Electrocatalytic oxidation of more stable 2,5-furanedimethanol (FDM) for 2,5-furanediformic acid (FDCA) generation with concurrent hydrogen production is attractive but still nascent compared to 5-Hydroxymethyl-2-furaldehyde (HMF). The need for effective and stable bifunctional electrocatalysts that are efficient for the FDM cell is thus quite significant. Wood serves as an ideal matrix for boosting the performance of catalysts, since its hierarchical porous structures facilitate mass transport and provide abundant active sites. Unfortunately, it has never been demonstrated for electrochemically organic synthesis. Herein, the effectiveness of Fe-CoP in catalyzing FDM oxidation was demonstrated by density functional theory (DFT) calculations and experiments, and a renewable carbonized porous wood decorated with Fe-doped CoP nanoleaves (Fe-CoP/CW) was constructed for electrocatalytic FDCA and hydrogen generation. The obtained Fe-CoP/CW as an anode in FDM solution afforded a current density of 100 mA cm⁻² with a yield of 90% FDCA at a potential no more than 1.50 V vs RHE, which was 90 mV and 350 mV lower than Fe-CoP/carbon cloth (CC) and IrO₂. In addition, Fe-CoP/CW showed excellent long-term stability for 108-h FDM oxidation in strong alkaline solution. Remarkably, in stark contrast to Fe-CoP/CC and Pt, the hydrogen evolution performance of Fe-CoP/CW was not impacted by FDM at the cathode, and it required exceptionally low overpotentials of 0.19 V to achieve 100 mA cm⁻². As a result, in terms of the overall cell, the hydrogen production rate was 0.756 mmol cm⁻² h⁻¹, which was 3.57 times higher than those of commonly used commercial Pt | IrO₂ cell, presenting a Faraday efficiency of near 100%. This work will pave the way towards the implementation of highly suited bifunctional electrodes and the possibility of affordable, effective, and environmentally-friendly wood-derived electrocatalysts for electrochemically organic synthesis.

This study investigates the adsorption of Brilliant Green (BG) dye onto biochar derived from Syzygium cumini (Jamun) leaves (JLB). Biochar was produced via pyrolysis at 800 °C and examined employing various methods, including Scanning electron microscopy (SEM–EDX), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), Brunauer–Emmett–Teller (BET) analysis, Raman spectroscopy, Zeta potential and X-ray photoelectron spectroscopy (XPS). The optimum parameters for BG dye adsorption, determined by batch adsorption studies, were a temperature of 80 °C, an initial dye concentration of 500 mg L⁻¹, a contact period of 30 min, and an agitation speed of 400 RPM. The maximum adsorption capacity of JLB for BG was 243.90 mg g⁻¹. It was found that the adsorption process adhered to the Freundlich isotherm model and pseudo-second-order kinetics, revealing heterogeneous adsorption with chemisorption. A novel "Theory of Pore Conflation" was proposed to explain enhanced adsorption at higher temperatures, supported by SEM and FTIR analyses. Additionally, a new equation termed "Shubhjyot's equation" was introduced to account for time dependency in adsorption capacity calculations. The thermodynamic analysis demonstrated that the process is endothermic and spontaneous. Isopropanol was the most effective organic solvent for desorption studies, demonstrating biochar regeneration potential for up to five cycles. Phytotoxicity and cyto-genotoxicity assessments demonstrated the environmental safety of JLB compared to BG dye. The use of JLB production offers a way to repurpose agricultural waste, contributing to circular economy principles. This extensive study demonstrates JLB's promise as an effective, economical, and environmentally safe adsorbent for wastewater treatment that eliminates textile dyes.

Over the past 10–15 years, biochar has garnered significant global attention in agriculture and environmental science. While most research has focused on the benefits of biochar application in soil enhancement, water quality improvement, and climate change mitigation, the potential risks associated with its use have often been overlooked. This oversight is critical, as the environmental fate of biochar is contingent upon understanding these risks. Once released into the environment, biochar can interact with environmental media, potentially releasing associated pollutants and threatening ecosystems. Therefore, it is essential to evaluate the unintended environmental and health risks associated with biochar during its production and application to select appropriate types for sustainable development. This review was conducted by systematically analyzing and synthesizing relevant studies from Web of Science, focusing on recent advancements and key debates in the field. It categorizes biochar risks into endogenous and exogenous risks based on the source of pollutants carried by biochar. The review analyzes in detail the impacts of raw materials, preparation processes, and application scenarios on the unintended environmental risks of biochar. Furthermore, it provides a thorough overview of the adverse effects on animals, plants, microorganisms, and human health, elucidating the mechanisms of pollutant release, aging, and nano-effects from environmental geochemical processes involving biochar. Additionally, this review summarizes the environmental risk assessment methods of biochar, providing a reference for its safe application and the sustainable development of biochar-related research.

Phosphorus (P) is essential for basic natural processes and can limit the productivity of entire ecosystems. However, agricultural lands worldwide currently suffer from P deficiency. The application of P fertilizers is not only poorly utilized, but also results in the gradual accumulation of P. Biochar, a substance produced by the pyrolysis of biomass under low oxygen levels, is frequently used as a soil amendment. It provides P in a form that is readily available for plant uptake, and thus addresses both short- and long-term soil P deficiencies. In this paper, we systematically reviewed relevant studies on “biochar and soil” or “biochar and soil P” published in the past decade (2013–2023). A synthesis of the reported results revealed that analyzing the effect of biochar on soil P through changes in soil physicochemical properties and microbial communities has gradually emerged as a prominent area of research in recent years. The purpose of this study was to analyze the differential effects of biochar addition on soil P availability, including the clarification of the underlying mechanisms. The results showed that although biochar application generally exerts a positive effect on soil P availability, there are differences in the extent of effects based on application conditions. Shifting to mechanisms, biochar application not only directly increases the available phosphorus (AP) content of soil, but also indirectly influences soil P availability via changes in soil physical, chemical, and biological properties. To summarize, biochar application can affect soil P availability to different degrees through direct or indirect pathways.

Per- and polyfluoroalkyl substances (PFASs), commonly known as ‘‘forever chemicals’’, are persistent organic pollutants that are widely distributed in the environment. Due to their toxicity and resistance to degradation, PFASs are classified as emerging contaminants, and increasing attention is being paid to their remediation. Biochar, an environmentally friendly and cost-effective adsorbent, shows potential for remediating PFASs contamination. The application of biochar for PFASs remediation has garnered growing interest. Compared to other adsorbents, biochar is more economical and the raw materials for its preparation are more readily available. However, there is currently no comprehensive review summarizing the effects of biochar on the environmental behavior of PFASs. This review aims to fill that gap by providing an in-depth discussion and synthesis of the existing literature in this area. It focuses on the environmental behavior of PFASs, specifically addressing the adsorption mechanisms and factors influencing the effectiveness of biochar in PFASs remediation. A proposed mechanism by which biochar photodegrades PFASs through the generation of free radicals, in addition to conventional adsorption mechanisms (such as pore filling, hydrogen bonding, hydrophobic interactions, and electrostatic interactions), is explored. Furthermore, this review discusses the ability of biochar to reduce the likelihood of PFASs entering the food chain through water and soil and evaluates the feasibility and limitations of using biochar for PFASs removal. Finally, we identify future research directions to support the safe and effective use of biochar for PFASs remediation, so as to promote the advancement of green remediation technologies.

Biochar has been proposed as a soil amendment in vegetable fields, where the widespread use of plastic film leads to significant retention of microplastics (MPs) in the soil. However, the interactive effect of biochar and MPs on plant growth and soil functions remains poorly understood. Here, we conducted a pot experiment to examine the effects of biochar application in the presence of conventional and biodegradable microplastics (0.05% w/w) on the growth of coriander, soil nitrogen (N) cycling processes, and microbial communities. The results showed that biochar application increased aboveground biomass by increasing plant available N of NH₄ ⁺, regardless of the presence of MPs. Biochar also significantly reduced soil nitrous oxide (N₂O) emissions by an average of 16% without MPs. However, when MPs were present, the effect of biochar on N₂O emissions was lessened depending on the MP type. Polylactic acid consistently reduced soil N₂O emissions and the abundance of N₂O production genes, irrespective of biochar application. Conversely, polyethylene without biochar reduced N₂O emissions primarily by inhibiting N-related functional genes responsible for nitrification and denitrification. This inhibitory effect was reversed when biochar was applied, leading to a 26% increase in N₂O emissions due to increased nifH and nirK gene abundance. Although biochar and MPs did not significantly alter microbial α-diversity, they altered the composition and structure of bacterial and fungal communities, linked to changes in soil N turnover. Our study underscores the critical role of MP type in assessing the effects of biochar on soil N cycling and N₂O emissions. Consequently, plastic pollution may complicate the ability of biochar to improve plant growth and soil functions, depending on the characteristics of the MPs.

The increased contamination of potentially toxic element (PTE) has posed remarkable ecological risks to environment. Application of functionalized biochar for the remediation of PTE contaminated water and soils are of great concern, and effective strategies are urgently needed to enhance the removal capacity of biochar for PTE. As a novel surface modification technology, the effect of layered double hydroxides (LDH) and sodium dodecyl sulfonate (SDS) on the remediation capacity of biochar for PTE polluted soils and water remains unclear. Sawdust biochar (SB) was coated with Mg and Fe to synthesize the Mg-Fe-LDH functionalized biochar (MFB); thereafter, the MFB was mixed with SDS solution to synthesize the organic-Mg-Fe-LDH biochar (MSB). The potential of SB, MFB, and MSB for remediation of Cd and Pb contaminated soil and water was evaluated in terms of adsorption capacity, immobilization efficiency, and stability. Loading of Mg-Fe-LDH into SB, along with SDS treatment created a regular micro-nano hierarchical structure and enhanced the surface roughness, aromaticity, and hydrophobicity of MSB as compared to SB. MSB exhibited a significantly higher maximum adsorption capacity (mg g⁻¹) for water Pb (405.2) and Cd (673.0) than MFB (335.9 for Pb and 209.0 for Cd) and SB (178.2 for Pb and 186.1 for Cd). MSB altered the soluble fraction of Cd/Pb to the residual fraction and thus significantly decreased their mobilization in soil. The higher removal/immobilization efficiency of MSB could be attributed to its alkalinity, and the enhanced synergistic interactions including surface precipitation, ion exchange, complexation, and hydrogen bonding. The resistance to carbon loss by H₂O₂, thermal recalcitrance index R ₅₀, and degree of graphitization in MSB were significantly improved compared to SB, indicating a more stable carbon fraction sequestered in MSB following aging in soil. These results indicate that MSB could be used for remediation of Cd and Pb contaminated soil and water.

The study highlights the critical mechanistic data supporting the ecological restoration advantages of biochar (BC) and its role in sustainable environmental management. Recognizing the substantial influence of specific feedstock sources and pyrolysis parameters on BC efficacy, this research aims to address these gaps through an extensive investigation into the potential benefits of BC application in ecological restoration. The methodology involves a systematic exploration of effects of BC from latest literature on various aspects of agricultural sustainability, including its ability to support crop growth, improve nutrient bioavailability, facilitate co-composting, enhance consumption efficiency, and contribute to water quality restoration. The main results of the study reveal that BC usage results in a net negative carbon (C) footprint, mitigates heavy metal pollution, and enhances soil and ecosystem health. In bioenergy production, BC serves as a versatile resource for generating renewable energy, reducing waste, and facilitating C sequestration. Advanced BC techniques, such as tailored pyrolysis processes and activation methods, further enhance its effectiveness in ecosystem restoration and sustainable resource management. Furthermore, the research identifies deficiencies in current literature and proposes future research directions to advance understanding of BC application. Overall, the study underscores the importance of considering feedstock and pyrolysis variables in BC research and highlights the potential of BC to contribute to ecological sustainability. However, concerns regarding potential health implications for humans in agricultural contexts warrant further investigation and risk assessment to ensure safe and sustainable BC application.

Material selection and production conditions are imperative for determining the functional performances of composite materials. Phase-change composites obtained from phase-change materials (PCMs) and supporting matrices exhibit high thermal energy storage density. They are used to overcome the intermittency issues of wind and solar energy, as well as to reduce waste heat dissipation to the environment. However, the large-scale utilization of composite and pristine materials has severe drawbacks, primarily stemming from the complex fabrication routes of the encapsulating agents, leakage, and inadequate thermal stability. In this study, biochar-based phase-change composites were fabricated using vacuum infiltration techniques, and the effects of biomass feedstock and pyrolysis temperature on the performance of the composite were elucidated using different types of biowastes and temperatures. This approach has several advantages, including facile production techniques, low-cost carbon sources, and environmental friendliness. The PCM adsorption ratio of biochars derived from rice husk (RH) and Miscanthus straw linearly correlated with the pyrolysis temperature (550–700 °C), while RH700 resulted in a composite with a high enthalpy per unit mass of hexadecane (HXD) in RH700/HXD (250.9 J g⁻¹) owing to the high surface area of RH700 (74.66 m² g⁻¹). The crystalline temperature increased slightly from 10.7 °C in RH550/HXD to 10.9 °C in RH700/HXD, suggesting improved molecular motion and crystal growth of HXD. Wheat straw biomass pyrolyzed at a low temperature (550 °C), displaying a reduced surface area at 700 °C (7.35 m² g⁻¹) and exhibiting the lowest energy storage density. The latent heat efficiency reached 99.5–100%, where RH700/HXD exhibited 100% efficiency. The composites demonstrated strong leakage resistance at high heating temperatures (60 °C, above the melting temperature of HXD), good chemical compatibility between the biochar and HXD, and high durability after 500 thermal cycles. Therefore, the extent of PCM loading and energy storage density improvements primarily depends on the pyrolysis conditions, feedstock used, and pore size distribution of the biochar samples. This research provides insights into the fabrication of phase-change composites and optimization of the carbonization process of different biomasses used for thermal management applications, such as building energy savings.

Application of advanced techniques and machine learning (ML) for designing and predicting the properties of engineered hydrochar/biochar is of great agro-environmental concern. Carbon (C) stability and phosphorus (P) availability in hydrochar (HC) are among the key limitations as they cannot be accurately predicted by traditional one-factor tests and might be overcome by engineering the pristine HC. Therefore, the aims of this study were (1) to determine the optimal production conditions of engineered swine manure HC with high C stability and P availability, and (2) to develop the best ML models to predict the properties of HC derived from different feedstocks. Pristine- (HC) and FeCl₃ impregnated swine manure-derived HC (HC-Fe) were produced by hydrothermal carbonization under different pH (4, 7, and 10), reaction temperature (180, 220, and 260 ℃), and residence time (60, 120, and 180 min) and characterized using thermo-gravimetric, microscopic, and spectroscopic analyses. Also, different ML algorithms were used to model and predict the hydrochar solid yield, properties, and nutrients content. FeCl₃ impregnation increased Fe-phosphate content, while it reduced H/C and O/C ratios and hydroxyapatite P content, and therefore improved C stability and P availability in the HC-Fe as compared to HC, particularly under lower pH (4), temperature of 220 ℃, and at 120 min. The generalized additive ML model outperformed the other models for predicting the HC properties with a correlation coefficient of 0.86. The ML analysis showed that the most influential features on the hydrochar C stability were the H and O contents in the biomass, while P availability in HC was more dependent on the C, N and O contents in biomass. These results provided optimal production conditions for Fe-engineered manure hydrochar and identified the best performing ML model for predicting hydrochar properties. The main implication of this study is that it offers a high potential to improve the utilization of biowastes and produce biowaste-derived engineered hydrochar with high C stability and P availability on a large scale.

Biochar is a promising technology for carbon storage and greenhouse gas (GHG) reduction, but optimizing it is challenging due to the complexity of natural systems. Machine learning (ML) and natural language processing (NLP) offer solutions through enhanced data analysis and pattern recognition, ushering in a new era of biochar research.

Considerable carbon emissions from the cement industry pose a notable challenge to achieving long-term sustainable development and creating an enriched social environment. Biochar (BC) obtained from biomass pyrolysis can be used as a carbon-negative material, and it plays a crucial role in the reduction of global carbon emissions. The development of more efficient and cost-effective technologies to fully realize this potential and reduce the environmental impact of BC production and use remains a formidable challenge. The utilization of BC to prepare sustainable cementitious composites with economically value-added benefits has recently attracted much research interest. Therefore, this review analyzes factors influencing the physicochemical properties of BC and their optimization methods, as well as the impact of BC addition on various cement composites and their potential applications. Besides, recent advances in machine learning for predicting the properties of composites and the environmental-economic implications of material are reviewed. The progress and challenges of BC–cement composites are discussed and potential directions for exploration are provided. Therefore, it is recommended to explore commercialization pathways tailored to local conditions and to develop machine learning models for performance prediction and life-cycle analysis, thereby promoting the widespread application of BC in industry and construction.

Biocomposite filaments for material extrusion (MEX) additive manufacturing, particularly those derived from agricultural biomass, have attracted significant research and industrial interest. Biochar is a well-documented reinforcement agent that is used in several polymeric matrices. However, systematic research efforts regarding the quality scores of parts built with MEX 3D printing with biochar-based filaments are marginal. Herein, the impact of biochar loading on the quality metrics of the five most popular polymers for MEX 3D printing (ABS, HDPE, PETG, PP, and PLA) is quantitatively examined in depth. Sophisticated and massive Non-Destructive Tests (NDTs) were conducted, and the impact of biochar loading on the critical quality indicators (CQIs), including porosity, dimensional conformity, and surface roughness, was documented. The quality scores for the biochar filler loading, also five in total, were statistically correlated with the corresponding reinforcement metrics for the five polymeric matrices. A statistically significant antagonistic interaction between the tensile strength course and porosity/dimensional deviation metrics, particularly for PETG, was observed. It can be concluded that the lowest porosity and dimensional deviation are associated with the highest strength. The 4 wt% biocomposite exhibited optimal quality performance in most polymers studied.

Cadmium (Cd) contamination in the environment is widespread, making it crucial to reduce Cd accumulation in cereal crops like wheat. However, strategies that not only mitigate Cd pollution but also address other environmental challenges, such as invasive species management, remain unclear. This study introduces an innovative approach combining molybdenum nanoparticles (Mo NPs, 1 µM) and biochar biofilters derived from the invasive plant Mikania micrantha (IPMM), targeting the biochemical and molecular responses of wheat under Cd stress (100 µM). Our findings showed that this novel combination significantly improved wheat physiological characteristics, growth, root architecture, elemental profile, osmoregulation, carotenoid, chlorophyll, gas exchange, and photosynthetic efficiency. Remarkably, simultaneous supply of IPMM biochar biofilters and Mo NPs substantially modulated the Cd translocation, reducing its accumulation in root (30.54%) and shoot (53.59%). Additionally, this strategy not only preserved mesophyll cell structures and the membrane integrity, but also strengthened and activated the oxidative defense systems through the regulation of genetic expressions. This synergistic approach advances the Cd alleviating techniques and offers a sustainable solution for utilizing invasive plants as a potential resource. By addressing both heavy metal pollution and ecological challenges, it provides a promising solution for safer crop production in Cd-contaminated environments.

This study investigated the application of biochar and microbial-inoculated biochar in municipal solid waste (MSW) composting to enhance and accelerate the process. Microbial consortium from the active composting phase was utilized for inoculation and biofilm formation on the biochar surface. Five experimental windrow piles were established, including a control pile without biochar, and piles amended with either biochar or microbial-inoculated biochar. The composting process and the quality of the final product were evaluated by analyzing a range of physicochemical and biological parameters. The results demonstrated that piles amended with inoculated biochar exhibited higher levels of FDA hydrolytic activity and organic matter reduction, indicating enhanced microbial activity. Notably, piles 3 and 5, amended with biochar inoculated with a bacterial consortium and a bacterial-fungal consortium, respectively, achieved the highest composting temperatures (65 °C) and produced the highest-quality end products (C/N ratio: 10.1–11.8, Germination index: 100, and fecal coliform levels within acceptable limits) compared to the control piles. These findings provide valuable insights into the practical application of microbial-inoculated biochar in the real field of MSW composting, offering a promising approach to optimize composting efficiency and product quality.

The effects of biochar on methane emissions from soils are well understood. However, biochar effects on methane production from livestock have received less attention. In this study, a biochar-mineral supplement for livestock was developed by pyrolyzing a mixture of wheat straw, aluminosilicates, iron sulfate, and zinc oxide at 600 ℃. The supplement was then activated using peracetic and propionic acids, and potassium nitrate. The activated biochar-mineral supplement was characterized using analytical techniques. A high surface area, a high concentration of oxygen-containing functional groups, and a high concentration of free radicals, associated with O and Fe unpaired electrons, assisted the supplement with catalysing the oxidation of methane. Microstructural analysis of the supplement suggested the formation of organo-mineral phases, rich in C, O, Fe, Si, Al, K and Ca, indicating that the biochar reacted with mineral additives to preserve them. To assess the potential of the supplement to reduce methane produced form livestock, an in vitro batch culture incubation was conducted (n = 3) with rumen fluid sourced from Holstein–Friesian steers. The supplement was incubated at inclusion rates of 0% (control), 1.5%, 4.0% and 6.0% of dry matter (DM), with a Rhodes grass hay substrate. Compared to the control, the supplement reduced cumulative gas production by 10.1% and 12.7% and methane production by 19.03% and 29.32% after 48 h when included at 4.0% and 6.0% DM (P < 0.05), respectively, without causing any detrimental impacts on fermentation parameters. The supplement assisted with reducing the concentration of dissolved mineral nutrients, such as P and Mg, when included at 4.0% and 6.0% DM (P < 0.05).

Climate change and unbalanced energy demand and consumption require innovative approaches to the development of sustainable and renewable energy technologies. Phase change materials (PCMs) present exceptional solutions for zero-energy thermal management due to their outstanding energy storage density at an isothermal phase transition. However, the low thermal transport and thermal stability of bulk PCMs, as well as the expensive and complex synthesis of additive materials, hinder their large-scale utilization. In this study, food-waste-derived engineered biochar (FW) is produced via slow pyrolysis to improve the thermal properties of a microencapsulated bio-PCM (B28). The thermal performance of biochar-PCM composites is evaluated based on two biochar preparation systems: varying activation temperatures (carbonized at 400 °C followed by KOH activation at different temperatures (500–800 °C)) and varying mass ratios between KOH and biochar. The introduction of a low (0.63 wt%) engineered biochar dopant significantly improves the thermal diffusivity of B28 by more than 1.3-fold. The biochar-PCM microcapsule composites present fusion and crystalline isothermal phase transition temperatures of 29.4 ± 0.38 °C and 16.7 ± 0.13 °C, respectively. Moreover, the bio-PCM exhibits a highly efficient energy per unit mass of 61.6 kJ kg^–1, which is 101.7% of the energy storage capacity of bulk B28. Additionally, the composite demonstrates high thermal stability with decomposition occurring above 195 °C, thus enabling an increase of > 20 °C in the onset decomposition point compared with pristine B28. Further analysis reveals the impact of the KOH/biochar mass ratio on the thermal properties of bio-PCM. Sample FW6PCM, in which the biochar is activated at 600 °C with a KOH/biochar mass ratio of 1, exhibits the highest enthalpy storage capacity. This study suggests a promising strategy for designing high-performance, eco-friendly, and scalable bio-based composite PCMs by overcoming the long-standing bottleneck of microcapsules, which is crucial for advanced thermal management applications such as cooling and green buildings.

Persistent free radicals (PFRs) in biochar have attracted wide attention due to their multifaceted roles in the environment. The regulation of PFRs in biochar is not only beneficial to broaden its application potential, but also eliminates its environmental risks. However, as a common biochar modification reagent, phosphoric acid (H₃PO₄) has not been studied in the field of PFRs regulation. Herein, this study systematically investigated the effect of H₃PO₄ on PFRs in biochar under various conditions. The results indicated that H₃PO₄ promoted the formation of PFRs in biochar at low pyrolysis temperature (< 500 °C), owing to the positive effect of catalytic cross-linking on the degradation of biomass precursor. Yet, H₃PO₄ reduced PFRs in biochar at high pyrolysis temperature (≥ 500 °C), since the capture of H∙ or HO∙ by PO∙ and the steric hindrance changed by H₃PO₄, which caused the rearrangement and polycondensation of carbon structure. H₃PO₄ also favored carbon-centered PFRs as the dominant type. The ingredients of biomass precursor, including cellulose, Fe, Ti, protein, etc., contributed to different effects on PFRs under H₃PO₄ modification. This study provided new insights into the roles of H₃PO₄ on the formation and transformation of PFRs in biochar, coupled with regulation strategies in the practical application.

In this research, a novel metal-organic framework-modified biochar composite (MIL-88b@BC) was created for the first time by modifying rice husk biochar using the excellent adsorption properties of metal-organic framework (MOF), as well as reducing the solubility of MOF using biochar as a substrate, aiming to improve the understanding of the adsorption characteristics of rare-earth metal recycling and to predict its adsorption mechanism. Density functional theory (DFT) computations allowed for rationally constructing the adsorption model. According to DFT calculations, the primary processes involved in the adsorption of La³⁺ were π–π interaction and ligand exchange, wherein the surface hydroxyl group played a crucial role. MIL-88b@BC interacted better with La³⁺ than biochar or MOF did. Accompanying batch tests with the theoretical conjecture's verification demonstrated that the pseudo-second-order model and the Langmuir model, respectively, provided a good fit for the adsorption kinetics and isotherms. The maximum La³⁺ adsorption capacity of MOF@BC (288.89 mg g⁻¹) was achieved at pH 6.0, which was significantly higher than the adsorbents' previously documented adsorption capacities. Confirming the DFT estimations, the adsorption capacity of BC@MIL-88b for La³⁺ was higher than that of MOF and BC. Additionally, MOF@BC can be recycled at least four times. To mitigate the growing scarcity of rare earth elements (REEs) and lessen their negative environmental effects, this work laid the path for effectively treating substantial volumes of wastewater produced while mining REEs.

Highlights

The enhancement of saline soil yield potential by biochar was well-documented, but the changes brought by biochar particle size on soil properties and crop performance are not well understood. To investigate the changes in soil properties and tomato yield due to biochar particle size under varying salt stress, we conducted a pot experiment in China Northwest’s solar greenhouse. A total of nine treatments were applied, with three different salt amounts of [S0 (no salt), S1 (0.3% dry weight), and S2 (0.6% dry weight)], and three biochar treatments of B0, B1, and B2 (0, 0.5% of large particles and 0.5% of small particles). Adding biochar did not significantly affect the measured soil chemical properties, except for pH, total nitrogen (TN), and Ca²⁺. Specifically, the addition of biochar significantly increased soil pH and TN, while reduced soil Ca²⁺ content likely due to biochar selective adsorption of Ca²⁺. Biochar particle size had opposite effects on tomato yield under varying salt stress levels. Compared to S0, the yield under B1 was 19.1% and 36.5% higher, whereas under B2, the yield was 33.1% and 44.2% lower for S1 and S2, respectively. Under no salt stress, small-size biochar increased yield by 51.0% compared to B0, largely due to the improved soil water and nutrient status. These results are of great value for developing better strategies for adding biochar with appropriate properties into saline soils to achieve greater productivity gains.

Highlights

Biochar is a porous carbon material that can effectively remove NO_x from flue gas. The influence of K element and active sites on the microscopic mechanism of NO₂ gas adsorption and reduction reaction remains elusive. Through density functional theory (DFT), two NO₂ molecules are selected on reasonable biochar models to calculate the reaction pathway. The reaction pathways involve the sequential adsorption of two NO₂ molecules at different active sites for reduction reaction, and desorption of two NO molecules and one CO₂ molecule. Through the energy barrier difference of the reaction path and interaction region indicator (IRI) analysis of important molecular structures, it was found that K atom promotes the adsorption reduction reaction in three reaction processes: the breakage of N–O bond, the desorption of NO molecule, and the dissociation of CO₂ molecule. Based on the different numbers of active sites in the four reactant models, it can be concluded that the promotion range of the K atom for the adsorption and reduction process of NO₂ molecules is 0.6157 nm. Thermodynamic and kinetic analyses indicate that the addition of K enhances the upper limit and the maximum reaction rate of the reaction pathways. This study provides certain theoretical guidance for preparing biochar to regulate NO₂ emissions.

Biochar application is known to improve soil quality, enhance nutrient bioavailability, and increase carbon retention. However, its effects on ecoenzymatic activities and stoichiometric relationships in saline-alkali soils remain poorly understood. This study examines how biochar amendments influence microbial stoichiometry, nutrient limitations, and carbon use efficiency in saline-alkali soils. We compared two types of biochar—acid-modified biochar (pH 2.3) and alkaline biochar (pH 8.8)—at application rates of 1%, 2%, and 5% in soils planted with Medicago sativa L. Our results demonstrated that alkaline biochar increased enzymatic C:N stoichiometry at higher rates, while acid-modified biochar decreased it at lower rates. Both biochar types reduced enzymatic C:P and N:P stoichiometry; alkaline biochar shifted microbial metabolism from nitrogen to phosphorus limitation, while acid-modified biochar alleviated nitrogen limitation at rates of 2% and 5%. Furthermore, alkaline biochar at rates of 2% and 5% reduced microbial carbon limitation and enhanced carbon use efficiency, whereas acid-modified biochar did not. Microbial carbon use efficiency was consistently higher with alkaline biochar than with acid-modified biochar at equivalent application rates. These findings highlight that the impact of biochar on soil microbial processes depends on the biochar feedstock type, with differences in surface adsorption properties, nutrient supply, pH, and liming effects driving changes in soil properties, microbial community dynamics, and plant growth. Our study offers insights into optimizing nutrient cycling and carbon sequestration in saline-alkali soils, demonstrating the potential of biochar in sustainable soil management.

The impact of field aged biochar (FABC) on the adsorption kinetics and transport behavior of weakly hydrophobic antibiotics in soil is scarcely discussed. This study investigated the impact of FABC on weakly hydrophobic antibiotics (sulfadiazine, SD and florfenicol, FF) transport in purple soil by comparing fresh biochar (FBC), one-year aged biochar (ABC1), and five-year aged biochar (ABC5). Through batch adsorption, soil column experiments, and Hydrus 1D modeling, this study examined the evolution of physicochemical properties of biochar, their effects on soil porosity and dispersion, and antibiotic adsorption. Results showed that aging significantly altered biochar characteristics, with carbon (C) content decreasing by 10.40% while oxygen (O) content increased by 40.52%. ABC1 demonstrated optimal performance with a 99.28% increase in specific surface area (SSA) and enhanced oxygen-containing functional groups, leading to maximum antibiotic retention rates of 16.57% for SD and 24.78% for FF. Although ABC5 showed decreased SSA and adsorption capacity, it maintained stable remediation effects through enhanced biochar–soil interactions, as evidenced by increased dispersivity (λ) and hydrodynamic dispersion coefficient (D). The two-site chemical nonequilibrium model (TSM) revealed that the fraction of equilibrium adsorption sites (f) increased from 0.1164 to 0.3514 after aging, indicating improved antibiotic retention. These findings demonstrate that while one-year aging enhanced remediation capacity, five-year aging stabilized environmental effects through modified soil structure.

Hydrogen evolution reaction (HER) and oxygen evolution reaction (OER), the two concurrent reactions for the electrolytic production of green H₂, require low-cost and sustainable electrocatalysts for their scale-up, as for example non-noble metals and carbonaceous structures with high surface area. Our hypothesis is that the activated-doped biochar decorated with Mo and Co provides high porosity and active site dispersion, enhancing HER and OER kinetics with low overpotentials and high stability in an alkaline medium. Here, a bifunctional Mo/Co electrocatalyst supported on N-doped biochar obtained from hazelnut shells has been developed, thus valorizing an agro-industrial residue of major importance in Chile. The activated biochar matrix, with interconnected hierarchical pores, offered a high surface area of 1102 m² g⁻¹ and I_D/I_G = 1.08 graphitization, while N-doping was observed by XPS, with the formation of N-pyridinic and N-graphitic functionalities that improved the catalytic performance. The addition of metals to the substrate allowed the formation of bimetallic Mo/Co active sites (Co₆Mo₆C), increasing the graphitization degree and improved the growth of these bimetallic sites. The electrocatalytic performance in the presence of the metals was good, revealing low overpotentials for HER (0.257 V) and OER (0.370 V) with low Tafel slopes (51 and 59 mV dec⁻¹, respectively) under alkaline conditions, also improving the electron transfer and stability.

CO₂ hydrogenation to methane is an interesting topic that can result in CO₂ mitigation, providing a solution for global warming. Using a sustainable catalyst in that process will be considered as a plus point that makes the whole system (material + application) an eco-friendly process. Therefore, scientists have focused on the biochar-supported catalysts used in the CO₂ methanation. The use of cobalt (Co) catalysts supported on sugarcane bagasse biochar (SCBB) has not been investigated for the methanation of CO₂. Therefore, this work investigated the Co/SCBB systems in the CO₂ methanation with different Co loadings starting from 0.1 to 0.8 mmol_Co-salt/g_SCB. In addition, the effect of Ce was studied, proving that Ce addition improved the catalytic activity significantly, as the catalyst 0.5Co-0.25Ce/SCBB showed the foremost conversion of CO₂ (60% at 500 °C) and the best selectivity of methane (80% at 430 °C). This research lays the foundation for utilizing Ce to enhance the catalytic properties of various transition metals that can not offer high catalytic activity alone in the carbon dioxide methanation.

Emphasizing its potential for environmental sustainability, this review investigated how biochar—a carbon-rich material obtained from biomass pyrolysis—might be used into nuclear science and technology. High surface area, porosity, and functional groups give biochar special adsorption capacity, which qualifies it as a potential instrument for radiation cleanup and improving energy economy in nuclear uses. From the historical development of nuclear physics to the creative application of biochar in nuclear waste management and radiation shielding as well as its contribution to sustainable nuclear energy, the study covers several spheres. Biochar presents amazing efficiency in adsorbing and immobilizing radionuclides in the field of nuclear waste management, therefore establishing itself as a viable substitute for more traditional approaches. Its uses cover handling of high-level radioactive materials as well as treating low-level radioactive effluents. The paper also looks at using biochar as radiation shielding since its carbonaceous character produces strong, light-weight protective barriers. Using controlled pyrolysis and later changes, the paper addresses advanced manufacturing processes for customizing nuclear-grade biochar for particular uses. Within the nuclear industry, economic studies emphasize the affordability and possible financial gains of biochar, as well as its market potential and commercialization techniques. Lifetime analysis helps to evaluate environmental effects and sustainability by stressing the part of biochar in carbon sequestration and lowering of ecological footprints. The paper discusses safety and regulatory issues, how artificial intelligence and machine learning might be used for material optimization, and the limits and difficulties in using biochar. Practical case studies highlight its success in nuclear environments. The study ends by placing biochar as a major component in creating sustainable nuclear technology, which calls for continuous research, cooperation, and creativity.

Soil continuous monocropping obstacles pose a significant challenge to the sustainable production of cut chrysanthemums. Yet, the effectiveness of integrating biochar and microbial antagonists in alleviating these obstacles in cut chrysanthemum production remains unclear. Here, we collected soils from a 12-year continuous cropping system with a high incidence of disease to establish a pot experiment comprising four treatments: control (CK), biochar (BC), Bacillus subtilis (BM), and their combined addition (BM_BC), investigating the effects of biochar and B. subtilis on the disease incidence, plant growth, pathogenic and antagonistic microbial populations, and the bacterial and fungal communities in diseased soil. The results showed that BM_BC treatment effectively controlled the disease and significantly increased (P < 0.05) the plant biomass and root activity of cut chrysanthemum by 41.3% and 254%, respectively, compared to the CK. Notably, the BM_BC exhibited the lowest population of Fusarium oxysporum and the highest population of B. subtilis, along with the greatest alpha diversity (measured by Chao1 and Shannon indices) of both bacterial and fungal communities among the four treatments. The amendments of BC, BM, and BM_BC significantly altered the structure and composition of bacterial and fungal communities, with BM_BC primarily enriching beneficial bacteria and suppressing pathogen. Microbial co-occurrence network analysis revealed that BM_BC increased the abundance of module 2, co-dominated by bacterial and fungal species, and strengthened the interactions between them. The PLS-PM analysis demonstrated that bacteria-fungi interkingdom interactions played a crucial role in promoting the growth of cut chrysanthemums in diseased soil. Therefore, our findings underscore the synergistic effects of biochar and B. subtilis in suppressing Fusarium wilt disease and enhancing the growth of cut chrysanthemums by strengthening microbial interkingdom interactions.

The photocatalytic activation of sulfites, a common by-product in industries, is a green and sustainable technology with great promise for the treatment of refractory pollutants in water. In this study, N vacancies and N doping were constructed at precise sites in graphitic carbon nitride (CN), following the combination with biochar (BC), synthesizing the BVCN with excellent photocatalytic activation of sulfites under solar light. When the BC was 5wt% (5BVCN), the reaction rate constant of reactive red 120 (RR120) in SO₃²⁻-containing solution reached 0.0247 min⁻¹, which was 5.49 times of CN and 15.43 times of 5BVCN in SO₃²⁻-free solution. Characterizations and density functional theory (DFT) calculations revealed that N vacancies could trap electrons, while N doping regulated the electronic structure, forming mid-gap states to enhance the separation of carriers. In BVCN, BC rich in pyridinic N serves as both electron transfer channel and electron storage medium, having π-π interaction with structurally regulated CN (VCN). BVCN has narrower band gap and low recombination rate of photogenerated carriers, responds well to visible light, and is easy to firmly associated with SO₃²⁻, enhancing the electron transfer from SO₃²⁻ to BVCN. In the SO₃²⁻-containing system, the primary active species were identified as SO₃^•−, •O₂⁻ and h⁺. Moreover, BVCN exhibited good stability and recyclability. The system shows potential for treating wastewater containing sulfites, realizing resource utilization.

Biochar, a versatile environmental material, has gained significant attention for its exceptional physical and chemical properties. This comprehensive review explores the innovative preparation methods of element-doped biochar, highlighting their enhanced functionalities and groundbreaking applications across diverse fields. Drawing from conventional approaches, this study systematically investigates in-situ and exogenous doping techniques, examining their distinct advantages, limitations, and profound impacts on the morphological structure and surface chemistry of biochar. By integrating multiple elements, the research reveals how doping significantly improves the adsorption capacity, catalytic efficiency, and electrochemical performance of biochar, offering opportunities for its potential use in environmental remediation, soil enhancement, energy conversion, and even cosmetic applications. Moreover, this study introduces an original framework of “preparation–structure–performance–application”, emphasizing the importance of optimizing doping strategies and element selection to maximize versatility of biochar across multiple domains. Beyond basic insights into existing knowledge, this review provides novel perspectives for future research, particularly in areas such as carbon sequestration, pollutant adsorption, and advanced catalysis. This comprehensive synthesis not only synthesizes existing knowledge but also delivers fresh, innovative insights into the untapped potential of element-doped biochar, propelling transformative progress in sustainable materials science and beyond.

Dealing with groundwater impacted by persistent, low-concentration chlorinated solvents is a major challenge for site remediation, as technologies designed for fast contaminant removal or destruction often are not cost-effective. For long-term plume management, in situ contaminant sequestration using carbonaceous materials is a more viable strategy. Here, we prove the concept that the effectiveness of this approach can be improved by modulating the compositional and surface properties of carbonaceous materials to maximize the synergy between contaminant binding and abiotic transformation. We found that two pine wood biochars pyrolyzed at 600 and 700 °C exhibit not only faster adsorption kinetics for 1,1,2,2-tetrachloroethane than those prepared at lower temperatures (500 °C and below), but also greater efficacy in enhancing the dehydrochlorination of the contaminant. The higher catalytic efficiency is counterintuitive, as it is commonly accepted that surface carboxyl and phenolic groups are the catalytic sites. With supplementary experiments carried out using modified materials and at varied pH values, we found that the surprisingly higher catalytic activities of these two samples are due to their higher carbonate contents. Interestingly, trichloroethylene, the hydrolysis product, is more adsorptive to the biochars than the parent compound. Thus, by promoting the abiotic transformation, these two biochars enable much more effective plume interception than the less-reactive materials. The findings have important implications for dealing with long-term, persistent groundwater contamination, particularly, the “rebounding” problem often occurring post active site remediation.

The efficient conversion of distiller’s grains (DGs) into high-value products will promote the sustainable development of the Chinese spirit industry and reduce related environmental issues. Herein, a composite adsorbent material (AC-SiO₂) composed of activated carbon (AC) and silica (SiO₂) was prepared from DGs via sequential pyrolysis, KOH etching, and steam activation processes. AC-SiO₂ was used to remove benzaldehyde from the Chinese spirit to improve the aroma and quality of the spirit. The experiment results showed that, KOH etching effectively removed SiO₂ from DGs and exposing the carbon substrate for further steam activation, then the specific surface area of AC-SiO₂ extremely increased to 1213.0 m² g^–1. Steam activation introduced Si–OH/Si–H bonds on SiO₂ and –OH/–COOH groups on the carbon surface and increased the graphitization degree of the materials. After optimization of the AC-SiO₂ preparation processes, the obtained AC-SiO₂ removed 68.7% of benzaldehyde from the spirit. The high benzaldehyde removal rate of AC-SiO₂ was attributed to the synergistic effect of AC and SiO₂ components (binding energy up to − 15.45 kcal mol^–1), where benzaldehyde was preferentially adsorbed on the AC-SiO₂ interface. Specifically, highly graphitized AC promoted the planar adsorption of the benzene ring in benzaldehyde via π-π stacking, and the Si–OH/Si–H bonds on SiO₂ adsorbed the aldehyde group of benzaldehyde via hydrogen bonding. This study not only presents a novel approach to DGs resource utilization, but also provides theoretical underpinnings and technical support for the spirit quality enhancement, significantly promoting the green and sustainable development of the spirit industry.

Demolition cementitious waste poses significant environmental challenges at the end of its lifecycle. To address this, fly ash (FA), a highly leachable material and a supplementary cementitious material, was combined with biochar (BC) to produce eco-friendly mortar bricks with reduced carbon emissions and contaminant leaching. BC was incorporated at 2%, 4%, and 6% by weight, and the resulting blocks achieved compressive strengths of 8–12 MPa after 28 days, meeting Eurocode 6 standards for use in harsh conditions. Leaching tests under synthetic precipitation showed reductions in Al, Se, Ba, and Cr concentrations by 72%, 48%, 58%, and 53%, respectively, with 6% BC. While Al remained above drinking water limits, Cr levels dropped below limits when BC exceeded 4%. Leaching followed typical pH-dependent behaviour: Al exhibited an amphoteric trend, and Cr showed an oxyanionic trend, with minimal leaching at neutral pH. This study highlights the role of BC in reducing leaching potential in cementitious composites and provides critical data for geochemical modelling in sustainable demolition waste management systems.

Owing to wide application and persistence, fluridone has demonstrated side-effects on non-target plants and aquatic organisms. This study investigated the potential of biochar as remediation in soil using rice hull biochar (BCR) produced at different temperatures and in four types of soil. The results indicated that, with increasing pyrolytic temperature from 300 to 700 ºC, biochar properties changed, for example, specific surface area values increased from 38.21 to 126.12 m² g⁻¹. Sorption affinity (K_f) of BCR ranged from 409 to 1352 and 1301 to 6666 (μg/g)/(mg/L)ⁿ for fluridone and its metabolite fluridone acid respectively. After amendment with 2% BCR500, fluridone and fluridone acid could easily be adsorbed in different types of soils, and K_f values were 1.30–3.73 times higher than those in pure soil. Half-lives values varied between different soils and fluridone acid (179–306 days) persisted significantly longer than fluridone (39–179 days) in soil. After amendment with 2% BCR500, fluridone and fluridone acid were degraded faster. Experiments under sterilized conditions demonstrated biodegradation to be the dominant process in unamended (61.59%–64.70%) and amended (67.71%–77.67%) soil. Bioinformatic analysis showed that fluridone reduced the diversity of the soil microbial community, but the abundance of microorganisms with degradation function increased and these became dominant species after BCR was added, particularly with higher numbers of degrading bacteria like Lysobacter, Pseudonocardia and Sphingomonas. Co-occurrences also revealed that BCR tightened bacterial connection and relieved fluridone stress. This work helps us better understand these processes and optimize the application of biochar for reducing pesticide contamination in agricultural soils.

Ball milling technology has become an important method for material modification due to its high efficiency, environmental protection and economy. However, previous studies mainly focused on the adjustment of ball milling parameters and lacked an in-depth understanding of the effect of ball milling atmosphere on material properties. To this end, siderite/biochar composites (BM-SD/BCs) were prepared by ball milling technique and the effects of different ball milling atmospheres (air, nitrogen, vacuum) on the physicochemical properties of the composites and their catalytic performance were systematically investigated. The results showed that the N/BM-SD/BC prepared under nitrogen atmosphere exhibited excellent catalytic performance in phenol removal efficiency of 90.3%, which was significantly higher than that of the A/BM-SD/BC prepared under air atmosphere (73.8%) and the V/BM-SD/BC prepared under vacuum atmosphere (81.3%). Characterization analysis revealed that the ball milling treatment markedly altered the surface morphology and structural properties of the composites. Specifically, the composites ball-milled under nitrogen atmosphere exhibited smaller particle sizes, larger specific surface area (ascending from 27.0 to 187.6 m² g⁻¹), and richer distribution of surface functional groups and Fe(II) species. All these characteristics significantly enhanced their redox activities. This structural optimization not only increased the active sites of the composites, but also effectively enhanced their activation of persulfate (PS), which was capable of generating a variety of reactive radicals (such as SO₄^−·, ^·OH, and ^·O₂⁻) for the efficient degradation of phenol, in which ^·OH and ^·O₂⁻ contributed 50.7% and 25.3% of phenol removal, respectively. In addition, the N/BM-SD/BC/PS system demonstrated its capability to degrade phenol across a broad pH spectrum (especially in the pH range of actual wastewater), showing good adaptability and potential for practical application. This study reveals the key role of ball milling atmosphere in the modulation of material physicochemical properties and reactivity, which provides theoretical support for the future application of ball milling in the engineering of nanomaterials.

Biochar has recently emerged as a cutting-edge solution for environmental remediation, distinguishing itself from traditional methods. This essay presents a comprehensive examination of the effectiveness and future prospects of biochar through innovative bibliometric analysis techniques. Since 2010, the global application of biochar as a soil amendment has surged, evolving from its conventional uses in fuel and carbon sequestration to enhancing soil functionality, a novel approach in environmental science. With over 250 research reports published during this period, biochar has demonstrated exceptional potential in improving soil properties, including water retention, nutrient cycling, and the promotion of beneficial microbial communities. However, this work identifies a critical innovation gap: the lack of a precise definition for biochar as a soil amendment in the United States, as well as the need for interdisciplinary research that bridges soil science with plant molecular biology and genetics. Our investigation not only confirms the effectiveness of biochar as a sustainable remediation method, but also suggests its potential applications in mitigating pollution and addressing climate change impacts. While current literature primarily focuses on the role of biochar in enhancing soil fertility, we have uncovered emerging trends, pointing to its use in remediating contaminated land and removing organic pollutants, which is innovative application in the field. Additionally, we highlight the novel use of advanced tools such as scanning electron microscopy (SEM) and X-ray diffraction (XRD) to study changes following biochar application, offering a new perspective on biochar research. The versatility and effectiveness of biochar in environmental remediation make it a promising tool for sustainable soil management and pollution mitigation, underscoring the need for continued interdisciplinary research to fully realize its potential.

Biochar has demonstrated to have ability to improve soil properties and boost plant productivity. However, the underlying mechanisms by which dissolved organic matter (DOM) fluorescent components and microbial communities in black soil regions contribute to plant productivity remain uncertain. To address this gap, a long-term field experiment was conducted in Northeastern China’s black soil region, investigating how varying biochar application rates (0, 15.75, 31.50, and 47.25 t ha⁻¹) influence DOM fluorescence properties and the composition of soil microbial communities. Employing fluorescence excitation–emission matrix-parallel factor analysis (EEM-PARAFAC) and high-throughput sequencing, the research systematically analyzed how biochar amendments influence DOM composition, fluorescence properties, microbial diversity, and their interrelations. The findings demonstrated that biochar significantly modified DOM composition, increasing the proportions of protein-like and humic substances while enhancing its aromaticity and stability. A medium application rate (31.5 t ha⁻¹) notably improved alpha- and beta-diversity within the soil microbial community, optimized a co-occurrence network dominated by Proteobacteria and Acidobacteria, and facilitated key DOM transformations and nutrient cycling. In contrast, a high biochar application rate (47.25 t ha⁻¹) negatively impacted the stability of microbial communities. Structural equation modeling (SEM) revealed that biochar indirectly boosted crop yields by modulating DOM fluorescence and microbial community dynamics. The insights gained from this study provide practical guidance for optimizing biochar application rates, maximizing its benefits, and mitigating potential ecological risks in black soil systems.

Biochar can regulate methane (CH₄) emissions from paddy soils. However, the mechanism through which biochar conductivity influences methanogenesis in paddy soils remains unclear. In this study, biochar samples with varying conductivity levels were prepared by incorporating different amounts of graphene. The dissolved organic matter (DOM) derived from biochar was completely eliminated before its application. The addition of conductive biochar in the paddy soil system increased CH₄ production by enhancing the electron transfer rate (ETR), as demonstrated by a significant positive correlation between CH₄ production and ETR. Electrochemical experiments conducted after the removal of DOM from paddy soil demonstrated that biochar enhanced the ETR in paddy soils by facilitating the electron transfer of dissolved organic matter. Anthraquinone-2,6-disulfonate (AQDS), a common analogue for quinone- and hydroquinone-containing molecules in DOM, facilitates electron transfer and serves as a model for electrochemically active DOM. An experiment with biochar and AQDS confirmed that biochar enhanced the ETR of AQDS, supporting previous findings. Following incubation, methanogenic archaea showed no significant change in relative abundance across systems, demonstrating that that biochar enhanced methanogenesis solely via accelerated ETRs, without altering the microbial community composition. This study deepens our understanding of how biochar conductivity affects methanogenesis and offers scientific guidance for optimising the use of biochar in paddy soils.

Manure-derived biochar is widely used for soil remediation, yet the long-term effects of aging on the stability of its endogenous heavy metals remain unclear. This study aims to investigate how freeze–thaw (FT) cycle aging influences the physicochemical properties and endogenous heavy metal stability of chicken manure (CM)-derived biochars produced at different pyrolysis temperatures (350 °C, 550 °C, and 750 °C). By subjecting these biochars to accelerated FT aging, we compared changes in structural integrity and heavy metal speciation. FT cycles significantly induced physical fragmentation in porous biochar, reducing pH, graphitization, and stability while increasing the total specific surface area (SSA) and oxygen-containing functional groups. Biochars produced at higher pyrolysis temperatures demonstrated greater susceptibility to structural breakdown during FT aging, which led to increased leachability and phyto-availability of heavy metals. Chemical speciation analysis revealed that biochar produced at 750 °C (CMB-750) experienced a pronounced transformation of heavy metals into less stable forms during FT aging, with acid-soluble (F1) fractions of Zn, Cu, Ni, Cr, Pb, and Cd in aged biochar (ACMB-750) increasing to 34.97%, 18.06%, 18.34%, 13.16%, 31.23%, and 6.31%, respectively. These findings highlight the risks of presuming that higher pyrolysis temperatures always enhance heavy metals retention and emphasize the importance of considering the entire biochar lifecycle, from fabrication and soil remediation to aging, when optimizing its safe and sustainable agricultural use.

Eliminating pesticide residues in soil through the Advanced Oxidation Processes (AOPs) has been attracted a lot of attention in recent years. However, the potential of converting them into small molecular nutrients such as ammonium nitrogen (NH₄⁺-N) has been significantly ignored. Herein, we systematically detected the transformation of clothianidin (CTD) into NH₄⁺-N through AOPs and the following effect on the growth of lettuce. Fe₃S₄-loaded biochar (BC@Fe₃S₄) was synthesized in one step through hydrothermal method, possessing excellent catalytic capacity to activate peroxymonosulfate (PMS). The results showed that the generated NH₄⁺-N could reach up to 3.029 mg L⁻¹ in soil–water system containing 20 mg L⁻¹ of CTD after the treatment of BC@Fe₃S₄ + PMS. However, when the concentration of CTD in soil was 20 mg kg⁻¹, the dry weight of lettuce was 17.3 mg/plant, and the dry weight of lettuce in CTD-contaminated soil with this concentration was 29.3 mg/plant after treatment by BC@Fe₃S₄ + PMS, and no CTD residue was detected. The results of lettuce cultivation showed that CTD in the system was converted to NH₄⁺-N after treatment with BC@Fe₃S₄ + PMS, which resulted in increased dry matter accumulation and decreased residue of lettuce seedlings. Meanwhile, LC–MS/MS analysis revealed three main degradation routes involved in the CTD degradation process. T.E.S.T-QSAR was carried out to simulate the toxicity of all degradation intermediates to Fathead minnow and T.pyriformis, manifesting that the CTD toxicity decreased after BC@Fe₃S₄ + PMS treatment. Further analysis indicated that the degradation of CTD and the formation of NH₄⁺-N occurred simultaneously, where •OH, ¹O₂ and SO₄^•− played a leading role in trigging those reactions. This work explains in detail the mechanism by which pesticides are converted into nutrients, providing feasible strategies and new perspectives for soil remediation.

This study evaluated the efficiency of different soilless growth media for sustainable basil cultivation compared to traditional potting mix with continuous monitoring. This paper presents a novel approach of continuous physico-chemical monitoring of basil growth using Internet of Things (IoT) enabled smart growth cabinets. Six growth media combinations—sand, coir, and biochar (unsoaked and nutrient-enriched), sand, coir, and perlite, and potting mix with 10% and 20% biochar—were tested over 30 days under controlled conditions, with potting mix as the control. The pH, electrical conductivity and cation exchange capacity of growth mixes were analyzed before and after, along with key growth metrics such as root length, shoot length, leaf number, fresh and dry plant weight and leaf area index (LAI) were analysed. Results indicated that incorporating 10 to 20% biochar into potting mix optimally enhanced basil growth, with significant improvements in root development and the LAI of the plant. Biochar soaked in nutrient solution demonstrated three times higher plant weight compared to unsoaked biochar, indicating the potential of biochar as a slow-release nutrient matrix. Despite the high exchangeable potassium and sodium of biochar, calcium and magnesium remained dominant in the potting mix, indicating the need for optimising biochar use as a horticultural growth media according to the plant type chosen. Replacement of 10 to 20% of potting mix by biochar supports the circular economy goals by enhancing plant growth and sequestering carbon.

Although the immediate benefits of biochar in enhancing nitrogen cycling and crop productivity are well documented, its residual effects across different biochar types and irrigation regimes over successive growing seasons have not been fully elucidated. Here, we assessed the residual effects of softwood (SWB) and wheat-straw (WSB) biochar on soil–plant nitrogen (N) dynamics and maize (Zea mays L.) productivity over two growing seasons following a one-time application. Experiments were conducted in 2021 and 2022 under full (FI), deficit (DI), and alternate partial root-zone drying (APRI) irrigation. In both years, despite limited changes in water consumption and total N uptake, WSB-APRI combination improved total dry biomass (+ 13.5%), harvest index (+ 4.4%), water use efficiency (+ 26.7%), and N use efficiency (+ 10.3%). These improvements were linked to enhanced microbial activity (+ 26.8–51.2%) and soil N availability (+ 4.8–13.2%), which stimulated root growth (+ 7.4–22.7%) and N uptake (+ 7.0–17.8%) under water stress. However, under reduced irrigation in 2021, SWB markedly suppressed microbial respiration (− 42.4%) and N availability (− 29.2%), which in turn led to compromised crop performance, particularly under DI. Partial least squares path modeling revealed that microbial activity and root traits indirectly affected maize water and N use efficiency by influencing water consumption, N uptake, and biomass accumulation. Notably, excessive N uptake reduced N use efficiency, whereas biomass accumulation enhanced it. Considering the residual effects of biochar, APRI combined with WSB offers a promising approach to continuously enhance water-nitrogen coordination and maintain maize productivity under limited irrigation.

Biochar-derived dissolved organic matter (DOM) is a highly active component that plays a critical and complex role in the immobilization of heavy metals. This study systematically investigated the impact of DOM on Pb(II) adsorption by comparing the adsorption capacities of biochar before and after DOM removal, thereby unveiling the underlying mechanisms through advanced spectroscopic techniques. Adsorption experiments demonstrated that water-washed biochar (WBC) exhibited a markedly reduced adsorption capacity (35.0 mg g⁻¹) compared to untreated biochar (BC) (96.2 mg g⁻¹), highlighting the essential role of DOM in enhancing Pb(II) adsorption. Kinetic and isothermal analyses revealed that the adsorption process was predominantly chemical in nature, as evidenced by the excellent fit of experimental data to the pseudo-second-order, Freundlich, and Temkin models. FTIR and XPS analyses confirmed that oxygen-containing functional groups, including hydroxyl, carboxyl, carbonyl, and ether groups, actively participated in Pb(II) complexation in BC, WBC, and DOM. Spectral shifts and changes in the relative abundance of C–O and C = O bonds further supported this conclusion. The Pb 4f spectra indicated that Pb(II) was primarily retained as Pb₃(OH)₂(CO₃)₂, with complexation identified as the dominant mechanism, followed by co-precipitation. UV differential log-transformed absorption spectra derived from titration experiments, revealed the heterogeneity of Pb(II) binding sites within DOM. Furthermore, excitation-emission matrix fluorescence spectroscopy coupled with parallel factor analysis (EEM-PARAFAC) identified three humic-like components. Among these, component C3 (humic-like and tyrosine substance) exhibited the strongest binding affinity for Pb(II). Hetero-2DCOS analysis, combined with additional spectroscopic techniques, demonstrated that carboxyl groups in humic-like substances were the most reactive sites for Pb(II) binding. These findings provide molecular-level insights into the structural and functional characteristics of biochar-derived DOM-Pb(II) complexes, offering a scientific basis for optimizing biochar-based strategies for heavy metal pollution remediation.

Biochar addition to soils is a promising strategy for mitigating cadmium (Cd) mobilization and carbon emission, but how biochar-to-soil interaction enabling a synergy between these two goals at redox heterointerface remains unclear. Herein, we conducted three types of paddy soil incubations with phosphorus/iron-doped biochar to explore the underlying factors and processes controlling Cd and carbon transformation under redox conditions. Upon flooding, lower soil redox potential resulted in soluble and extractable Cd transformed into Fe/Mn-bound fraction, coinciding with elevated CO₂ and CH₄ fluxes. During subsequent drainage, soil pH decrease caused associated Cd transformed back into exchangeable fraction, coupled with cumulative CO₂ dropped. Both porewater and sequential extraction results revealed that the remobilization of Cd and carbon during redox fluctuations is largely related to Fe/Mn (hydr)oxide-induced effects. Microscopic and spectroscopic techniques determined that the organo-mineral (e.g., aliphatic C and Fe–O/Si–O groups) interactions are of crucial importance in influencing Cd and carbon distribution patterns on soil microaggregates. Further sequencing and correlation analyses vertified that this biochar facilitated simultaneous Cd and carbon retention via altering soil biogeochemistry, especially redox-controlled abiotic and microbial transformation processes. Overall, these findings shed light on the interactive effects of Cd and carbon mitigation with biochar amendment for redox paddy environments.

Biochar offers promising solutions for agricultural sustainability, yet the intricate mechanisms governing rhizosphere metabolite-microbe-soil interactions remain poorly understood. Through a decade-long field experiment, the effects of sustained biochar application (BC1: 3 t ha⁻¹ and BC2: 6 t ha⁻¹) versus conventional fertilization (CF) in a continuous soybean system were investigated. The results showed that biochar improved soil properties, especially, BC2, which significantly enhanced porosity (+ 12.71%), pH (+ 11.60%), soil organic carbon (+ 112.45%), enzymatic activities and nutrient content, while reducing bulk density (− 9.92%). Notably, the biochar restructured microbial community networks, increasing beneficial taxa (Firmicutes, Enterococcus, Pseudomonas, Ascomycota and Mortierellomycota) while suppressing potential pathogens. Meanwhile, the biochar significantly optimized rhizosphere metabolites, including key defensive compounds (di-O-methyl quercetin, capric acid, hypoxanthines, etc.), and optimized the differential metabolites enriched in the isoflavonoid biosynthesis pathway. Multi-omics analysis revealed strong correlations between differential metabolites and improved soil properties under biochar amendment. Accordingly, these improvements manifested in plant performance, including enhanced root development, plant height, biomass accumulation, and yield. Furthermore, the PLS-PM analysis demonstrated that biochar could promote soybean growth in two key pathway mechanisms that directly enhance soil properties, and indirectly improve soil properties by negatively regulating the key metabolites (capric acid, phosphocreatine, beta 1-tomatine, and daidzin). Our findings provide critical theoretical insights for addressing challenges in soybean continuous cropping systems and advancing sustainable farming practices.

As the benefits of biochar amendment for soil remediation have been widely recognized, the potential risk of downward nematode migration has received increasing attention. Dissolved biochar (DBC) is an essential component of biochar that is easily absorbed and utilized by organisms. However, the effect of DBC on nematodes remains unclear. This study aimed to assess the effect of DBC on Caenorhabditis elegans. The response of C. elegans to different DBC concentrations (0, 250, 500, and 1000 mg L⁻¹) was investigated using culture assays and RNA-seq analysis. The results revealed a hormetic effect of DBC, with low concentrations (250–500 mg L⁻¹) promoting growth and high concentrations (≥ 1000 mg L⁻¹) inhibiting growth. Meanwhile, DBC affected nematode movement and neuromuscular function. Transcriptome analysis revealed a dose-dependent increase in the number of differentially expressed genes (DEGs), with key changes related to metabolism, the stress response, and cellular processes. Weighted gene coexpression network analysis (WGCNA) revealed that gene modules, such as dyf-11, ins-16, and hsp-12.6, were strongly correlated with traits such as body size and reproduction. Additionally, genes involved in ciliary function, insulin signaling, and neurotransmitter biosynthesis were affected, highlighting the impact of DBC on growth and movement regulation. These findings suggest the need to carefully manage biochar application in agriculture to balance its benefits and potential risks to soil organisms like nematodes.

Biochar has great potential in the application areas of carbon sequestration and environmental remediation. A significant amount of dissolved organic matter (DOM) may be released from biochar, which is highly reactive and mobile. However, it is unknown how this highly reactive DOM migrates in soil column, especially in rainfall events. In this study, pristine and aged corn biochars were applied to simulated soil columns filled with hematite/quartz or montmorillonite/quartz (3:7, w:w), and the DOM vertical migration was investigated under high- and low-intensity rainfalls. Results showed that montmorillonite could significantly inhibit the migration of the DOM by over 80% compared to the pure quartz system and 50% compared to hematite/quartz system. Minerals, especially montmorillonite, mainly preferentially adsorbed humic-like substance of DOM compared to polycyclic aromatic-like substance. Notably, under the same cumulative rainfall amount, DOM concentration gradually increased with the number of rainfall events in low-intensity rainfalls, but decreased sharply in high-intensity rainfalls. The relatively higher DOM concentration is beneficial to DOM sorption on minerals. These findings demonstrated that low-intensity rainfall facilitated the DOM retention on minerals especially in montmorillonite-rich soils.