Search Results (37)

Heavy metals represent long-lasting contaminants that pose significant risks to both human health and ecosystem integrity. Originating from both natural and anthropogenic activities, they bioaccumulate in organisms through the food web, leading to widespread and long-lasting contamination. Industrialization, agriculture, and urbanization have exacerbated soil and water contamination through activities such as mining, industrial production, and wastewater use. In response to this challenge, biochar produced from waste materials such as sewage sludge has emerged as a promising remediation strategy, offering a cost-effective and sustainable means to immobilize heavy metals and reduce their bioavailability in contaminated environments. Here we explore the potential of phosphate-enriched biochar, derived from sewage sludge, to adsorb and stabilize heavy metals in polluted soils. Sewage sludge was pyrolyzed at various temperatures to produce biochar. A soil incubation experiment was conducted by adding phosphate-amended biochar to contaminated soil and maintaining it for one month. Heavy metals were extracted using a CaCl₂ extraction method and analyzed using atomic absorption spectrophotometry. Results demonstrated that phosphate amendment significantly enhanced the biochar’s capacity to immobilize heavy metals. Amending soils with 2.5 wt% phosphate-enriched sewage sludge biochar led to reductions in bioavailable Cd (by 65–82%), Zn (40–75%), and Pb (52–88%) across varying pyrolysis temperatures. Specifically, phosphate-amended biochar reduced the mobility of Cd and Zn more effectively than unamended biochar, with a significant decrease in their concentrations in soil extracts. For Cu and Pb, the effectiveness varied with pyrolysis temperature and phosphate amendment, highlighting the importance of optimization for specific metal contaminants. Biochar generated from elevated pyrolysis temperatures (500 °C) showed an increase in ash content and pH, which improved their ability to retain heavy metals and limit their mobility. These findings suggest that phosphate-amended biochar reduces heavy metal bioavailability, minimizing their entry into the food chain. This supports a sustainable approach for managing hazardous waste and remediating contaminated soils, safeguarding ecosystem health, and mitigating public health risks. Full article

This study describes the development and characterization of materials based on activated carbon (AC). Pellets composed of dried biomass of willow, knotweed, and maple were formed and pyrolyzed to obtain different types of AC. Nickel (Ni) nanoparticles were synthesized on these materials using a bottom-up strategy by impregnating the carbons with a nickel nitrate solution. To characterize the surface and structure of these materials, SEM, MP-AES, and DSC-TGA techniques were employed. The ash content was analyzed to determine the input of mineral components in the carbons. The DSC-TGA results showed good thermal stability for each of the carbons, even at a temperature of 800 °C. BET analysis was also conducted, and the isotherms revealed well-developed surfaces for most of the specimens. The high efficiency of the impregnation process was confirmed by the MP-AES results: 165 mg of Ni was deposited on 1 g of carbon derived from maple leaves. The adsorbed Ni was well distributed across the carbon surfaces, as demonstrated in micrographs taken with the SEM-EDS apparatus. A comparison with similar materials reported in other studies was also performed. Full article

Biochar-based adsorbents synthesized from agricultural wastes have emerged as economical and environmentally sustainable materials for water purification. In this study, coffee shell-derived biochars were synthesized via pyrolysis at 500 and 700 °C, with and without water washing, and comprehensively characterized to evaluate their potential for removing Rhodamine B (RhB) from aqueous solution. Structural and surface analyses indicated that a higher pyrolysis temperature enhanced pore development and aromaticity, whereas water washing effectively removed inorganic ash, thereby exposing additional active sites. Among all samples, water-washed biochar pyrolyzed at 700 °C (WCB700) exhibited the highest surface area (273.6 m²/g) and adsorption capacity (193.5 mg/g). The adsorption kinetics conformed to a pseudo-second-order model, indicating chemisorption, and the equilibrium data fit the Langmuir model, suggesting monolayer coverage. Mechanism analysis highlighted the roles of π–π stacking, hydrogen bonding, electrostatic interaction, and pore filling. Additionally, WCB700 retained more than 85% of its original capacity after five regeneration cycles, demonstrating excellent stability and reusability. This study presents an economical approach to valorizing coffee waste as well as provides mechanistic insights into optimizing biochar surface chemistry for enhanced dye removal. These findings support the application of engineered biochar in scalable and sustainable wastewater treatment technologies. Full article

Potassium chloride (KCl) is the main source of potassium (K) in Brazilian agriculture, but its high import dependency and the need for split applications increase costs and expose the system to supply and efficiency risks. Understanding the availability and release kinetics of potassium (K) from biochar-based fertilizers (K-BBFs) is crucial for optimizing their use as full or partial substitutes for KCl in Brazilian agriculture. This study evaluated biochars derived from banana peel (BP), coffee husk (CH), and chicken manure (CM), both in their pure form and co-pyrolyzed with KCl (composites) at 300 °C and 650 °C, as K sources for corn grown in two contrasting Oxisols. For pure biochars, feedstock type and pyrolysis temperature significantly influenced K content and release kinetics. Higher pyrolysis temperatures increased K content in BP and CH biochars but not in CM, while also slowing K release in CH and CM. Co-pyrolysis with KCl increased biochar yield, ash content, and K availability. Composites released more K than pure biochar but less than KCl, and at a slower rate. Notably, banana peel biochar co-pyrolyzed with KCl at 650 °C (CBP650) exhibited 36% slower K release and reduced KCl use by 82% while maintaining similar K use efficiency and corn growth. All K-BBFs matched KCl in promoting robust corn growth in clay soil, increasing biomass by 5.3 times and K uptake by 9 times compared to unfertilized (no K addition) plants. In sandy Oxisol, K-BBFs boosted biomass by up to 3.5 times compared to unfertilized plants, though some pure biochars were less effective than KCl in supporting full corn growth. Soil texture strongly influenced K availability, with sandier soils exhibiting higher K levels in solution. These findings suggest that kinetic release studies in abiotic systems, such as lysimeters with sand, are not suitable for evaluating K-BBFs as slow-release fertilizers. Due to lower K retention in sandy soil and solution K levels exceeding 1100 mg L⁻¹, split applications of some K-BBFs are recommended to prevent corn cation uptake imbalances and soil K leaching. Additionally, granulating biochar–KCl composites may enhance K retention and regulate its release in sandy Oxisols. Full article

There is an urgent need for energy-efficient disposal and resource utilization of the fly ashes from municipal solid waste incineration (MSWI). The low-energy pyrolysis-based detoxification of is a prerequisite for the harmless treatment and sustainable utilization of the fly ashes. In this study, the nitrogen-doped hierarchical porous carbon (NHPC) was prepared from the biomass-derived corn cobs and used to enhance the low-temperature destruction of PCDD/Fs in the MSWI fly ash. On thermal treatment in pure nitrogen (referring to pyrolysis in) at 350 °C for 30 min, the removal efficiencies of PCDD/Fs in fly ash based on mass (η_mass) and TEQ (η_TEQ) are 87.4% and 76.2%, respectively. After 5 wt.% NHPC is added in fly ash, the η_mass and η_TEQ values can be increased to 94.9% and 90.2%. The NHPC can enhance the decomposition and inhibit the regeneration of PCDD/Fs in fly ash, for the NHPC can regulate the structural properties and optimize the chemical environment of the fly ash. It can eliminate the need for the washing process. In addition, the leaching concentrations of heavy metals such as Cu, Zn, Pb and Cr in fly ash experience significant reductions of 83.3%, 73.7%, 35.6% and 22.9% when the fly ash is pyrolyzed at 350 °C with NHPC. This finding suggests that NHPC cannot only facilitate the decomposition of PCDD/Fs but also immobilizes the typical heavy metals in fly ash during low-energy pyrolysis. It is anticipated that the application of NHPC in the low-temperature pyrolysis of fly ash is of great energy-saving effect and can tackle the issues of PCDD/Fs and heavy metals for fly ash within a single step. Full article

In order to reduce the content of sulfur and ash in coal, improve the desulfurization and deashing rates, a combined experiment method of microwave magnetic separation-flotation was proposed for raw coal. The desulfurization and deashing rates of three experiment methods, namely, single magnetic separation, microwave magnetic separation, and microwave magnetic separation–flotation, were compared. Taking the microwave magnetic separation–flotation experiment method as the main line, the effects of the microwave irradiation time, microwave power, grinding time, magnetic field intensity, plate seam width, foaming agent dosage, collector dosage, and inhibitor dosage on desulfurization and deashing were discussed, and the mechanism of microwave irradiation on magnetic separation and flotation was revealed. The results show that under the conditions of a microwave irradiation time of 60 s, a microwave power of 80% of the rated power (800 W), a grinding time of 8 min, a plate seam width (the plate seam width of a magnetic separator sorting box) of 1 mm, a magnetic field intensity of 2.32 T, a foaming agent dosage of 90 g/t, a collector dosage of 2125 g/t, and an inhibitor dosage of 1500 g/t, the desulfurization and deashing effect is the best. The desulphurization rate is 76.51%, the sulfur removal rate of pyrite is 96.50%, and the deashing rate is 61.91%. Microwaves have the characteristic of selective heating, and the thermal conductivity of organic matter in coal is greater than that of mineral. Microwave irradiation can improve the reactivity of pyrite in coal, pyrolyze pyrite into high-magnetic pyrite, improve the magnetic properties, and improve the magnetic separation effect. Therefore, microwave irradiation plays a role in promoting magnetic separation. Through microwave irradiation, the positive and negative charges in coal molecules constantly vibrate and create friction under the action of an electric field force, and the thermal action generated by this vibration and friction process affects the structural changes in oxygen-containing functional groups in coal. With the increase in the irradiation time and power, the hydrophilic functional groups of –OH and –COOH decrease and the hydrophilicity decreases. Microwave heating evaporates the water in the pores of coal samples and weakens surface hydration. At the same time, microwave irradiation destroys the structure of coal and impurity minerals, produces cracks at the junction, increases the surface area of coal to a certain extent, enhances the hydrophobicity, and then improves the effect of flotation desulfurization and deashing. Therefore, after the microwave irradiation of raw coal, the magnetic separation effect is enhanced, and the flotation desulfurization effect is also enhanced. Full article

The unregulated discharge of synthetic dyes from various anthropogenic and industrial activities has resulted in the contamination of different environmental compartments. These dyes can contaminate water bodies, soil, and even the air, resulting in many environmental and health issues. True colors may persist for long periods, thereby affecting the aesthetics and ecology of dye-contaminated areas. Furthermore, they pose potential risks to aquatic life and human health through the ingestion or absorption of dye-contaminated water or food. Acid orange 7 (AO7) is a synthetic azo dye used in the textile, tanning, food, pharmaceutical, paint, electronics, cosmetics, and paper and pulp industries. AO7 can have various human health implications, such as dermatitis, nausea, severe headache, respiratory tract irritation, and bone marrow depletion, due to its high toxicity, mutagenicity, and carcinogenicity. Efforts to regulate and mitigate dye pollution (AO7) are crucial for environmental sustainability and public health. Therefore, this study aimed to remove AO7 from water using sustainable biochar. This objective was accomplished by pyrolyzing dried Napier grass at 700 °C to develop affordable and sustainable Napier grass biochar (NGBC700). The developed biochar was characterized for its surface morphology, surface functional groups, surface area, and elemental composition. The yield, moisture content, and ash content of the NGBC700 were approximately 31%, 6%, and 21%, respectively. The NGBC700’s BET (Brunauer–Emmett–Teller) surface area was 108 m² g⁻¹. Batch sorption studies were carried out at different pH levels (2–10), biochar dosages (1, 2, 3, and 4 g L⁻¹), and AO7 concentrations (10, 20, and 30 mg L⁻¹). The kinetic data were better fitted to the pseudo-second-order (PSO) equation (R² = 0.964–0.997) than the pseudo-first-order (PFO) equation (R² = 0.789–0.988). The Freundlich isotherm equation (R² = 0.965–0.994) fitted the sorption equilibrium data better than the Langmuir equation (R² = 0.788–0.987), suggesting AO7 sorption on heterogenous NGBC700. The maximum monolayer AO7 adsorption capacities of the NGBC700 were 14.3, 12.7, and 8.4 mg g⁻¹ at 10, 25, and 40 °C, respectively. The column AO7 sorption capacity was 4.4 mg g⁻¹. Fixed-bed AO7 sorption data were fitted to the Thomas and Yoon–Nelson column models. The NGBC700 efficiently removed AO7 from locally available dye-laden wastewater. NGBC700 was regenerated using different NaOH concentrations. Possible interactions contributing to AO7 sorption on NGBC700 include hydrogen bonding, electrostatic interactions, and π–π electron donor–acceptor attractions. The estimated total preparation cost of NGBC700 was US$ 6.02 kg⁻¹. The developed sustainable NGBC700 is potentially cost-effective and environmentally friendly, and it utilizes waste (Napier grass) to eliminate fatal AO7 dye from aqueous media. Full article

Costa Rica produces a considerable, important quantity of wood residues. This waste can be pyrolyzed to produce charcoals as main products that can be effectively used as an energy source or to immobilize carbon for soil treatment. However, there is a lack of information about the pyrogenic carbonaceous materials (PCMs), such as charcoal or biochar, obtained at different pyrolysis temperatures. Hence, this study aimed to evaluate the quality of PCMs (physical, mechanical, ultimate analysis, and FTIR analysis) and charcoal characteristics (energetic properties and thermogravimetric analysis—TGA) and biochar characteristics (conductivity, pH, initial contact angle, and wetting rates) for four tropical wood residues produced in five temperatures (300 °C, 350 °C, 400 °C, 450 °C, and 500 °C). In general, pyrolysis temperature between 450 °C and 500 °C produced charcoals with lower values of density, moisture content, compression strength, volatiles, H and O content, and higher values of C and ash contents, conductivity, pH, initial contact angle, and wetting rates. FTIR and TGA analyses show that celluloses and lignin are pyrolyzed at these temperatures, so these temperatures are recommended. The range of 300–350 °C is not recommended, as these parameters were inverse. Multivariate analysis shows that (i) PCMs obtained at lower temperatures (300–350 °C) from Dipteryx panamensis, Hieronyma alchorneoides, and Tectona grandis belong to a cluster with poorer properties, indicating that these temperatures are not adequate for pyrolysis of these species; (ii) all the PCMs obtained from Gmelina arborea were grouped into one cluster, suggesting different PCM quality; and (iii) the PCMs produced from D. panamensis, H. alchorneoides, and T. grandis at 400–500 °C were grouped into another cluster with better properties, suggesting this pyrolysis temperature range as the best for these species. Full article

In the past few years, wind power has become a viable alternative in Brazil to diversify the energy mix and mitigate pollutant emissions from fossil fuels. Significant wind energy generation potential is inherent in the Brazilian Northeast state of Rio Grande do Norte, due to prevailing strong winds along the coastline and elevated regions. However, clean and renewable wind energy may lead to potential biodiversity impacts, including the removal of native vegetation during plant construction and operation. This case study explores the flash pyrolysis-based valorization of three commonly suppressed species, namely Cenostigma pyramidale (CP), Commiphora leptophloeos (CL), and Aspidosperma pyrifolium (AP), in a wind farm situated within the Mato Grande region of Rio Grande do Norte State. The study centers on determining their bioenergy-related properties and assessing their potential for producing phenolic-rich bio-oil. The investigation of three wood residues as potential sources of high-value chemicals, specifically phenolic compounds, was conducted using a micro-furnace type temperature programmable pyrolyzer combined with gas chromatography/mass spectrometry (Py–GC/MS setup). The range of higher heating values observed for three wood residues was 17.5–18.4 MJ kg⁻¹, with the highest value attributed to AP wood residue. The bulk density ranged from 126.5 to 268.7 kg m⁻³, while ash content, volatile matter content, fixed carbon content, and lignin content were within the respective ranges of 0.8–2.9 wt.%, 78.5–89.6 wt.%, 2.6–9.5 wt.%, and 19.1–30.6 wt.%. Although the energy-related properties signifying the potential value of three wood residues as energy resources are evident, their applicability in the bioenergy sector can be expanded via pelleting or briquetting. Yields of phenolic compounds exceeding 40% from the volatile pyrolysis products of CL and AP wood residues at 500 °C make them favorable for phenolic-rich bio-oil production. The findings of this study endorse the utilization of wood residues resulting from vegetation suppression during the installation of wind energy plants as potential feedstocks for producing bioenergy and sustainable phenolic compounds. This presents a solution for addressing a regional environmental concern following the principles of green chemistry. Full article

Temperature determines biochar structure during pyrolysis. However, differences in holding time and feedstock types may affect this relationship. The conditional process analysis model was used in this paper to investigate the potential to affect this mechanism. The branch and leaf parts of Taxodium ascendens were separately pyrolyzed at 350, 450, 650, and 750 °C, and kept for 0.5, 1, and 2 h at each target temperature. We measured the fixed carbon and ash contents and the elemental composition (C, H, O and N) of the raw materials and their char samples. After plotting a Van Krevelen (VK) diagram to determine the aromatization of chars, the changes in the functional groups were analyzed using Fourier transform infrared (FTIR), Raman, and X-ray photoelectron spectroscopy (XPS). The results revealed that pyrolysis at temperatures between 450 and 750 °C accounted for the aromatization of biochar because the atomic H/C ratio of branch-based chars (BC) decreased from 0.53–0.59 to 0.15–0.18, and the ratio of leaf-based chars (LC) decreased from 0.56–0.68 to 0.20–0.22; the atomic O/C ratio of BC decreased from 0.22–0.27 to 0.08–0.11, while that of LC decreased from 0.26–0.28 to 0.18–0.21. Moreover, the average contents of N (1.89%) and ash (13%) in LC were evidently greater than that in BC (N:0.62%; Ash: 4%). Therefore, BC was superior to LC in terms of the stability of biochar. In addition, the increasing I_D/I_G and I_D/I_(DR+GL) ratios in BC and LC indicated an increasing amount of the amorphous aromatic carbon structure with medium-sized (2~6 rings) fused benzene rings. According to the CPA analysis, an extension of the holding time significantly enhanced the increase in aromatic structures of LC with temperature. But this extension slightly reduced the growth in aromatic structures of BC. All indicate that holding time and feedstock types (branch or leaf feedstock) could significantly affect the variation in biochar aromatic structure with respect to temperature. Full article

Nitrate-nitrogen (NO₃⁻–N) removal and garden waste disposal are critical concerns in urban environmental protection. In this study, biochars were produced by pyrolyzing various garden waste materials, including grass clippings (GC), Rosa chinensis Jacq. branches (RC), Prunus persica branches (PP), Armeniaca vulgaris Lam. branches (AV), Morus alba Linn. sp. branches (MA), Platycladus orientalis (L.) Franco branches (PO), Pinus tabuliformis Carrière branches (PT), and Sophorajaponica Linn. branches (SL) at three different temperatures (300 °C, 500 °C, and 700 °C). These biochars, labeled as GC300, GC500, GC700, and so on., were then used to adsorb NO₃⁻–N under various conditions, such as initial pH value, contact time, initial NO₃⁻–N concentration, and biochar dosage. Kinetic data were analyzed by pseudo-first-order and pseudo-second-order kinetic models. The equilibrium adsorption data were evaluated by Langmuir, Freundlich, Temkin and Dubinin–Radushkevich models. The results revealed that the biochar yields varied between 14.43% (PT700) and 47.09% (AV300) and were significantly influenced by the type of garden waste and decreased with increasing pyrolysis temperature, while the pH and ash content showed an opposite trend (p < 0.05). The efficiency of NO₃⁻–N removal was significantly influenced by the type of feedstock, preparation process, and adsorption conditions. Higher pH values had a negative influence on NO₃⁻–N adsorption, while longer contact time, higher initial concentration of NO₃⁻–N, and increased biochar dosage positively affected NO₃⁻–N adsorption. Most of the kinetic data were better fitted to the pseudo-second-order kinetic model (0.998 > R² > 0.927). Positive b values obtained from the Temkin model indicated an exothermic process of NO₃⁻–N adsorption. The Langmuir model provided better fits for more equilibrium adsorption data than the Freundlich model, with the maximum NO₃⁻–N removal efficiency (62.11%) and adsorption capacity (1.339 mg·g⁻¹) in PO700 under the conditions of pH = 2, biochar dosage = 50 mg·L⁻¹, and a reaction time of 24 h. The outcomes of this study contribute valuable insights into garden waste disposal and NO₃⁻–N removal from wastewater, providing a theoretical basis for sustainable environmental management practices. Full article

Coal is the primary energy source in China, and coal pyrolysis is considered an essential and efficient method for clean coal utilization. Three high arsenic coals collected from the southwestern Guizhou province of China were chosen in this study. Low-temperature ashing plus X-ray diffraction analysis (XRD) was used to identify the minerals in coals. The three coals were pyrolyzed in a tube furnace in an N₂ atmosphere at 950 °C, 1200 °C, and 1400 °C, respectively. Environment scanning electron microscope (ESEM), XRD, X-ray fluorescence analysis (XRF), and inductively coupled plasma-mass spectrometry (ICP-MS) were adopted to determine the morphology, mineral compositions, and element compositions and arsenic contents of the coal pyrolysis ashes, respectively. It can be found that minerals in coal are mainly composed of quartz, pyrite, muscovite, and rutile. The minerals in the ashes generated from coal pyrolysis mainly contain quartz, dehydroxylated muscovite, iron oxide minerals, mullite, and silicon nitride. Oldhamite and gupeite exist at 950 °C and 1400 °C, respectively. The morphologies of oldhamite and gupeite at these temperatures are irregular block-shaped particles and irregular spherical particles, respectively. The mineralogical transformations in the process of coal pyrolysis affect coal utilization. The arsenic release rate is higher than 87% during pyrolysis at 1400 °C. The arsenic in organic matter is more able to be volatilized than mineral components. The retention time can slightly influence the arsenic release rate, and the influence of temperature is much more significant than the influence of retention time. The understanding of mineral evolution and arsenic environmental emission is helpful for the safety of high-arsenic coal pyrolysis. Full article

Recently, there has been so much interest in using biomass waste for bio-based products. Nigeria is one of the countries with an extensive availability of palm biomass. During palm oil production, an empty palm fruit bunch (biomass) is formed, and a lot of ash is generated. This study aimed to extract and characterize silica from empty palm fruit bunch (EPFB) ash using the thermochemical method. The results show that EPFB ash contains a large amount of biogenic silica in its amorphous form. It could be extracted for further use via calcination at different temperatures and compared effectively to other biomass materials, such as rice husk ash, sugarcane bagasse, and cassava periderm. The extracted silica was characterized using XRF, XRD, TGA, SEM, and FTIR, revealing the highest silica concentration of 49.94% obtained at a temperature of 800 °C. The XRF analysis showed 99.44 wt.% pure silica, while the XRD spectrum showed that the silica in EPFB is inherently amorphous. As is evident from the study, silica obtained from EPFB ash is a potential source of silica and it is comparable to the commercial silica. Thus, it is potentially usable as a support for catalysts, in the development of zeolite-based catalysts and as an adsorbent. Full article

Biochar is a carbonaceous and porous material with limited adsorption capacity, which increases by modifying its surface. Many of the biochars modified with magnetic nanoparticles reported previously were obtained in two steps: first, the biomass was pyrolyzed, and then the modification was performed. In this research, a biochar with Fe₃O₄ particles was obtained during the pyrolysis process. Corn cob residues were used to obtain the biochar (i.e., BCM) and the magnetic one (i.e., BCM_Fe). The BCM_Fe biochar was synthesized by a chemical coprecipitation technique prior to the pyrolysis process. The biochars obtained were characterized to determine their physicochemical, surface, and structural properties. The characterization revealed a porous surface with a 1013.52 m²/g area for BCM and 903.67 m²/g for BCM_Fe. The pores were uniformly distributed, as observed in SEM images. BCM_Fe showed Fe₃O₄ particles on the surface with a spherical shape and a uniform distribution. According to FTIR analysis, the functional groups formed on the surface were aliphatic and carbonyl functional groups. Ash content in the biochar was 4.0% in BCM and 8.0% in BCM_Fe; the difference corresponded to the presence of inorganic elements. The TGA showed that BCM lost 93.8 wt% while BCM_Fe was more thermally stable due to the inorganic species on the biochar surface, with a weight loss of 78.6%. Both biochars were tested as adsorbent materials for methylene blue. BCM and BCM_Fe obtained a maximum adsorption capacity (q_m) of 23.17 mg/g and 39.66 mg/g, respectively. The obtained biochars are promising materials for the efficient removal of organic pollutants. Full article

Walnut, pistachio, and peanut nutshells were treated by pyrolysis to biochar and analyzed for their possible usage as fuels or soil fertilizers. All the samples were pyrolyzed to five different temperatures, i.e., 250 °C, 300 °C, 350 °C, 450 °C, and 550 °C. Proximate and elemental analyses were carried out for all the samples, as well as calorific value and stoichiometric analysis. For sample usage as a soil amendment, phytotoxicity testing was performed and the content of phenolics, flavonoids, tannin, juglone, and antioxidant activity were determined. To characterize the chemical composition of walnut, pistachio, and peanut shells, lignin, cellulose, holocellulose, hemicellulose, and extractives were determined. As a result, it was found that walnut shells and pistachio shells are best pyrolyzed at the temperature of 300 °C and peanut shells at the temperature of 550 °C for their use as alternative fuels. The highest measured net calorific value was in pistachio shells, which were biochar pyrolyzed at 550 °C, of 31.35 MJ kg⁻¹. On the other hand, walnut biochar pyrolyzed at 550 °C had the highest ash share of 10.12% wt. For their use as soil fertilizers, peanut shells were the most suitable when pyrolyzed at 300 °C, walnut shells at 300 and 350 °C, and pistachio shells at 350 °C. Full article