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The elevated level of pollutants in water highlights the urgency of effective wastewater treatment. Hence, the concern about the potential of microalgae as an economically and environmentally sustainable for wastewater treatment is addressed. Wastewater treatment using microalgae resulted in significant reductions in micropollutants by 82 % for chemical oxygen demand (COD) and biological oxygen demand (BOD). Iron (Fe) concentration was reduced by 99 %, while calcium (Ca) decreased by 25 %. Algal biomass obtained from wastewater is executed for biochar production and bio-stimulant preparation. Bio-stimulant treatment significantly enhanced seed germination and increased shoot and root lengths in maize (Zea mays) and beans (Phaseolus vulgaris) compared to the control. Conversely, seed germination was completely suppressed in both maize and beans in the presence of biochar of bio-stimulant treatment. The GC-MS and NMR analysis study revealed the presence of key compounds in the microalgal extract that have a great contribution to plant growth. Hence, the study concludes the multifaceted and potential application of microalgae as a remediation and bio-stimulant in a sustainable way. [Display omitted] • Integrated wastewater treatment, recycling and reuse technology (SDG 6a). • Utilization of wastewater treated C. sorokiniana for biochar & bio stimulant generation. • Bio-stimulant influenced germination and growth of Zea Maize and Phaseolus vulgaris. • GC-MS analysis identified key compounds in bio-stimulant for plant growth promotion. [ABSTRACT FROM AUTHOR]

Large-scale application of MFCs is limited by the high cost of electrode and low power density. In this study, the electrochemical structure and power output performance of three novel straw-derived biochar are discussed and characterized by scanning electron microscope, specific surface area, cyclic voltammetry, Raman spectrum, electrochemical impedance spectroscopy etc. Compared with the common carbon felt electrode, the optimal electricity generation ability and electrochemical affinity are obtained in corn straw biochar electrode: the rough surface with macroporous structure and high degree of graphitization facilitates the attachment of electroactive bacteria; the maximum output voltage, open circuit voltage, power density and coulombic efficiency reach 662.64±4.03 mV, 798.24±3.65 mV, 1.54±0.18 W m−2 and 50.39±1.68 %, respectively; the maximum COD removal efficiency of 77.45±1.69 % is achieved; exchange current density (4.6142×10−4 A cm−2) in corn straw electrode presents the better electrochemical activity than that of carbon felt electrode. These implies that corn straw-derived biochar is a competitive raw material for MFC anode. [Display omitted] • Biochar is equipped with natural macroporous structure and excellent conductivity. • Straw biochar electrode is economical and environmentally friendly. • Corn straw biochar electrode is superior in electrochemical performance and pollutant removal effect. [ABSTRACT FROM AUTHOR]

• Co-composting slightly enhanced seaweed's plant stimulant effect, all GIs above 101%. • Biochar, high-buffering salts, and MgO raised organic matter degradation by 33.8%. • Biochar, high-buffer phosphates, and MgO enhanced NO 3 –-N by 16.8% and TN by 4.8%. • Biochar, high-buffer phosphates, and MgO increased HA/FA in humification by 49.6%. Seaweed waste, abundant and rich in plant-stimulating properties, has the potential to be transformed into valuable soil amendments through proper composting and utilization management. Given its low carbon-to-nitrogen ratio, co-composting seaweed with carbon-rich cornstarch dregs is an effective strategy. However, the potential application of co-composting largely depends on the efficiency of the composting and the quality of the product. This study explores the effects of adding 10 % corn stalk biochar to a co-composting system of seaweed and cornstarch dregs, alongside varying buffering capacities of phosphates (KH 2 PO 4 and K 2 HPO 4 ·3H 2 O-KH 2 PO 4) and MgO, on the degradation efficiency of organic matter, nitrogen transformation, and humification. The results indicate that the addition of biochar and salts enhances the oxygen utilization rate (OUR) and cellulase activity during the thermophilic phase. Additionally, X-ray diffraction (XRD) and parallel factor analysis (PARAFAC) demonstrate more intense solubilization and transformation of proteinaceous substances, along with cellulose degradation. These processes are crucial for enhancing organic matter degradation and humification, significantly boosting degradation (with an increase of 28.6 % to 33.8 %) and humification levels (HA/FA increased by 37.1 % to 49.6 %). Specifically, groups with high buffering capacity significantly promote the formation of NO 3 –-N and NH 4 +-N, and a higher degree of humification, creating an optimal environment for significantly improving nitrogen retention (increased by 4.80 %). Additionally, this treatment retains and slightly enhances the plant-stimulating properties of seaweed. These findings underscore the potential of integrating biochar with specific ratios of phosphates and MgO to enhance composting efficiency and product quality while preserving the plant-stimulating effects of seaweed. [ABSTRACT FROM AUTHOR]

• Bacillus sp.+Fe-modified BC was effective to improve wheat growth. • Bacillus sp.+Fe-modified BC effectively improved enzymatic activity in wheat plants. • Bacillus sp.+Fe-modified BC neutralized soil pH and immobilized Pb translocation. • Microbes+Fe-modified BC reduced Pb bioaccumulation and uptake factors in plants. Soil contamination with heavy metals (HMs) has become a severe environmental problem for crop production. The efficacy of bacillus strain (N18) and Fe-modified biochar (FeB2%) on plant growth, lead (Pb) bioaccumulation and oxidative stress in wheat plants was studied under Pb contaminated soil. Lead stress caused significant reduction in plant growth, chlorophyll contents, antioxidant enzymes activity and Pb tolerance index. The Bacillus strain inoculated seeds stimulated the plant growth, chlorophyll content, antioxidative enzymatic activity with reduced oxidative stress and Pb bioavailability in soil, Pb biological accumulation, translocation and uptake factor in plants. The FeB2% treatment had shown prominently positive results relative to N18 inoculated treatment. Whereas, combined application of N18 and FeB2% depicted maximum significant improvement in root length (37, 36 and 30%), shoot length (45 %, 46 % and 47 %), total chlorophyll (43 %, 51 % and 48 %), carotenoid contents (36 %, 49 % and 48 %) and antioxidative enzymes activities such as; superoxide dismutase (19 %, 35 % and 40 %), peroxidase (29 %, 18 % and 20 %), catalase (19 %, 35 % and 40 %) and ascorbate peroxidase (23 %, 23 % and 13 %) in Pb-0, 400 and 600 mg kg-1 soil, respectively. Reduction in malondialdehyde content (MDA) (52 %, 61 % and 56 %), Pb biological accumulation (48 %, 41 % and 37 %), soil-root translocation factor (11 %, 15 % and 9 %), root-shoot translocation factor (42 %, 36 % and 35 %) and uptake factor (19 %, 22 % and 17 %) in wheat plants observed with combined N18+ FeB2% application as compared to control treatments in Pb-0, 400 and 600 mg kg-1 soil, respectively. The study suggested that combined application of N18+ FeB2% treatment prominently increased plant health with reduction in Pb bio-availability compared to sole application of N18 strain and FeB2% treatment under (Pb) contaminated soils. [ABSTRACT FROM AUTHOR]

Nano zero-valent iron (nZVI) is widely used in soil remediation due to its high reactivity. However, the easy agglomeration, poor antioxidant ability and passivation layer of Fe−Cr coprecipitates of nZVI have limited its application scale in Cr-contaminated soil remediation, especially in high concentration of Cr-contaminated soil. Herein, we found that the carboxymethyl cellulose on nZVI particles could increase the zeta potential value of soil and change the phase of nZVI. Along with the presence of biochar, 97.0% and 96.6% Cr immobilization efficiency through CMC-nZVI/BC were respectively achieved in high and low concentrations of Cr-contaminated soils after 90-days remediation. In addition, the immobilization efficiency of Cr(VI) only decreased by 5.1% through CMC-nZVI/BC treatment after 10 weeks aging in air, attributing to the strong antioxidation ability. As for the surrounding Cr-contaminated groundwater, the Cr(VI) removal capacity of CMC-nZVI/BC was evaluated under different reaction conditions through column experiments and COMSOL Multiphysics. CMC-nZVI/BC could efficiently remove 85% of Cr(VI) in about 400 hr when the initial Cr(VI) concentration was 40 mg/L and the flow rate was 0.5 mL/min. This study demonstrates that uniformly dispersed CMC-nZVI/BC has an excellent remediation effect on different concentrations of Cr-contaminated soils. [ABSTRACT FROM AUTHOR]

Arsenic (As) pollution in soils is a pervasive environmental issue. Biochar immobilization offers a promising solution for addressing soil As contamination. The efficiency of biochar in immobilizing As in soils primarily hinges on the characteristics of both the soil and the biochar. However, the influence of a specific property on As immobilization varies among different studies, and the development and application of arsenic passivation materials based on biochar often rely on empirical knowledge. To enhance immobilization efficiency and reduce labor and time costs, a machine learning (ML) model was employed to predict As immobilization efficiency before biochar application. In this study, we collected a dataset comprising 182 data points on As immobilization efficiency from 17 publications to construct three ML models. The results demonstrated that the random forest (RF) model outperformed gradient boost regression tree and support vector regression models in predictive performance. Relative importance analysis and partial dependence plots based on the RF model were conducted to identify the most crucial factors influencing As immobilization. These findings highlighted the significant roles of biochar application time and biochar pH in As immobilization efficiency in soils. Furthermore, the study revealed that Fe-modified biochar exhibited a substantial improvement in As immobilization. These insights can facilitate targeted biochar property design and optimization of biochar application conditions to enhance As immobilization efficiency. [Display omitted] [ABSTRACT FROM AUTHOR]

• Wheat-derived Cd-stabilizing endophytic strains M14 and R27 strains were obtained. • Grain Cd content treated with BC+MR did not exceed Cd limited standard in wheat. • BC+MR showed higher ability to reduce Cd availability and Cd transfer than BC or MR. • BC+MR decreased soil Cd availability by affecting soil specific biomarker abundances. • BC+MR reduced Cd transfer by affecting root interior specific biomarker abundances. In this study, two wheat-derived cadmium (Cd)-immobilizing endophytic Pseudomonas paralactis M14 and Priestia megaterium R27 were evaluated for their effects on wheat tissue Cd uptake under hydroponic conditions. Then, the impacts of the biochar (BC), M14+R27 (MR), and BC+MR treatments on wheat Cd uptake and the mechanisms involved were investigated at the jointing, heading, and mature stages of wheat plants under field-plot conditions. A hydroponic experiment showed that the MR treatment significantly decreased the above-ground tissue Cd content compared with the M14 or R27 treatment. The BC+MR treatment reduced the grain Cd content by 51.5%–67.7% and Cd translocation factor at the mature stage of wheat plants and increased the organic matter-bound Cd content by 31%–75% in the rhizosphere soils compared with the BC or MR treatment. Compared with the BC or MR treatment, the relative abundances of the biomarkers associated with Gemmatimonas, Altererythrobacter, Gammaproteobacteria, Xanthomonadaceae, Phenylobacterium, and Nocardioides in the BC+MR-treated rhizosphere microbiome decreased and negatively correlated with the organic matter-bound Cd contents. In the BC+MR-treated root interior microbiome, the relative abundance of the biomarker belonging to Exiguobacterium increased and negatively correlated with the Cd translocation factor, while the relative abundance of the biomarker belonging to Pseudonocardiaceae decreased and positively correlated with the Cd translocation factor. Our findings suggested that the BC+MR treatment reduced Cd availability and Cd transfer through affecting the abundances of these specific biomarkers in the rhizosphere soil and root interior microbiomes, leading to decreased wheat grain Cd uptake in the contaminated soil. [Display omitted] [ABSTRACT FROM AUTHOR]

• Straw biochar-derived DBC possess more oxygen-containing groups and high aromaticity. • Bacteria and light both affect the phenolic and carboxylic groups of DBC. • Fe3+ complex with DBC can promote the dissolution of ferrous mineral. • Complexation between DBC and iron ions increases the bioavailable Fe in water. Dissolved black carbon (DBC) plays a crucial role in the migration and bioavailability of iron in water. However, the properties of DBC releasing under diverse pyrolysis conditions and dissolving processes have not been systematically studied. Here, the compositions of DBC released from biochar through redox processes dominated by bacteria and light were thoroughly studied. It was found that the DBC released from straw biochar possess more oxygen-containing functional groups and aromatic substances. The content of phenolic and carboxylic groups in DBC was increased under influence of microorganisms and light, respectively. The concentration of phenolic hydroxyl groups increased from 10.0∼57.5 mmol/gC to 6.6 ∼65.2 mmol/gC, and the concentration of carboxyl groups increased from 49.7∼97.5 mmol/gC to 62.1 ∼113.3 mmol/gC. Then the impacts of DBC on pyrite dissolution and microalgae growth were also investigated. The complexing Fe3+ was proved to play a predominant role in the dissolution of ferrous mineral in DBC solution. Due to complexing between iron ion and DBC, the amount of dissolved Fe in aquatic water may rise as a result of elevated number of aromatic components with oxygen containing groups and low molecular weight generated under light conditions. Fe-DBC complexations in solution significantly promoted microalga growth, which might be attributed to the stimulating effect of dissolved Fe on the chlorophyll synthesis. The results of study will deepen our understanding of the behavior and ultimate destiny of DBC released into an iron-rich environment under redox conditions. [Display omitted] [ABSTRACT FROM AUTHOR]

• SC, Mg/SC and ZVI decreased concentrations of Cd and iAs in rice grain concurrently. • Mg/SC and ZVI simultaneously reduced Cd and iAs concentrations in soil porewater. • ZVI raised DMA concentrations in porewater and rice grain, but SC and Mg/SC didn't. • SC, Mg/SC and ZVI affected Cd/As accumulation through divergent mechanisms. Cadmium (Cd) and arsenic (As) co-contamination has threatened rice production and food safety. It is challenging to mitigate Cd and As contamination in rice simultaneously due to their opposite geochemical behaviors. Mg-loaded biochar with outstanding adsorption capacity for As and Cd was used for the first time to remediate Cd/As contaminated paddy soils. In addition, the effect of zero-valent iron (ZVI) on grain As speciation accumulation in alkaline paddy soils was first investigated. The effect of rice straw biochar (SC), magnesium-loaded rice straw biochar (Mg/SC), and ZVI on concentrations of Cd and As speciation in soil porewater and their accumulation in rice tissues was investigated in a pot experiment. Addition of SC, Mg/SC and ZVI to soil reduced Cd concentrations in rice grain by 46.1%, 90.3% and 100%, and inorganic As (iAs) by 35.4%, 33.1% and 29.1%, respectively, and reduced Cd concentrations in porewater by 74.3%, 96.5% and 96.2%, respectively. Reductions of 51.6% and 87.7% in porewater iAs concentrations were observed with Mg/SC and ZVI amendments, but not with SC. Dimethylarsinic acid (DMA) concentrations in porewater and grain increased by a factor of 4.9 and 3.3, respectively, with ZVI amendment. The three amendments affected grain concentrations of iAs, DMA and Cd mainly by modulating their translocation within plant and the levels of As(III), silicon, dissolved organic carbon, iron or Cd in porewater. All three amendments (SC, Mg/SC and ZVI) have the potential to simultaneously mitigate Cd and iAs accumulation in rice grain, although the pathways are different. [Display omitted] [ABSTRACT FROM AUTHOR]

Dibromoethane is a widespread, persistent organic pollutant. Biochars are known mediators of reductive dehalogenation by layered FeII-FeIII hydroxides (green rust), which can reduce 1,2-dibromoethane to innocuous bromide and ethylene. However, the critical characteristics that determine mediator functionality are lesser known. Fifteen biochar substrates were pyrolyzed at 600 °C and 800 °C, characterized by elemental analysis, X-ray photo spectrometry C and N surface speciation, X-ray powder diffraction, specific surface area analysis, and tested for mediation of reductive debromination of 1,2-dibromoethane by a green rust reductant under anoxic conditions. A statistical analysis was performed to determine the biochar properties, critical for debromination kinetics and total debromination extent. It was shown that selected plant based biochars can mediate debromination of 1,2-dibromoethane, that the highest first order rate constant was 0.082/hr, and the highest debromination extent was 27% in reactivity experiments with 0.1 µmol (20 µmol/L) 1,2-dibromoethane, ≈ 22 mmol/L FeII GR , and 0.12 g/L soybean meal biochar (7 days). Contents of Ni, Zn, N, and P, and the relative contribution of quinone surface functional groups were significantly (p < 0.05) positively correlated with 1,2-dibromoethane debromination, while adsorption, specific surface area, and the relative contribution of pyridinic N oxide surface groups were significantly negatively correlated with debromination. [ABSTRACT FROM AUTHOR]

• Biochar accelerated the conversion of acetic and propionic acids in AnMBR. • Biochar enriched the functional bacteria degrading polysaccharides and protein. • Biochar facilitated the enrichment of autotrophic methanogenic bacteria. • Biochar increased c-type cytochromes-mediated DIET. • SCG-BC has a high electron accepting and donating capacities of 0.0362 ± 0.002 mmole− g−1. A biochar-assisted anaerobic membrane bioreactor (BC-AnMBR) was conducted to evaluate the performance in treating swine wastewater with different organic loading rates (OLR) ranging from 0.38 to 1.13 kg-COD/(m3.d). Results indicated that adding spent coffee grounds biochar (SCG-BC) improved the organic removal efficiency compared to the conventional AnMBR, with an overall COD removal rate of > 95.01%. Meanwhile, methane production of up to 0.22 LCH 4 /gCOD with an improvement of 45.45% was achieved under a high OLR of 1.13 kg-COD/(m3.d). Furthermore, the transmembrane pressure (TMP) in the BC-AnMBR system was stable at 4.5 kPa, and no irreversible membrane fouling occurred within 125 days. Microbial community analysis revealed that the addition of SCG-BC increased the relative abundance of autotrophic methanogenic archaea, particularly Methanosarcina (from 0.11% to 11.16%) and Methanothrix (from 16.34% to 24.05%). More importantly, Desulfobacterota and Firmicutes phylum with direct interspecific electron transfer (DIET) capabilities were also enriched with autotrophic methanogens. Analysis of the electron transfer pathway showed that the concentration of c-type cytochromes increased by 38.60% in the presence of SCG-BC, and thus facilitated the establishment of DIET and maintained high activity of the electron transfer system even at high OLR. In short, the BC-AnMBR system performs well under various OLR conditions and is stable in the recovery energy system for swine wastewater. [Display omitted] [ABSTRACT FROM AUTHOR]

In this work, a simple hydrothermal synthesis method is used to prepare photocatalytic NiO/WO 3 -biochar composite material, which is applied to catalyze the one-step conversion of 5-hydroxymethylfurfural to 2,5-furandicarboxylic acid with synergistic hydrogen production. The optoelectronic properties of NiO/WO 3 -biochar composite material are characterized. The results indicate that the p-n heterojunction-coupled biochar structure between NiO and WO 3 in the NiO/WO 3 -biochar composite is an important prerequisite for ensuring the one-step oxidation reaction of 5-hydroxymethylfurfural. The experimental results reveal the possible reaction pathways. Under the optimal ratio of NiO/WO 3 -biochar composite material, the 5-hydroxymethylfurfural conversion rate reaches 100%, the 2,5-furandicarboxylic acid yield reaches 99.6%, and the Faraday efficiency of hydrogen evolution is 98%. This study provides a new approach for the one-step photocatalytic synthesis of 2,5-furandicarboxylic acid from 5-hydroxymethylfurfural, as well as a novel and efficient catalyst for photocatalytic oxidation technology. [Display omitted] • NiO/WO 3 -biochar composite is successfully prepared. • Mechanism of hydrogen production by photocatalytic reaction of straw is analyzed. • HMF undergoes photocatalytic one-step oxidation to FDCA with 99.6% efficiency. [ABSTRACT FROM AUTHOR]

[Display omitted] • Steam gasification of a genetically modified (GMO) rice straw is investigated. • GMO rice straw exhibits superior gasification performance compared to regular one. • Co-gasification of GMO rice straw with Giant Miscanthus is investigated. • Seaweed biochar addition can greatly enhance co-gasification with reduced tar. • Promoting synergistic effect by low-cost catalyst for co-gasification is clarified. Future sustainability visions include clean, renewable energy from hydrogen, which can be produced, among other ways, by biomass steam gasification. This study explores strategies addressing the limitations in steam co-gasification of herbaceous biomass, using Monster-TUAT1 rice straw, a genetically modified rice plant with a taller and bigger stalk developed by Tokyo University of Agriculture and Technology (TUAT), and Giant Miscanthus, a promising energy crop, as the feedstock. Firstly, compared with the typical rice straw, the Monster TUAT1 demonstrated superior steam gasification performance with a 1.75 times higher hydrogen gas yield and 27.0 % less tar generation. With a focus on overcoming the challenges posed by high silica content in the Monster TUAT1, co-gasification of it with an energy crop of Giant Miscanthus was performed. However, even under the optimum operation condition (750 °C, steam flowrate: 0.15 g/min), the hydrogen gas yield was only 29.3 mmol/g-C with a tar yield of 27.6 %wt. and a carbon conversion efficiency of 45.9 %, which is deemed unsatisfactory for hydrogen production. Thus, strategies for enhancement were proposed, including the incorporation seaweed biochar with high alkali and alkaline earth species, calcined scallop shell powder, and alkali metal salt into the gasifier. Consequently, the introduction of 10 %wt. of calcined scallop shell resulted in an increase in H 2 yield to 37.0 mmol/g-C and 24.3 % CO 2 reduction. The addition of alkali metal salt led to 43.9 % increase of H 2 product with a 15 %wt. tar yield. The most significant improvement occurred with the introduction of seaweed biochar at 50 %wt., increasing of the hydrogen gas yield to 62.0 mmol/g-C with 86 % of carbon conversion efficiency and tar reduction to 5.5 %. These findings demonstrate the viability of utilizing herbaceous biomass such as rice straw in conjunction with the strategic solutions of co-gasification to overcome constraints in improving hydrogen production. [ABSTRACT FROM AUTHOR]

[Display omitted] • The controllability of N and metal elements transformation was achieved. • Hydrothermal-pyrolysis offered DFW efficient utilization and control NO x emissions. • Hydrothermal pretreatment enhances biochar pore structure and surface area. • O-containing functional groups and doped metal Ca were enriched on the biochar. • Maximum P removal efficiency of wastewater by DFW biochar upped to 94%. Pyrolysis has emerged as a promising technology for valorizing digestate resulting from the anaerobic digestion of food waste. However, the high NO X emissions during pyrolysis limit its application. This study proposed a hydrothermal coupled pyrolysis process to control the element transfer in digestate during biochar production. The efficient reduction of NO X emissions and the improvement of biochar adsorbability were realized. The hydrothermal process reduced the nitrogen content in solid digestate by 49.10 %–81.79 %, thus reducing the NO X precursors in syngas and the N-containing substances in bio-oil. Additionally, the specific surface area and the total pore volume of biochar were enhanced from 25 m2/g to 60–73 m2/g and 0.06 cm3/g to 0.12–0.14 cm3/g, respectively. More defects, oxygen-containing functional groups, and doped Ca on the biochar resulted in a high phosphate removal efficiency of 94 %. The proposed technology provides an efficient and environmentally friendly way to utilize the digestate. [ABSTRACT FROM AUTHOR]

A biochar-incorporated g-C 3 N 4 composite was obtained by co-calcining the mixture of spent coffee grounds and melamine and used to anchor highly dispersed amorphous cobalt boride nanoparticles via an impregnation-reduction method. The as-prepared Co 2 B/BC-g-C 3 N 4 was applied to the catalytic hydrolysis of sodium borohydride to produce hydrogen. The physicochemical properties of Co 2 B/BC, Co 2 B/g-C 3 N 4 , and Co 2 B/BC-g-C 3 N 4 were evaluated by various techniques to help elucidate the effect of the composite structure on the performance of Co 2 B/BC-g-C 3 N 4. The Co 2 B/BC-g-C 3 N 4 exhibits much better activity than Co 2 B/BC and Co 2 B/g-C 3 N 4 because of a synergistic effect between the biochar and g-C 3 N 4. In addition, the reaction kinetics can be improved by exposing the reaction system to visible light irradiation, yielding a hydrogen generation rate of 10.3 L min−1 g Co −1 in comparison to that of 9.1 L min−1 g Co −1 under darkness. The possible mechanism of the H 2 generation from the catalytic hydrolysis of sodium borohydride over Co 2 B/BC-g-C 3 N 4 under visible light irradiation was proposed. This work highlights the potential application of biochar-incorporated g-C 3 N 4 composite in synthesizing metallic catalysts and their practical use for photo-assisted catalytic hydrolysis of sodium borohydride. [Display omitted] • A biochar-g-C 3 N 4 composite is prepared by co-calcination of spent coffee and melamine. • Co 2 B nanoparticles are immobilized on the BC-g-C 3 N 4 composite. • Co 2 B/BC-g-C 3 N 4 exhibits improved activity toward hydrolysis of NaBH 4 under visible light irradiation. • A possible reaction mechanism of photo-assisted NaBH 4 hydrolysis for H 2 release is proposed. • Regulation of the local electron density of Co active sites occur under visible light irradiation. [ABSTRACT FROM AUTHOR]

[Display omitted] • This study reviewed the effect of biomass type on the properties of biochar. • The biomass composition significantly impacted biochar specifications. • Pyrolysis condition was a key parameter influencing biochar properties. • Suggestions are given to obtain biochar of desired property. Owing to the diversity of biomasses and many variables in pyrolysis process, the property of biochar from varied biomass feedstock or even same biomass could differ significantly. Since the property of biochar governs the further application of biochar, this review paid particular attention to the correlation between the nature of biomass feedstock and the specifications of biochar in terms of yield, elemental composition, pH, functionalities, heating value, pore structures, morphologies, etc. The property of the biochar from the pyrolysis of cellulose, hemicellulose, lignin, woody biomass (pine, mallee, poplar, acacia, oak, eucalyptus and beech), bark of woody biomass, leaves of woody biomass, straw, algae, fruit peels, tea waste was compared and summarized. In addition, the differences of the biochar of these varied origins were also analyzed. The remaining questions, about the correlation of biomass nature with biochar characteristics, to be further investigated are analyzed in detail. The deduced information about the relationship of the nature of biochar and biomass feedstock as well as key pyrolysis parameters is of importance for further development of the methods for tailoring or production of the biochar of desirable properties. The results from this study could be interesting technically and commercially for the technology developer using biochar as the source of carbon in different applications. [ABSTRACT FROM AUTHOR]

Catalytic methane decomposition (CMD) stands out as a promising alternative for hydrogen production, distinguished by its ability to generate hydrogen with minimal byproducts. While some studies have explored the use of biochar as an alternative catalyst in the CMD process, the role of biochar surface functional groups and inherent properties have not been well understood. This study aimed to explore the influence of various woody biochar types, acidic sites, physicochemical properties, and operating temperatures on their catalytic activity in catalytic methane decomposition (CMD) process. Biochar derived from three biomass sources (pine, poplar, and bark) were examined at 600, 800, and 1000 °C reaction temperature. The findings revealed that heat-treated (HT) poplar biochar exhibited the lowest specific surface area (215.1 m2g⁻1) and the highest concentration of acidic sites. All samples exhibited improved performance at 1000 °C compared to other temperatures. The CH 4 conversion order was observed as HT poplar > HT red pine > HT bark, with the initial conversion of approximately 50%, 35%, and 25%, respectively. Additionally, employing genetic algorithms, kinetics models for the CMD reaction were developed. The study concluded a consistent second order reaction and an activation energy in the range of 300–330 kJ/mol for all three biochar samples. [Display omitted] • The role of acidic functional groups on biochar activity during CMD was revealed. • Poplar demonstrated the highest acidity and best catalytic performance at 1000 °C. • The O:C and H:C ratios suggested potential for carbon sequestration potential. • Biocarbon-catalyzed CMD exhibited an activation energy between 300 and 330 kJ/mol. [ABSTRACT FROM AUTHOR]

Metal/biochar catalyst features with the advantages for easy recovery of chemical energy of biochar carrier and metal species via simply combustion. Another unique feature of biochar carrier is intrinsic inorganic species, which might also interact with metal species in resulting catalyst. This was investigated herein by synthesis of the Ni/biochar with rice husk-derived biochar carrier pretreated with NaOH for removal of SiO 2 and evaluation of the resulting catalysts in steam reforming of glycerol. The solid phase reactions between NaOH and biochar (mass ratio: 2) plus subsequent washing removed 94.6% of ash (mainly SiO 2). This formed Ni/biochar of fragmented surface with specific surface area increasing from 207.8 to 457.4 m2g-1 and simultaneously increasing mesopore percentage from 15.5% to 24.0%. NaOH treatment also effectively removed significant portion of both Lewis and Brønsted acidic sites but created abundant alkaline sites. These drastically enhanced nickel dispersion and activity for steam reforming. In-situ IR characterization suggested enhanced adsorption/activation of CO 2 and H 2 O over Ni/biochar treated with NaOH (Ni/biochar-NaOH), which mitigated accumulation of coke precursors bearing C O or C C via accelerated gasification reactions. This led to the reduced amount of coke (mass ratio to catalyst) from 193.4% to 94.7% over Ni/biochar treated with 2-fold of NaOH or to 111.3% over Ni/biochar treated with 1-fold of NaOH. The coke formed was mainly catalytic type in form of carbon nanotube over Ni/biochar-NaOH. The superior resistivity to coking originated from developed pores, enhanced Ni dispersion and abundant alkaline sites from the NaOH treatment. [Display omitted] • NaOH treatment removes SiO 2 in rice husk-biochar and creates developed pores. • NaOH treatment brings abundant alkaline sites while removes Lewis and Brønsted acidic sites. • NaOH treatment enhances Ni dispersion in Ni/biochar and activity for reforming. • NaOH treatment enhances activation of CO 2 /H 2 O, promoting gasification of coke precursors bearing C O/C C. • NaOH pretreatment effectively increases resistivity of Ni/biochar to coking. [ABSTRACT FROM AUTHOR]

[Display omitted] • The release of Zn and Pb were mitigated by the synergistic effect. • Bioavailable fractions of HMs were reduced by SiO 2 and Al 2 O 3 from the sludge. • Bioavailable phosphorus was increased from 18.79 to 49.69 mg/g by co-pyrolysis. Phosphate tailings (PT) was used to reduce the release of heavy metals (HMs) during pyrolysis and the leachable rate of residual HMs, and simultaneously improve the bioavailability of phosphorus in the sludge-based biochar. The concentration of heavy metals and the fractions determined by BCR method was used to investigate the release and the transformation of Zn, Pb, Mn, Ni and Cu during pyrolysis involved with the effects of temperature and the addition of PT. The respective pyrolysis experiments shows that the release of Zn and Pb increases with temperature for both sewage sludge (SS) and PT, and the bioavailable fractions (F1 + F2) of Mn, Ni, and Cu increases with temperature for PT. During co-pyrolysis, blended samples released lower quantities of Zn and Pb and presented lower bioavailability of HMs than the individual SS or PT. A synergistic effect of co-pyrolysis was evident for volatile Zn and Pb. The decomposition of CaMg (CO 3) 2 from PT produced CaO, by which the volatile ZnCl 2 and PbCl 2 were transformed into ZnO and PbO with less volatility and higher reactivity with SiO 2 and Al 2 O 3 than the chlorides. Then SiO 2 and Al 2 O 3 from SS acted as the final stabilizer to immobilize the oxides. The final product combined with SiO 2 and Al 2 O 3 , such as ZnSiO 4 and ZnAl 2 O 4 , were detected. The addition of PT also introduced more Ca and P into sludge to produce biochar with higher concentration of apatite phosphorus with higher bioavailability. [ABSTRACT FROM AUTHOR]

Metal/biochar is an important category of catalyst that can be prepared via direct impregnation of metal salt to a biomass feedstock. However, during pyrolysis of metal salt@biomass for catalyst preparation, metal-volatiles interaction might affect exposure or dispersion of metal species. To verify this, loading of nickel acetate to poplar sawdust directly and to the sawdust-derived biochar was conducted to prepare Ni/biochar and biochar/Ni at 500 or 750 °C, aiming to understand the effect of metal-volatiles interaction on exposure of nickel species in resulting Ni/biochar. The results indicated Ni species catalyzed cracking, dehydrogenation, and reforming reactions in sawdust pyrolysis, producing more bio-oil/gases at the expense of biochar and also making biochar of higher aromatic degree with improved thermal stability. The in-situ IR characterizations also evidenced high activity of Ni towards dehydration and cracking of carbonyls for enhancing aromatization of biochar. In biochar/Ni catalysts prepared via loading nickel to biochar, little metal-volatiles interaction existed and nickel species weakly interacted with the biochar, resulting in remarkable migration and agglomeration of nickel, forming nickel size of 2–3 times larger than that in Ni/biochar. However, biochar/Ni possessed higher capability for adsorption/activation of H 2 , thus exhibiting superior catalytic activity than Ni/biochar for hydrogenation of phenolics. [Display omitted] • Ni accelerates removal of O-containing species in pyrolysis, enhancing aromatization of Ni/biochar. • In-situ IR characterization shows superior activity of Ni for dehydration, dehydrogenation, and cracking. • Migration of Ni in biochar/Ni prepared from impregnating biochar forms larger Ni size. • Ni in Ni/biochar is partially covered by deposits from cracking/polymerization of volatiles. • Biochar/Ni shows higher capability for H 2 adsorption and hydrogenation than Ni/biochar. [ABSTRACT FROM AUTHOR]

• Six types of campus fallen leaves were collected to produce biochar at 300 °C. • Adsorption capacity of leaf biochars for Pb vary from 31 to 209 mg/g. • Intraparticle diffusion controlled the adsorption kinetics of Pb onto PB. • 27% of total adsorbed Pb existed as the exchangeable fraction on PB. • Hydrocerussite and cerussite contributed to the great acid soluble Pb on YDB. Realizing campus sustainability requires the environmental-friendly and economical treatment of tremendous fallen leaves. Producing fallen leaf biochar at a low temperature is a candidate approach. In this study, six common types of fallen leaves on the campus were pyrolyzed at 300 °C. The obtained biochars were characterized and the adsorption mechanisms of lead (Pb) by the fallen leaf biochars were investigated. The adsorption capacity of leaf biochar for Pb was relatively high, up to 209 mg/g (Yulania denudata leaf biochar). Adsorption of Pb onto active sites was the rate-limiting step for most leaf biochars. But for Platanus leaf biochar, intraparticle diffusion of Pb2+ dominated owing to the lowest adsorption capacity. However, the highest exchangeable Pb fraction (27%) indicated its potential for removing aqueous Pb2+. Ginkgo and Prunus cerasifera leaf biochar immobilized Pb by surface complexation and precipitation as lead oxalate. Hence, they were suitable for soil heavy metal remediation. This study shed the light on the sustainable utilization of campus fallen leaves and the application of fallen leaf biochars in heavy metal remediation. [Display omitted] [ABSTRACT FROM AUTHOR]

• Ferrihydrite-biochar composite simultaneously removed Cd(II) and As(V). • As(V) presence promoted Cd(II) retention in the ferrihydrite-biochar composite. • The distribution of Cd(II)/As(V) in single system is different in the ferrihydrite-biochar composite. • Cd(II) and As(V) were closely associated with ferrihydrite in the mixed Cd&As system. The coexistence of cadmium (Cd(II)) and arsenate (As(V)) pollution has long been an environmental problem. Biochar, a porous carbonaceous material with tunable functionality, has been used for the remediation of contaminated soils. However, it is still challenging for the dynamic quantification and mechanistic understanding of the simultaneous sequestration of multi-metals in biochar-engineered environment, especially in the presence of anions. In this study, ferrihydrite was coprecipitated with biochar to investigate how ferrihydrite-biochar composite affects the fate of heavy metals, especially in the coexistence of Cd(II) and As(V). In the solution system containing both Cd(II) and As(V), the maximum adsorption capacities of ferrihydrite-biochar composite for Cd(II) and As(V) reached 82.03 µmol/g and 531.53 µmol/g, respectively, much higher than those of the pure biochar (26.90 µmol/g for Cd(II), and 40.24 µmol/g for As(V)) and ferrihydrite (42.26 µmol/g for Cd(II), and 248.25 µmol/g for As(V)). Cd(II) adsorption increased in the presence of As(V), possibly due to the changes in composite surface charge in the presence of As(V), and the increased dispersion of ferrihydrite by biochar. Further microscopic and mechanistic results showed that Cd(II) complexed with both biochar and ferrihydrite, while As(V) was mainly complexed by ferrihydrite in the Cd(II) and As(V) coexistence system. Ferrihydrite posed vital importance for the co-adsorption of Cd(II) and As(V). The different distribution patterns revealed by this study help to a deeper understanding of the behaviors of cations and anions in the natural environment. [Display omitted] [ABSTRACT FROM AUTHOR]

Iron ore tailings (IOT) are industrial solid wastes that pose environmental threats. This study prepared IOT-biochar composite materials as multifunctional soil conditioners through an in-situ growth method. Biochar served as a carrier to improve the dispersity and reactivity of IOT in soil. The IOT-biochar composite (FeOT-BC) showed balanced impacts on soil properties, increasing pH, organic matter and available nutrients compared to IOT alone. This was due to the buffering effects of biochar. In pot experiments, FeOT-BC significantly promoted rice plant growth compared to IOT alone. The improvements were attributed to the improved soil fertility and increased microbial activities induced by biochar. The results suggest that integrating IOT with biochar can mitigate the negative effects of tailings and convert them into a value-added product. The biochar component can optimize the performance of IOT by moderating soil acidification, enhancing nutrient release from iron minerals, and stimulating microbial activities. The IOT-biochar composite materials integrate the functionalities of both components for optimized soil conditioning effects, providing a promising strategy for comprehensive tailings utilization. [ABSTRACT FROM AUTHOR]

[Display omitted] • Waste furfural residue is deliberated as feedstock for pyrolysis/gasification. • Furfural residue is used to prepare catalysts with one-step method for tar cracking. • Increase in cracking temperature is helpful to the catalytic ability of catalysts. • Ni-loaded catalyst shows higher thermal stability and tar conversion efficiency. • Mechanism of tar catalytic cracking over catalysts is proposed. This study proposed an innovative strategy of catalytic cracking of tar during biomass pyrolysis/gasification using furfural residue derived biochar-based catalysts. Fe, Co, and Ni modified furfural residue char (FRC-Fe, FRC-Co, and FRC-Ni) were prepared by one-step impregnation method. The influences of cracking temperature and metal species on the tar cracking characteristics were investigated. The results showed that the tar conversion efficiency for all catalysts were improved with the cracking temperature increasing, the higher tar conversion efficiency achieved at 800 °C were 66.72 %, 89.58 %, 84.58 %, and 94.70 % for FRC, FRC-Fe, FRC-Co, and FRC-Ni respectively. FRC-Ni achieved the higher gas (H 2 , CO, CH 4 , CO 2) yield 681.81 mL/g. At 800 °C, the catalyst (FRC-Ni) still reached a high tar conversion efficiency over 85.90 % after 5 cycles. SEM-EDS results showed that the distribution of Ni particles on the biochar support was uniform. TGA results demonstrated that FRC-Ni exhibited better thermal stability. XRD results indicated that there was no significant change in the grain size of Ni before and after the reaction. The FRC-Ni catalyst was reasonably stable due to its better anti-sintering and coke-resistant capabilities. [ABSTRACT FROM AUTHOR]

Hexavalent chromium [Cr(VI)] is a toxic metal that poses huge threat to environment and living bodies. Recently, microbial fuel cell (MFC) systems based on highly efficient cathodes have been widely applied for Cr(VI) remediation. In this study, a novel cathode loaded with magnetic nanoparticles (NPs)-doped biochar (Fe NPs/biochar) is introduced into a two-chamber MFC to investigate its power output and Cr(VI) reduction. Results showed that the removal efficiency of Cr(VI) using Fe NPs/biochar group was 98.19%, which is significantly higher than that of carbon felt (53.31%). The maximum power density of the Fe NPs/biochar is 8.41 times higher than that of carbon felt. An adsorption–reduction mechanism is obtained for Cr(VI) reduction of Fe NPs/biochar through characteristic and electrochemical analyses, such as scanning electron microscopy-energy dispersive spectroscopy, X-ray photoelectron spectroscopy, and cyclic voltammetry test. The microbial community analysis showed that the biofilm of the anode were enriched with electrochemically active bacteria, such as Geobacter and Pseudomonas , after operation. Thus, this study presents a highly effective electrode for enhancing the power output and Cr(VI) reduction for Cr(VI)-containing wastewater treatment. • The system showed high removal efficiency (∼98.19 %) for Cr(VI). • Fe NPs/Biochar cathode produced 144 mV of the bioelectricity. • Fe NPs can improve the performance of MFC as an electron shuttle carrier. [ABSTRACT FROM AUTHOR]

• Biochar ammoniacal nitrogen adsorption capacity was measured. • Nitric acid increased biochar capacity to reduce aerobic degradation ammonia losses. • Biochar ammoniacal nitrogen adsorption explains its capacity to reduce ammonia losses. • Biochar adsorption properties is related to its surface electrical charge. One of the technical barriers to the wider use of biochar in the composting practices is the lack of accurate quantification linking biochar properties to application outcomes. To address this issue, this paper investigates the use of ammonia nitrogen adsorption capacity by biochar as a predictor of ammonia emission during composting in the presence of biochar. With this in mind, this work investigated the use of ammonia nitrogen adsorption capacity of biochar when mixed with solid digestate, and the reduction in ammonia emissions resulting from the addition of biochar during aerobic degradation of solid digestate. A biochar synthesized at 900 °C, another synthesized at 450 °C, and two derivatives of the latter biochar, one chemically modified with nitric acid and the other with potassium hydroxide, were tested. This study concluded that the chemical characteristics of the biochar, including pH and oxygen/carbon atomic ratio, had a greater influence on the adsorption of ammonia nitrogen than physical attributes such as specific surface area. In this regard, nitric acid modification had superior performance compared to hydroxide potassium modification to increase biochar chemical attributes and reduce ammonia emissions when applied to aerobic degradation. Finally, a significant linear correlation (p-value < 0.05, r2 = 0.79) was found between biochar ammonia nitrogen adsorption capacity and ammonia emissions along composting, showing the potential of this variable as a predictive parameter. This study provides insights for future explorations aiming to develop predictive tests for biochar performance. [ABSTRACT FROM AUTHOR]

[Display omitted] • Biochar amendment to the digestate-based bioponics improved plant yield. • Biochar adsorbed heavy metals and decreased their bioaccumulation in plants. • Noncancer and cancer risks were found from ingestion of the plants. • Biochar enhanced microbial communities, aiding metal stabilization in bioponics. • Biochar promoted genera in sludge and plant roots for efficient P and N recovery. Bioponics is a nutrient-recovery technology that transforms nutrient-rich organic waste into plant biomass/bioproducts. Integrating biochar with digestate from anaerobic wastewater treatment process can improve resource recovery while mitigating heavy metal contamination. The overarching goal of this study was to investigate the application of biochar in digestate-based bioponics, focusing on its efficacy in nutrient recovery and heavy metal removal, while also exploring the microbial community dynamics. In this study, biochar was applied at 50 % w/w with 500 g dry weight of digestate during two 28-day crop cycles (uncontrolled pH and pH 5.5) using white stem pak choi (Brassica rapa var. chinensis) as a model crop. The results showed that the digestate provided sufficient phosphorus and nitrogen, supporting plant growth. Biochar amendment improved plant yield and phosphate solubilization and reduced nitrogen loss, especially at the pH 5.5. Furthermore, biochar reduced the heavy metal accumulation in plants, while concentrating these metals in the residual sludge. However, owing to potential non-carcinogenic and carcinogenic health risks, it is still not recommended to directly consume plants cultivated in digestate-based bioponic systems. Additionally, biochar amendment exhibited pronounced impact on the microbial community, promoting microbes responsible for nutrient solubilization and cycling (e.g., Tetrasphaera , Herpetosiphon , Hyphomicrobium , and Pseudorhodoplanes) and heavy metal stabilization (e.g., Leptolinea , Fonticella , Romboutsia , and Desulfurispora) in both the residual sludge and plants. Overall, the addition of biochar enhanced the microbial community and facilitated the metal stabilization and the cycling of nutrients within both residual sludge and root systems, thereby improving the overall efficiency of the bioponics. [ABSTRACT FROM AUTHOR]

This study aimed to analyze a technology of hydrogen-rich gas from full-component oriented pyrolysis (FCOP) of biomass using energy, economic, and environmental life cycle assessment. Firstly, the study taked corn straw (CS) as the research object, the yield of hydrogen-rich gas and char produced by the oriented pyrolysis method are 78.26% and 20.35%, and the yield of biochar produced by activating char with phosphoric acid is 40%. Secondly, the system boundary of FCOP of biomass to produce hydrogen-rich gas and biochar was creatively designed, establishing the energy, environmental, and economic analysis comprehensive model. Various energy, economic, and environmental indicators were computed to facilitate process optimization for hydrogen-rich gas co-production biochar and explored the feasibility of the process. The results show that the stage of hydrogen-rich gas prepared by FCOP of biomass is an important factor affecting energy output and input, and has the highest standard pollutant emissions (92.11%). This process has low carbon emissions and GHG emissions, showing good sustainability and application prospects, which has important guiding significance for realizing cleaner production and solving the energy crisis. Thirdly, taking the large-scale system of producing hydrogen-rich gas co-production biochar, which processes 40,000 t of CS per year, as an example, the economic benefit analysis results were obtained, that is, IRR , NPV , and P m are 22%, 6.33 million yuan, and 7.3 years, respectively. Meanwhile, the key factors, including the initial investment, expenses of biomass and catalyst, and the sale income of hydrogen and biochar, which are the main factors affecting the economic efficiency of technology, and uncertainties were identified through sensitivity analysis. Finally, we put forward in the background of ecological civilization, the research focus and thinking for the development of hydrogen production technology from pyrolysis/gasification of biomass were proposed. The results obtained can be valuable in practical applications to enhance the sustainability and viability of hydrogen production in biomass conversion and utilization activities. The applied energy, economic, and environmental methodologies appear to be reliable and comprehensive tools for assessing the whole-life sustainability and viability of biofuel. [Display omitted] • Provides a detailed inventory for a hydrogen produced from pyrolysis of biomass. • An energy, environmental and economic model and indicators were established. • Anergy consumption, economic benefits and environmental emissions were studied. • Technology of hydrogen production has good feasibility and application prospects. • Enhance the sustainability and viability of hydrogen production from biomass. [ABSTRACT FROM AUTHOR]

Tannery sludge with high chromium content has been identified as hazardous solid waste due to its potential toxic effects. The safety disposal and valorization of the tannery sludge remains a challenge. In this study, the chromium stabilization mechanism was systematically investigated during chromium-rich tannery sludge was converted to biochar and the removal performance of the sludge biochar (SBC) for Cr(VI) from tannery wastewater was also investigated. The results showed that increase in pyrolysis temperature was conductive to the stabilization of Cr and significant reduction of the proportion of Cr(VI) in SBC. It was confirmed that the stabilization of chromium mainly was attributed to the embedding of chromium in the C matrix and the transformation of the chromium-containing substances from the amorphous Cr(OH) 3 to the crystalline state, such as (FeMg)Cr 2 O 5. The biochar presented high adsorption capacity of Cr(VI) at low pH and the maximal theoretical adsorption capacity of SBC produced at 800°C can reach 352 mg Cr(VI)/g, the process of which can be well expressed by Langmuir adsorption isotherm and pseudo second order model. The electrostatic effect and reduction reaction were dominantly responsible for the Cr(VI) adsorption by SBC800. Overall, this study provided a novel strategy for the harmless disposal and resource utilization for the solid waste containing chromium in leather industry. [Display omitted] [ABSTRACT FROM AUTHOR]

• Pristine/modified biochar in different aspects of petroleum remediation is reviewed. • Biochar facilitates both adsorption and biodegradation mechanisms of oil removal. • Surface-modified biochar enhances adsorption of petroleum hydrocarbons from water. • Biochar use with nutrient, surfactant, and plant enhanced oil degradation in soil. • Potential minimization of biochar ecotoxicity for oil remediation is highlighted. Petroleum contamination is considered as a major risk to the health of humans and environment. Biochars as low-cost and eco-friendly carbon materials, have been widely used for the removal of petroleum hydrocarbon in the environment. The purpose of this paper is to review the performance, mechanisms, and potential environmental toxicity of biochar, modified biochar and its integration use with other materials in petroleum contaminated soil and water. Specifically, the use of biochar in oil-contaminated water and soil as well as the factors that could influence the removal ability of biochar were systematically evaluated. In addition, the modification and integrated use of biochar for improving the removal efficiency were summarized from the aspects of sorption, biodegradation, chemical degradation, and reusability. Moreover, the functional impacts and associated ecotoxicity of pristine and modified biochars in various environments were demonstrated. Finally, some shortcoming of current approaches, and future research needs were provided for the future direction and challenges of modified biochar research. Overall, this paper gain insight into biochar application in petroleum remediation from the perspectives of performance enhancement and environmental sustainability. [Display omitted] [ABSTRACT FROM AUTHOR]

As a H 2 O 2 electrochemical biomimetic enzyme sensor, the stability, repeatability and sensitivity of hemin-based composites are closely connected with the loading of hemin on high-performance matrix. Herein, polypyrrole/paper-derived carbon (PPy/PC) nanocomposite was used for the construction of a hemin-based non-enzymatic sensor to detect H 2 O 2. Where the poplar wood is used to obtain crude cellulose through a straightforward paper-making process. This crude cellulose is then subjected to pyrolysis to yield the desired paper-based carbon material. The hemin-decorated PPy/PC was demonstrated possessing remarkable electrocatalytic activity for H 2 O 2 reduction, and the possible mechanism of the reactions was discussed. The electrochemical sensor, utilizing the H-PPy/PC composite, achieved a low detection limit of 30 ​nM, along with enhanced selectivity and stability under optimized conditions. The favorable results observed can primarily be attributed to the superior electrochemical performance of PPy/PC, as well as its unique 3D interconnected structure. This structure effectively impedes the self-dimerization of hemin, thereby ensuring the generation of active catalytic species. [ABSTRACT FROM AUTHOR]

[Display omitted] • Biochar could reduce 6% CO 2 , 66% CH 4 and 32% NH 3 emissions. • Particle size distributions of compost tend to be smaller. • Wheat straw biochar improves proportion of < 200 μm size distributions. • Wheat straw biochar improves aerobic layer thickness (Lp) and oxygen infiltration. • Along the compost material to biochar, aromatic compounds are gradually increasing. In recent research, biochar has been proven to reduce the greenhouse gases and promote organic matter during the composting. However, gas degradation may be related to the microstructure of compost. To investigate the mechanism of biochar additive, composting was performed using swine manure, wheat straw and biochar and representative solid compost samples were analyzed to characterize the mixed biochar and compost particles. We focused on the microscale, such as the particle size distributions, surface morphologies, aerobic layer thicknesses and the functional groups. The biochar and compost particle agglomerations gradually became weaker and the predominant particle size in the experiment group was < 200 μm. The aerobic layer thickness (Lp) was determined by infrared spectroscopy using the wavenumbers 2856 and 1568 cm−1, which was 0–50 μm increased as composting proceeded in both groups. The biochar increased Lp and facilitated oxygen penetrating the compost particle cores. Besides, in the biochar-swine manure particle interface, the aliphatic compound in the organic components degraded and the content of aromaticity increased with the composting process, which was indicated by the absorption intensity at 2856 cm−1 decreasing trend and the absorption intensity at 1568 cm−1 increasing trend. In summary, biochar performed well in the microscale of compost pile. [ABSTRACT FROM AUTHOR]

Carbonaceous catalysts obtained from agricultural residue could have potential in the production of biofuels such as biodiesel. This review paper discusses the preparation conditions (temperature, heating rate, hold time, inert gas flow rate, etc play key roles in development of textural characteristics of the catalysts) and functionalization methods of biochar and activated carbon derived from agricultural residues and their application to produce biodiesel. Research works reported in achieving maximum yield of biodiesel in terms of variable precursors, alcohol-to-oil ratio, reaction time and temperatures have been profoundly tabulated. Effect of textural properties of the biochar and activated carbon (such as surface area, total pore volume, average pore size, and functional group attached with the catalyst) on the biodiesel yield are examined. Studies on Regeneration and reusing of the spent catalysts are carefully inspected. The economic evaluation studies for the biochar and activated carbon and the applications of these for biodiesel production are scrutinized. Finally, the strategies to increase biomass and catalyst productivity, future prospect and research directions to enhance biofuel/biodiesel production and for the development of biochar and activated carbon from agricultural residues for sustainable biodiesel production is suggested. [Display omitted] • Preparation methods of biochar & activated carbon (AC) from AR examined. • Reaction conditions and mechanisms for biodiesel synthesis discussed. • Biodiesel yield correlated with surface area, pore volume & pore size of catalysts. • Regeneration & recycling of biochar & AC catalysts discussed for biodiesel yield. • Economic studies for biochar & AC production & application for biodiesel covered. [ABSTRACT FROM AUTHOR]

Arsenic contamination, at lower concentrations (up to 500 µg L-1), is an important environmental concern but has received limited attention. Adsorption capacities, kinetics and equilibrium phenomena are concentration dependent. Previous studies focused on higher arsenic concentrations associated with industrial discharges, failing to address arsenic contamination in drinking water. This study investigates arsenic adsorption using Eleocharis dulcis biochar loaded with CuO (EDB-CuO) at lower concentrations (up to 500 µg L-1). The synthesized biochar was characterized by X-ray Diffraction (XRD), Fourier Transform Infrared (FTIR), Point of Zero Charge (PZC) and Scanning Electron Microscopy (SEM). Batch adsorption experiments were conducted, varying time, concentration, temperature and pH. Results indicated that increasing temperature positively influenced arsenic adsorption onto EDB-CuO, while pH had an opposite effect, with maximum adsorption occurring at lower pH levels (2−3). The equilibrium time was established at 240 min for arsenate adsorption. Kinetic data best fitted the Ho and McKay's plot and the Langmuir model calculated a maximum adsorption capacity of 26.1 mg g-1. Thermodynamic parameters, including enthalpy, entropy and activation energy, supported the conclusion that the arsenate adsorption process was spontaneous and chemisorptive. Column studies demonstrated remarkable adsorption retention performance (>88%) of the composite for arsenate removal over 8 h. Similarly, a fixed-bed column experiment was conducted to study the adsorption mechanism of arsenate on EDB-CuO by employing the Bohart-Adams, Thomas, and Clark models. The Clark model was found to best describe the arsenate removal mechanism. Additionally, recycling studies of arsenate from the loaded EDB-CuO surface were investigated up to 4 adsorption-desorption cycles. A small decrease was observed in the second cycle, from 92.06% removal to 85.15%, which further decreased in the third cycle (62.18%), and even more in the fourth cycle (30.8%). • Efficient arsenate adsorption onto Eleocharis dulcis biochar composite with copper. • Mechanism showing the applicability of Langmuir isotherms to the adsorption data. • Kinetics is explained by Ho and Mckay's plot. • Remarkable retention capacity of the composite in column experiment. [ABSTRACT FROM AUTHOR]

[Display omitted] • eDNA sorption on carbonized cuttlefish bone greatly exceeds that of most adsorbents. • Excellent sorption of CCB is attributed to carbon film, large pore and fluent channel. • Ligand exchange, Ca2+ bridge and π-π interaction are dominated sorption mechanisms. • A high-efficient, nontoxic and low-cost adsorbent is exploited for eDNA removal. Environmental DNA (eDNA) carrying antibiotic resistance gene (ARG) has attracted a great deal of attention because of its threat to the ecology and human health. Traditional porous adsorbents, such as microporous biochar and natural mineral, are low-effective in removing eDNA from sewage. This study used cuttlefish-bone (CB), a fishery waste, as an anticipated material to adsorb a model compound of eDNA from herring sperm (hsDNA). An interesting result was firstly observed that extremely high DNA adsorption on cuttlefish-bone pyrolysis derivative (CCB) was up to 88.7 mg/g, 3–10 folds higher than that of most other adsorbents in the existing literatures, which was attributed to the carbon film and large pores. To achieve an adsorption rate of 75 %, hsDNA adsorption took 96 h on CB but only 24 h on CCB, which was attributed to the fluent channel of CCB. The ligand exchange, Ca2+ bridge and π-π interaction were identified as dominated adsorption mechanisms, based on FTIR and phosphate competition experiments. This study exploited a high-efficient, environmentally friendly, and low-cost adsorbent for treating ARG-contaminated soil and water. [ABSTRACT FROM AUTHOR]

[Display omitted] • ML effectively predicted specific surface area and capacitance retention. • ML predicted corn straw as the best raw material. • Co-doping and freeze-drying control the pore structure of materials. • A corn-straw-based biochar was prepared for energy storage. The rapid screening of agricultural waste materials for capacitor preparation holds significant importance in comprehending the relationship between material properties and enhancing experimental efficiency. In this study, we developed two machine learning models to predict electrode material characteristics using 2997 data points extracted from 235 articles. The identification and influence of key features on prediction indices provide a theoretical foundation for subsequent practical preparation. Through regression analysis and index evaluation, corn straw emerged as the optimal material for capacitor preparation, leading us to propose a one-step activation and two-step modification approach to convert corn straw into porous biochar. By modifying biochar with Co(NO 3) 2 ·6H 2 O, the maximum electrode capacitance of porous carbon reached 732.6 F/g. Furthermore, the electrode exhibited exceptional cycle stability with a remaining capacitance of 96 % after 5000 cycles. The prepared symmetric capacitor demonstrated pseudocapacitance behavior with a capacitance of 183.15 F/g at a current density of 1.0 A/g, power density of 22 kW/kg, and energy density of 9.03 Wh/kg. Considering the increasing annual output of corn straw and its superior industrial application prospects compared to acid-, base-, or precious metal-based alternatives due to their cost-effectiveness and environmental friendliness, these findings highlight the potential practical value in utilizing modified corn straw biochar as an efficient energy storage electrode material. [ABSTRACT FROM AUTHOR]

Transition metal iron and persistent free radicals (PFRs) both affect the redox properties of biochar, but the electron transfer relationship between them and the coupling reduction mechanism of Cr(VI) requires further investigation. To untangle the interplay between iron and PFRs in biochar and the influences on redox properties, FeCl 3 -modified rice husk biochar (FBCs) was prepared and its reduction mechanism for Cr(VI) without light was evaluated. The FBCs had higher surface positive charges, oxygen-containing functional groups, and PFRs compared with pristine rice husk biochar (BC). Phenoxyl PFRs with high electron-donating capability formed in biochar. The pronounced electron paramagnetic resonance signals showed that the PFRs preferred to form at lower Fe(III) concentrations. While a high concentration of Fe(III) would be reduced to Fe(II) and consumed the formed PFRs. Adsorption kinetics and X-ray photoelectron spectroscopy analysis indicated that the FBCs effectively enhanced the Cr(VI) removal efficiency by 1.54-8.20 fold and the Cr(VI) reduction efficiency by 1.88-9.29 fold compared to those of BC. PFRs quenching and competitive reductant addition experiments revealed that the higher Cr(VI) reduction performance of FBCs was mainly attributed to the formed PFRs, which could contribute to ∼74.0% of Cr(VI) reduction by direct or indirect electron transfer. The PFRs on FBCs surfaces could promote the Fe(III)/Fe(II) cycle through single electron transfer and synergistically accelerate ∼52.3% of Cr(VI) reduction. This study provides an improved understanding of the reduction mechanism of iron-modified biochar PFRs on Cr(VI) in environments. [Display omitted] [ABSTRACT FROM AUTHOR]

A new nitrogen doped sinocalamus oldhami lignin-based activated biochar (denoted as N-BGAC) with a notably high adsorption efficiency was prepared for the removal of malachite green (MG). The properties and structure of N-BGAC were thoroughly characterized, alongside an investigation into the MG adsorption process. The findings revealed that N-BGAC possessed a substantial specific surface area of 2238 m2 g−1, nearly double that of the activated biochar lacking nitrogen doping (BGAC). Additionally, N-BGAC exhibited exceptional adsorption efficiency for MG, boasting a maximum adsorption capacity of 1372.5 mg g−1, marking an enhancement of nearly 2.5 times compared to BGAC. By exploring the adsorption mechanism, it could be found that the adsorption process was a spontaneous exothermic reaction, and mainly controlled by pore-filling effect, electrostatic interactions, hydrogen bonding, hydrophobic interactions and π-π bonding interactions. Crucially, in the regeneration experiments, the removal percentage of MG could still reach 81.5% after four cycles of regeneration, making it promising in the contaminant removal. [Display omitted] [ABSTRACT FROM AUTHOR]

The development of biomass pyrolysis technology is important for alleviating energy shortages and environmental pollution. To investigate the generation trends in three-phase products, biomass pyrolysis experiments at different temperatures were carried out using a tubular furnace. The results showed that hemicellulose and cellulose structures began to dehydrate and break down and that alkyl-aryl lignin began to decompose between 200 ℃ and 400 ℃. After the temperature reached 400 °C, C O functional groups in the biochar began to decline, and a part of the biochar was converted into CO. After the temperature reached 500 °C, the biochar gradually formed a complex fused-ring structure. The tar yield increased first and then decreased with increasing pyrolysis temperature, reaching a maximum (32.82%) at 700 °C. On the one hand, tar generation occurred due to the biomass pyrolysis reaction, mainly at temperatures below 500 ℃. On the other hand, it occurred due to the homogeneous transformation reaction of tar, mainly above 500 ℃. The maximum value of the H 2 release curve increased with increasing temperature, and its change was most obvious relative to that of the other gases. The formation of H 2 at higher temperatures was mainly due to dehydrogenation, condensation and polycondensation reactions. [ABSTRACT FROM AUTHOR]

Dark fermentation is considered a promising strategy for clean energy production, where hydrogen can directly be produced from organic residues in the role of functional microbes. However, the low efficiency and poor stability of dark fermentation systems inhibit them from moving to industrial-scale applications. Biochar, the carbonaceous additive, has demonstrated great potential in improving the fermentation performance of the systems resulting from its outstanding physicochemical properties. This review critically summarizes the recent advances in adding biochar to improve the performance of dark fermentation systems. The production methods and physicochemical properties of biochar, as well as their influencing factors during pyrolysis, are first discussed. Then, the promoting effect of biochar on hydrogen production and its underlying mechanisms are explained in detail. Finally, the concluding remarks and perspectives are proposed. This review will deepen the understanding on the specific mechanisms by which biochar enhances hydrogen production in dark fermentation systems. It can also provide a reference for future study to build better biochar-added systems with higher efficiency and more stable environment. •Biochar exhibits great application potential in enhancing biohydrogen production. • The achievements and challenges of biochar in dark fermentation systems are reviewed. • The correlation between hydrogen promotion and biochar properties is analyzed. • The underlying mechanisms of biochar in hydrogen promotion are elucidated. • The impact of biochar on EET in dark fermentation systems is intensively discussed. [ABSTRACT FROM AUTHOR]

This study investigated the role of K and steam in upgrading syngas quality over biochar in a two-stage fixed-bed reactor. The integration of K-char catalyst and steam greatly increased syngas (H 2 +CO) and H 2 production. The syngas products yield (19.76 mmol/g biomass) and a H 2 yield (11.14 mmol/g biomass) were achieved when K-char was used as catalyst in the presence of steam. In general, four ways could be concluded to promote volatiles reforming to improve syngas quality by K and steam: Firstly, K and steam interaction with biochar increased the surface area and developed the porous structure of biochar, providing the pyrolytic intermediates with full complete contact with the char surface, and improving the chance of contact with the active sites. Secondly, the condensation reactions of biochar were inhibited by K and steam, thus preventing the reduction of active groups on the aromatic ring of biochar. Thirdly, K and steam promoted the formation of O-containing groups with high reactive activity on the char surface, such as –COO and –CO. Moreover, volatile K migrated in biochar matrix during catalytic reforming, and steam inhibited the release of K in biochar, resulting in more K retaining on the char surface in the form of -COK and -COOK acting as the active sites, which ultimately improved the catalytic activity of biochar, and promoted tar destruction and hydrocarbon reforming. [Display omitted] • K-form char combined with steam greatly increased syngas (H 2 +CO) and H 2 production. • Steam, carbon skeleton and K in biochar improved the secondary catalytic reforming reaction efficiency. • The catalytic effect of biochar is related to its surface area, O-containing groups and K migration. • Mechanism of K-form char combined with steam to improve syngas quality is well discussed. [ABSTRACT FROM AUTHOR]

Biochar is one of the most environmentally friendly and cost-effective materials that has shown potential properties for applications in various areas. Several studies have therefore been conducted in the past years, covering several aspects of biochar production, properties, and applications. This study employed both traditional and bibliometric methods to conduct a comprehensive review of the research field in the past decade (2013–2023). The Biblioshiny package in the R software and the VOSviewer tool were used for the analysis. Data from the largest research database, i.e., Scopus, was used for bibliometric analysis. The outcome of the study indicates that China sits on top in terms of research output and collaborations. An annual growth rate of 13.6 % is recorded for biochar research. The study also identified an evolution with respect to the themes studied in the past years to cover topics such as life cycle assessment, circular bioeconomy, and the techno-economics of biochar. Even though biochar's efficiency depends on the pyrolysis conditions and the nature of biomass, its development is also expected to focus on fine-tuning its properties. The environmental as well as the agronomical benefits of biochar have been well researched during the study period. This review provides stakeholders and researchers with the needed information on the most studied topics in feedstocks, production, and applications of biochar. • Recent advancements in the production and utilization of biochar are reviewed in this study. • The traditional and bibliometric review approaches were adopted for the study. • The study found an annual growth rate of 13.6 % for biochar research in the last decade. • It was found that research into biochar production and utilization has become more diversified in the last 3 years. • Most studies are focused on its utilization and economic viability in the last three years. [ABSTRACT FROM AUTHOR]