unclear. The study examined the impact of pristine and oxidized biochar combined with two types of nitrogen fertilizers on the N2O/(N2O + N2) ratio and N2O emissions in an incubation experiment with seven treatments: (1) CK (no application of chemical fertilizer); (2) N1 (applying (NH4)2SO4); (3) N1B ((NH4)2SO4 + pristine biochar); (4) N1BO ((NH4)2SO4 + oxidized biochar); (5) N2 (applying KNO3); (6) N2B (KNO3 + pristine biochar); (7) N2BO (KNO3 + oxidized biochar). The study found that in comparison with applying nitrogen fertilizer alone, combining pristine biochar decreased soil N2O concentration by 7.1 %–85.8 %, while combining oxidized biochar increased it by 15.7 %–125.6 %. Applying pristine biochar reduced N2O/(N2O + N2) ratio by 10.4 %–86.2 %, whereas applying oxidized biochar increased it by 12.9 %–121.6 %. The application of pristine biochar increased the nosZ gene abundance and decreased the (nirS + nirK)/nosZ ratio, which contributed to reducing N2O to N2. Compared with oxidized biochar, the oxygen-containing functional groups of pristine biochar decreased by 46.6 %, and it possessed a higher specific surface area (23.01 m2 g−1) and electrical conductivity (0.003 mS cm−1). The correlation analysis showed that DOC and inorganic nitrogen were the key environmental factors affecting N2O emissions. Additionally, the electrical conductivity, specific capacitance, and oxygen-containing functional groups of the biochar were identified as the main factors driving N2O emissions. The SEM analysis suggested that the indirect influence of biochar electrochemical properties on N2O emissions was greater than its direct influence. Our work provides fresh perspectives on reducing soil N2O emissions and establishes a theoretical foundation for the subsequent preparation of biochar materials with enhanced N2O reduction capabilities.

Feedstock type and pyrolysis temperature of rosemary wastes in a fixed-bed reactor affect the characteristics and application potentials of the bio-chars

Rosemary waste was used as a precursor to produce biochar by slow pyrolysis, examining the influence of feedstock type (leaves or stems) and pyrolysis temperature on biochar properties. The structural, thermal, morphological and physicochemical characteristics of the original feedstocks and biochars were analyzed by XRD, FTIR, SEM, DTA/TGA and EA (CHNSO). The study revealed differences in the chemical composition of rosemary leaves and stems. Leaves showed higher levels of hemicellulose and extractive, while stems contained more cellulose and lignin. Biochar yields from stems are higher than those from leaves, and both decrease as pyrolysis temperature rises from 400 to 900°C. The density increases with increasing pyrolysis temperature, that of leaf biochars is greater. Stem biochars had a higher surface electronegativity than leaf biochars. Two pyrolysis temperature ranges have been determined. At T < 700°C, most of the hydrolyzable functional groups in the feedstock were retained in the biochars. Leaf biochar leachates have very high electrical conductivities compared to stem biochars and feedstocks, indicating significant salt content. At T ≥ 700°C, stem biochars have greater chemical stability to oxidation (average = 106.9 %) than leaf biochars (average = 100.6 %). Stems biochars, prepared at T <700°C, can be better valorized in carbon storage as a long-term C sink or replaces fossil carbon in industrial manufacturing, it can also be better valorized in the agricultural sector.

Peanut shell biochar for Rhodamine B removal: Efficiency, desorption, and reusability

A high-performance and affordable peanut shell-derived biochar was employed for the efficient removal of Rhodamine B (RhB) from aqueous solutions. The properties of peanut shell biochar (PSB) were investigated through Fourier transform infrared (FTIR) spectroscopy and Brunauer–Emmett–Teller surface area measurements. The FTIR analysis revealed numerous active sites and functional groups for the binding of dye molecules, while the BET surface area was determined to be 351.11 m2g-1. Four different isotherms and kinetic models were applied to determine the equilibrium adsorption of RhB, and the results indicated that the Freundlich isotherm was the most appropriate model. A maximum dye removal rate of 94.0% occurred at a pH of 3 with an adsorbent dose of 0.325 g L−1. The prepared adsorbent showed excellent sorbent behaviour and can be reused multiple times after regeneration, with the surface area decreasing from 351.11 m2g-1 to 140.13 m2g-1 after the third cycle. The negative Gibbs free energy ΔGo at all applied temperatures suggested that spontaneous adsorption occurred and RhB adsorption on the PSB was found exothermic, as evidenced by the negative value of ΔHo. The regenerated PSB can be utilized as an efficient, environmentally friendly, and cost-effective sorbent for the removal of dyes at temperatures lower than ambient temperature, providing both technical and financial advantages for sustainable environmental management.

Predictive Machine Learning Model to Assess the Adsorption Efficiency of Biochar-Heavy Metals for Effective Remediation of Soil-Plant Environment.

Biochar is crucial for agricultural output and plays a significant role in effectively eliminating heavy metals (HMs) from the soil, which is essential for maintaining a soil-plant environment. This work aimed to assess machine learning models to analyze the impact of soil parameters on the transformation of HMs in biochar-soil-plant environments, considering the intricate non-linear relationships involved. A total of 211 datasets from pot or field experiments were evaluated. Fourteen factors were taken into account to assess the efficiency and bioavailability of HM-biochar amendment immobilization. Four predictive models, namely linear regression (LR), partial least squares (PLS), support vector regression (SVR), and random forest (RF), were compared to predict the immobilization efficiency of biochar-HM. The findings revealed that the RF model was created using 5-fold cross-validation, which exhibited a more reliable prediction performance. The results indicated that soil features accounted for 79.7% of the absorption of HM by crops, followed by biochar properties at 17.1% and crop properties at 3.2%. The main elements that influenced the result have been determined as the characteristics of the soil (including the presence of different HM species and the amount of clay) and the quantity and attributes of the biochar (such as the temperature at which it was produced by pyrolysis). Furthermore, the RF model was further developed to predict bioaccumulation factors (BAF) and variations in crop uptake (CCU). The R2 values were found to be 0.7338 and 0.6997, respectively. Thus, machine learning (ML) models could be useful in understanding the behavior of HMs in soil-plant ecosystems by employing biochar additions.

Enhancing torrefaction process efficiency for biochar production from filter cake residue in the sugar industry

The torrefaction process is a promising technique for enhancing the quality of solid biomass fuels. This study investigates the effects of torrefaction on biochar produced from filter cake residue, a byproduct of the sugar industry. The primary objectives were to evaluate the impact of process parameters on biochar properties and identify optimal conditions for maximizing the higher heating value (HHV). Filter cake residue was subjected to torrefaction at temperatures ranging from 220-340°C under an inert atmosphere. The influence of particle size (20, 60, and 100 mesh), nitrogen flow rate (20-30 ml/min), temperature (220-340°C), and residence time (30-90 min) on biochar properties was examined using response surface methodology. Proximate analysis revealed that torrefaction significantly reduced moisture, volatile matter, and ash content while increasing fixed carbon content. The maximum HHV of 21.9571 MJ/kg was achieved at a particle size of 20 mesh, nitrogen flow rate of 25 ml/min, temperature of 340°C, and residence time of 60 min. The experimental results agreed with predicted values from the developed models, with an average error of 3.64%. Optimal torrefaction conditions were determined to be a particle size of 21.77 mesh, nitrogen flow rate of 22.50 ml/min, temperature of 311.13°C, and residence time of 42.58 min, yielding a maximum HHV of 18.4853 MJ/kg. These findings demonstrate the potential of torrefaction for upgrading filter cake residue into a high-quality solid biofuel, providing a sustainable solution for waste utilization in the sugar industry.

Biochar from Co-Pyrolyzed Municipal Sewage Sludge (MSS): Part 2: Biochar Characterization and Application in the Remediation of Heavy Metal-Contaminated Soils.

The disposal of municipal sewage sludge (MSS) from wastewater treatment plants poses a major environmental challenge due to the presence of inorganic and organic pollutants. Co-pyrolysis, in which MSS is thermally decomposed in combination with biomass feedstocks, has proven to be a promising method to immobilize inorganic pollutants, reduce the content of organic pollutants, reduce the toxicity of biochar and improve biochar's physical and chemical properties. This part of the review systematically examines the effects of various co-substrates on the physical and chemical properties of MSS biochar. This review also addresses the effects of the pyrolysis conditions (temperature and mixing ratio) on the content and stability of the emerging pollutants in biochar. Finally, this review summarizes the results of recent studies to provide an overview of the current status of the application of MSS biochar from pyrolysis and co-pyrolysis for the remediation of HM-contaminated soils. This includes consideration of the soil and heavy metal types, experimental conditions, and the efficiency of HM immobilization. This review provides a comprehensive analysis of the potential of MSS biochar for environmental sustainability and offers insights into future research directions for optimizing biochar applications in soil remediation.

Investigating the properties and agronomic benefits of onion peel and chicken feather-derived biochars

Biochar production from unconventional biomass, specifically onion peel (OP) and chicken feathers (CF), was investigated in this study. Two distinct biochars were produced by doping each biomass with the other, with the aim of exploring the synergistic effects of different feedstock combinations on biochar properties. The biochar production process was conducted using a retort heating method and characterized using several techniques. A yield of 36 % was obtained for OP-doped biochar (OP92CF8-BC) and 23 % for CF-doped biochar (F92OP8-BC). Fourier Transform Infrared Spectroscopy analysis revealed characteristic functional groups from cellulose, hemicellulose, and lignin in OP92CF8-BC, while CF92OP8-BC displayed keratin-related peaks. Scanning Electron Microscopy imaging showed surface morphology differences, with OP92CF8-BC exhibiting a rougher and more porous structure compared to CF92OP8-BC. Energy-Dispersive X-ray Spectroscopy analysis confirmed the elemental composition, with OP92CF8-BC having higher carbon, calcium, and sulfur contents and CF92OP8-BC having higher nitrogen and oxygen contents. The biochar had specific surface areas of 342.4 and 200.80 m2/g for OP92CF8-BC and CF92OP8-BC, respectively. According to the results, using biochar treatments-more especially, CF92OP8-BC-can significantly enhance cob weight. This could be good for agricultural productivity. These findings highlight the influence of feedstock composition on the properties of biochar and provide insights for its potential applications in soil amendment and pollutant removal.

The Potential Significance of Microwave-Assisted Catalytic Pyrolysis for Valuable Bio-Products Driven from Albizia Tree

The objective of this study is to investigate the feasibility of Na2CO3 and ZSM-5 as catalysts in the microwave pyrolysis of Albizia branches. An evaluation was conducted to determine the influence of power applied, experimental time, particle size, and catalysis type and ratio on the quality and quantity of pyrolysis products. Established methods such as GC-MS, FTIR, HHV, SEM, EDX, and BET were used to characterize the properties of bio-oil and biochar produced. The results demonstrated that using both catalyst types led to a substantial enhancement in biogas production. The improvement ranged from 5% to 41% with Na2CO3 and reached 45% with ZSM-5. At a lower power level of 300 W, the bio-oil yield augmented from 28% to 40% and 53% when using ZSM-5 and Na2CO3, respectively. The GC-MS analysis revealed that the utilizing of catalysts enhanced the levels of aromatic compounds, esters, and alcohols in bio-oil, along with an increase in the higher heating value (HHV) from 19.5 MJ/kg to 22 MJ/kg and 24.2 MJ/kg using Na2CO3 and ZSM-5, respectively. Moreover, the biochar's surface area and pore volume experienced a considerable rise, going from 0.5512 m2/g and 0.00011 cm3/g to a higher value of 115.2073 m2/g and 0.0774 cm3/g when treated with Na2CO3. The data indicated that both catalyst types enhanced the generation of CH4, and CO2 was lower with ZSM-5. The utilization of catalysts improves the quality of the biofuel produced and promotes the efficiency of the process in terms of energy consumption and processing time.

Mechanistic insight into the effects of interaction between biochar and soil with different properties on phenanthrene sorption

Soil composition varies considerably in nature, so it is vital to investigate the mechanism of the effect of various soil parameters on biochar sorption capacity. In this study, two biochars (W4 and W7) were derived from wheat straw at temperatures of 400 and 700 °C and were incubated with three different soils. Changes in biochar surface features by aging in the soils and the consequent impact on phenanthrene sorption were examined. The results showed that the effect of adding biochar on phenanthrene sorption capacity (Koc) varied by soil. When biochar was freshly mixed with soil, the Koc value in soil with higher clay content was more dramatically altered by biochar, which is due to clay particles adhering to the biochar surface. Moreover, the Koc value was significantly decreased by the addition of W4 but increased by the addition of W7 in general. After aging, most of the Koc value decreased. The greatest decrease in Koc value was observed in biochar and soil composed with the highest clay content for W4 (24–63%), as well as soil composed with the highest organic matter content for W7 (46–64%). This is because the surface polarity and micropores of biochar dropped the most rapidly in these mixes, resulting in a significant decrease in hydrophobic and pore-filling properties. The results revealed that the impact of biochar-soil interactions on phenanthrene sorption is related to not only biochar properties but also soil clay particles, soil organic matter content and pH. The findings of the study can be utilized to assess the efficacy of biochar application in soil remediation for various features.

Can Aqueous Na2SO4-Based Neutral Electrolyte Increase Energy Density of Monolithic Wood Biochar Electrode Supercapacitor?

The performance of supercapacitors is significantly influenced by both the nature and the concentration of the electrolyte employed. This study investigates the impact of a neutral electrolyte on the electrochemical properties of the maple-derived monolithic wood biochar (MWB)–sodium sulfate (Na2SO4) supercapacitor. The goal is to determine if a neutral electrolyte, in this case Na2SO4, can increase the supercapacitor energy density compared to a previous study employing a KOH electrolyte. Starting from examining the ion sizes and conductivities of salt species in KOH and Na2SO4 electrolytes, the difference in voltage window, measured specific capacitance, and resistance are discussed. By switching the electrolyte from 4 M KOH to 0.5/1 M Na2SO4, the voltage stability window was extended from 0.8 V to 1.4 V. For 1 M Na2SO4, the supercapacitor attains a specific capacitance of 46 F/g at 5 mA/g, accompanied by an energy density of 12.5 Wh/kg and a maximum power density of 300 W/kg. The MWB electrode, derived from naturally abundant wood, when combined with the non-toxic Na2SO4 electrolyte, offers an environmentally friendly and cost-effective energy storage solution. With a prolonged lifetime and minimal maintenance requirements, MWB-Na2SO4 supercapacitors emerge as a promising choice for diverse applications.

Insight into catalytic effects of alkali metal salts addition on bamboo and cellulose pyrolysis

Alkali metal compounds have vital influence on biomass pyrolysis conversion. In this study, cellulose, and bamboo catalytic pyrolysis with different alkali metal salts catalysts (KCl, K2SO4, K2CO3, NaCl, Na2SO4, and Na2CO3) were investigated in the fixed-bed reaction system. The effects of cations (K+ and Na+) and anions (Cl-, SO42−, and CO32-) on the evolution properties of biochar, bio-oil, and gas products were explored under both in-situ and ex-situ catalytic pyrolysis. Results showed that alkali metal salts facilitated the yields of biochar and gases at the expense of that of bio-oil. Alkali metal chloride and sulfate showed a weaker catalytic effect, while alkali metal carbonate greatly promoted the generation of gas products and increased the condensation degree of biochar. With the addition of K2CO3 and Na2CO3, cyclopentanones content was over 50% from cellulose catalytic pyrolysis, and phenols content (mainly alkylphenols) reached over 80% from bamboo catalytic pyrolysis. Moreover, solid-solid catalytic reactions with K2CO3 and Na2CO3 catalysts had an important role in strikingly promoting conversion of pyrolysis products, and the solid-solid and gas-solid catalytic reactions with alkali metal carbonate catalysts were stronger than those with alkali metal chloride and sulfate catalysts. Furthermore, the possible catalytic pyrolysis mechanism of alkali metal salts on biomass pyrolysis was proposed, which is important to the high-value utilization of biomass.

Progress of metal-loaded biochar-activated persulfate for degradation of emerging organic contaminants.

In recent years, studies on the degradation of emerging organic contaminants by sulfate radical (SO4-·) based advanced oxidation processes (SR-AOPs) have triggered increasing attention. Metal-loaded biochar (Me-BC) can effectively prevent the agglomeration and leaching of transition metals, and its good physicochemical properties and abundant active sites induce outstanding in activating persulfate (PS) for pollutant degradation, which is of great significance in the field of advanced oxidation. In this paper, we reviewed the preparation method and stability of Me-BC, the effect of metal loading on the physicochemical properties of biochar, the pathways of pollutant degradation by Me-BC-activated PS (including free radical pathways: SO4-·, hydroxyl radical (·OH), superoxide radicals (O2-·); non-free radical pathways: singlet oxygen (1O2), direct electron transfer), and discussed the activation of different active sites (including metal ions, persistent free radicals, oxygen-containing functional groups, defective structures, etc.) in the SR-AOPs system. Finally, the prospect was presented for the current research progress of Me-BC in SR-AOPs technology.

Improving biochar properties through liquid-phase exfoliation of onion peel biochar doped with chicken feathers

In recent decades, heightened environmental awareness has spurred a global push for innovative waste-to-wealth solutions. This study explores liquid-phase exfoliation as a strategy to enhance biochar properties. By doping onion peels and chicken feathers, hybrid biochar (HBC) was produced using a low-temperature co-carbonization system. Two exfoliation routes, the nitric acid and acetone routes, were compared with the un-exfoliated HBC through material characterization. Material characterization revealed distinct morphological features and a range of functional groups being introduced by exfoliation. It was also observed through the BET analysis that the HBC samples are mesoporous, with the exfoliated HBCs having an enhanced surface area and pore volume. Elemental analysis showcased HBC's fortification, highlighting potential applications such as adsorbents and soil amendments. This investigation shows the efficacy of liquid-phase exfoliation in enhancing biochar surface characteristics, opening avenues for diverse applications.

A review on utilization potential of functionalized biochar for the removal of antibiotics from water

Globally, water resources are facing serious threat owing to the increasing concentration of various emerging contaminants. Indiscriminately discarded and/or excreted antibiotics and their residues are one such emerging contaminants. Since long-term persistence of these residues in environment is responsible for developing antimicrobial (antibacterial) resistance in the organisms, their removal from water / wastewater is essential. Hence, scientists are attempting to evolve novel methods to encounter antibiotics and their residues in water. One such method is the adsorption of antibiotics onto a suitable matrix thereby reducing their concentration in water. Biochar has been proven to act as a suitable adsorbent for various contaminants; however, their removal efficiency remains a concern. Therefore, functionalization of biochar using various physical and chemical modifications, was developed as a technique that can help in efficient removal of antibiotics. Functionalization has been seen to improve the physical and chemical properties of biochar; such as, pore volume, pore diameter, surface morphology, surface functional groups, polarity, porosity etc. In this review, functionalized biochars have been explored to understand their efficacy and mechanism for the removal of antibiotics and their residues. The discussion includes biochar functionalization methods, impact of property modifications on the removal of antibiotic residues, and their removal mechanism. In addition, cost-effectiveness, economy of the adsorption process, and its environmental effects have also been dealt with.

Influence of varying aluminum-based combustion compartment sizes on groundnut shell biochar properties

The process variables during biochar production play a crucial role in determining its properties. Factors like temperature, heating rate, reactor configuration, and residence time can significantly impact biochar quality. The aim of this study is to determine the impact of reactor configuration on the yield and properties of groundnut shell biochar. For this investigation, the volumes of aluminum-based combustion compartments in a biomass-fueled TLUD biomass gasifier were varied, and the resulting biochar was analyzed using SEM, EDX, and FTIR. It was observed that the increase in the combustion chamber of the gasifier led to an increase in the amount of biomass fuel utilized in the system, which led to an increased reactor’s temperature and varied carbonization duration and yield. Elemental composition showed that an increase in reactor volume led to an increase in biochar carbon content and reduced silica content. The SEM analysis confirmed that decreasing the combustion compartment sizes increased porosity and roughness, as well as visible fissures and crevices on the biochar surface. FTIR analysis revealed similarities in functional groups, with many peaks appearing at higher wavenumbers as the combustion compartment sizes decreased. This study innovatively examines how varying aluminum-based combustion compartment sizes and biofuel mass affect groundnut shell biochar properties using a TLUD gasifier, emphasizing its significance for optimizing biochar production and advancing sustainable practices.

Machine learning modeling of the capacitive performance of N-doped porous biochar electrodes with experimental verification

N-doped porous biochar is considered as a promising carbon material for supercapacitor electrodes application. However, the intrinsic relations and effect mechanisms of the pore structure and N-doping to the capacitive performance are still inscrutable, giving rise to the challenges for enhancing the capacitive performance by regulating the physicochemical properties of N-doped biochar. In this study, various machine learning models were established to predict the specific capacitance of N-doped biochar electrodes based on the pore structure and N-doping properties. The effect mechanisms of pore structure and N-doping to the specific capacitance were also explored. Results showed that Random Forest model predicted the specific capacitance most accurately. The generalization performance of the model was verified to be quite well with our experiments. It is suggested that developing pore structure with abundant micropores plays more important role than N-doping in enhancing the specific capacitance. The optimal interval of each physiochemical property of N-doped biochar were also determined to maximize the specific capacitance. Furthermore, synergistic effects of pore structure and N-doping to the specific capacitance were revealed. This study provides a useful guideline for N-doped porous biochar production with the aim of capacitive performance enhancement.

Properties of biochars derived from different straw at 500℃ pyrolytic temperature: Implications for their use to improving acidic soil water retention

Climate change cause extreme weather effects with temperature increases and drops in humidity, such as drought and heatwaves, which will lead to more evaporation in arid and semi-arid lands. The application of biochar made from crop straw without burning to farmland can effectively improve the water retention capacity of soil. A testing program has been carried out in a climate simulation laboratory to study the effects of different straw biochars on the cracking and evaporation of soils due to drying. Biochar from wheat straw (WS), corn straw (CS) and rice straw (RS) is produced at a pyrolysis temperature of 500℃. Thermogravimetric analysis and elemental analysis are carried out to obtain the properties of the biochar. Five percent of WS, CS and RS biochar by weight is added to acidic soil. Digital camera and digital image processing technology are used to analyze the crack morphology of the samples during evaporation. The results indicate that the RS biochar has the highest ash content (32.5 %), CS biochar has the highest content of volatile solid (25.36 %) and WS biochar has the highest content of fixed carbon (55.38 %). Biochar can effectively improve the water retention capacity of soil. The final water contents of the WS, CS and RS biochar soil samples are 132.3 %, 101.0 %, and 20.7 % respectively higher than that of the soil without biochar. Moreover, biochar can effectively reduce the degree of soil cracking. The addition of WS, CS and RS biochar can reduce soil cracking by 9.21 %, 16.57 %, and 7.46 %, respectively. WS contains more total cellulose than CS and RS, so WS biochar is the best choice to improve soil water retention ability. Therefore, biochar technology helps to optimize soil water retention while avoiding environmental pollution from straw burning.

Microwave-assisted pyrolysis of biomass waste for production of high-quality biochar: Corn stover and hemp stem case studies

The efficient conversion of biomass waste into valuable products is a critical challenge in sustainable energy and environmental management. Microwave pyrolysis of hemp stem and corn stover was studied for producing biochar suitable for CO2 adsorption, catalysts, water treatment, and soil enhancement. The effects of microwave power and absorbent agents on maximum temperature, yields, and biochar properties were investigated. Elevated power (33–120 W/g) reduced yield (42–16 wt%, 38 to 16 wt%) but increased carbon content (67–78 wt%, 65 to 75 wt%), BET surface area (1.05–69.37 m2/g, 0.59–43.18 m2/g) for hemp stem and corn stover respectively. Microwave absorbents like graphite, activated carbon, and water improved heating and biochar quality. Activated carbon notably increased carbon content (76–82 % wt, 71–80 % wt) and surface area (6.59–91.99 m2/g, 9.99–50.51 m2/g) for hemp stem and corn stover respectively. CO2 adsorption highlighted biochar microstructure with pore sizes averaging around 1 nm for both biomass. These findings demonstrate the potential of microwave-assisted pyrolysis and the use of absorbent agents to produce high-quality biochar for various applications.

Intermediate pyrolysis of Ficus nitida wood in a fixed-bed reactor: effect of pyrolysis parameters on bio-oil and bio-char yields and properties

Intermediate pyrolysis of Ficus nitida wood in a fixed-bed reactor: effect of pyrolysis parameters on bio-oil and bio-char yields and properties