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Recycling of phosphorus (P) from waste streams such as sewage sludge to agriculture is essential in order to ensure future food security. Land application of sewage sludge is controversial due to its content of pollutants, such as heavy metals and toxic organic compounds. Pyrolysis is a technology that can eliminate harmful contaminants while enabling the recycling of P in the sludge. Organic pollutants are degraded during pyrolysis, while most of the P remains and approximately 40 % of the carbon is retained in a stable form in the biochar. When performing pyrolysis at a temperature of around 800 °C or more, cadmium is evaporated and can be separated from the biochar. Electricity-driven pyrolysis facilitates this by means of easier temperature control. The aim of the present study was to undertake a Life Cycle Assessment (LCA) to evaluate the environmental impacts of high-temperature electricity-driven pyrolysis of sewage sludge, including the separation of cadmium, and field application of sludge biochar as compared with sewage sludge storage and field application. The results showed that pyrolysis can offer a more climate-friendly solution due to avoided greenhouse gas emissions from the sludge and to carbon sequestration of the biochar. However, field application of untreated sludge resulted in a higher application of nitrogen (N) and more plant-available P. Agricultural modelling tools indicated that this produces higher crop yields than biochar application. In the LCA model, higher crop yields lead to savings in land use and water consumption as the higher yields can replace other crop production. The lower plant availability of biochar P implies a possible risk of lower yields when the P application is restricted based on total P, and a risk of greater P loss with soil erosion to the environment. Overall, the present study stresses the importance of including the long-term agronomic impacts of sludge and biochar field application in LCAs, and highlights the trade-offs that need to be considered in decision-making regarding the implementation of pyrolysis technology. [Display omitted] • LCA of electricity-driven pyrolysis, with temperature control for cadmium removal. • Pyrolysis benefits the climate through C sequestration and reduced GHG emissions. • Pyrolysis reduces human toxicity due to removal of cadmium and organic chemicals. • Agricultural modelling suggests higher crop yields after sewage sludge application. • Low P-availability in biochar risks higher P loss with erosion and lower crop yield. [ABSTRACT FROM AUTHOR]

Photogenerated electrons and holes are transferred to g-C 3 N 4 and h-BN, respectively. Biochar acts as an electron transmitter to accelerate electron transport in the heterojunction. Biochar as an electron reservoir and the heterojunction together inhibit the recombination of photogenerated carriers. ·O 2 – and h+ jointly attack the dye azo dye molecules to degrade them. [Display omitted] • BC/h-BN/g-C 3 N 4 with spherical lamellar cluster morphology was synthesized. • Biochar is the excellent electron transfer and storage in BNC. • Biochar made the photoresponse range of photocatalyst appear obvious redshift. • LVRPA, TRPA and τ app of photocatalyst were calculated by SFM model. • Electrons and holes migrated and separated efficiently in BNC. The biochar/h-BN/g-C 3 N 4 (BNC) composite photocatalyst with a spherical sheet cluster structure, was successfully synthesized. Under simulated solar light irradiation, the photocatalytic degradation rate of reactive red 120 by BNC was 87.94 % within 90 min, corresponding to a 3.57-fold higher kinetic constant than that of g-C 3 N 4. The band structure and electron transfer path in BNC were determined using characterizations and density functional theory (DFT) calculations, confirming a type II heterojunction forming. The attraction of h-BN to h+ by electrostatic interaction and biochar's capacity for both electron transfer and storage were confirmed. Doping of biochar was also found to enhance light absorption and provide O vacancy. The existence of piezoelectric effect assisted the movement of photogenerated carriers to the material surface. In the system, the main active oxidation species were h+ and ·O 2 –. By calculating optical characteristics, the practical activity of photocatalysts is evaluated. Results indicated that the optimal dosage of BNC was 0.5 g/L in the planar reactor, corresponding to an optical thickness of 2.61 calculated by the six-flux radiation absorption–scattering model (SFM). Biochar doping was found to enhance light absorption. A novel photocatalytic mechanism was proposed for promising matel-free BNC. [ABSTRACT FROM AUTHOR]

[Display omitted] • S-nZVI-BC/PSSA can simultaneously remove Microcystis aeruginosa and MC-LR. • MC-LR is degraded mainly through the oxidation of SO 4 -• and •OH. • DFT shows that C = C-C = C bond on Adda was more vulnerable to attack by SO 4 -• and •OH. • S-nZVI-BC/PSSA inhibits algae by regulating genes such as ATP and cytochrome. • The degradation pathways of MC-LR are proposed. As a hepatotoxin generated by the excessive proliferation of Microcystis aeruginosa , Microcystin - LR (MC-LR) has posed serious threat to humans and wildlife. In this study, biochar supported sulfide nZVI and persulfate sustained-release agent (S-nZVI-BC/PSSA) were prepared to simultaneously remove MC-LR and Microcystis aeruginosa. Batch experiments showed that the removal efficiency of MC-LR (100 μg/L) by S-nZVI-BC/PSSA could reach 92.0 % when the BC pyrolysis temperature, the Fe/C mass ratio and the Fe/S molar ratio were 700 °C, 1:2 and 40:1, respectively. According to the results of EPR and density functional theory (DFT), the carbon–carbon conjugated diene bond (C = C-C = C) on Adda were most vulnerable to attack by the free radicals such as •OH and SO 4 -• generated by S-nZVI-BC/PSSA. The results of reactor experiments indicated that S-nZVI-BC/PSSA had good removal effect on MC-LR and Microcystis aeruginosa. According to the transcriptome analysis, S-nZVI-BC/PSSA led to the disorder of cell metabolic process by up-regulating ATP and pigment synthesis genes and down-regulating photosynthesis genes, eventually inhibiting the growth of Microcystis aeruginosa and even causing their death. In addition, the up-regulation of biological transport processes could enhance the release of MC-LR from Microcystis aeruginosa , which was completely removed by S-nZVI-BC/PSSA. Moreover, four degradation pathways of MC-LR were analyzed, and the final products were CO 2 and H 2 O. Therefore, this S-nZVI-BC/PSSA system showed great promise for practical applications in the removal of Microcystis aeruginosa and MC-LR. [ABSTRACT FROM AUTHOR]

• We made CW-MFCs with 100% biochar electrodes and biochar fillers by reeds harvested in nature. • The addition of biochar filler can improve the electricity generation performance but may cause severe filler clogging. • Adding biochar filler can improve the denitrification effect. This article investigated the electrochemical performance, water purification capacity and packing clogging of constructed wetland-microbial fuel cells coupled reactors (CW-MFCs). The CW-MFCs-B (B = 100 % biochar filler) reactor performed the best under intermittent conditions, with a power density of up to 33.7 mW/m2. Regarding TOC removal, CW-MFCs-G (G = no biochar filler) was the least effective when the system was in continuous flow. The effect of the other two reactors with biochar filler addition (BG = 50 % and B = 100 %) was similar, indicating that the biochar functioned well as the CW filler to remove organic matter. Regarding NH 4 +-N removal, removal rates varied at different HRTs: HRT = 2 days > intermittent flow > HRT = 0.5 days. Among them, CW-MFCs-B was the most effective, with a maximum of 65.10 %. The clogging index Φ b of the three reactors were 2.83 (B), 1.77 (BG), and 0.72 (G). The CW-MFCs-B reactor showed good effluent treatment and had the best electricity production but the most severe clogging. There may be a certain connection between H 2 O 2 concentration and the degree of CW clogging. CW-MFC with biochar electrode and gravel filler may be suitable for long-term operation. [ABSTRACT FROM AUTHOR]

• Propose a design route for novel iron-based catalysts to overcome the macroscopic pH limitation of AOPs. • Construction of acidic microenvironments at catalyst heterogeneous interfaces guided the activation of PMS and degradation of pollutants. • The mechanism of the macro-chemical environment influences reactive oxygen components in the process of AOPs. Iron-based catalysts are considered one of the most promising catalysts for AOPs. However, the dependence on an acidic working environment is a bottleneck for its development and widespread application. Meanwhile, the strong acidity of persulfate makes the mechanism of pH influence on the process of AOPs ambiguous. In this study, we report a co-catalyzed non-homogeneous phase-like Fenton-like system to achieve sustained degradation of organic pollutants such as sulfamethoxazole in neutral or alkaline buffer solutions. It exploits the proton trapping property of active sulfur in MoS 2 to construct an acidic microenvironment at the heterogeneous interface of the catalyst, which ensures the stable cycling of iron ions on the catalyst's surface and effectively inhibits the generation of iron sludge. Meanwhile, the influence of the chemical environment on ROS during PMS activation was explored using a buffer solution system, which provided new insights into the transformation mechanism of ROS during AOPs. [ABSTRACT FROM AUTHOR]

[Display omitted] • Protein-like substances contributed a lot to heavy metals removal in CWs. • Pyrite oxidation facilitated TP removal via the complexation of ferric hydroxide. • Biochar and pyrite promoted heterotrophic and autotrophic denitrification in CWs. • Functional bacteria related to autotrophic denitrification were enriched by pyrite. Wastewater polluted by heavy metals with low C/N ratio posed a big challenge to constructed wetlands (CWs) for sustainable advanced wastewater purification. In this study, biochar coupled with pyrite was successfully applied in CWs to simultaneously remove organics, total nitrogen (TN), total phosphorus (TP) and heavy metals, with the highest removal efficiency of 95.78%, 98.78%, 96.22% and 99.91%, respectively. Batch tests proved that the complexation of ferric hydroxide from pyrite oxidation played an important role in TP and heavy metals removal. Meanwhile, fluorescence excitation-emission matrix combined with parallel factor analysis (EEM-PARAFAC) further manifested that protein-like substances contributed a lot to heavy metals stabilization. Moreover, the multiplication of Proteobacteria , Chloroflexi at phylum level and Dechloromonas at genus level, which were capable of heterotrophic or autotrophic nitrate reducing process indicated that the denitrification capacity of CWs was significantly enhanced by biochar and pyrite. This study provided a feasible insight into the application of CWs with biochar and pyrite addition to enhance the treatment of low C/N wastewater. [ABSTRACT FROM AUTHOR]

[Display omitted] • Humins obtained from the dehydration of fructose was transformed into a novel furanyl functionalized porous biochar material. • Characterization confirms that calcination at 600 °C creates large surface area and retains abundant furan groups in biochar. • Pd/biochar catalyst provides 95% and 85% yield of THFF and 5-HMTHFF in the selective ring hydrogenation of FF and 5-HMF. • The furan rings preferential adsorption of biochar enhances hydrogenation performance and furan derivatives stability. Humins, an unavoidable by-product of the acid-catalyzed conversion of carbohydrates, significantly limits the yield of platform molecules and accounts for the majority of carbon loss in the biomass utilization processes. Therefore, the utilization and recovery of humins is highly importance to enhance the atom efficiency of biomass valorization. In this work, using potassium ferrate (K 2 FeO 4) to realize synchronous carbonization and graphitization, humins obtained from the dehydration of fructose is transformed into a novel porous biochar material and further applied to prepare noble metal based hydrogenation catalysts. By tuning the carbonization temperature, we demonstrate biochar calcined at 600 °C has large mass specific surface area while retaining abundant furan groups in the framework. With the high density of furan groups in structure, the Pd/biochar catalysts enhances the preferential adsorption capability of furanyl functional groups, thereby promoting the hydrogenation rate of furan compounds and improving the hydrogenation selectivity of furan rings. The demonstration of this novel application of humins will not only enhance the carbon efficiency of biomass conversion processes but also provide functionalized materials for catalytic applications. [ABSTRACT FROM AUTHOR]

[Display omitted] • Magnetic biochar enhanced SCFAs production efficiency during FW fermentation. • Magnetic biochar accelerated interfacial and microbial electron transfers. • Magnetic biochar enriched acid-forming bacteria associated with electroactivity. • Magnetic biochar enhanced SCFAs biosynthesis through electron transfer networks. Electron transfer is vital for microbial communities in anaerobic fermentation systems for food waste treatment. Considerable endeavors highlight the importance of interspecific electron transfer between acid-producing bacteria and methanogenic archaea. However, the contribution of electron transfer network from intracellular to extracellular in these microbes with conducive materials is unclear, and deserves more attention. This work demonstrated that magnetic biochar (as a typical conducive material) could enhance interfacial, extracellular and intracellular electron transfer networks during food waste fermentation, resulting in the improved production of short-chain fatty acids, accompanied by synchronous enhancements in solubilization, hydrolysis, and acidification steps. Further study revealed that magnetic biochar exhibited large surface area (28.5 m2/g) and high conductivity (97.6 μS/cm) with low charge transfer resistance and high catalytic activity, resulting in enriching acid-forming bacteria associated with electroactivity (e.g., Clostridium , Parabacteroides , and Fonticella). Also, magnetic biochar up-regulated the gene expressions involved in extracellular electron transfer, including membrane proteins (e.g., MtrA and MtrB) and conductive flagella (especially type IV pilus, e.g., PilA , PilB , and PilC), and intracellular electron transfer, particularly in the central pathway TCA cycle (e.g., acnA and sucA). In response to the evident stimulation of electron transfer networks (electron transport system activity increased by 204.1 % compared with the control), the critical gene expressions involved in fatty acid biosynthesis, requiring sufficient electrons and energy, were corresponding up-regulated (e.g., accA , accC , and accD), resulting in the promotion of short-chain fatty acids generation. This work would improve the in-depth understanding of electron transfer impacts on anaerobic systems and provide useful guidance for FW disposal. [ABSTRACT FROM AUTHOR]

[Display omitted] • Synergistic SO 2 reduction in carbonation process by the CaO-Char system is proposed. • Desulfurization prefers to take the reduction pathway with Ca-based sulfation suppressed. • The carbonation conversion of per CaO for LS-CSC(1:3) is 34% higher over LS. • The proportion of reduced-sulfur under LS-CSC(1:3) reaches about 85%. • Produced-CO via the CO 2 -Char Boudouard reaction plays an important role in SO 2 reduction. A novel method to effectively achieve synergistic SO 2 reduction during the carbonation process by the as-designed CaO-biochar system is developed. Coconut shells and calcined-limestone were used as biochar and calcium sources (denoted as CSC and LS), respectively. The introduced reductant creates the reduction condition making the Ca-based sulfation suppressed and the desulfurization prefers to undertake the reduction pathway during the simultaneous CO 2 /SO 2 removal process. The competition of SO 2 and CO 2 for the calcium active sites is weakened, effectively alleviating the negative effect of SO 2 presence on CO 2 carbonation and generating valuable sulfur-product. With the mass ratio of LS and CSC is 3, the carbonation conversion of the LS-CSC(1:3) is 34% higher than that of the LS and the reduced-sulfur ratio of the system reaches about 85% indicating an effective CO 2 capture synergistic SO 2 reduction. The CO produced via the Boudouard reaction between CO 2 and char is sufficient to play an important role in SO 2 reduction, which effectively promotes the decarboxylation process in the reduction of SO 2. It also facilitates the sulfur transfer from the reduced intermediate on the solid phase to the gas phase as a form of COS, promoting the reduction of SO 2 through the Claus reaction. [ABSTRACT FROM AUTHOR]

In today's technologically advancing and increasingly urbanized world, the search for new materials like biochar has become crucial to address environmental challenges such as pollution and agricultural needs. Biochar, derived from pyrolyzed biomass, offers a sustainable solution for soil improvement and pollution control. This review explores biochar's diverse applications in waste management, pollution control, and agriculture, emphasizing its potential for promoting sustainability and circular economy practices, while also discussing emerging applications like supercapacitors. Compared to previous works, this review offers a comprehensive examination of biochar's diverse applications and its potential for future trends in environmental sustainability. [Display omitted] • A review was conducted on the use of biochar for environmental remediation purposes. • Biochar plays a crucial role in enhancing soil health and boosting crop productivity. • Future research in biochar is poised to explore unconventional applications. • Biochar holds significant potential for addressing global. [ABSTRACT FROM AUTHOR]

In the pursuit of sustainability and circularity, this study aimed to develop a multi-purpose biorefinery pipeline using extracts from the green seaweed Codium sp. and transforming its post-extracted biomass into biochars, emphasizing holistic resource utilization. Five extracts from Codium sp. were evaluated, testing their antioxidant potential, cytotoxicity, photoprotective effects, anti-inflammatory activity, and inhibitory capabilities against enzymes hyaluronidase, collagenase, and elastase. The ethyl acetate extract showed the highest values in the ORAC assay, indicating antioxidant activity. However, no relevant antioxidant activity was observed in the FRAP and DPPH assays for the other extracts. The hydroethanolic extract exhibited the best anti-enzymatic capacity, inhibiting elastase by 88% at 200 μg/mL. It also demonstrated a photoprotective effect and reduced ROS production (30%) induced by UVB exposure. The hydroethanolic and ethanol extracts significantly reduced the concentration of the tumour necrosis factor-alpha (TNF-α) in response to LPS stimulation, indicating anti-inflammatory activity. The hydroethanolic post-extracted biomass was converted into biochars using conventional slow pyrolysis, hydrothermal carbonization (HTC), and acid-mediated carbonization (AMC). The biochars contained 56–75% C and 22–30% O and the one synthesized by HTC had the highest textural development. The biochar obtained by AMC showed better performance in improving soil water retention capacity, suggesting that acid surface chemistry plays a more significant role than porosity. The Codium sp. extracts and biochars produced from the post-extracted biomass have demonstrated potential as a source of valuable bioactive compounds and biomaterials for a circular economy framework and biorefinery pipeline with wide-ranging applications. [Display omitted] • Sustainable exploitation of Codium sp. within a bio-circular economy concept. • Extract bioactives with antioxidant, anti-inflammatory and photoprotective properties. • Seaweed by-products yield biochar by conventional and advanced processes. • Biochars from acid-mediated carbonization enhanced soil water retention capacity. [ABSTRACT FROM AUTHOR]

Algae is increasingly used to produce biochar by pyrolysis, while the process often makes biochar with micropore-dominant and limited porosity, showing limited removal capacity of dyes. Herein, kelp biochar with hierarchical pores and superior methylene blue (MB) removal performance is obtained by a mild KOH activation after pyrolysis to consolidate intrinsic pores, constituting to be a critical step for mesopores introduction. The as-made AKC-800 has high-surface-area and average pores of 2392 m2/g and 2.25 nm, enabling it to have amazing MB uptake of 964.5 mg/g, much larger than that of commercial activated carbons with close surface areas. The importance of mesopores in kelp biochar is clearly confirmed towards the diffusion of MB molecules. Adsorption kinetics and isotherms are well-fitted by pseudo-second-order and Langmuir model with a spontaneous endothermic behavior, and the superior removal performance is mainly owned to an increase in surface areas and decrease in ion-transport resistance by mesopores. This strategy is promising to convert kelp into efficient adsorbents for dyes removal and also cost-effective process for environmental protection on an industrial scale. [Display omitted] • Kelp biochar was produced via pre-pyrolysis and mild KOH etching process. • Biochar had mesopore-dominant structure with surface areas up to 2392 m2/g. • Self-template effect of minerals played key roles to create mesopores in biochar. • The maximum methylene blue over biochar is up to 964.5 mg/g at 25 °C. [ABSTRACT FROM AUTHOR]

In this research, a high-performance Polyamide 6/Polyvinyl Alcohol/Activated biochar (PA6/PVA/AB) composite nanofibrous membrane was developed for effective separation of oil-in-water emulsions. The membrane was produced by blend electrospinning of Polyamide 6 (PA6), Polyvinyl Alcohol (PVA), and Activated biochar (AB) derived from peanut shell biomass. Glutaraldehyde (GA) cross-linking was applied to enhance stability in aqueous environments to prevent PVA swelling. The resulting nanofibrous membrane exhibited a cost-effective design with a superhydrophilic/underwater superoleophobic surface (WCA of 0° and UWOCA of 164°), a porous structure (93% porosity), and robust mechanical properties (Tensile strength: 7.73 MPa, Young modulus: 45 MPa). Optimization of the membrane composition, with 5%wt. PVA and 2%wt. AB relative to the total polymer weight in the electrospinning solution, yielded a superhydrophilic membrane capable of withstanding 2 bar pressure. Pure water flux measurements in the pressure range of 0.5–2 bar demonstrated a high permeability of 1727.5 LMH/bar and a pure water flux of 3455 LMH. The PA6/PVA/AB composite membrane exhibited exceptional performance in separating non-surfactant (NS) and surfactant-stabilized (SS) toluene-in-water emulsions (separation flux: 2006 LMH, oil rejection: 99.52%). Furthermore, it demonstrated high efficiency in the separation of SS oil-in-water emulsions of different types of oil (separation flux >1800 LMH, oil rejection >98%). The membrane's durability and chemical stability were confirmed through 15 cycles of oil-in-water emulsion separation, showcasing anti-fouling properties and reusability (separation flux >833, Oil rejection >97%). Considering its superior performance in oil-in-water emulsion separation and robust reusability, the developed nanofibrous membrane holds significant promise for practical applications. [Display omitted] • Novel Polyamide 6/Polyvinyl Alcohol/Activated Biochar composite nanofibrous membrane. • Combining Polyamide 6, Polyvinyl Alcohol, and Activated Biochar derived from peanut shell biomass by blend electrospinning. • Cross-linking Polyvinyl Alcohol with glutaraldehyde, to enhance the stability of membrane in aqueous environments. • Superior performance in separation of non-surfactant and surfactant-stabilized oil-in-water emulsions. • Highly promising nanofibrous membrane with antifouling and reusability properties. [ABSTRACT FROM AUTHOR]

[Display omitted] • Root penetration into soils result in increased gas permeability. • Biochar addition alters pore-filling and increases soil capillarity. • Gas permeability function is dependent on root length density. Biochar amendment have been explored recently for improving hydro-mechanical properties of landfill cover system and enhancing the vegetation for the ecological restoration of post closure landfills. Existing studies have predominantly focused on the hydro-mechanical properties of biochar-amended rooted soils and yet few studies have comprehensively investigated their gas permeability functions in response to unsaturated conditions. The objective of this study is to experimentally and theoretically investigate the coupled effects of biochar and root intensity on CO 2 gas permeability in unsaturated soil. Biochar-amended rooted soil was prepared by growing Chrysopogon zizanioides on granite residual soils with biochar at a mas ratio of 5 %. Gas permeability and unsaturated soil properties (i.e., suction and degree of saturation) were monitored simultaneously. Due to the presence of roots, the maximum gas permeability, hydraulic conductivity, and suction increased by 200 %, 600 %, and 50 %, respectively, compared with bare soil. This was attributed to preferential flow, micropore increasement and negative pressure induced by root growth. However, biochar addition decreased the maximum gas permeability and hydraulic conductivity by 21 % and 33 %, respectively. This was attributed to the pore filling function of biochar, increased capillarity due to intrapore of biochar, and presence of surface functional groups in biochar promoting CO 2 adsorption. A newly developed model was proposed to predict gas permeability with respected to unsaturated soil properties. It was revealed that the gas permeability function of rooted soils showed a strong dependence on the measured root length density. This study highlights the significance of adopting biochar in mitigation of gas emissions in vegetated landfill cover system. [ABSTRACT FROM AUTHOR]

• Nitrogen doped modified palm kernel shell were used as potential adsorbents for 2,4-Dichlorophenoxyacetic acid removal. • pH value, adsorbent doses, initial concentration and contact time were studied for 2,4-Dichlorophenoxyacetic acid removal. • The modified biochar were characterise through different analytical instrumental techniques. • Maximum adsorption capacity of 2,4-Dichlorophenoxyacetic acid was 990.10 mg/g observed. The 2,4-Dichlorophenoxyacetic acid (2,4-D) is extensively used herbicide to boost crop productivity by reducing weed and pest infestation in agricultural fields. Due to the high solubility, mobility and low biodegradability, the ubiquitous presence of 2,4-D in the soil, surface and underground water has become serious threat for environment and human health.The present study addresses removal of hazardous 2,4-D by melamine-modified palm kernel shell biochar. A thorough examination was carried out, encompassing proximate analysis, elemental analysis, X-Ray Diffraction (XRD), Fourier-Transform Infrared Spectroscopy (FTIR), Brunauer-Emmett-Teller (BET) analysis, particle size distribution assessment, SEM (Scanning Electron Microscopy), and TEM (Transmission Electron Microscopy). Additionally, a comparative analysis was conducted, comparing palm kernel shell powder with biochar activated by KOH. The melamine-modified biochar (PKS-BM) exhibited notable characteristics, including nitrogen composition of 4.2 %, enhanced surface groups, a BET surface area 794.70 m2/g, total pore volume 0.449 cm3/g, particle size of 1400 nm, and 85 % removal of 2,4-D. Adsorption kinetics were accurately described by both pseudo-second-order model. According to the Langmuir model, the adsorption process was favorable, demonstrating a maximum adsorption capacity 990.10 mg/g. Enthalpy, entropy, and Gibbs free energy were computed from adsorption data, revealing exothermic and thermodynamically spontaneous 2,4-D adsorption on PKS-BM. These findings confirm the suitability of the synthesized melamine-impregnated palm kernel shell biochar to be used as adsorbent for removal of toxic herbicide from contaminated water. [ABSTRACT FROM AUTHOR]

Contamination of agricultural soil with Cadmium (Cd) poses life-threatening risks to human health via the food chain. To alleviate Cd toxicity, biochar is a safe and efficient technique to reduce their availability in soil and subsequently their uptake by roots and translocation towards edible parts of plants. This study provides an in-depth understanding of the biochar underlying mechanisms for Cd-contaminated soils. Biochar improves soil's physicochemical properties and microbial community structure due to its unique properties including large surface area, porosity, aromatic hydrocarbons, diverse functional groups, nutrient potential, and variable pH. Based on its general and specific characteristics, Cd adsorption and immobilization in soil occur by the mechanisms of improving soil pH, ion exchange, electrostatic interactions, complexation, precipitation, surface adsorption, and activation of microorganisms. Simultaneously, biochar regulates several non-selective channels that are responsible for Cd uptake into the roots, distribute it, and redistribute it to the shoots/grains, thereby reducing their accumulation in edible parts of plants. Finally, the use of biochar may reduce the risk of Cd exposure to humans from food crops. Conclusively, this study gives a detailed account of biochar-induced Cd immobilization in soil, its absorption by roots, and accumulation in edible parts of plants. [Display omitted] • The presence of cadmium in agricultural soil poses a serious threat to human health. • Biochar could be a suitable strategy to reduce Cd availability in soil for plants. • Biochar improves soil physical and chemical adsorption of Cd on their surface. • It regulates channels that are responsible for Cd uptake and translocation in plants. [ABSTRACT FROM AUTHOR]

Biochar (BC) is a carbonaceous material obtained from the thermal decomposition of organic matter under limited oxygen supply that plays an attractive role in waste management. In this study, biochar was prepared from sugarcane bagasse, using pyrolysis temperatures from 300 to 700 °C, and chemically activated with HNO 3. Structural characterizations showed that degradation increased as pyrolysis temperature increased. Furthermore, a higher number of functional groups were observed for the materials produced under the lowest temperatures. Chemical activation resulted in oxidation and nitration of carbonaceous structure, increasing the number of functional groups on the materials. All materials were evaluated for the construction of electrochemical sensors towards Cu2+ ions voltammetric determination. The material produced at 400 °C pyrolysis temperature and activated (BCA400) provided the most intense response, which can be related to the presence of one of the highest numbers of surface groups, such as oxygen groups, on it. A method for Cu2+ determination was successfully developed based on differential pulse adsorptive stripping voltammetry (DPAdSV). A linear dynamic range (LDR) from 1.0 to 15.0 μmol L−1 was achieved, with limit of detection (LOD) of 0.36 μmol L−1, and limit of quantification (LOQ) of 1.09 μmol L−1. The method was also adequate in terms of accuracy and precision, as well as selective against most cationic species commonly found in tap water. The analyte was determined in tap water samples, in natura and spiked with the maximum concentration allowed by Brazilian legislation, and successful recovery values were obtained. Therefore, biochar from sugarcane bagasse, an environmentally-friendly material, was successfully used to construct an electrochemical sensor and determining an environmental and health interest analyte. [Display omitted] • Biochar and activated biochar production from sugarcane bagasse pyrolysis. • Characterization and elucidation of structural characteristics of the materials. • Use of carbon paste electrodes modified with biochar for Cu2+ preconcentration. • Development of a voltammetric procedure for analyte determination in tap water. [ABSTRACT FROM AUTHOR]

Manganese oxide biochar composites (MnOx-BCs) are at the frontier of materials development for current environmental and engineering challenges in contaminant sorption and degradation, capacitive deionisation, as well as supercapacitor research. However, the parameter space for optimisation of such composites is vast, spanning from the choice of feedstocks and synthesis procedure to post-processing. This study uses a systematic literature review methodology to provide a comprehensive view into the synthesis methods and applications of MnOx-BCs. The focus is on the manganese phase oxidation states, which are often decisive for a material's properties but not directly comparable with the (well-explored) synthesis of pure MnOx due to the chemical variability of biochars. The relationships between synthesis method, manganese phase, crystallinity and morphology, as well as biochar type are characterised. We argue that careful selection of the desired manganese phase and oxidation state are as important as careful consideration of the bulk chemistry and microstructure of the biochar phase. Much evidence already exists for fine-tuning these combinations, but there is still a clear research gap in systematically studying the biochar impact on the final MnOx phase. [Display omitted] • 418 publications on manganese oxide — biochar composites (MnOx-BC) were reviewed. • Fine-tuning of MnOx-BC properties requires systematic study of precursor materials. • For controlled MnOx phases and nanomorphology, synthesis protocol choice is highly relevant. • The influence of biochar feedstocks and pyrolysis procedures on MnOx-BC remains a literature gap. [ABSTRACT FROM AUTHOR]

Biochars are an exciting class of environmental materials with a wide range of applications, including carbon storage and sequestration, soil enhancement, and pollution remediation. However, the limited knowledge of their molecular structures and compositions and the lack of comprehensive understanding of the relationship between these structures and biochars' diverse functionality, is hindering advancements in their development. In this work, we further advance the approach, first introduced by Wood et al. (2023), to constructing biochar molecular models; and now include control of microporosity (pores ≤ 2 nm size) within the developed models. We construct biochar models representative of woody biochars which are experimentally produced at 600–650 ° C highest heating temperatures. Our models reproduce experimental H/C and O/C atomic ratios, percentage aromatic carbon, true density, cumulative porosity, and pore size distribution. The development of microporous biochar molecular models allows us to identify the importance of chemical structures involved in the assembly of biochar materials, and describe the relationship between these structures and obtained micropores. To facilitate other researchers integrating our approach into their work, we detail the steps taken, including the tests and reasons for each decision, in the construction of the biochar models. Furthermore, we share our developed molecular models in a format that can be easily integrated into other group's work in the form of molecular dynamics simulations. • Molecular models of biochar with controlled pore volumes and pore size distribution. • Models truthful to experimental H/C, O/C, aromaticity, true density and microporosity. • Identification of structural moieties within biochar – key to supporting micropores. [ABSTRACT FROM AUTHOR]

Biochar is made from organic materials and plays an important role in greenhouse gas removal (GGR) and achieving net-zero target. However, economic feasibility has become a primary constraint hindering the large-scale production of biochar. Existing research lacks consideration of practical factors such as feedstock supply, pricing, and factory scale, and cannot accurately evaluate the greenhouse gas (GHG) reduction effect and corresponding costs at scale. We develop a space-based environmental economic model to quantify the impact of feedstock supply and plant strategies on costs and benefits. The results show that biochar production in the East of England and the East Midlands could achieve significant net GHG reduction and GGR benefits. Environmental benefits are not related to factory strategy but are positively correlated with feedstock supply strategy. Biochar production imposes additional financial burdens that are affected by feedstock supply and factory strategy. The main factors influencing biochar scalability are the quantity and pricing of feedstock and the price of byproducts. Spatial heterogeneity significantly influences the unit cost of GGR benefits. Compared to previous studies, spatial analysis provides a more detailed understanding of the costs associated with scaling up biochar production and the spatial distribution of production costs. This has crucial implications for biochar promotion and the implementation of effective policies. • Biochar production can bring significant greenhouse gas removal benefits. • Additional economic support is still required for the biochar application. • Biochar scalability is primarily affected by the price of feedstock and byproduct. • Spatial variability has a significant impact on the unit cost of biochar production. [ABSTRACT FROM AUTHOR]

Carbon dioxide methanation is a promising approach to convert captured CO 2 into green natural gas. Developing high performance biochar-supported nickel catalysts promotes a circular economy and the application of sustainable catalysts. Western red cedar biochar was produced via pyrolysis at 400, 500, and 600 °C and loaded with nickel via incipient wetness impregnation. Methanation was done at 400, 500, and 600 °C with the highest methane yield of 59% achieved at 500 °C with 10 wt.% Ni loading. This is comparable to a γ-Al 2 O 3 supported catalyst prepared and tested similarly, which achieved a methane yield of 53%. Biochar-supported catalysts showed deactivation whereby methane yield decreased from 59% to 51% over 5 h, likely due to coking and/or the sintering of nickel. Various space velocities were tested, and results demonstrated that with a space velocity of 37.5 mL/g.min methane selectivity was 89% after 1 h on stream compared to methane selectivity of 42%, which was achieved at a space velocity of 112.5 mL/g.min. This shows that a much higher rate of deactivation is observed at higher space velocities. Increasing the nickel loading from 5 wt.% to 10 wt.% increased methane yield from 40% to 58% after 1 h on stream. The higher loading also showed significantly less deactivation. Future work focusing on the extent and impact of metal-support interactions and metal dispersion on catalytic performance and deactivation during CO 2 methanation is recommended. [Display omitted] • Biochar catalysts perform comparably to alumina catalysts for CO 2 methanation. • 58% CH 4 yield was reached at 10 wt.% Ni loading and 500 °C methanation temperature. • Deactivation was observed over 5 h likely due to sintering and/or coking. • Pyrolysis temperature from 400 to 600 °C did not significantly affect performance. • Methanation performed at 500 °C balanced thermodynamic and kinetic limitations. [ABSTRACT FROM AUTHOR]

Porous carbons derived from lignocellulosic biomass and their use in electrochemical applications are attracting a growing level of interest due to the sustainable nature of the materials and its favourable properties. This study investigates the influence of feedstocks and three activation methods (CO 2 , steam, and KOH) on the electrochemical properties of lignocellulosic biochars. The results showed that activated biochars derived from straw biomass had a higher specific capacitance than wood-derived activated biochars, despite lower electrical conductivity and porosity. Furthermore, chemical activation using KOH was found to increase the capacitance of activated biochars compared to physical activation using steam and CO 2, although sometimes at the expense of electrical conductivity. The study highlights the importance of carefully selecting the feedstocks and activation methods to optimise the electrochemical properties of biochar for potential use as a sustainable supercapacitor material. [Display omitted] • Woody and straw biomass are used to produce biochar for supercapacitor electrodes. • Chemical activation promotes better porosity and functionality for biochar despite their low electrical conductivity. • Miscanthus straw pellet biochar with KOH activation has the highest capacitance. [ABSTRACT FROM AUTHOR]

Biochar can be prepared from biomass through pyrolysis in a low-oxygen or anaerobic environment. The characteristics of biochar are influenced by raw materials and the specific preparation process employed. To enhance the efficacy of biochar, various modification methods can be applied. These primarily include chemical modification, physical modification, and biological modification. This paper conducts a literature review covering the period from 2018 to 2023, focusing on biochar preparation, modification methods, and environmental applications. It is a comprehensive overview of the processes involved in preparing biochar, analyzes its characteristics, and explores various modification techniques. Additionally, the paper discusses the diverse and highly efficient application of biochar in environmental remediation, with a particular emphasis on its use in soil, water, and the atmosphere. While biochar holds significant potential for environmental remediation, a thorough understanding of its mechanism in environmental applications is still lacking. Further in-depth studies are required to elucidate the complex roles biochar plays in various environmental contexts. • A summary of the application of modified biochar to soil, water, and atmosphere remediation is presented to show its remediation effect. • Alkali modification of biochar greatly enhances its specific surface area. • Metal salt modification significantly boosts oxygen-containing functional groups in biochar. • Some research directions and future perspectives for modified biochar are highlighted. [ABSTRACT FROM AUTHOR]

Biochar synthesized from corn starch with three different amylose/amylopectin ratios were characterized and their reinforcing performance in styrene-butadiene rubber (SBR) rubber was compared to carbon black N772. Biochar samples were produced via slow pyrolysis. Additionally, 3 different activated biochar samples were created, notably (1) activation under CO 2 , (2) activation with steam and N 2 (Steam), and (3) steam activation via pyrolysis of a biochar-water slurry (SteamT2). The properties of the fillers were examined, and all biochar samples were blended with SBR to form composites, which were tested to evaluate their cure profiles and tensile properties. The results indicate that the amylose and amylopectin ratios of the feedstock had little effect on the reinforcing performance of the composites, but composites with biochar from high amylose corn starch had longer scorch periods during curing. Physical activation treatments, however, had a significant impact on the physicochemical properties of the biochar, specifically on the porosity, carbon, oxygen, and ash content. In terms of performance in SBR, composites with biochar pyrolyzed under normal N 2 conditions and biochar activated with Steam had the most consistent tensile performance with the least brittle characteristics. Conversely, composites made with biochar activated with SteamT2 were exceptionally brittle, with limited reinforcement capabilities, despite having a comparatively higher carbon content. Thus, though physical activation can increase the carbon concentration of biochar, this does not necessarily correlate to improvements in its mechanical performance in SBR. As such, other optimization techniques may be more useful to tailor biochar for application in the rubber filler industry. [Display omitted] • Biochar synthesized from corn starch with three amylose/amylopectin ratios. • Biochar characterized and performance in styrene-butadiene rubber were compared. • Biochar activated under CO 2 , with steam and N 2 , and activated as slurry. [ABSTRACT FROM AUTHOR]

In this work, nitrogen-rich porous carbon with abundant pore size distribution was fabricated by microwave-assisted two-step co-pyrolysis of kapok wood (KW) with Chlorella vulgaris (CS), which revealed two nitrogen doping ways of CS as a green nitrogen source. The porous carbon K3C7PC obtained at a mixing ratio of 3:7 between KW and CS possesses the highest specific surface area (SSA) of 2909.78 m2/g, and its pore volume reaches 3.44 cm3/g. The weight loss curves show that the KW biochar retains some of the nitrogenous compounds produced by CS. The three-electrode test shows that the specific capacitance of KWPC obtained from the pyrolysis of KW is only 253.8 F/g, while the specific capacitance of K3C7PC reaches 380 F/g after 70% of CS is mixed with KW. Besides, the symmetric supercapacitors of K3C7PC exabits the maximum energy density of 8.09 Wh/kg at 125 W/kg power density, and after 10,000 cycles, the capacitance retention rate is still 98.49%. This work is convenient for directing the co-pyrolysis of lignocellulosic and algal biomass for the preparation of nitrogen-rich porous carbon. [Display omitted] • Nitrogen-containing compounds in CS undergo a Maillard reaction with KW biochar. • Some nitrogen-containing compounds in CS biochar undergo self-retaining. • Pyrolysis vapors from KW and CS broaden the pore structure of porous carbon. • Co-pyrolysis reduces the energy consumption of microwave pyrolysis process. • K3C7PC possesses 380 F/g at 0.2 A/g and 2909.78 m2/g specific surface area. [ABSTRACT FROM AUTHOR]

Coffee is one of the most traded commodities in the world. Coffee husk makes up the majority of the solid debris generated during the dry processing of coffee, which is between 30% and 50%. Pyrolysis is a reliable and feasible technology to valorise the coffee husk. The present study proposes and investigates a novel method for producing carbon dots from coffee husk char through pyrolysis. Nanomaterials are becoming more popular to improve the thermal and optical properties of working fluids used in solar photovoltaic and thermal conversion systems. The coffee husk-char derived carbon dot (CHC-CD) nanofluids are prepared with different char concentrations (1%, 2%, 3% and 4%). The chemical and optical properties of the nanofluid produced from coffee husk char (CHC-CD nanofluid) are investigated. The morphology, size and particle size distribution of the CHC-CD particles were studied using field emission scanning electron microscopy (FESEM) and high-resolution transmission electron microscopy (HRTEM). The particles were found to have an average size of 5.38 nm. The CHC-CD nanofluid had a basic pH and negative zeta potential, which was found to decrease with an increase in the char concentration and pH. The nanofluid prepared with 2% char was found to have a zeta potential of −61.4 mV. It was evident from the UV–vis transmittance spectra that the CHC-CD nanofluid prepared with a char concentration of 2% had very limited transmittance in the UV region and good transmittance above 735 nm. This transmittance range is found to be favourable for the smooth and efficient operation of silicon-based solar PV cells. The CHC-CD nanofluid also showed a maximum intensity emission wavelength of 522 nm at an excitation wavelength of 450 nm. Characterisation of the carbon phase, surface functional groups, and surface defects was also done using XRD, FTIR, and Raman spectroscopy, respectively. The optical and chemical properties indicate that the developed CHC-CD nanofluid can find application not only in solar photovoltaic and thermal systems but also in applications in biomedical and chemical sensor applications. • Integration of biomass and solar resources in achieving sustainable energy goals. • Carbon dot nanofluid was synthesized from coffee husk through pyrolysis. • A simple, economical and novel method of synthesizing carbon dot. • The carbon dot nano particles had a mean size of 5.38 nm. • Characteristics show feasibility in solar photovoltaic-thermal applications. [ABSTRACT FROM AUTHOR]

Nitrogen atom doping is widely employed to prepare efficient adsorbents to handle target pollutants thanks to its similarity in radius to carbon atoms and excellent functionality. In this study, three types of nitrogen-enriched biochars (NBCs) were prepared to use the corn straw as the raw material and melamine as the nitrogen source by pyrolyzing at 700, 800, and 900 °C (named 700NBC, 800NBC and 900NBC), which were used to remove tetracycline (TC) from water. Results showed that the 900NBC exhibited the highest specific surface area (324.29 m2/g) as well as the maximum adsorption capacity (194.42 mg/g) for TC, compared to 800NBC (176.44 mg/g) and 700NBC (163.32 mg/g). What's more, the adsorption kinetics and adsorption isotherms were well-fitted by the pseudo-second-order and Langmuir models, indicating that for the adsorption of TC by NBCs, monolayer adsorption and chemisorption were dominant. Specifically, the excellent adsorption performance of NBCs for TC was mostly attributed to the pore filling, hydrogen bonding, π-π interactions, Lewis acid-base interactions, and electrostatic interactions. Importantly, the graphitic N serves as the primary TC adsorption site, followed by pyridinic N. This study would provide new insight into the impact of nitrogen configuration on the adsorption mechanism of NBCs for TC. [Display omitted] • Three types of nitrogen-enriched biochars were prepared at pyrolysed at 700, 800 and 900 °C. • Graphitic N played a key role in TC adsorption. • The main mechanisms were pore filling, π-π interactions and Lewis acid-base interactions. [ABSTRACT FROM AUTHOR]

The perpetual market demand for polystyrene results in the gradual accumulation of polystyrene waste, placing a serious burden on the environment. This study proposed a promising method to upcycle polystyrene for styrene-derived monomers through catalytic fast pyrolysis. The metals-incorporated biochar catalysts were synthesized from heavy metals-contaminated manure waste for catalytic fast pyrolysis of polystyrene. The experimental results showed that the bimetallic biochar-derived catalyst containing Zn and Cr (Zn-Cr/C) was more conducive to the liquid production, with an extremely high yield of 88.22 wt%. Monometallic Pb-incorporated biochar catalyst (Pb/C) and bimetallic Zn-Cu co-doped on biochar (Zn-Cu/C) were more favorable for the production of pure styrene, with the mass yield of 61.26 wt% and 60.39 wt%, respectively. Additionally, the study elucidated a deep understanding of the reaction mechanisms involved in the catalytic fast pyrolysis of polystyrene. Simply put, this study introduced a new concept to convert heavy metal-contaminated animal manure into metal-incorporated biochar catalysts for catalytic conversion of polystyrene waste in pure styrene-based monomers. [Display omitted] • A new concept of upcycling polystyrene into pure monomers. • Mono-/bi-/tri-metallic Zn, Cu, Pb, Cr-containing biochar catalysts were prepared. • Bimetallic Zn-Cr/C favored the liquid production, with the high yield of 88.22 wt%. • Pb/C was more favorable for pure styrene production, reaching 61.26 wt%. • Trimetallic Zn-Cu-Pb/C had an obviously negative impact on the liquid production. [ABSTRACT FROM AUTHOR]

This review systematically examines the role of Computational Fluid Dynamics (CFD) in enhancing the understanding of microwave-assisted pyrolysis (MAP) for efficient biomass conversion into valuable chemicals. By critically analyzing recent advancements in CFD modeling, this paper highlights the significant contributions of CFD to optimize process parameters, improve reactor designs, and predict the yield and quality of bio-oil, biochar, and syngas. The synthesis of literature reveals key insights into the microwave energy absorption mechanisms, thermal and electromagnetic field distributions, and their impact on pyrolysis outcomes. The novelty of this review lies in its comprehensive aggregation of CFD-based studies, offering a holistic understanding of MAP processes, identifying gaps in current research, and proposing future directions for integrating CFD simulations with experimental studies to advance biomass conversion technologies. • Simulations and modeling: Understand and optimize microwave-assisted pyrolysis (MAP). • Optimization: Power, biomass type, reactor design influence MAP efficiency. • Addressing challenges: Limited simulation studies, need for further research. • Bio-oil, activated carbon, biofuels from waste biomass showcase MAP potential. • Future: Optimize conditions, explore feedstocks, integrate technologies, and scale-up. [ABSTRACT FROM AUTHOR]

To elucidate the impact of a modified reaction medium on the hydrothermal carbonization (HTC) coupled pyrolysis process, a two-stage conversion of rice straw (RS) was investigated in the present work. RS was initially treated hydrothermally in a conventional medium (water) and a modified reaction medium (metal chlorides and ammonium persulfate AP), followed by an upgrade of the obtained hydrochar via pyrolysis. The characteristics of the modified hydrochar and the pyrolysis biochar were examined. It was shown that a modified reaction medium promoted a higher mass yield of hydrochar. Compared to conventional hydrochar, modified hydrochar exhibited higher ash and fixed carbon content, and lower carbon and oxygen content. Furthermore, the pyrolysis behavior of modified hydrochar was more complex. Not only the DTG curve entirely different was, but the values of activation energy and pre-exponential factor also significantly increased. Ultimately, the modified medium enhanced the adsorption capacity of the HTC coupled pyrolysis biochar. Among them, B-HTC-AP had the highest S BET (544.83 m²/g) and the largest pore volume (0.4644 cm³/g). The TC adsorption capacity of B-HTC-AP reached 187.31 mg/g. The pseudo-second-order kinetic model and the Freundlich isotherm model provided a better description of the TC adsorption process on B-HTC-AP. Possible adsorption mechanisms of B-HTC-AP could encompass pore filling, electron transfer, hydrogen bonding, and π-π interactions. Therefore, the use of a modified reaction medium in the two-stage process could be an effective strategy for upgrading biomass. • Modified medium increased the yield of hydrochar. • HTC-MgAl exhibited the highest apparent activation energy. • Modified medium enriched the metals contents in hydrochar and biochar. • Modified medium enhanced the BET surface area of biochar. • Modified medium enhanced the adsorption capacity of biochar. [ABSTRACT FROM AUTHOR]

The development and utilization of biomass play a vital role in reducing fossil fuel dependency and mitigating greenhouse gas emissions. High-temperature pyrolysis provides a promising route for converting biomass into valuable products without tar formation. Kinetic models are essential for understanding biomass pyrolysis processes, aiding reactor design and optimization. In this study, rice husk (RH) and corn straw (CS) are selected, which exhibit significant differences in ash content but are widely present. Pyrolysis is performed using a thermogravimetric analyzer coupled with a mass spectrometer (TGA-MS). The results show a rapid decrease in solid residue oxygen content at elevated temperatures, which stabilized after reaching 900°C, accounting for about 8–10%. MS quantification indicates increased release of H 2 O and CO during this stage. Fourier transform infrared spectroscopy (FTIR) analysis on the biochar unveils that this phenomenon is attributed to the stretching vibration of C-O bonds and the conversion of -OH groups. The remaining oxygen primarily exists as carbonyl and carboxyl groups. Subsequently, the CRECK-S-B biomass pyrolysis kinetic model is updated, specifically targeting the transformation mechanism of oxygen-containing solids at high temperatures to improve the prediction of biochar yield and elemental composition. The relative error of oxygen content prediction is less than 10%. The accuracy of the model is validated through experimental data and an extensive literature database, leading to the establishment of a comprehensive database. The updated model demonstrates significantly enhanced prediction accuracy for pyrolysis temperatures above 800°C, expanding its applicability range. Moreover, it achieves an accuracy rate exceeding 80% for char yield and elemental content in the temperature range of 200–1000°C, including torrefaction conditions. It provides a theoretical foundation for the effective utilization of high-temperature biochar, offers a novel insight into biomass thermochemical conversion, and contributes to the sustainable development of biomass energy. • The distinct thermal behaviors at high temperatures are revealed. • The remaining oxygen exists as carbonyl and carboxyl groups in the solid residue. • The CRECK-S-B biomass pyrolysis kinetic model is updated. • A comprehensive database comprising pyrolysis experiments is established. [ABSTRACT FROM AUTHOR]

The co-transport behavior of environmental pollutants with biochar particles has aroused great interests from researchers due to the concerns about pollutant diffusion and environmental exposure after biochar is applied to soil. In this work, the recovery and co-transport behavior of biochar micron-/nano-particles (BCMP and BCNP) and lead (Pb2+) in saturated porous media were investigated under different ionic strength conditions (IS = 1, 5 and 10 mM) under a direct current electric field. The results showed that the electric field could significantly enhance the mobility of Pb adsorbed biochar particles, particularly BCNP. The recovery of Pb laden biochar particles was improved by 1.8 folds, reaching 78.8% at maximum under favorable condition at +0.5 V cm−1. According to the CDE (Convection-Dispersion-Equation) model and DLVO (Derjaguin-Landau-Verwey-Overbeek) theory analysis, the electric field facilitated the transport of Pb carried biochar mainly by increasing the negative charges on biochar surface and improving the repulsive force between biochar and porous media. High IS was favorable for biochar transport under the electric field, but inhibited desorbing Pb2+ from biochar (18% by maximum at IS = 10 mM). By switching the electric field power, a two-stage strategy was established to maximize the recovery of both biochar particles and Pb, where BCNP and Pb recovery were higher than electric field free case by 90% and 35%, respectively. The findings of this study can help build a biochar recovery approach to prevent potential risks from biochar application in heavy metal contaminated soil remediation. [Display omitted] • Electric field promoted the migration of both Pb laden/free biochar particles. • Up to 78.8% of Pb2+ laden biochar nano-particles recovered under 0.5 V·cm-1. • Electric field detach about 18% adsorbed Pb from biochar under high ionic strength. • Two-stage strategy were proposed to recover both biochar and Pb2+. [ABSTRACT FROM AUTHOR]

Biochar-based materials for air treatment have gained significant attention for removing health-detrimental volatile organic compounds (VOCs) and particulate matter (PM) in indoor air settings. However, high turnaround time, multiple pretreatment processes involved, and high pore size and low surface area (>10 μm, <100 m2 g−1) of lignocellulosic feedstocks demand alternative biochar feedstock material. Considering this, we designed a simple first-of-its-kind indoor air scrubbing material using diatoms-enriched microalgae biochar. In the present study, the microalgae were cultivated on waste anaerobic digestate (biogas slurry) and were pyrolyzed at three different temperatures: 300 °C (BC300), 500 °C (BC500), and 700 °C (BC700). The BC500 and BC700 showed the highest removal efficiencies (99 %) for total volatile organic carbons (TVOCs) and formaldehyde (HCHO) at concentrations of 1.22 mg m−3 HCHO and 8.57 mg m−3 TVOC compared to 50% efficiency obtained with commercially available surgical, cloth, and N95 masks. The biochar obtained showed a high Brunauer–Emmett–Teller (BET) surface area of 238 m2 g−1 (BC500) and 480 m2 g−1 (BC700) and an average pore size of 9–11 nm due to the mesoporous characteristic of diatom frustules. The comparatively poor performance of BC300 was due to lower surface area (150 m2 g−1) arising from incomplete organic removal, as evidenced by FESEM-EDX and FTIR. The high removal efficiencies in BC500 and BC700 were also attributed to the presence of reactive functional groups such as –OH and R–NH 2. Concurrently, the average particulate matter (PM10, PM2.5, and PM1) removal efficiency for BC500 and BC 700 ranged between 66 and 82.69 %. The PM removal performance of BC500 and BC700 was lower (15–20%) than commercially available masks. Overall, the present study highlights the importance of diatoms (reactive Si) present inside the pores of microalgal biochar for enhanced removal of PM, TVOCs, and HCHO at temperatures above 500 °C. This complete approach signifies a step towards establishing a self-sustainable and circular process characterized by minimal waste generation for indoor air treatment. [Display omitted] • Simultaneous removal of particulate matter PM10, PM2.5, PM1, TVOC's and HCHO. • Microalgal biochar contained 21.2 %w/w silica diatoms with pore size of 9–11 nm. • Diatoms increased specific surface area 2X (482 m2 g−1) than conventional biochars. • Developed material highly specific in removal of TVOC's and HCHO (∼99%). [ABSTRACT FROM AUTHOR]

Soil salinization is a major environmental hazard that limits land availability. Human-induced salt pollutants (HISPs) are regularly presented in large quantities on the contaminated site (such as brine leakages and salt-water spills), causing a devastating shock with high salt stress to the ecosystem. For instance, Saskatchewan resulted in a 48% drop in wheat production and a 0.3% decline in provincial GDP. As the calcium-modified biochar can potentially ameliorate the negative effects of HISPs on plants and improve the plant, phytoremediation with calcium-modified biochar can have increased detoxification of hazardous pollutants from sites. Therefore, the objective of our study was to develop a biochar-assisted phytoremediation employing diverse approaches to calcium modification for the sustainable removal of HISPs. The co-pyrolyzed calcium biochar achieved a remarkable removal rate of 18.06%, reducing salinity from 9.44 to 7.81 dS/m. During a 90-day long-term phytoremediation, the overall reduction rate of calcium-modified biochar stimulated the germination and growth of Thinopyrum ponticum. The result of post-treatment further indicated that co-pyrolyzed biochar with Ca transferred salt into the plant compared to Ca-coated biochar, which only immobilized HISPs on its surface. These results offer two different treatment approaches for diverse situations involving HISPs contamination, addressing current in-situ spills and providing a calcium-related biochar technology for further research in desalination. [Display omitted] • Ca-coated and Ca-copyrolyzed biochar for phytoremediation of saline soil were investigated. • Ca-modified biochars generated from copyrolysis and coating. • Ca-modified biochars displayed enhanced capability in direct removing salt from brine water • In a 90-day phytoremediation, Ca-modified biochar reduced salinity and improved soil quality • Ca-copyrolyzed and Ca-coated biochar have diverse roles in salt migration into vegetations [ABSTRACT FROM AUTHOR]

Polycyclic aromatic hydrocarbons (PAHs) are pervasive ecological pollutants produced essentially during the inadequate burning of organic materials. PAHs are a group of different organic compounds that are made out of various aromatic rings. PAHs pose a serious risk to humans and aquatic ecosystems because of their mutagenic and carcinogenic properties. In this way, there is a critical prerequisite to utilizing successful remediation strategies and methods to limit the dangerous effect of these pollutants on the ecosystem. Biochar has believed of intriguing properties such as simple manufacturing operations and more affordable and more productive materials. Biochar is a sustainable carbonaceous material that has an enormous surface area with bountiful functional groups and pore structure, which has huge potential for the remediation of toxic pollutants. This review emphasizes the occurrence, development, and fate of toxic PAHs in the environment. In the present review, the properties and role of biochar in the removal of PAHs were illustrated, and the influencing factors and an efficient key mechanism of biochar for the remediation of PAHs were discussed in detail. Various surface modification methods can be utilized to improve the biochar properties with the magnetization process; the advancements of modified biochar are pointed out in this review. Finally, the constraints and prospects for the large-scale application of biochar in the remediation of toxic pollutants are highlighted. [Display omitted] • Utilization of biochar as an effective strategy for PAH remediation has been reviewed. • Overview on Surface and functional properties of biochar used for PAH removal was emphasized. • Role and primary mechanisms of different biochar in PAH removal has been detailed in the review. • Modification for enhancement of biochar properties for effective removal of PAH was described. [ABSTRACT FROM AUTHOR]

The fertosphere, as the interfaces between fertilizer granular and soil particles, represents a key hotspot for nitrogen transformation processes, particularly for ammonia (NH 3) and nitrous oxide (N 2 O) emissions. Understanding the heterogeneity of the fertosphere, especially when incorporating organic amendments like biochars, is crucial for predicting NH 3 and N 2 O emissions after soil fertilization. In this study, we investigated the effects of three types of biochar (pristine, aged, and acid-washed biochar) on heterogeneity of fertosphere induced by localized urea application. pH-specific planar optodes were employed to visualize pH gradients in fertosphere hotspots with high spatial and temporal resolution. In addition, we conducted thorough measurements of the gradient distribution of electric conductivity (EC), mineral N, aqueous NH 3 in soil and enzyme activities relevant to nitrification. Concurrently, NH 3 and N 2 O emissions from the soil were continuously monitored at a high temporal resolution. Initially, urea-induced fertosphere exhibited significant NH 3 emissions, primarily attributed to the pH elevation resulting from urea hydrolysis. However, after 6 days, NH 3 emissions subsided, and there was a notable sharp increase in N 2 O emissions. Importantly, compared to urea application alone, the inclusion of pristine biochar led to a delay in soil pH decline with a 19% rise in NH 3 emission. Aged biochar, characterized by a higher content of oxygen functional groups, demonstrated increased NH 4 +/NH 3 adsorption capacity and enhanced ammonia monooxygenase (AMO) activity in soil, resulting in an 18% reduction in NH 3 emission. While a slight decrease of 5% in NH 3 cumulative emission was observed in the acid-washed biochar treatment. Notably, biochar could potentially promote nitrification-derived N 2 O emissions due to the accumulation of NH 3 oxidation products (NH 2 OH). These findings could contribute to refining N transformation models for fertilized soils, and optimizing N fertilizer application strategies. [Display omitted] • Localized urea application induced pH gradients along fertosphere up to 25 mm. • TAN and NO 3 −-N had opposite gradients across the fertosphere. • Biochar could attenuate the heterogeneity of fertosphere, but promote NH 3 emissions. • Increased AMO and decreased HAO nitrification enzyme activities raised N 2 O emission. [ABSTRACT FROM AUTHOR]

Activated carbon (AC) has important industrial and environmental applications as it has excellent abilities to sorb contaminants such as per- and polyfluoroalkyl substances (PFAS). Current research aims to develop activated biochars (AB) from renewable biomass to replace AC that is produced from fossil feedstock. Both AC and AB are primarily comprised of condensed aromatic carbon (ConAC), the component that is the focus of this study. ConAC is characterized to determine its relationship with biochar activation conditions and PFAS sorption, which are understudied at present. Benzenepolycarboxylic acid (BPCA) markers for ConAC were quantified in steam-activated biochars (AB-Steam) and carbon dioxide-activated biochars (AB-CO 2) prepared from waste timber at different temperatures (800, 850, 900 °C) and molar ratios of feedstock-carbon:steam (0.50 – 1.25). A non-activated biochar was also included as a reference. ConAC relative to total organic carbon content was higher in AB-Steam than in AB-CO 2 (92 ± 2 % vs. 81 ± 11%). The ratio of benzenehexa- (B6CA) to benzenepentacarboxylic (B5CA) acids revealed that AB-Steam also had larger ConAC clusters than AB-CO 2. These findings provide novel evidence that steam activation is more effective than CO 2 activation in creating ConAC. To assess how ConAC impacts AB sorption abilities, AB-Steam were used to remediate PFAS from contaminated soils. The observed strong correlations between ConAC content and sorption of long-chain PFAS suggest the importance of hydrophobic interactions between PFAS tails and ConAC. Poor correlations for short-chain PFAS, on the other hand, indicated the existence of electrostatic repulsion interactions between PFAS head groups and ConAC. Collectively, these results explain the great ability of AB-Steam to sorb PFAS from contaminated soils (up to 100% remediation). More broadly, this work demonstrates that the BPCA method can be a valuable tool to assess the quality of biochars and other carbonaceous sorbents in relation to their production conditions or contaminant sorption abilities. [Display omitted] • Condensed aromatic carbon (ConAC) content was determined by benzenepolycarboxylic acid (BPCA) markers. • Steam-activated biochars had more ConAC (92 ± 2 %) of larger cluster size than CO 2 -activated biochars (81 ± 11%). • More PFAS sorption (71 ± 25%) was observed at higher ConAC content (> 92%). • Hydrophobic and electrostatic repulsion interactions likely exist between PFAS and ConAC. [ABSTRACT FROM AUTHOR]

The application of carbon nanoparticles (CNPs) and biochar in agriculture for improving plant health and soil quality and alleviating metal stress offers alternative approaches to meet the ever-increasing demand for food. However, poor understanding of their roles in improving crop production under Cu stress represents a significant obstacle to their wide application in agriculture. To clarify how CNPs and biochar affect corn (Zea mays L.) seed germination, seedling growth, plant health, and nutrient uptake under different Cu stress levels, soil-less Petri-dish and greenhouse soil-based bioassays were conducted. The results revealed that CNPs and biochar stimulated corn seed germination and seedling growth. Besides, they were effective in immobilizing Cu2+ sorption in sandy soil and alleviating Cu stress for plant growth, as shown by the increased plant height and dry biomass. The plant nutrient uptake efficiency (NUE) was significantly increased by CNPs, with a maximum increase of 63.1% for N and 63.3% for K at the highest Cu2+ stress level (400 mg Cu2+ L−1). In contrast, non-significant effects on NUE were observed with biochar treatments regardless of Cu stress levels. Interestingly, CNPs significantly increased plant uptake of Cu in the Petri dish test, while biochar inhibited plant uptake of Cu under both experimental conditions. Principle component analysis (PCA) and Pearson correlation analysis indicated that CNPs mitigated Cu stress mainly by elevating antioxidant enzyme activities, enhancing plant photochemical efficiency, and increasing plant uptake of N and K, while biochar was more likely to reduce bioavailability and uptake of Cu in the plant. These findings have great implications for the application of CNPs and biochar as plant growth stimulators and de-toxicity agents in agriculture. [Display omitted] • CNPs and biochar improved seed germination and plant growth under Cu stress. • CNPs elevated antioxidant enzyme activities, enhanced plant photochemical efficiency and plant uptake of N and K. • Biochar reduced Cu concentration and decreased activities of antioxidant enzymes in plants. [ABSTRACT FROM AUTHOR]

This study evaluates pyrolysis products obtained from biomasses (silver grass, pine, and acacia) harvested from heavy-metal-contaminated soil. To do so, we utilized two methods: a batch one-stage pyrolysis, and a continuous two-stage pyrolysis. The study results show that the yields and characteristics of bio-oils and biochars varied depending on the pyrolysis process and the type of biomass. The two-stage pyrolysis having two reactors (auger and fluidized bed reactors) appeared to be very suitable for specific chemicals production such as acetic acid, acetol, catechol, and levoglucosan. The biochar obtained from the fluidized-bed reactor of two-stage pyrolysis had high thermal stability, high crystallinity, high inorganic content, and a small number of functional groups. In contrast, the biochar obtained from the one-stage pyrolysis had low thermal stability, low crystallinity, a high carbon content, and a large number of functional groups. The biochar obtained from the two-stage pyrolysis appeared to be suitable as a material for catalyst support and as an adsorbent. The biochar obtained from one-stage pyrolysis appeared to be a suitable as a soil amendment, as an adsorbent, and as a precursor of activated carbon. All biochars showed a negative carbon footprint. In the end, this study, which was conducted using two different processes, was able to obtain the fact that products of pyrolysis biomass contaminated with heavy metals have different characteristics depending on the process characteristics and that their utilization plans are different accordingly. If the optimal utilization method proposed through this study is found, pyrolysis will be able to gain importance as an effective treatment method for biomass contaminated with heavy metals. [Display omitted] • Results of one-stage and two-stage pyrolysis of contaminated biomass were compared. • Two-stage pyrolysis turned out to be suitable for specific chemicals production. • Biochar from fluidized-bed reactor has potential as catalyst support and absorbent. • Biochar from fixed-bed reactor has potential as soil amendment and absorbent. • All biochars seemed to be applicable in construction field as sustainable materials. [ABSTRACT FROM AUTHOR]

In this study, a novel Fe 3 O 4 -based biochar coupled surface-imprinted polymer was constructed via simple hydrothermal route for salicylic acid recognition and degradation in advanced oxidation processes. The material exhibited excellent adsorption capability, up to 118.23 mg g−1, and efficient degradation performance, 87.44% removal rate within 240 min, based on integrating the advantages of both huge specific surface area as well as abundant functional groups from biochars and specific recognition sites from imprinted cavities. Moreover, high selectivity coefficient (11.67) showed stable recognition in single and binary systems. SO 4 •− and •OH were confirmed as reactive oxygen species in catalytic reaction according to quenching experiments and EPR analysis. The degradation mechanism and pathway were unraveled by DFT calculations and LC-MS. Furthermore, the results of toxicity evaluation, stability and reusability demonstrated application potential in the field of water environment restoration. This study confirmed that molecular imprinting provided a promising solution to targeted removal of emerging environmental pollutants by degrading after the enrichment of pollutants to the composites surface. [Display omitted] • A novel molecularly imprinted polymers coated Fe 3 O 4 -BC was successfully synthesized. • Adsorption-degradation activities and specific recognition of SA by MI-FBC were improved. • MI-FBC exhibited good stability and regenerability with tolerance to wide pH and anions. • The mechanism and pathway of SA removal were proposed based on experiments and DFT calculations. [ABSTRACT FROM AUTHOR]

The utilization of agricultural solid biowastes is essential for resource saving and bioenergy conversion. By this way, the demand of industrial furnace for biomass would be compensated, and the energy structure would also be greener. Among them, torrefaction is a hopeful technology for solid biofuel production. This study investigates the grinding performance of torrefied biochar to achieve the grindability and component variation analysis of torrefied agricultural wastes for fluidized bed boiler, and thus realize pulverized biochar injection for industrial application. Totally crystallinity index (CrI), average particle size distribution, energy input for grinding process, component analysis, and elemental carbon state are adopted and analyzed around Hardgrove grindability index (HGI). The values of HGI are in the range of 45–120, 45–105, 60–120, and 60–135, respectively. The results indicate that torrefaction is conducive for biochar properties upgrading, especially for a higher temperature, and thus contributes to a higher HGI, lower particle size and grinding energy input, as well as better elemental carbon state. The produced powder from torrefied biochar is highly correlated to torrefaction temperature and biochar component, and thus leads to an excellent industrial application potential. Overall, this study is conducive for the agricultural biowastes conversion and solid biofuel production. [Display omitted] • The grindability of four agricultural solid biowastes were analyzed. • Torrefaction is conducive to achieving biochar grindability improvement. • Grindability is correlated to crystallinity index and grinding energy input. • A higher torrefaction temperature is conducive for biochar powder size reduction. • Biochar component and carbon state are correlated to grindability. [ABSTRACT FROM AUTHOR]

Biochar has demonstrated the potential in mitigating pollutant gaseous emission during composting. However, little is known about the difference among biochars derived from different plant feedstocks on the critical genes' expression and microbial communities' succession for gaseous emissions. In this study, the effects of biochar (from wood chips, cornstalks, and rice husks) on gaseous emissions during chicken manure composting were investigated. Environmental factors, bacterial communities, and functional genes related to CH 4 , N 2 O, NH 3 , and H 2 S emissions were analyzed to reveal the reduction pathways of different biochar amendments during composting. Results showed that all biochar treatments improved the seed germination index of the compost from unmature (55.74%) to mature (70.28–75.23%). The CH 4 , N 2 O, NH 3 , and H 2 S emissions from all biochar-treated composts were reduced by 18.93–27.47%, 35.74–52.82%, 1.26–36.38%, and 8.57–24.14%, respectively, and the cornstalk biochar had the highest emission reduction performance. Temperature, pH, and NH 4 + were the major environmental factors that affected Lactobacillus and Bacillus activities, which critically influenced the CH 4 , N 2 O, NH 3 , and H 2 S emissions during composting. Furthermore, cornstalk biochar mainly improved pmoA for CH 4 reduction, whereas wood chip biochar increased amoA for NH 3 oxidation. Rice husk biochar mostly decreased nirS and nirK and increased norB , narG , and nosZ during N 2 O reduction. Cornstalk biochar also increased dsrB and decreased aprA during H 2 S reduction. Overall, cornstalk biochar was determined to be an optimal additive for simultaneously improving compost maturity and reducing gaseous pollutant emissions during chicken manure composting. This study verified the mechanisms of three plant derived biochars in pollutant gas control in composting, and thus provided evidence for facilitating the sustainable development of composting technologies. [Display omitted] • Cornstalk biochar emitted the lowest CH 4 , N 2 O, NH 3 , and H 2 S in composting. • Temperature, pH, and NH 4 + regulated Lactobacillus and Bacillus to reduce emissions. • Cornstalk biochar increased pmoA and decreased mcrA abundances for lower CH 4 emissions. • Rice husk biochar reduced nirS and nirK and increased norB , narG , and nosZ to lower N 2 O. • Cornstalk biochar increased dsrB and decreased aprA abundances for lower H 2 S emissions. [ABSTRACT FROM AUTHOR]

[Display omitted] • A Fe/graphene-loaded biochar (FeGB) gel was prepared via a self-assembly method. • FeGB-gel showed a 4-fold increase in Sb(III) adsorption capacity than raw biochar. • Fe–O–Sb complexation and π–π stacking were key Sb(III) adsorption mechanisms. • The higher electron exchange capacity of FeGB-gel favored Sb(III) oxidation. • Graphene defects aided FeO x anchoring on biochar and promoted electron transfer. Environmental contamination posed by trivalent antimony [Sb(III)] in water has been globally recognized as a complex challenge, garnering considerable public concern. To enhance the adsorption efficiency of pristine biochar (BC) for Sb(III), a novel Fe/graphene-loaded biochar (FeGB) gel was synthesized through a facile in-situ self-assembly method. This study aimed to investigate the adsorption performance and elucidate the electron-scale adsorption mechanism for Sb(III) by the FeGB-gel. The Sb(III) adsorption isotherm data fitted well with the Langmuir model, and the maximum Sb(III) adsorption capacity of FeGB-gel (113.1 mg g−1) was significantly higher compared to that of BC (28.6 mg g−1). Spectroscopic investigations revealed that surface complexation and π–π stacking were the key mechanisms for Sb(III) adsorption. Electrochemical analyses confirmed an enhanced electron-accepting capacity (0.815 mmol e- g−1) of FeGB-gel, linked to the formation of Fe-related functional groups (Fe–O and Fe–O–OH), which contributed to a stronger Sb(III) oxidation capacity than BC (78.5% v.s. 49.3%). Density functional theory calculations highlighted that the presence of defects on graphene nanosheets enhanced the anchoring of FeO x on biochar, thereby elevating the Sb(III) adsorption energy of FeGB-gel to −1.96 eV. Additionally, the projected density of states profile suggested that the enhanced adsorption of FeGB-gel could be attributable to the orbital hybridization of Sb-p, O-p, and Fe-p/d orbitals (i.e., Fe–O–Sb bonding), which strengthened the electron transfer and chemical interaction during the Sb(III) removal process. The functionalization of biochar surface characteristics with Fe/graphene offers possibilities for a diverse range of biochar-based adsorbents and their application in addressing numerous environmental concerns. [ABSTRACT FROM AUTHOR]

[Display omitted] • Biodegradation of biochar-adsorbed trichloroethylene (TCE) by Dhc 195 was studied. • 87.5 % of biochar-adsorbed TCE was biodegraded to ethene within 63 days. • Adsorption capacity of biochar remained 80.4% after 5-time bioregeneration cycles. • Electron transfer from Dhc 195 to TCE was mediated by biochar for biodegradation. • Biodegradation of adsorbed TCE required more VB 12 but had a wider pH tolerance. Biochars was widely employed to immobilize chlorinated aliphatic hydrocarbons (CAHs) in groundwater. Biodegradation of adsorbed CAHs may be able to regenerate biochars, but was scarcely explored. In this study, therefore, biodegradation of trichloroethylene (TCE) adsorbed on a biochar prepared at 700 °C (WBC700) by Dehalococcoides mccartyi 195 (Dhc 195) was investigated. Aqueous TCE was completely degraded to ethene by Dhc 195 within 28 days, while 87.5 % of WBC700-adsorbed TCE was degraded to ethene within 63 days. The slower biodegradation of WBC700-adsorbed TCE could be attributed to its lower accessibility to Dhc 195 caused by the steric effects of WBC700. The adsorption capacity of WBC700 for TCE remained 80.4 % after five adsorption-bioregeneration cycles, indicating that the microbial degradation could be a highly efficient method to regenerate biochars. The microbial degradation was mainly through the electron transfer from Dhc 195 to TCE mediated by biochars as electron conductor or shuttle, but was not assisted by desorption or extracellular redox active species. Compared with biodegradation of aqueous TCE, the biodegradation of WBC700-adsorbed TCE by Dhc 195 had a wider pH tolerance and required more VB 12 , due to the buffer effect and adsorption of WBC700, respectively. The obtained results could provide a cost-effective method of biochar regeneration for CAHs removal in groundwater. [ABSTRACT FROM AUTHOR]

[Display omitted] • Stability of biochar to Cd, Zn and Pb in soil enhanced after KMnO 4 modification. • Biotoxicity of metals was reduced by 28%-95% at 10% KMnO 4 -modified biochar dose. • Biochar was oxidized and C-O stretching change was prior during freeze–thaw cycles. • Ion exchange and precipitation were mechanisms for MBC to stabilize Cd, Zn and Pb. • KMnO 4 -modified biochar resisted the adverse effects of freeze–thaw cycles in soil. Biochar has been widely used in soil remediation because of its porosity and impressive efficiency. Many studies have demonstrated the good affinity of biochar for heavy metals (HMs), but efficient modification methods to increase the stability of multiple HMs are lacking. Moreover, few studies focus on biochar's potential ability to ageing resistance and changes in its physicochemical properties during freeze–thaw (F/T) cycles. Here, KMnO 4 -modification biochar (MBC) was prepared and the immobilization and anti-freeze performance of MBC on Cd, Zn and Pb in soil were investigated. The addition of 10 % MBC decreased concentrations of toxicity characteristic leaching procedure (TCLP) by 66.80 %, 25.39 % and 99.68 % for Cd, Zn and Pb, respectively, after 28 days, accompanied by a significant decrease in the phytoavailability and bioaccessibility of HMs in soil. Soil fertility was also improved by MBC application. Furthermore, frequent F/T cycles obviously induced the fragmentation of soil particles and enhanced the activity of HMs. Conversely, MBC particles became finer, accompanied by further oxidation and higher alkalinity but degraded pore structures during F/T cycles. The oxidation of lignocellulose and changes in C-O stretching were greatest among all functional groups in biochar. Therefore, MBC could suppress the migration of HMs through precipitation, cohesion of soil particles, and stronger complexation by oxygen-containing functional groups. Moreover, fractions of HMs were also transferred from exchangeable to potentially labile or nonlabile species. Overall, MBC displayed advantages in the stabilization of HMs and showed higher resistance to F/T cycles and promise for long-term remediation of HM-contaminated soils in cold regions. [ABSTRACT FROM AUTHOR]

• Significant errors in the kinetics analysis for PMSO degradation was investigated. • Interference and error were negligible under the optimized concentration of terminator. • Calculated the steady-state concentrations of reactive species. • High-valent species is metal dependent. • Fe(IV) is the dominant reactive species in the ZVI-BC/PS system. In this paper, Fe(IV) was analyzed in the zero-valent iron biochar (ZVI-BC) activated persulfate (PS) process with methyl phenyl sulfoxide (PMSO) as the probe compound. Without a reaction terminator, PMSO degradation continued during the sample holding time, resulting in significant errors in the kinetics analysis. When 1 mM NaNO 2 , 1 mM NH 2 OH, 10 mM Na 2 S 2 O 3 , or 10 mM dimethyl sulfoxide were used as terminators, the concentrations of PMSO and its oxidation product, methyl phenyl sulfone (PMSO 2), were effectively maintained without changes during the sample holding period. Furthermore, the terminators did not interfere with PMSO or PMSO 2 analysis by high performance liquid chromatography. In addition to Fe(IV), free radical (i.e. , SO 4 −, OH, O 2 −) and nonradical (i.e. , 1O 2) reactive species were also involved in the ZVI-BC/PS system; however, Fe(IV) was the predominant reactive species. Organic contaminants with electron-donating moieties rapidly reacted with Fe(IV), and the relative contribution of Fe(IV) to overall contaminant degradation decreased as the solution pH was increased. Overall, this study provided new insights into the quantitative analysis of Fe(IV) in the ZVI-BC/PS system and its application to treatment of organic contaminants in solutions with variable water quality. [ABSTRACT FROM AUTHOR]

[Display omitted] • The floating biochar accelerated the immobilized FeCo PBA to absorb sunlight. • The substrate biochar facilitated photogenerated electron transfer of FeCo PBA. • The immobilization enhanced the stability of FeCo PBA in water. • Possible pathway of CQ degradation was proposed based on nine identified products. Fe-Co Prussian blue analogue (PBA) nanospheres were immobilized on biochar (PBA-on-biochar) to remove contaminants via photo-Fenton process. The loading weight of FeCo PBA on biochar increased with increasing PBA aging temperature and time. The PBA exhibited efficient chloroquine phosphate (CQ) degradation under both LED light and sunlight, where OH and 1O 2 dominated the oxidation. The CQ degradation was slightly affected by pH value (3.5–9.5) and co-existing anions like SO 4 2−, Cl− and NO 3 –. The application potential of the PBA-on-biochar was evaluated in a continuous reaction device. Theoretical calculation revealed the dominant role of Fe sites in PBA for H 2 O 2 activation. The degradation pathway was proposed based on nine intermediate products. Also, the excellent photo-Fenton activity and good floatability enable PBA-on-biochar to be efficient in inhibiting the activity of Microcystis aeruginosa under sunlight. The results implied that PBA-on-biochar is applicable for fast micropollutant oxidation from water. [ABSTRACT FROM AUTHOR]

[Display omitted] • UDB and DB at different pyrolysis temperatures played contrasting roles. • DB800-amended group displayed superior nitrogen removal performance. • DB at lower pyrolysis temperature imposed suppression. • Properties of dissolved organic matter released by DB were tracked at molecular level. Biochar has attracted increasingly attention in the biological wastewater treatment owing to its unique environmental behavior. However, the differential effects of undissolved and dissolved fractions of biochar (hereafter named as UDB and DB, respectively) on the anaerobic ammonium oxidation (anammox) process remain unclear. The study evaluated the nitrogen removal performance of anammox system in response to UDB and DB prepared at different pyrolysis temperatures (300 °C, 550 °C and 800 °C). The DB800-amended group displayed superior nitrogen removal performance with the total nitrogen removal efficiency (TNRE) of 92.8 ± 1.4 %. Compared with CK, TNRE was changed by +5.0 % (UDB300), +0.4 % (UDB550) and −22.3 % (UDB800) for UDB-amended groups, and by −16.0 % (DB300), −9.4 % (DB550), and +9.2 % (DB800) for DB-amended groups, respectively. The differences were closely related to the physicochemical properties of UDB and DB. Particularly, dissolved organic matter released by DB were tracked at molecular level, which revealed that CHO occupied the highest proportion of 70.3 % and lignin-like and carboxylic rich alicyclic molecules were dominant in DB800. This study would facilitate the understanding of the differences between the nitrogen removal performance of UDB and DB-amended anammox, thus providing deeper insights for the comprehensive assessment of the impacts of biochar on the anammox process. [ABSTRACT FROM AUTHOR]

[Display omitted] • Mango pit biochar as an alternative fuel was first reported for ironmaking. • Biochar closest to pulverized coal was identified by principal component analysis. • Life cycle assessment unraveled the maximum reduction of GWP was 220 kg CO 2 eq/tHM. Biochar, produced by the pyrolysis of carbon–neutral biomass, has great potential to replace pulverized coal (PC) injection in blast furnace (BF) ironmaking. Herein, this study aimed to develop a low-ash and low-alkali metal biochar from mango pit (MP) and evaluate its environmental impact as an alternative fuel for BF ironmaking. This paper first studied the feasibility of mango pit biochar (MPB) as an alternative fuel. Compared with other preparation conditions, MPB prepared at 600 °C for 60 min (MPB-600–60) had the most similar fuel performance to PC, which was confirmed by principal component analysis (PCA). Moreover, MPB-600–60 exhibited lower ash and alkali metal content compared to PC. The co-combustion experiment demonstrated that MPB-600–60 could promote the combustion of mixed fuel, and the optimal combustibility was achieved when the addition ratio of MPB-600–60 was 80%. Comprehensive life cycle assessment (LCA) revealed that the reduction of global warming potential (GWP) amounted to 220 kg CO 2 eq/tHM if MPB 100% replaced PC. These results indicated that MPB could significantly reduce the greenhouse gas emissions and the environmental impact of BF ironmaking. This study provides a novel and promising approach for developing low-carbon and clean alternative fuels in BF ironmaking. [ABSTRACT FROM AUTHOR]