Biochar Samples Research Articles

Waste management of straw to manufacture biochar: An alternative reinforcing filler for natural rubber biocomposites

To achieve climate neutrality, alternative processes and materials should be proposed to replace those currently in use, which excessively burden the environment. Fossil fuels are non-renewable, and their resources are slowly being depleted, leading to increased prices.The aim of this work was to determine the potential of using agro-industrial residues in the form of oat straw for the production of biochar and its utilization as a filler in natural rubber biocomposites. The process of pyrolysis of plant material was used to obtain biochar with a high carbon content and a characteristic structure, which can affect selected rubber properties. The influence of the applied temperature of the pyrolysis process on the properties of the filler was determined. In this work, analysis techniques were used to enable the evaluation of both filler activity and specific properties of the final vulcanizates. The course of straw pyrolysis process, the carbon content in the fillers, and the size distribution of the bio-additive were examined. The structural, morphological, dispersion, processing, and functional properties of the compositions were examined. The reference in assessing the impact of the produced bio-additive on the properties of the product were composites filled with a commercial carbon black.The conducted research proved that the pyrolysis of straw at a temperature of 600°C was as effective as that carried out at a higher temperature, with comparable weight loss for both samples. The increase in torque was the highest in the case of biochar samples (torque gain 4,4-6,5 dNm), indicating greater intensity of the cross-linking process after the use of this type of additive. This was also confirmed by differential scanning calorimetry. Moreover, the obtained biocomposites were characterized by much higher strength parameters (tensile strength 18,3-21,3MPa) than conventional composites. Unfortunately, vulcanizates containing biochar as a filler exhibited poor resistance to thermo-oxidative aging (aging factor 0,24-0,54).

Assessment of the adsorption capacity of biochar samples obtained from agricultural biomasses

The study consists of adsorption tests on two samples of biochar, obtained from rice husk and coconut fiber biochar biomass, as well as a sample of charcarbon, both prepared under different conditions: macerated and non-macerated; impregnation with and without HCl and H3PO4; and washing or not with deionized water after impregnation. The test was performed in duplicate, for 30 min, with masses of 0.5 g; 0.3 g; 0.1 g; and 0.05 g, and an initial methylene blue concentration of 0.01 g∙L-1. The study was carried out with the objective of identifying, in the analyzed samples, the material with the greatest adsorption capacity of methylene blue dye, comparing the data with commercial activated carbon. The results identified removal above 70 % in both types of biochars, suggesting the feasibility of application as an adsorbent material to remove organic contaminants. The sample that most closely resembled the removal percentage of commercial activated carbon (98.84 %) was that of biochar obtained from coconut fibers, with 91.71 %. Thus, the research showed promise in studying the application and valorization of biochars, produced from agro-industrial waste, in adsorption processes.

A Thermogravimetric Analysis of Biomass Conversion to Biochar: Experimental and Kinetic Modeling

This study investigates the pyrolytic decomposition of apple and potato peel waste using thermogravimetric analysis (TGA). In addition, using Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS), the influence of pyrolysis temperature on the physicochemical characteristics and structural properties of biochar was studied. The degradation of biomass samples was studied between 25 °C and 800 °C. Although apple and potato peel decomposition present similar thermogravimetric profiles, there are some differences that can be evidenced from DTG curves. Potato peel showed one degradation peak in the range 205–375 °C with 50% weight loss; meanwhile, the apple peel exhibited two stages: one with a maximum at around 220 °C and about 38% weight loss caused by degradation of simple carbohydrates and a second peak between 280 °C and 380 °C with a maximum at 330 °C, having a weight loss of approximately 24%, attributed to cellulose degradation. To gain more insight into the phenomena involved in biomass conversion, the kinetics of the reaction were analyzed using thermal data collected in non-isothermal conditions with a constant heating rate of 5, 10, 20, or 30 °C /min. The kinetic analysis for each decomposed biomass (apple and potato) was carried out based on single-step and multi-step type techniques by combining the Arrhenius form of the decomposition rate constant with the mass action law. The multi-step approaches provided further insight into the degradation mechanisms for the whole range of the decomposition temperatures. The effect of temperature on biomass waste structure showed that the surface morphologies and surface functional groups of both samples are influenced by the pyrolysis temperature. A higher pyrolysis temperature of 800 °C results in the disappearance of the bands characteristic of the hydroxyl, aliphatic, ether, and ester functional groups, characteristic of a porous surface with increased adsorption capacity. Therefore, this study concludes that biomass waste samples (apple and potato) can produce high yields of biochar and are a potential ecological basis for a sustainable approach. The preliminary adsorption tests show a reasonably good nitrate removal capacity for our biochar samples.

Relationship of CO2 adsorption performance and physicochemical property of biochar prepared by different types of biomass waste

The physicochemical property of biochar prepared by biomass waste is crucial for CO2 adsorption performance. However, the quantified relationship between the physicochemical property and CO2 adsorption capacity for biochar is still unclear. In this study, biochar samples with different physicochemical properties were prepared from six representative biomass of sewage sludge, chicken manure, apple and prickly ash branch, corn and rice straw. The quantitative investigation was conducted and the relationship between the physicochemical properties and CO2 adsorption capacity of biochar was analysed using Pearson correlation analysis method. The results showed that the biochar prepared from prickly ash branch at 800 °C pyrolysis exhibited a better CO2 adsorption capacity of 154.44 mg/g and larger specific surface area of 160.83 m2/g, compared with other biochars. According to the quantitative data about physicochemical properties of twenty-four kinds of biochar samples, the correlations between CO2 adsorption capacity and microcrystalline structure, surface functional groups, nitrogen content and specific surface area were obtained. The CO2 adsorption capacity showed a significant positive correlation with the specific surface area (SBET), stacking height of aromatic layers (Lc), number of aromatic layers (N) and nitrogen content, and the correlation order was SBET >N >Lc = nitrogen content. Moreover, the CO2 adsorption capacity showed a negative correlation with diameter of aromatic planes (La), CO, O-H and index of aromaticity (Aal/Aar), and the order of correlation was CO > O-H >La >Aal/Aar. The effect mechanism of physicochemical properties on CO2 adsorption of biochar was that microcrystalline structure had an influence on CO2 adsorption by van der Waals force, and nitrogen, oxygen-containing functional groups, and so on by Lewis acid-base interaction and hydrogen bonding.

Activated Carbon and Biochar Derived from Sargassum sp. Applied in Polyurethane-Based Materials Development.

Activated carbon (AC) and biochar (BC) are porous materials with large surface areas and widely used in environmental and industrial applications. In this study, different types of AC and BC samples were produced from Sargassum sp. by a chemical activation and pyrolysis process and compared to commercial activated carbon samples. All samples were characterized using various techniques to understand their structure and functionalities. The metal content of the samples was characterized by using an inductively coupled optical emission spectrometer (ICP-OES). A toxicity test was applied to investigate the effect of AC/BC on organisms, where Sinapis alba seed and Escherichia coli bacteria-based toxicity tests were used. The results revealed that the samples did not negatively affect these two organisms. Thus, it is safe to use them in various applications. Therefore, the samples were tested as fillers in polyurethane composites and, thus, polyurethane-AC/BC samples were prepared. The amounts of AC/BC mixed into the polyurethane formulation were 1%, 2%, and 3%. Mechanical and acoustic properties of these composites were analyzed, showing that by adding the AC/BC to the system an increase in the compression strength for all the samples was achieved. A similar effect of the AC/BC was noticed in the acoustic measurements, where adding AC/BC enhanced the sound adsorption coefficient (α) for all composite materials.

Biochar mitigation potential in Norway estimated by IPCC Tier 1 and Tier 2 methods

Biochar is a recalcitrant carbon-rich solid produced by pyrolysis of organic residues, and its application to soil is considered a promising approach to mitigate climate change, as biochar resists decomposition to readily contributes to soil carbon (C) sequestration. The IPCC provides a basis for future national-scale accounting of the changes in soil C stocks following biochar application to cropland soils. The IPCC Tier 1 approach for biochar is based on fixed emission factors to estimate biochar C sequestration. In contrast, the Tier 2 approach allows countries to use local emission factors and climate data to calculate the contribution of biochar to soil C sequestration. Accurate accounting of biochar C sequestration is essential for ensuring the credibility of C offsetting projects, as well as providing incentives for implementing biochar in C credit schemes, calling for comparative analyses of the different biochar Tier approaches. Here we retrieved biochar samples from local producers and measured their H/Corg to estimate the persistence of biochar in Norwegian croplands post application. Various feedstocks were considered, including forest residues, woody wastes, manure, sludge, and straw. For all biochar samples, the 100-year stable C fraction was calculated at ≥ 0.945, thus exceeding the default Tier 1 value (0.8). Biochar sourced from woody- and forestry residues had a Corg content above the default Tier 1 value (0.77). Based on this and data about national feedstock supplies, we compared the theoretical potential of biochar soil C sequestration to mitigate climate change in Norway, using the IPCC Tier 1 and Tier 2 approaches. Biochar C sequestration in soil was calculated at 0.79 Tg CO2-eq yr−1 and 0.92 to 0.96 Tg CO2-eq yr−1, respectively for the Tier 1 and Tier 2 approaches, thus, underlining that the choice of IPCC Tier approach can have a large impact on the estimated mitigation potential of biochar.

The Effect of Biochar Particle Size on the Leaching of Organic Molecules and Macro- and Microelements

Biochar is a carbon-rich material that has recently received attention due to its increasing agronomical potential. The agricultural utilization of biochar relates to its potential to act in the soil as a soil conditioner; nevertheless, complex information on the direct dependence of biochar’s physical properties (texture, particle size) and corresponding leaching and availability of organic molecules (e.g., the polycyclic and heterocyclic organic compounds) and inorganic mineral salts (based on micro- and macroelements) is still inconsistent. Multi-elemental analysis by using inductively coupled plasma atomic emission spectroscopy (ICP-OES) was used to assess the information on the contents and availability of macro- and microelements in studied commercial biochar samples. The results showed a statistically significant indirect relation between an increase in the size fraction of biochar and the content of aqueous-extractable K and Na and the direct relation with the aqueous-extractable Ca, Mg, and P. Compared to the macroelements, the detected contents of aqueous-extractable microelements were almost three orders lower, and the dependence on fraction size was not consistent or statistically significant. In addition, gas chromatography (GC) coupled with mass spectroscopy (MS) was further used to reveal the concentrations of available polycyclic aromatic and heterocyclic compounds in biochar samples. The detected concentrations of these types of organic compounds were far below the certified limits, and a statistically significant indirect correlation with particle size was also observed for all the studied biochar samples. The proposed methodological concept could provide the necessary insights into the description of biochar mineral content and its connection to biochar texture, the physicochemical properties, and the potential of biochar to release nutrients into the soil. These findings could help in the further assessment of biochar as a soil conditioner in modern agriculture.

Adsorption of dibenzofuran by modified biochar derived from microwave gasification: Impact factors and adsorption mechanism

Dioxins, emanating from the waste incineration, constitutes an organic pollutant that poses considerable risks to the human health and environment. In this study, the corn straw char (CSC) and oak char (OC) derived from the electric heating or microwave gasification, and the coconut-shell activated carbon (AC) are employed as absorbents for the adsorption of dibenzofuran (DBF, dioxins model compound). Characterization techniques, including BET, X-ray CT, SEM-EDS, FTIR, and XPS, are performed to identify the DBF adsorption mechanism on the biochar. The results show that the biochar prepared by the microwave gasification has a more well-developed pore structure than that of the electric heating gasification. The higher porosity (16.94 %) and lower mineral content (1.75 %) are responsible for the effective adsorption of DBF onto AC. The adsorption capacity of CSC is proportional to the modified concentration of KOH. It is mainly ascribed to the decrement of carboxyl and lactone groups and the enhancement of alkaline functional groups on the biochar surface, which augments the hydrophobicity and π–π electron donor–acceptor (EDA) interaction. Instead, DBF adsorption capacity on the biochar is adversely affected by the HNO3 modification. For all biochar samples, the corresponding maximum adsorption ratios are AC (87.11 %) > KOH-modified CSC (77.14 %) > unmodified CSC (49.11 %) > unmodified OC (39.70 %) > HNO3-modified CSC (36.09 %). The adsorption mechanisms of DBF on the gasified biochar encompass the pore filling, hydrophobicity, and π–π EDA interaction. A desirable adsorption capacity of DBF on the biochar prepared by the microwave gasification is attainable through augmenting the specific surface area while diminishing the oxygen-containing groups of the surface simultaneously.

Unlocking Nature’s Potential: Modelling Acacia melanoxylon as a Renewable Resource for Bio-Oil Production through Thermochemical Liquefaction

This study is focused on the modelling of the production of bio-oil by thermochemical liquefaction. Species Acacia melanoxylon was used as the source of biomass, the standard chemical 2-Ethylhexanol (2-EHEX) was used as solvent, p-Toluenesulfonic acid (pTSA) was used as the catalyst, and acetone was used for the washing process. This procedure consisted of a moderate acid-catalysed liquefaction process and was applied at 3 different temperatures to determine the proper model: 100, 135, and 170 °C, and at 30-, 115-, and 200-min periods with 0.5%, 5.25%, and 10% (m/m) catalyst concentrations of overall mass. Optimized results showed a bio-oil yield of 83.29% and an HHV of 34.31 MJ/kg. A central composite face-centred (CCF) design was applied to the liquefaction reaction optimization. Reaction time, reaction temperature, as well as catalyst concentration, were chosen as independent variables. The resulting model exhibited very good results, with a highly adjusted R-squared (1.000). The liquefied products and biochar samples were characterized by Fourier-transformed infrared (FTIR) and thermogravimetric analysis (TGA); scanning electron microscopy (SEM) was also performed. The results show that invasive species such as acacia may have very good potential to generate biofuels and utilize lignocellulosic biomass in different ways. Additionally, using acacia as feedstock for bio-oil liquefaction will allow the valorisation of woody biomass and prevent forest fires as well. Besides, this process may provide a chance to control the invasive species in the forests, reduce the effect of forest fires, and produce bio-oil as a renewable energy.

Influence of pyrolysis time on removal of heavy metals using biochar derived from macroalgal biomass (Oedogonium sp.)

In this study, pyrolysis was performed at different times to convert Oedogonium biomass into biochar. The physicochemical properties show that the pyrolysis time significantly impacts structural and morphological changes in biochar samples. The influence of pyrolysis time on the removal of multiple heavy metals was investigated. Owing to the presence of abundant functional groups, inorganic minerals and porous nature, biochar obtained from a 40 min pyrolysis time showed higher removal efficiency of heavy metals compared to biochars pyrolyzed at 20 mins and 60 mins even with higher concentrations of metal ions. The maximum adsorption capacity was observed 9.33, 10.74, 322.58, 13.70 and 9.11 mg/g with the biochar prepared at the pyrolysis time of 40 mins for Co, Ni, Cu, Zn and Cd, respectively. The adsorption isotherm is well fitted with the Langmuir adsorption model for heavy metals adsorption, and the kinetic study is well-defined by a pseudo second-order model.

Oxidative pyrolysis for enhanced-CO2 adsorption capacity in biosolid-derived biochar

The study conducts the adsorption kinetic analysis of biosolid-derived biochar produced from pyrolysis and oxidative pyrolysis. The adsorption kinetic analysis is performed at three different temperatures. The characteristics of the adsorption and diffusion mechanisms are evaluated by applying adsorption kinetic models and diffusion mechanism models. The pseudo-first-order model (PFO) and the pseudo-second-order model (PSO) reveal that the CO2 adsorption process of the biosolid can be categorised as physisorption with activation energy below 40 kJ/mol. The CO2 adsorption capacities of the biochar produced at 700 °C, 800 °C, and 900 °C are 6.3, 7.9, and 6.4 mg/g at 45 °C, respectively. In contrast, the biochar produced from oxidative pyrolysis shows a CO2 adsorption capacity of 7.5 mg/g at 45 °C. Film and intraparticle diffusions are primary rate-limiting factors of the adsorption process. The biochar samples maintain 84–85 % of their adsorption capacities after five cyclic tests. The present study demonstrates the CO2 adsorption capacity of biosolid-derived biochar produced from different conditions of pyrolysis, providing an energy-efficient and sustainable solution to CO2 adsorption with solid adsorbents.

Producing Animal Originated Charcoal Production and its Characterization Analysis Compared to Brown Coal

On place research was conducted on a farm where cows were fed by a mixture of traditional pasturing and feed supply. Pyrolysis was carried out directly on the farm to produce a ready-to-use biochar product. The product of biochar after pyrolysis was mixed with an organic adhesive dopant into 100 gram processed products for commercial use. This processed product was analyzed by elemental analysis, proximate analysis, TGA, FTIR and electron paramagnetic resonance spectroscopy. Data from these analyses was compared to those of brown coal Aduunchuluun, which is originally from the same place as the bio waste. Heavy elements content in biochar such as silicon, aluminium, sulphur, etc. is significantly less than compared to the brown coal. TGA and DTG analysis on the biochar product showed a total weight loss of 0.87%, where nearly 0.26% of the moisture was released in the temperature interval of 30 - 300°C, 0.46% of devolatilization occurred in 300 - 600°C, and 0.15% of mass loss in combustion reaction in 600 - 700°C. The residue after the thermal processing was minimal and consisted of hemicellulose and cellulose after volatilization. From the FTIR analysis, we see a disappearance of hydroxyl group vibration around 3400 cm-1 and carbonyl C=O stretching 1733 cm-1 from the biochar product compared to brown coal. The aromatic absorption near 1600 cm-1 is shifted to 1392 cm-1 in biochar. EPR spectrum of bio product consists of two lines, broad and narrow in the resonance field of ≈ 3500 Gs. Corresponding g-factor of narrow line and broad line 2.0022. It is calculated the spin numbers in biochar sample, that is compared to brown coal related data.

Exploring the impact of rice husk biochar on oxidative mechanisms and salt stress tolerance in lettuce plants

Salt stress, which impairs plant growth and induces oxidative stress, presents a major challenge in agriculture. In response, biochar has emerged as a promising soil amendment, capable of enhancing plants’ stress tolerance mechanisms. This study investigated the impact of rice husk biochar (RBC), derived from rice husks, on enhancing salt stress tolerance in lettuce plants grown under greenhouse conditions. Molecular and chemical characterization of the biochar samples was performed using Scanning Electron Microscopy (SEM) and Raman spectroscopy. Salinity reduced the fresh and dry weights of the plants from 25.0 g plant−1 and 1.83 g plant−1 to 20.4 g plant−1 and 1.42 g plant−1, respectively. The application of RBC recovered the growth decline caused by salinity, increasing the fresh and dry weights of the plants to 28.1 g plant−1 and 1.83 g plant−1, respectively. While the concentrations of sodium and chloride in plants decreased with RBC application, potassium and silicon concentrations significantly increased. As a result of salt stress, hydrogen peroxide levels (H2O2) increased in plant tissues, and a decrease in H2O2 levels was observed with an increase in superoxide dismutase, catalase, and ascorbate peroxidase activities. Consequently, RBC proved to be effective in enhancing salt tolerance in lettuce plants. In conclusion, while RBC demonstrates significant potential for enhancing salt tolerance, its successful application depends on several factors such as biochar dosage, application method, soil type, and plant species, underscoring the need for further research to elucidate the mechanisms at play and optimize its use for sustainable soil management in saline conditions.

Molten salt-assisted microporous biochar derived from poplar sawdust as an efficient cathode matrix for Li-Se battery applications

This study focuses on the employment of molten salts (ZnCl2-KCl-NaCl and K2CO3-Na2CO3-Li2CO3) as alternative activating agents to prepare porous biochars, which serve as efficient cathode matrices for Li-Se battery applications. Poplar sawdust was employed as the biomass feedstock, mixed with molten salts in a 1:5 mass ratio, and then pyrolyzed at a low temperature of 500 ℃ to obtain PB-Cl and PB-Carb, respectively. The obtained porous biochar samples were investigated, and processed for selenium (Se) loading using the melt-diffusion technique, resulting in composites named Se@PB-Cl and Se@PB-Carb, respectively. The composite Se@PB-Cl, with a BET surface area of 787.11 m2 g−1 and a t-plot micropores area of 691.65 m2 g−1, displayed a Se loading of 41.86 % and exhibited enhanced electrochemical performance. At 0.5 C, Se@PB-Cl after 100 cycles delivered a specific capacity of 617.03 mAh g−1. After 500 cycles, at 1 C a specific capacity of 505.9 mAh g−1 was observed. Moreover, the specific capacity of Se@PB-Carb was found to be 339.74 mAh g−1 at 0.5 C after 100 cycles, and 235.97 mAh g−1 at 1 C after 500 cycles. These findings highlight the potential of molten salt-assisted porous biochar obtained from poplar sawdust, as a cost-effective precursor for selenium-based cathodes.

AI-guided investigation of biochar’s efficacy in Pb immobilization for remediation of Pb contaminated agricultural land

This study evaluated the lead (Pb) immobilization efficiency of biochar in contaminated agricultural soil. The biochar was produced from a range of major biomass residues and pyrolyzed under well-controlled conditions. Ten different types of standard biochar samples were derived from five different feedstocks (i.e., softwood, miscanthus straw, rice husk, oilseed rape straw, wheat straw) and pyrolyzed at 550 ℃ and 700 ℃. Pb-contaminated soil near an abandoned mine was incubated with 2.5% (w w− 1) of biochar. Incubation was conducted for various durations at room temperature under both short-term (21 days) and long-term (214 days) conditions. This variation explicitly accounted for the simulated microplastic contamination during the long-term incubation period. A novel framework has been developed to predict the long-term immobilization effect of various biochar types using a machine-learning approach, following the successful identification of optimal biochar implementations. This prediction method utilizes a small on-field dataset by employing a data augmentation approach, showcasing an innovative approach to forecasting the effects of different biochar types over time. After the incubation period, soil samples were analyzed for their chemical properties. As a result, oil seed rape biochar was the highest in pH, EC, exchangeable Ca2+, Mg2+, and K+, total nitrogen content, soil organic matter content, and available phosphate. In return, OSR 700 treated soils showed the highest content of exchangeable cations and the lowest content of available Pb after the incubation period. The most efficient biochar for immobilizing lead (Pb) in soil appears to be OSR 700, based on the available evidence.

From Transformation to Life Cycle Assessment of Biochar: A Case Study of Wheat Straw Biochar.

Biochar, as a carbon-rich material, exhibits significant potential for industrial applications. While numerous research endeavors have focused on its interactions within soil ecosystems, scant attention has been given to its behavior and potential impact on aquatic environments. In this study, we conducted an investigation to compare the environmental implications of pristine biochar with those of aged biochar. Initially, we assessed the interaction between biochar and key water quality indicators, revealing the release of endogenous ions (e.g., NH4+, NO3-, PO43-, Cu2+, and Cd2+) as well as organic substances (e.g., DOC) from both pristine and aged biochar samples. Aged biochar released higher amounts of ions and organic substances than pristine biochar due to the change in the structure and properties of aged biochar. Environmental risk and toxicity of pristine and aged biochar were subsequently evaluated using the potential ecological risk index (RI) and the impact on growth of Chlorella vulgaris, respectively. The values of RI for Cu indicated a very low degree of environmental risk, while those for Cd were dependent on water quality for surface water. Our study provided thorough analysis on the environmental assessment of biochar by combining experimental environmental transformation and life cycle assessment (LCA) analysis, suggesting biochar could have excellent environmental applications.

Surface characterization of biochar from agricultural residues for environmental applications

Bio-waste materials banana (Musa ealbisiana) leaves, cassava (Manihot esculenta) peels, mango (Mangifera indica) leaves, plantain (Plantago lanceolata) leaves and peels were pyrolyzed at different temperatures; 300, 400, 450, 500 and 600 oC using a muffle furnace. The biochar samples obtained were characterized and properties evaluated for their potential application in soil for agronomic and environmental benefits. The measured physico-chemical properties; pH, bulk density, percentage yield and electrical conductivity varied with temperature of pyrolysis and somewhat with the source of the bio-waste. Surface morphology and elemental composition were determined from Scanning Electron Microscopic (SEM) and Energy Dispersive X-ray (EDX) measurements and showed variations in texture, porosity and elemental composition with pyrolysis temperature. The produced biochar yields were in the range 16.1 to 84.6% and highest for banana leaves (BL) pyrolysed at 300 oC. The scanned images showed a remarkable surface morphology for all the biochar samples obtained at temperatures ≥ 450 oC. The pH obtained indicate the alkaline nature of the biochars with mean values > 7.5 except for cassava peels (CP) pyrolysed at 300 oC having a value of 5.5. From the elemental analysis, the high carbon content (> 60%) at higher temperatures (> 450 oC) of the biochars and the molar O/C ratios may suggest the suitability of the biochars in applications for long-term carbon sequestration and also promising candidates for soil amendment due to increase in macro porosity.

Fennel Seed Biochar: A Sustainable Approach for Methylene Blue Removal from Aqueous Solutions.

In this study, biochars were produced from by-products of the herbal industry, specifically fennel seeds (Foeniculum vulgare), through direct activation by carbon dioxide at two different temperatures. The biochar samples were comprehensively analysed. Additionally, adsorption studies were conducted for methylene blue. The resulting adsorbents exhibited a specific surface area ranging from 2.29 to 14.60 m2/g. The resulting materials displayed a basic character on their surface. The constants for adsorption models were determined for each dye as well as thermodynamic parameters and the kinetics of the process. The sorption capacities of methylene blue for the samples exhibited a range of 22 to 43 mg/g. The adsorption kinetics of the dye on the biochar materials were found to follow a pseudo-second-order model, with the adsorption process best described by the Langmuir isotherm for the DA-800 sample and the Freundlich isotherm for the DA-750 sample. This indicates the development of a monolayer adsorbate on the biochar surfaces. The efficacy of the adsorption process in aqueous solutions of methylene blue was found to increase with rising temperature. Furthermore, based on thermodynamic studies, the adsorption process was found to be spontaneous and endothermic.

Investigation of biochars derived from waste lignocellulosic biomass and insulation electric cables: A comprehensive TGA and Macro-TGA analysis

This study investigates the thermochemical decomposition and gasification performance of biochars produced from blends of waste lignocellulosic biomass and waste insulation electrical cables at varying temperatures. Characterization tests revealed changes, particularly in ash content (27.5 %–34 %) and elemental composition, with nitrogen content increasing notably in biochar samples compared to the original feedstock. Van Krevelen diagrams demonstrated a reduction in O/C and H/C ratios with increasing production temperature, resembling fossil fuels more closely. The thermogravimetric and the derived thermogravimetric profiles illustrated distinct degradation stages influenced by heating rates and production temperature. Macro-TGA tests provided insights into biomass residue behavior under gasification conditions, indicating higher reaction rates at elevated temperatures. Syngas analysis highlighted the impact of temperature and equivalence ratio on syngas composition, with higher temperatures favoring hydrogen-rich gas production. The observed trends in cold gas efficiency (42.61 %–50.40 %) and carbon conversion efficiency (45.83 %–50.40 %) underscore the significance of temperature control in maximizing gasification performance. Biochars produced at higher temperatures demonstrated superior gasification performance, suggesting potential for optimizing biochar production processes to enhance energy recovery and waste valorization.

Combined experimental and density functional theory approaches to address different mechanisms of nitrogen and sulfur doping on the enhancement of capacitive performance of hierarchical porous biochars

Activated carbon derived from biomass as hierarchical porous biochars (HPB) has been developed as electrode materials for supercapacitors. Nitrogen is known as the doping element that enhances quantum capacitance, but the mechanisms of sulfur doping on the quantum capacitance enhancement remain ambiguous. In this study, conventional approaches to assess the characteristics and capacitive performance of biochars were combined with density functional theory (DFT) calculations to assess different mechanisms of nitrogen and sulfur doping. The Bbiochar samples were prepared from the pyrolyzed fish bone powder at 800 °C without additional doping possessed a specific capacitance of 240 F g−1 at 1 A/g within 1 M H2SO4. Interestingly, additional nitrogen doping through urea mixing and additional sulfur doping through thiosulfate mixing prior to the pyrolysis enhanced the specific capacitance of biochar samples to exceed 400 F g−1 under the same condition. The urea mixed sample possessed low porosity but high charge transfer resistance, while the thiosulfate mixed sample possessed high porosity but low charge transfer resistance. The different underlying mechanisms were discussed through DFT calculations on graphene models designed based on the x-ray photoelectron spectroscopy (XPS) results. Nitrogen-doped configurations with topological defects mainly stored charge at the dangling atoms and possessed a relatively high quantum capacitance. Meanwhile, doped configurations of oxidized sulfur groups required relatively low formation energy and possessed large bond dipoles, corresponding to larger pore size and surface area of the thiosulfate mixed biochars. Understanding the contrary between effects of nitrogen and sulfur doping could resolve the bottleneck on enhancing the performance of electronic double layer supercapacitors.