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To mitigate global warming and the greenhouse effect, biochar (BC) has been regarded as an important way of carbon sink. Therefore, this research explored the development trend of BC for soil carbon sequestration and mitigation from 2001 to 2020 based on bibliometric analysis. The results show that Yong Sik Ok and Johannes Lehmann are the top 2 high-impact authors. China, America, and Germany are the most widely collaborated countries, but China's research impact is lower than that of America. The Chinese Academy of Sciences has far more publications than any other institution, but Cornell University and Kangwon National University lead the way in terms of impact. Research hotspots can be divided into five clusters: (1) pyrolysis, nutrient, and microbial communities; (2) the immobilization of heavy metals; (3) crop yield and soil properties; (4) greenhouse gas, meta-analysis, and field experiment; (5) carbon fraction and sequestration. Reviews account for 60 % of the top 10 most highly cited papers, and eight of the top 10 focus on the early research period, setting the stage for the development of the BC field. Science of the Total Environment has the highest number of publications and total citations, and literature published in Soil Biology and Biochemistry is to some extent more likely to be cited. In the future, we need to carry out research in the following aspects: (1) Interaction mechanisms between BC, soil, and soil microbial communities. (2) Designing low-cost, high-yield, and high-effect optimization methods to improve the characteristics of BC. (3) Effect of BC on the environment and human health in long-term localization experiments. (4) Carbon sinks of BC need to be further evaluated on a global scale., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023. Published by Elsevier Inc.)

To achieve the ambitious goal of carbon neutrality, more carbon sequestration channels need to be developed. In this study, we tried to combine biochar with cold-bonded artificial lightweight coarse aggregate (ALCA) which is made from municipal solid household waste incineration bottom ash (MSWIBA).The strong carbon capture ability of biochar was used to attract external CO 2 into the interior of ALCAs, which combined with CaO in MSWIBA to form CaCO 3 to achieve the effect of chemical carbon sequestration. The total carbon sequestration and carbon sequestration rate of biochar-ALCAs were quantified by a self-designed CO 2 concentration change test box, the physical and mechanical properties of biochar-ALCAs were investigated, as well as the changes before and after carbonization. The results showed that biochar and ALCAs had good synergistic carbon sequestration ability. The total carbon sequestration of biochar-ALCAs could reach 30.58-33.06 kg/ton. The carbon sequestration efficiency could reach 70.2 % and 84.9 % at 28 d/56 d in a low CO 2 concentration environment (0.05 % VOL). In addition, the water absorption of biochar-ALCAs decreased by 4.3 %-13.9 %, the apparent density increased by 0.9 %-2.8 %, and the strength increased by 4.3 %-7.0 % after carbon sequestration, and the physical and mechanical properties were significantly improved. The purpose of this paper is to investigate the synergistic carbon sequestration of biochar in combination with ALCAs and to quantitatively assess its ability to solidify low concentrations of CO 2 in the natural environment. A new test apparatus and test method were designed for this purpose. This paper may contribute for an important advance on the preparation of recyclable cement-type composites able to capture and solidify CO 2 from the natural environment., Competing Interests: Declaration of competing interest All the authors, including Jun Liu, Weizhuo Zhang, Hesong jin, Zhenlin Li, Guang Liu, Feng Xing and Luping Tang, have declared that no conflict of interest exists., (Copyright © 2022 Elsevier B.V. All rights reserved.)

Biochars have been highlighted as a means of carbon sequestration, which is significant for achieving carbon neutrality. Mixtures of wood chips and either bentonite or kaolin were co-pyrolysed at temperatures of 350 °C and 550 °C, and the microstructural characteristics and the carbon sequestration potential of the resultant biochar were explored in the study. The addition of minerals promoted the formation of a stable carbon structure in biochar, especially the proportion of SiC bonds in the high-temperature mineral-composited biochar increased by 3.56-3.82 times compared with the original biochar. After bentonite or kaolin was added to wood chips pyrolysed at 550 °C, the carbon loss after H 2 O 2 oxidation was reduced to no more than 19.2%, and the Recalcitrance Index (R 50 ) of biochar increased to no less than 0.89. The combined action of high temperature and minerals promoted the formation of highly aromatic structures of biochar (H:C < 0.4) and reduced the amount of dissolved organic carbon to 4.89 mg g -1 . Furthermore, minerals directly covered the surface of biochar, and the content of SiC bond increased, thus strengthening the chemical and thermal stability of biochar. However, the addition of minerals had no significant effect on the biological stability of biochar. The study indicates that the pre-pyrolysis mineral addition is an effective way to increase the carbon sequestration potential of biochar., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2022 Elsevier B.V. All rights reserved.)

Biochar-amended soils have been explored to enhance microbial methane (CH 4 ) oxidation in landfill cover systems. Recently, research priorities have expanded to include the mitigation of other components of landfill gas such as carbon dioxide (CO 2 ) and hydrogen sulfide (H 2 S) along with CH 4 . In this study, column tests were performed to simulate the newly proposed biogeochemical cover systems, which incorporate biochar-amended soil for CH 4 oxidation and basic oxygen furnace (BOF) slag for CO 2 and H 2 S mitigation, to evaluate the effect of cover configuration on microbial CH 4 oxidation and community composition. Biogeochemical covers included a biochar-amended soil (10% w/w), and methanotroph-enriched activated biochar amended soil (5% or 10% w/w) as a biocover layer or CH 4 oxidation layer. The primary outcome measures of interest were CH 4 oxidation rates and the structure and abundance of methane-oxidation bacteria in the covers. All column reactors were active in CH 4 oxidation, but columns containing activated biochar-amended soils had higher CH 4 oxidation rates (133 to 143 μg CH 4 g -1 day -1 ) than those containing non-activated biochar-amended soil (50 μg CH 4 g -1 day -1 ) and no-biochar soil or control soil (43 μg CH 4 g -1 day -1 ). All treatments showed significant increases in the relative abundance of methanotrophs from an average relative abundance of 5.6% before incubation to a maximum of 45% following incubation. In activated biochar, the abundance of Type II methanotrophs, primarily Methylocystis and Methylosinus, was greater than that of Type I methanotrophs (Methylobacter) due to which activated biochar-amended soils also showed higher abundance of Type II methanotrophs. Overall, biogeochemical cover profiles showed promising potential for CH 4 oxidation without any adverse effect on microbial community composition and methane oxidation. Biochar activation led to an alteration of the dominant methanotrophic communities and increased CH 4 oxidation., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2022 Elsevier B.V. All rights reserved.)

Converting biomass waste into biochar by slow pyrolysis with subsequent soil amendment is a prospective approach with multiple environmental benefits including soil contamination remediation, soil amelioration and carbon sequestration. This study selected cow manure as precursor to produce biochar under 300 °C, 400 °C, 500 °C and 600 °C, and a remarkable promotion of carbon (C) retention in biochar by incorporation of exogenous Ca was achieved at all investigated pyrolysis temperatures. The C retention was elevated from 49.2 to 68.3% of pristine biochars to 66.1-79.7% of Ca-composite biochars. It was interesting that extent of this improvement increased gradually with rising of pyrolysis temperature, i.e., doping Ca in biomass promoted pyrolytic C retention in biochar by 16.6%, 23.4%, 29.1% and 31.1% for 300 °C, 400 °C, 500 °C and 600 °C, respectively. Thermogravimetric-mass spectrometer (TG-MS) and X-ray photoelectron spectroscopy (XPS) showed that Ca catalyzed thermal-chemical reactions and simultaneously suppressed the release of small organic molecular substances (C 2 -C 7 ) via physical blocking (CaO, CaCO 3 , and CaClOH) and chemical bonding (CO and OC-O). The catalyzation mainly occurred at 200-400 °C, while the suppression was more prominent at higher temperatures. Raman spectra and 2D FTIR analysis on biochar microstructure showed that presence of Ca had negative influence on carbon aromatization and thus weakened biochar's stability, while increasing pyrolysis temperature enhanced the stability of carbon structure. Finally, with integrating "C retention" during pyrolysis and "C stability" in biochar, the maximum C sequestration (56.3%) was achieved at 600 °C with the participation of Ca. The study highlights the importance of both Ca and pyrolysis temperature in enhancing biochar's capacity of sequestrating C., (Copyright © 2021 Elsevier Ltd. All rights reserved.)

Soil carbon (SC) is important for food security, ecosystem functioning, and environmental health, especially in light of global climate change. The physico-chemical character of biochar (pyrolyzed crop residue) has been shown to augment SC levels. This review systematically compares the environmental and economic benefits of applying crop residue versus biochar produced from crop residues to soils and the potential implications for SC sequestration. Crop residues enhance the mineralization rate of SC, while biochar can increase or decrease SC depending on the types of biochar/soil and duration. Therefore, converting crop residues to biochar may be more efficient for sequestering SC, but may/may not be more cost-effective. In this review, special emphasis is given to understanding the underlying mechanisms and biogeochemical processes of biochar production, in particular: surface (crystallinity), redox, and ability to control electron transfer reactions. By using meta-analytics, we determined the role of biochar compared to crop residue to enhance the status of organic SC., (Copyright © 2019 Elsevier Ltd. All rights reserved.)

The synthesis of manufactured soils converts waste materials to value-added products, alleviating pressures on both waste disposal infrastructure and topsoils. For manufactured soils to be effective media for plant growth, they must retain and store plant-available nutrients, including nitrogen. In this study, biochar applications were tested for their ability to retain nitrogen in a soil manufactured from waste materials. A biochar, produced from horticultural green waste, was added to a manufactured soil at 2, 5 and 10 % (by weight), then maintained at 15 °C and irrigated with water (0.84 mL m -2  d -1 ) over 6 weeks. Total dissolved nitrogen concentrations in soil leachate decreased by 25.2, 30.6 and 44.0 % at biochar concentrations of 2, 5 and 10 %, respectively. Biochar also changed the proportions of each nitrogen-fraction in collected samples. Three mechanisms for biochar-induced nitrogen retention were possible: i) increased cation and anion exchange capacity of the substrate; ii) retention of molecules within the biochar pore spaces; iii) immobilisation of nitrogen through microbial utilisation of labile carbon further supported by increased soil moisture content, surface area, and pH. Dissolved organic carbon concentrations in leachate were reduced (-34.7 %, -28.9 %, and -16.7 %) in the substrate with 2, 5 and 10 % biochar additions, respectively. Fluorescein diacetate hydrolysis data showed increased microbial metabolic activity with biochar application (14.7 ± 0.5, 25.4 ± 5.3, 27.0 ± 0.1, 46.1 ± 6.1 µg FL g -1 h -1 for applications at 0, 2, 5, and 10 %, respectively), linking biochar addition to enhanced microbial activity. These data highlight the potential for biochar to suppress the long-term turnover of SOM and promote carbon sequestration, and a long-term sustainable growth substrate provided by the reuse of waste materials diverted from landfill., (Copyright © 2019 Elsevier B.V. All rights reserved.)

Climate-smart agriculture (CSA) management practices (e.g., conservation tillage, cover crops, and biochar applications) have been widely adopted to enhance soil organic carbon (SOC) sequestration and to reduce greenhouse gas emissions while ensuring crop productivity. However, current measurements regarding the influences of CSA management practices on SOC sequestration diverge widely, making it difficult to derive conclusions about individual and combined CSA management effects and bringing large uncertainties in quantifying the potential of the agricultural sector to mitigate climate change. We conducted a meta-analysis of 3,049 paired measurements from 417 peer-reviewed articles to examine the effects of three common CSA management practices on SOC sequestration as well as the environmental controlling factors. We found that, on average, biochar applications represented the most effective approach for increasing SOC content (39%), followed by cover crops (6%) and conservation tillage (5%). Further analysis suggested that the effects of CSA management practices were more pronounced in areas with relatively warmer climates or lower nitrogen fertilizer inputs. Our meta-analysis demonstrated that, through adopting CSA practices, cropland could be an improved carbon sink. We also highlight the importance of considering local environmental factors (e.g., climate and soil conditions and their combination with other management practices) in identifying appropriate CSA practices for mitigating greenhouse gas emissions while ensuring crop productivity., (© 2019 John Wiley & Sons Ltd.)

Different types of crop straw and their derived biochars and compost treatments have huge potential for carbon sequestration to sustain crop productivity. In this study, cotton straw (straw), cotton straw-derived compost (compost) and cotton straw-derived biochar (biochar) with equivalent carbon (C) content were added to soil and incubated for 30 and 180 days. The C sequestration potential of these organic materials was determined by 13 C isotope trace method. The structural characteristic of soil organic carbon (SOC) was analyzed by solid-state 13 C NMR spectroscopy. The SOC concentration was measured by wet oxidation and dry combustion methods. The results showed that 50.84%, 41.03% and 38.55% of native SOC were replaced by biochar, compost, and straw, respectively. The carbohydrate C and methoxyl C contents were significantly higher in straw and biochar amendments respectively, while phenolic C and alkyl C were high in compost amendment and a higher proportion of aryl C occurred in biochar treatment. These findings revealed that straw material was easier to be decomposed, but compost and biochar showing better stability., (Copyright © 2019. Published by Elsevier B.V.)

Little is known on the effect of application of different nitrogen (N) fertilizers on soil organic carbon (SOC) sequestration in soil humic substances (HS). We investigated HS molecular characteristics in an Orthic Acrisol, southwestern China, under 2-year field fertilization of a urea (U), a polymer-coated urea (PCU) and a biochar-coated urea (BCU) using 13 C-CPMAS-NMR spectroscopy. Results showed that N fertilization promoted SOC sequestration into HS and favored alkyl-C and aromatic-C rather than O-alkyl-C and carbonyl-C for humic acids and humin in soil. Application of PCU and BCU may better enhance vegetable yield, SOC sequestration, and HS stability than the U application, which may benefit from longer time of N existence and higher total N in soil. Among the N treatments, BCU application mostly affected the compositions and stability of SOC in the HS for the OC input and prime effect of biochar for SOC transformation.

Improved soil management is increasingly pursued to ensure food security for the world's rising global population, with the ancillary benefit of storing carbon in soils to lower the threat of climate change. While all increments to soil organic matter are laudable, we suggest caution in ascribing large, potential climate change mitigation to enhanced soil management. We find that the most promising techniques, including applications of biochar and enhanced silicate weathering, collectively are not likely to balance more than 5% of annual emissions of CO 2 from fossil fuel combustion., (© 2018 John Wiley & Sons Ltd.)

Improved soil carbon sink capability is important for the mitigation of carbon dioxide emissions and the enhancement of soil productivity. Biochar and organic fertilizer (OF) showed a significant improving effect on microalgae in soil carbon sink capacity, and the ultimate soil total organic carbons with microalgae-OF, microalgae-biochar, microalgae-OF-biochar were about 16, 67 and 58% higher than that with microalgae alone, respectively, indicating that carbon fixation efficiency of microalgae applied in soil was improved with biochar and OF whilst the soil carbon capacity was promoted, the mechanism of which is illustrated through simulative experiments. Organic fertilizer could spur algal conversion of carbon into cell molecules by increasing intracellular polysaccharide production of microalgae. Biochar could change carbon metabolism pathway of microalgae through altering the yield of intracellular saccharides, and yield and type of extracellular saccharides. There was a superimposition effect on the soil carbon sink when biochar and OF were both present with microalgae.

This work assessed the potential environmental impact of recycling organic materials in agriculture via pyrolysis (biochar) and composting (compost), as well its combination (biochar-compost blend) versus business-as-usual represented by mineral fertiliser. Life cycle assessment methodology was applied using data sourced from experiments (FP7 project Fertiplus) in three countries (Spain, Italy and Belgium), and considering three environmental impact categories, (i) global warming; (ii) acidification and (iii) eutrophication. The novelty of this analysis is the inclusion of the biochar-compost blend with a focus on multiple European countries, and the inclusion of the acidification and eutrophication impact categories. Biochar, compost and biochar-compost blend all resulted in lower environmental impacts than mineral fertiliser from a systems perspective. Regional differences were found between biochar, compost and biochar-compost blend. The biochar-compost blend offered benefits related to available nutrients and sequestered C. It also produced yields of similar magnitude to mineral fertiliser, which makes its acceptance by farmers more likely whilst reducing environmental impacts. However, careful consideration of feedstock is required., (Copyright © 2018 Elsevier Ltd. All rights reserved.)

Biochar application to soil has been proposed for soil carbon sequestration and global warming mitigation. While recent studies have demonstrated that soil pH was a main factor affecting soil microbial community and stability of biochar, little information is available for the microbiome across different soil pH and the subsequently CO 2 emission. To investigate soil microbial response and CO 2 emission of biochar across different pH levels, comparative incubation studies on CO 2 emission, degradation of biochar, and microbial communities in a ferralsol (pH5.19) and a phaeozems (pH7.81) with 4 biochar addition rates (0.5%, 1.0%, 2.0%, 5.0%) were conducted. Biochar induced higher CO 2 emission in acidic ferralsol, largely due to the higher biochar degradation, while the more drastic negative priming effect (PE) of SOC resulted in decreased total CO 2 emission in alkaline phaeozems. The higher bacteria diversity, especially the enrichment of copiotrophic bacteria such as Bacteroidetes, Gemmatimonadetes, and decrease of oligotrophic bacteria such as Acidobacteria, were responsible for the increased CO 2 emission and initial positive PE of SOC in ferralsol, whereas biochar did not change the relative abundances of most bacteria at phylum level in phaeozems. The relative abundances of other bacterial taxa (i.e. Actinobacteria, Anaerolineae) known to degrade aromatic compounds were also elevated in both soils. Soil pH was considered to be the dominant factor to affect CO 2 emission by increasing the bioavailability of organic carbon and abundance of copiotrophic bacteria after biochar addition in ferralsol. However, the decreased bioavailability of SOC via adsorption of biochar resulted in higher abundance of oligotrophic bacteria in phaeozems, leading to the decrease in CO 2 emission., (Copyright © 2017. Published by Elsevier B.V.)

Soil organic carbon is essential to improve soil fertility and ecosystem functioning. Soil microorganisms contribute significantly to the carbon transformation and immobilisation processes. However, microorganisms are sensitive to environmental stresses such as heavy metals. Applying amendments, such as biochar, to contaminated soils can alleviate the metal toxicity and add carbon inputs. In this study, Cd and Pb spiked soils treated with macadamia nutshell biochar (5% w/w) were monitored during a 49days incubation period. Microbial phospholipid fatty acids (PLFAs) were extracted and analysed as biomarkers in order to identify the microbial community composition. Soil properties, metal bioavailability, microbial respiration, and microbial biomass carbon were measured after the incubation period. Microbial carbon use efficiency (CUE) was calculated from the ratio of carbon incorporated into microbial biomass to the carbon mineralised. Total PLFA concentration decreased to a greater extent in metal contaminated soils than uncontaminated soils. Microbial CUE also decreased due to metal toxicity. However, biochar addition alleviated the metal toxicity, and increased total PLFA concentration. Both microbial respiration and biomass carbon increased due to biochar application, and CUE was significantly (p<0.01) higher in biochar treated soils than untreated soils. Heavy metals reduced the microbial carbon sequestration in contaminated soils by negatively influencing the CUE. The improvement of CUE through biochar addition in the contaminated soils could be attributed to the decrease in metal bioavailability, thereby mitigating the biotoxicity to soil microorganisms., (Copyright © 2017 Elsevier B.V. All rights reserved.)

Biochar, a natural sourced carbon-rich material, has been used commonly in particle shape for carbon sequestration, soil fertility and environmental remediation. Here, we report a facile approach to fabricate freestanding biochar composite membranes for the first time. Wood biochars pyrolyzed at 300 °C and 700 °C were blended with polyvinylidene fluoride (PVdF) in three percentages (10%, 30% and 50%) to construct membranes through thermal phase inversion process. The resultant biochar composite membranes possess high mechanical strength and porous structure with uniform distribution of biochar particles throughout the membrane surface and cross-section. The membrane pure water flux was increased with B300 content (4825-5411 ± 21 L m -2 h -1 ) and B700 content (5823-6895 ± 72 L m -2 h -1 ). The membranes with B300 were more hydrophilic with higher surface free energy (58.84-60.31 mJ m -2 ) in comparison to B700 (56.32-51.91 mJ m -2 ). The biochar composite membranes indicated promising adsorption capacities (47-187 mg g -1 ) to Rhodamine B (RhB) dye. The biochar membranes also exhibited high retention (74-93%) for E. coli bacterial suspensions through filtration. After simple physical cleaning, both the adsorption and sieving capabilities of the biochar composite membranes could be effectively recovered. Synergistic mechanisms of biochar/PVdF in the composite membrane are proposed to elucidate the high performance of the membrane in pollutant management. The multifunctional biochar composite membrane not only effectively prevent the problems caused by directly using biochar particle as sorbent but also can be produced in large scale, indicating great potential for practical applications., (Copyright © 2017 Elsevier Ltd. All rights reserved.)

The aim of this work is to understand the effects of straw and biochar return in soil on the content, distribution, stability, and relative contribution rate of organic carbon for soil aggregates, which could be used to better understanding the stability of the soil carbon pool and the protection mechanisms under straw and biochar return. In this study, a field experiment was conducted to study the effects of straw and biochar return on soil aggregates and carbon sequestration characteristics in a rape-maize rotation planting system. Five treatments, including a control (no organic material added, CK), straw (CS), straw and microorganism (CSD), Biochar (BC), half straw and half biochar (CSBC), were used. The results indicated that ① Straw and biochar could improve the content of soil organic carbon, and the BC and CSBC treatments increased it by 16.88-17.37 g·kg -1 , values higher than those with the CS and CSD treatments (13.76-14.68 g·kg -1 ); ② Compared with the CK treatment, CS and CSD treatments could increase the stability of the aggregates through significantly increasing the content of macro-aggregate by 94.00%-117.78% and significantly increasing the mean weight diameter (MWD), geometric mean diameter (GMD), and R 0.25 of water stable aggregates, but reducing the D value ( P <0.05); and ③ With the increase in aggregate particle size, the content of organic carbon in the aggregates decreased first and then increased. The contribution rate of soil organic carbon in silt and clay was the highest (29.61%-42.18%), and the contribution rate of organic carbon in the macro-aggregate was the lowest (9.19%-17.81%). In addition to the CSD treatment, the CS, BC, and CSBC treatments reduced the contribution of larger aggregates (2-0.25 mm) and micro-aggregates (0.25-0.053 mm). In general, the benefit of straw return was better than that of biochar in promoting soil aggregation. However, the application of biochar was better than straw in improving the aggregates organic carbon content. The newly generated carbon from straw degradation was mainly distributed in large aggregates. Straw with microorganisms could promote the combination of carbon by different components in the larger aggregates. The carbon from biochar and straw with biochar treatments were mainly concentrated in micro-aggregates.

In recent years, studies on carbon sequestration of biochar in soil has been in spotlight owing to the specific characteristics of biochar such as strong carbon stability and well developed pore structure. However, whether biochar will ultimately increase soil carbon storage or promote soil carbon emissions when applied into the soil? This question remains controversial in current academic circles. Further research is required on priming effect of biochar on mineralization of native soil organic carbon and its mechanisms. Based on the analysis of biochar characteristics, such as its carbon composition and stability, pore structure and surface morphology, research progress on the priming effect of biochar on the decomposition of native soil organic carbon was reviewed in this paper. Furthermore, possible mechanisms of both positive and negative priming effect, that is promoting and suppressing the mineralization, were put forward. Positive priming effect is mainly due to the promotion of soil microbial activity caused by biochar, the preferential mineralization of easily decomposed components in biochar, and the co-metabolism of soil microbes. While negative priming effect is mainly based on the encapsulation and adsorption protection of soil organic matter due to the internal pore structure and the external surface of biochar. Other potential reasons for negative priming effect can be the stabilization resulted from the formation of organic-inorganic complex promoted by biochar in the soil, and the inhibition of activity of soil microbes and its enzymes by biochar. Finally, future research directions were proposed in order to provide theoretical basis for the application of biochar in soil carbon sequestration.

Biochar typically consists of both carbon and mineral fractions, and the carbon fraction has been generally considered to determine its properties and applications. Recently, an increasing body of research has demonstrated that mineral components inherent in biochar, such as alkali or alkaline earth metals in the form of carbonates, phosphates, or oxides, could also influence the properties and thus the applications. The review articles published thus far have mainly focused on multiple environmental and agronomic applications of biochar, including carbon sequestration, soil improvement, environmental remediation, etc. This review aims to highlight the indispensable role of the mineral fraction of biochar in these different applications, especially in environmental applications. Specifically, it provides a critical review of current research findings related to the mineral composition of biochar and the effect of the mineral fraction on the physicochemical properties, contaminant sorption, carbon retention and stability, and nutrient bioavailability of biochar. Furthermore, the role of minerals in the emerging applications of biochar, as a precursor for fuel cells, supercapacitors, and photoactive components, is also summarized. Overall, inherent minerals should be fully considered while determining the most appropriate application for any given biochar. A thorough understanding of the role of biochar-bound minerals in different applications will also allow the design or selection of the most suitable biochar for specific applications based on the consideration of feedstock composition, production parameters, and post-treatment., (Copyright © 2017 Elsevier Ltd. All rights reserved.)

Biochar application in soil has been proposed as a promising method for carbon sequestration. While factors affecting its carbon sequestration potential have been widely investigated, the number of studies on the effect of soil pH is limited. To investigate the carbon sequestration potential of biochar across a series of soil pH levels, the total carbon emission, CO 2 release from inorganic carbon, and phospholipid fatty acids (PLFAs) of six soils with various pH levels were compared after the addition of straw biochar produced at different pyrolysis temperatures. The results show that the acidic soils released more CO 2 (1.5-3.5 times higher than the control) after the application of biochar compared with neutral and alkaline soils. The degradation of both native soil organic carbon (SOC) and biochar were accelerated. More inorganic CO 2 release in acidic soil contributed to the increased degradation of biochar. Higher proportion of gram-positive bacteria in acidic soil (25%-36%) was responsible for the enhanced biochar degradation and simultaneously co-metabolism of SOC. In addition, lower substrate limitation for bacteria, indicated by higher C-O stretching after the biochar application in the acidic soil, also caused more CO 2 release. In addition to the soil pH, other factors such as clay contents and experimental duration also affected the phsico-chemical and biotic processes of SOC dynamics. Gram-negative/gram-positive bacteria ratio was found to be negatively related to priming effects, and suggested to serve as an indicator for priming effect. In general, the carbon sequestration potential of rice-straw biochar in soil reduced along with the decrease of soil pH especially in a short-term. Given wide spread of acidic soils in China, carbon sequestration potential of biochar may be overestimated without taking into account the impact of soil pH., (Copyright © 2016 Elsevier B.V. All rights reserved.)

Despite 20 years of effort to curb emissions, greenhouse gas (GHG) emissions grew faster during the 2000s than in the 1990s, which presents a major challenge for meeting the international goal of limiting warming to <2 °C relative to the preindustrial era. Most recent scenarios from integrated assessment models require large-scale deployment of negative emissions technologies (NETs) to reach the 2 °C target. A recent analysis of NETs, including direct air capture, enhanced weathering, bioenergy with carbon capture and storage and afforestation/deforestation, showed that all NETs have significant limits to implementation, including economic cost, energy requirements, land use, and water use. In this paper, I assess the potential for negative emissions from soil carbon sequestration and biochar addition to land, and also the potential global impacts on land use, water, nutrients, albedo, energy and cost. Results indicate that soil carbon sequestration and biochar have useful negative emission potential (each 0.7 GtCeq. yr(-1) ) and that they potentially have lower impact on land, water use, nutrients, albedo, energy requirement and cost, so have fewer disadvantages than many NETs. Limitations of soil carbon sequestration as a NET centre around issues of sink saturation and reversibility. Biochar could be implemented in combination with bioenergy with carbon capture and storage. Current integrated assessment models do not represent soil carbon sequestration or biochar. Given the negative emission potential of SCS and biochar and their potential advantages compared to other NETs, efforts should be made to include these options within IAMs, so that their potential can be explored further in comparison with other NETs for climate stabilization., (© 2016 John Wiley & Sons Ltd.)

'Biochar' represents an emerging technology that is increasingly being recognized for its potential role in carbon sequestration, reducing greenhouse gas emissions, waste management, renewable energy, soil improvement, crop productivity enhancement and environmental remediation. Published reviews have so far focused mainly on the above listed agronomic and environmental benefits of applying biochar, yet paid little or no attention to its harmful effects on the ecological system. This review highlights a balanced overview of the advantages and disadvantages of the pyrolysis process of biochar production, end-product quality and the benefits versus drawbacks of biochar on: (a) soil geochemistry and albedo, (b) microflora and fauna, (c) agrochemicals, (d) greenhouse gas efflux, (e) nutrients, (f) crop yield, and (g) contaminants (organic and inorganic). Future research should focus more on the unintended long-term consequences of biochar on biological organisms and their processes in the soil., (Copyright © 2015 Elsevier Ltd. All rights reserved.)

Many studies have reported the positive effect of biochar on soil carbon sequestration and soil fertility improvement in acidic soils. However, biochar may have different impacts on calcareous sandy soils. A 90-day incubation experiment was conducted to quantify the effects of woody waste biochar (10 g kg(-1)) on CO2-C emissions, K2SO4-extractable C and macro-(N, P and K) and micro-(Fe, Mn, Zn and Cu) nutrient availability in the presence or absence of poultry manure (5 g kg(-1) soil). The following six treatments were applied: (1) conocarpus (Conocarpus erectus L.) waste (CW), (2) conocarpus biochar (BC), (3) poultry manure (PM), (4) PM+CW, (5) PM+BC and (6) untreated soil (CK). Poultry manure increased CO2-C emissions and K2SO4-extractable C, and the highest increases in CO2-C emission rate and cumulative CO2-C and K2SO4-extractable C were observed for the PM+CW treatment. On the contrary, treatments with BC halted the CO2-C emission rate, indicating that the contribution of BC to CO2-C emissions is negligible compared with the soils amended with CW and PM. Furthermore, the combined addition of PM+BC increased available N, P and K compared with the PM or BC treatments. Overall, the incorporation of biochar into calcareous soils might have benefits in carbon sequestration and soil fertility improvement., (Copyright © 2015 Elsevier Ltd. All rights reserved.)

Sub-Saharan Africa (SSA) experiences soil degradation, food and livelihood insecurity, environmental pollution and lack of access to energy. Biochar has gained international research attention, but few studies have investigated the potential of biochar to address the challenges in SSA. This paper seeks to identify and evaluate generic potential opportunities and constraints associated with biochar application in sub-Saharan Africa using Zimbabwe as case study. Specific objectives were to; (1) identify and quantify feedstocks for biochar production; (2) review literature on the biochar properties, and evaluate its potential applications in agriculture, environmental remediation and energy provision, and (3) identify research gaps, risks and constraints associated with biochar technology. Biochar feedstocks in Zimbabwe were estimated to be 9.9 Mton yr(-1), predominantly derived from manure (88%) and firewood (10%). This will yield 3.5, 1.7 and 3.1 Mton yr(-1) of biochar, bio-oil and synthetic gas, respectively. Land application of the 3.5 Mton yr(-1) of biochar (≈63% C) would sequester approximately 2.2 Mton yr(-1) of soil carbon in Zimbabwe alone, while simultaneously minimizing the environmental and public health risks, and greenhouse gas emissions associated with solid organic wastes. Biochar potentially enhances soil and crop productivity through enhanced nutrient and soil moisture availability, amelioration of acidic soils and stimulation of microbial diversity and activity. Due to its excellent adsorption properties, biochar has potential applications in industrial and environmental applications including water and wastewater treatment, remediation and revegetation of contaminated soils and water. Biochar products have energy values comparable or higher than those of traditional biomass fuels; thereby making them ideal alternative sources of energy especially for poor households without access to electricity. Before the benefits of biochar can be realized in SSA, there is need to overcome multiple risks and constraints such as lack of finance, socio-economic constraints including negative perceptions and attitudes among both researchers and consumers, and environmental and public health risks. Therefore, there is need to conduct fundamental research to demonstrate the benefits of biochar applications, and develop policy framework and criteria for its production and subsequent adoption., (Copyright © 2014 Elsevier Ltd. All rights reserved.)

Biochars were produced from pinewood, peanut shell, and bamboo biomass through hydrothermal conversion (HTC) at 300 °C and comparatively by slow pyrolysis over a temperature range of 300, 400, and 500 °C. These biochars were characterized by FT-IR, cation exchange capacity (CEC) assay, methylene blue adsorption, as well as proximate and elemental analysis. The experimental results demonstrated higher retained oxygen content in biochars produced at lower pyrolysis temperatures and through HTC, which also correlated to the higher CEC of respective biochars. Furthermore, all types of biochar studied herein were capable of adsorption of methylene blue from solution and the adsorption did not appear to strongly correlate with CEC, indicating that the methylene blue adsorption appears to be dependent more upon the non-electrostatic molecular interactions such as the likely dispersive π-π interactions between the graphene-like sheets of the biochar with the aromatic ring structure of the dye, than the electrostatic CEC. A direct comparison of hydrothermal and pyrolysis converted biochars reveals that biochars produced through HTC have much higher CEC than the biochars produced by slow pyrolysis. Analysis by FT-IR reveals a higher retention of oxygen functional groups in HTC biochars; additionally, there is an apparent trend of increasing aromaticity of the pyrolysis biochars when produced at higher temperatures. The CEC value of the HTC biochar appears correlated with its oxygen functional group content as indicated by the FT-IR measurements and its O:C ratio., (Copyright © 2014 Elsevier Ltd. All rights reserved.)

Biochar has potential to sequester carbon in soils and simultaneously improve soil quality and plant growth. More understanding of biochar variation is needed to optimise these potential benefits. Slow pyrolysis at 600 °C was undertaken to determine how yields and characteristics of biochars differ when produced from eight different agricultural residues. Biochar properties such as carbon content, surface area, pH, ultimate and proximate analysis, nutrient and metal content and the R50 recalcitrance index were determined. Significant variations seen in biochar characteristics were attributed to feedstock variation since pyrolysis conditions were constant. Biochar yields varied from 28% to 39%. Average carbon content was 51%. Ash content of both feedstocks and biochars were correlated with biochar carbon content. Macronutrients were concentrated during pyrolysis, but biochar macronutrient content was low in comparison to biochars produced from more nutrient rich feedstocks. Most biochars were slightly alkaline, ranging from pH 6.1 to pH 11.6. pH was correlated with biochar K content. Aromaticity was increased with pyrolysis, shown by a reduction in biochar H/C and O/C ratios relative to feedstock values. The R50 recalcitrance index showed biochars to be either class 2 or class 3. Biochar carbon sequestration potential was 21.3%-32.5%. The R50 recalcitrance index is influenced by the presence of alkali metals in the biochar which may lead to an under-estimation of biochar stability. The residues assessed here, at current global availability, could produce 373 Mt of biochar. This quantity of biochar has the potential to sequester 0.55 Pg CO2 yr(-1) in soils over long time periods., (Copyright © 2014 Elsevier Ltd. All rights reserved.)

Biochar possesses unique characteristics, including a substantial surface area, a high carbon content, sufficient capacity for cation exchange, and a robust structure. However, biochar contains hazardous pollutants like volatile organic compounds that harm soil properties and functionality. Although several studies on biochar production from various feedstocks have been undertaken in recent years, several issues about feedstock preparation, economic feasibility, influencing factors, and the proper utilization of biochar production processes need to be addressed. This paper thus addresses these issues by providing potential solutions identified through a comprehensive review. Slow pyrolysis of lignocellulosic biomass and Acacia nilotica yields biochar from 20 to 52 wt% at various temperatures and residence times. Biochar yield varies from 29 to 48.3 wt% when waste tires and corn stalks are rapidly pyrolyzed at higher temperatures and for shorter periods. Torrefaction of algal biomass at moderate temperatures with different residence times can result in a substantial yield of 50–60 wt%. However, the variability and heterogeneity of waste feedstocks pose potential challenges affecting biochar's quality and properties. Given its widespread use in carbon sequestration, soil remediation, wastewater purification, and organic waste composting, the mechanisms of biochar production in environmental usage need to be investigated. [ABSTRACT FROM AUTHOR]

Using carbon-based materials (CBMs) to facilitate phytoremediation shows great promise for simultaneously enhancing the restoration efficiency of contaminated soil and reducing carbon dioxide in the context of global warming, which is still in the exploring and attempting phase. In addition to direct degradation or alteration of pollutant bioavailability, CBMs can enhance phytoremediation by alleviating plant nutrient deprivation and oxidative stress, as well as by modulating soil microbial communities and root secretions. Photosynthetic carbon fixation predominantly affects both phytoremediation efficiency and carbon cycle turnover in terrestrial ecosystems. In this regard, CBMs have extremely positive properties in facilitating plant carbon capture, with intrinsic mechanisms including (1) promoting photosynthetic pigment synthesis and acting as artificial built-in antennae to improve photon capture efficiency, (2) accelerating the photosynthetic electron transport rate in photosystems, (3) improving the Calvin cycle, and (4) maintaining the structural integrity of chloroplasts. Besides, as an ultra-stable type of CBM derived from waste biomass, biochar can preserve the native biomass carbon in the soil environment for decades and attenuate the rhizosphere priming effect by influencing the structure of rhizosphere soil aggregates and microbial communities, thus retarding the native soil organic carbon efflux. This review critically elaborates on the mechanisms by which CBMs assist in improving the efficiency of phytoremediation and their positive effects on the plant-root soil carbon balance. Additionally, a simple full-life cycle analysis encompassing cost analysis as well as ecological, economic, and social benefits is concluded to evaluate the feasibility and sustainability of CBMs-phytoremediation systems. [ABSTRACT FROM AUTHOR]

To date, clothing has been produced and disposed of in large quantities. It is also known that each process, from the procurement of raw materials to production, transportation, sales, laundry, and disposal, has a significant environmental impact. According to the Global Fashion Agenda, greenhouse gas (GHG) emissions from the fashion industry account for 4% of the global total. Therefore, apparel makers are shifting from a linear economy to a circular economy. For example, the Japanese start-up Curelabo Co., Ltd. (Okinawa, Japan) developed jeans (bagasse washi jeans) made from bagasse, which is a residual material derived from sugarcane after the extraction of cane juice. Furthermore, the use of improved dyeing reduces boiler fuel consumption and eliminates the need for detergents and acid. For disposal, the used jeans and their production waste are processed into biochar for carbon sequestration. In this study, we attempted to calculate GHG emissions using life cycle assessment (LCA) for the circular economy model developed by Curelabo Co., Ltd. GHG emissions from the production of bagasse washi jeans were 1.09 × 101 kg-CO2e. Dyeing, bleaching, and fabric finishing, known as the wet processes, were found to contribute a large proportion of GHG emissions due to their high energy consumption. Furthermore, the entire lifecycle of GHG emissions from bagasse washi jeans, including transport, sales, laundry, and disposal, were 1.53 × 101 kg-CO2e. First, the use of bagasse washi yarn for the weft reduced by 2.99 × 10−1 kg-CO2e compared with the use of conventional 100% bleached cotton yarn. Second, compared with conventional dyeing, GHG emissions from the improved dyeing process were reduced by 2.78 kg-CO2e. Third, the disposal of the used jeans and their production waste into biochar reduced GHG emissions by 9.01 × 10−1 kg-CO2e. Additionally, GHG emissions can be reduced by re-inputting waste in the paper-making process and by using liquefied natural gas as boiler fuel in the dyeing process. [ABSTRACT FROM AUTHOR]

Microalgae technology is a viable solution for environmental conservation (carbon capture and wastewater treatment) and energy production. However, the nutrient cost, slow-kinetics, and low biosorption capacity of microalgae hindered its application. To overcome them, algal-biochar (BC) can be integrated with microalgae to treat textile wastewater (TWW) due to its low cost, its ability to rapidly adsorb pollutants, and its ability to serve as a nutrient source for microalgal-growth to capture CO2 and biodiesel production. Chlorella vulgaris (CV) and algal-BC were combined in this work to assess microalgal growth, carbon capture, TWW bioremediation, and biodiesel production. Results showed the highest optical density (3.70 ± 0.07 OD680), biomass productivity (42.31 ± 0.50 mg L−1 d−1), and dry weight biomass production (255.11 ± 6.01 mg L−1) in an integrated system of CV-BC-TWW by capturing atmospheric CO2 (77.57 ± 2.52 mg L−1 d−1). More than 99% bioremediation (removal of MB-pollutant, COD, nitrates, and phosphates) of TWW was achieved in CV-BC-TWW system due to biosorption and biodegradation processes. The addition of algal-BC and CV microalgae to TWW not only enhanced the algal growth but also increased the bioremediation of TWW and biodiesel content. The highest fatty acid methylesters (biodiesel) were also produced, up to 76.79 ± 2.01 mg g−1 from CV-BC-TWW cultivated-biomass. Biodiesel's oxidative stability and low-temperature characteristics are enhanced by the presence of palmitoleic (C16:1) and linolenic (C18:3) acids. Hence, this study revealed that the integration of algal-biochar, as a biosorbent and source of nutrients, with living-microalgae offers an efficient, economical, and sustainable approach for microalgae growth, CO2 fixation, TWW treatment, and biodiesel production. [ABSTRACT FROM AUTHOR]

Biochar is a carbon-rich solid by-product formed by treating biomass to high temperatures in an oxygen-deprived environment. It has recently increased in popularity due to its positive impacts on soils and climate change mitigation among others. Four production processes of biochar have been described in this review; Pyrolysis, Hydrothermal carbonization, Torrefaction, and Gasification. These processes differ in their temperatures, heating rates, usable feedstock, reaction environment, and complexity, ultimately determining the characteristics of biochar produced and their usage. Along with biochar, other products such as bio-oil and syngas are produced in different quantities. The quantities and qualities of these products are based on the temperature of the production process and the type of feedstock utilized respectively. Biochar usage includes and is not limited to soil management, organic waste management, water purification, greenhouse gas emission mitigation, carbon sequestration, fuel alternative, and land reclamation. This review finds biochar extremely important in climate-smart agriculture, mitigating global warming, and contributing a small part to fulfilling global energy needs. The gap in research regarding the effect of biochar from different feedstock needs to be filled, along with the standardization of production methods and application of biochar in various fields to increase the benefits while decreasing the harmful effects on the environment and human health. The research gap can be used as a guide to direct further research on biochar. The production of biochar is seen to have an upward trend, but its adoption by people in agriculture or land management is hindered by the economics surrounding it. Biochar can be an 'environmental savior' but proper policy-making and widespread research and extension must accompany its production. [ABSTRACT FROM AUTHOR]

Integrating innovation and environmental responsibility has become important in pursuing sustainable industrial practices in the contemporary world. These twin imperatives have stimulated research into developing methods that optimize industrial processes, enhancing efficiency and effectiveness while mitigating undesirable ecological impacts. This objective is exemplified by the emergence of biochar derived from the thermo-chemical transformation of biomass. This review examines biochar production methods and their potential applications across various aspects of the iron and steel industries (ISI). The technical, economic, and sustainable implications of integrating biochar into the ISI were explored. Slow pyrolysis and hydrothermal carbonization are the most efficient methods for higher biochar yield (25–90%). Biochar has several advantages- higher heating value (30–32 MJ/kg), more porosity (58.22%), and significantly larger surface area (113 m2/g) compared to coal and coke. However, the presence of biochar often reduces fluidity in a coal-biochar mixture. The findings highlighted that biochar production and implementation in ISI often come with higher costs, primarily due to the higher expense of substitute fuels compared to traditional fossil fuels. The economic viability and societal desirability of biochar are highly uncertain and vary significantly based on factors such as location, feedstock type, production scale, and biochar pricing, among others. Furthermore, biomass and biochar supply chain is another important factor which determines its large scale implementation. Despite these challenges, there are opportunities to reduce emissions from BF-BOF operations by utilizing biochar technologies. Overall, the present study explored integrating diverse biochar production methods into the ISI aiming to contribute to the ongoing research on sustainable manufacturing practices, underscoring their significance in shaping a more environmentally conscious future. [ABSTRACT FROM AUTHOR]

Plastic waste has emerged as a pressing global concern, with a significant portion of it being discarded into the environment. Concurrently, wastewater sludge has also become an environmental threat due to the potential contaminants in it. In response, in this study, we took a novel approach that focused on the development of a sustainable composite matrix made from sludge-derived biochar and plastic. The physical, mechanical, and mineralogical properties of plastic–biochar (PB) composite matrices, including water absorption capacity (WAC), bulk density, wet transverse strength, and thermal conductivity, were assessed. The WAC increased with a higher biochar content in the matrix, ranging from 1.39% to 2.40%. The bulk density increased from 0.66 to 0.94 g/cc with increasing biochar content. The wet transverse strength exceeded the minimum requirement of 3 MPa in all tested samples, demonstrating the matrices' robustness. The thermal conductivity values ranged from 0.2 to 0.3 W/m · K, indicating the matrices' potential as insulating materials. Fourier-transform infrared (FTIR) spectroscopy confirmed the presence of the biochar and its bonding with polyethylene terephthalate (PET) in the composite matrices. X-ray diffraction (XRD) analysis revealed shifts in the peak patterns with varying biochar content, demonstrating alterations in the crystallinity. Field emission scanning electron microscopy (FE-SEM) micrographs illustrated the interactions between the biochar and the PET, highlighting their distinctive attributes. A cost analysis showed that the PB composite matrices were cheaper than traditional cement concrete tiles. Finally, the potential of PB composite matrices to sequester carbon was assessed, which could contribute to reducing the carbon footprint of construction. This study demonstrated the potential of BP composite matrices as sustainable and cost-effective materials with satisfactory physical properties and the ability to reduce environmental impact. [ABSTRACT FROM AUTHOR]

Biochar, a carbon-rich material produced from biomass waste through thermal conversion, holds great environmental promise. This article offers a comprehensive overview of the various feedstocks used in biochar production, the different types of thermal degradation processes, biochar characterization, properties, modifications to engineered materials, and their applications in the environment. The quality of biochar, including surface area, pore size and volume, and functional group formation, is significantly influenced by the specific conditions under which thermal conversion takes place. Each of the diverse processes employed to produce biochar yields a distinct set of properties in the final product. In recent years, biochar has gained widespread recognition and utilization in diverse fields such as wastewater treatment, carbon sequestration, reduction of greenhouse gas emissions, biogas production, catalysis in biofuel industries, construction, and soil enhancement. In summary, biochar is a promising environmental mitigation tool to achieve a sustainable environment. In addition to its benefits, the application of biochar presents several challenges, including the selection of feedstocks, methods of biochar production, modifications to biochar, the properties of biochar, and the specific applications of biochar. The current review summarizes factors that could lead to significant advancements in future applications. Highlights: The feedstocks and production of biochar were discussed. Activation of biochar and properties of biochar were narrated and summarized. Application of biochar for sustainable environment was discussed. [ABSTRACT FROM AUTHOR]

Anthropogenic activities have caused irreversible consequences on our planet, including climate change and environmental pollution. Nevertheless, reducing greenhouse gas (GHG) emissions and capturing carbon can mitigate global warming. Biochar and hydrochar are increasingly used for soil remediation due to their stable adsorption qualities. As soil amendments, these materials improve soil quality and reduce water loss, prevent cracking and shrinkage, and interact with microbial communities, resulting in a promising treatment method for reducing gas emissions from the top layer of soil. However, during long-term studies, contradictory results were found, suggesting that higher biochar application rates led to higher soil CO2 effluxes, biodiversity loss, an increase in invasive species, and changes in nutrient cycling. Hydrochar, generated through hydrothermal carbonization, might be less stable when introduced into the soil, which could lead to heightened GHG emissions due to quicker carbon breakdown and increased microbial activity. On the other hand, biochar, created via pyrolysis, demonstrates stability and can beneficially impact GHG emissions. Biochar could be the preferred red option for carbon sequestration purposes, while hydrochar might be more advantageous for use as a gas adsorbent. This review paper highlights the ecological impact of long-term applications of biochar and hydrochar in soil. In general, using these materials as soil amendments helps establish a sustainable pool of organic carbon, decreasing atmospheric GHG concentration and mitigating the impacts of climate change. [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]

Green carbon-based materials (GCM), i.e., carbon materials produced using renewable biomass or recycled waste, ought to be used to make processes sustainable and carbon-neutral. Carbon nanomaterials, like carbon dots and the nanobichar families, and carbon materials, like activated carbon and biochar substances, are sustainable materials with great potential to be used in different technological applications. In this review, the following four applications were selected, and the works published in the last two years (since 2022) were critically reviewed: agriculture, water treatment, energy management, and carbon dioxide reduction and sequestration. GCM improved the performance of the technological applications under revision and played an important role in the sustainability of the processes, contributing to the mitigation of climate change, by reducing emissions and increasing the sequestration of CO2eq. [ABSTRACT FROM AUTHOR]

Human activities are responsible for emitting greenhouse gases (GHGs) that contribute to global warming and climate change. As the world's second-largest producer of staple food and the third-largest emitter of GHGs, India has been witnessing an increase in demand for food and energy, resulting in increased emissions. Thus, to achieve net carbon neutrality by 2070, India must focus urgently on climate change mitigation. Its agriculture sector has the potential to transition from being a net emitter to a net absorber of GHGs by adopting sustainable farming practices such as zero tillage, laser-assisted precision land leveling, direct seeding of rice, intercropping, biochar application, use of solar energy, and more efficient management of irrigation water, soil nutrients, livestock feed, and manure. To incentivize climate consciousness, a voluntary carbon credit trading system could be utilized in agriculture, supported by a measurement, monitoring, reporting, and verification platform. This system would also bring about social, environmental, and financial co-benefits for its stakeholders. Specifically, the agriculture sector could substantially reduce the country's annual emissions by 84% from 2019 to 2070. But to realize their potential, the carbon markets must overcome the limitations currently set by policy, economic, cultural, and biophysical factors. [ABSTRACT FROM AUTHOR]

Municipal sewage sludge (MSS) is an inevitable byproduct of wastewater treatment, with increasing amounts year by year worldwide. The development of environmentally and economically acceptable methods for the sustainable management of MSS is a major environmental challenge. Nowadays, sludge management practices, besides the commonly used stabilization methods, focus attention on alternative sludge-disposal pathways, which encompass enhanced energy and valuable-resource recovery. This review presents the recent advances in the recovery of selected value-added products from sludge. Because of the high nitrogen and phosphorus concentrations, waste MSS can be a nutrient source (e.g., struvite). This paper discusses the conditions of and advances in the technology of struvite recovery. As in the extracellular polymeric substances (EPSs) of biological sludge, alginate-like exopolymers (ALEs) are present in MSS systems that treat municipal wastewater. The yields, dynamics in content, and characterization of ALEs and their possible applications were analyzed. MSS is an important source of humic substances. Their occurrence, characterization, and yields in various types of MSS (e.g., untreated, composted, and digested sludge) and main methods of application are presented. The important aspects and trends of MSS pyrolysis, including the thermochemical conversion to biochar, are discussed in this review. The characterization of biochar derived from MSS and the assessment of the environmental risks are also covered. This paper explores the potential use of biochar derived from MSS in various applications, including soil amendment, carbon sequestration, and environmental remediation. [ABSTRACT FROM AUTHOR]

Biochar from crop residues plays an important role in reclamation of degraded rice soil due to imbalance fertilizer application and soil carbon sequestration. The objective of this study aimed to evaluate the best type and rate of biochar application for rice dry matter and soil organic carbon improvement. Therefore, pot experiments were carried out in two seasons of spring and summer 2023 at the University of Agriculture and Forestry, Hue University. Twelve treatments including 2 types of biochar (rice husk and peanut shell) and 6 application rates (0, 1, 2, 3, 4, 5%) were used and arranged in a randomized block design with three replications. Research results showed that the shoot dry matter was higher 9.5-27.0% (spring season) and 19.1-26.9% (summer season) at a rate of 5% application in both types of biochar than control. Rice husk biochar application had higher shoot dry matter than peanut shell biochar application in the same application rate from 0.30-0.46 g/plant in both seasons. Similarly, organic carbon was found the highest content (2.15-2.21%) when the application of biochar from crop residues at a rate of 5%. Biochar from crop residues is considered as a good amendment for increasing crop dry matter and soil organic carbon. [ABSTRACT FROM AUTHOR]

Abstract Integrating innovation and environmental responsibility has become important in pursuing sustainable industrial practices in the contemporary world. These twin imperatives have stimulated research into developing methods that optimize industrial processes, enhancing efficiency and effectiveness while mitigating undesirable ecological impacts. This objective is exemplified by the emergence of biochar derived from the thermo-chemical transformation of biomass. This review examines biochar production methods and their potential applications across various aspects of the iron and steel industries (ISI). The technical, economic, and sustainable implications of integrating biochar into the ISI were explored. Slow pyrolysis and hydrothermal carbonization are the most efficient methods for higher biochar yield (25–90%). Biochar has several advantages- higher heating value (30–32 MJ/kg), more porosity (58.22%), and significantly larger surface area (113 m2/g) compared to coal and coke. However, the presence of biochar often reduces fluidity in a coal-biochar mixture. The findings highlighted that biochar production and implementation in ISI often come with higher costs, primarily due to the higher expense of substitute fuels compared to traditional fossil fuels. The economic viability and societal desirability of biochar are highly uncertain and vary significantly based on factors such as location, feedstock type, production scale, and biochar pricing, among others. Furthermore, biomass and biochar supply chain is another important factor which determines its large scale implementation. Despite these challenges, there are opportunities to reduce emissions from BF-BOF operations by utilizing biochar technologies. Overall, the present study explored integrating diverse biochar production methods into the ISI aiming to contribute to the ongoing research on sustainable manufacturing practices, underscoring their significance in shaping a more environmentally conscious future.

Biochar is a carbon-rich product obtained by biomass pyrolysis and is considered as a means of carbon sequestration. However, there is limited knowledge regarding responses of soil respiration and C-cycle enzyme activities to BC in a calcareous soil. In this study, different biochar AS, TS, PP, CS were applied to the soil at different rates (0.5, 1.0, and 1.5%) The highest increase in soil organic C content was observed in the TS treatment, while the AS treatment caused a slight increase of soil organic C. The highest MBC content was recorded in AS treatment and the lowest was observed in TS. The highest CO2-C emission was recorded in the TS treatment. In contrast, the lowest CO2-C emission was observed in the PP treatment due to its high recalcitrant C content and was attributed to a positive priming effect, stabilizing BC mineralization to improve the soil. The highest β-galactosidase enzyme activity was observed in the CS treatment and the lowest activity was observed in AS. The highest change in β-glycosidase enzyme activity was observed of PP treatment and the lowest was in AS biochar application. Thus, TS treatment is recommended to increase the organic C content of soils, and the PP biochar can be used to reduce CO2-C emission. The TS, PP, and CS can be applied to increase enzyme activities. The study clearly shows that the addition of BC to arid soils may have a high potential to improve soil enzyme activities and subsequent carbon sequestration and biochemical cycles. [ABSTRACT FROM AUTHOR]

The study was conducted to investigate carbon stock, flux, and sequestration potential as well as the response of groundnut (yield) to different fortification approaches. A greenhouse experiment was conducted using four treatment combinations, fortified biochar with T. albuminosus (B + T), biochar (B), T. albuminosus, and control laid in a Complete Randomized Design (CRD). The result showed increased carbon sequestration, stock, and a subsequent decrease in carbon emission in treatment B + T relative to other treatments. Untreated samples recorded the lowest values with 3.69 g kg-1 sequestered carbon 24.97 kg ha- stock 4.92% carbon emission and a net flux of -20.70. The highest groundnut yield was also recorded in the B + T treatment with a value of 1131.10 kg ha-1. However, biochar treatment recorded the highest biomass and stover yield 5.62 t ha-1 and 3.82 t ha-1 respectively. In conclusion, the Fortification of biochar with T. albuminosus proved efficient in improving carbon sequestration, increasing carbon stock, and reducing emission as well as other nutrients in soils under cultivation. Also, using B + T as an amendment under optimal growth conditions is recommended for better groundnut production. The study's constraints lie in its execution within controlled greenhouse settings, potentially limiting its applicability to real-world field conditions. Thus, caution should be exercised when extending these findings to field applications, ensuring the validation of the approach's effectiveness.

Abstract Biochar can improve soil health and fix CO2 by altering soil microenvironment, thus impacting the global carbon cycle and the change of soil ecological environment. Recent studies show that cotton byproduct-derived biochar is a potential effective amendment for soil improvement so that it could play an important role in agricultural and environmental conservation. In this work, research topics on cotton byproduct-derived biochar in soil in last decade and so are systematically reviewed for better understanding of the progresses of cotton byproduct-derived biochar in (i) the morphologic and physicochemical characterization, (ii) latest research hotspots and trends, (iii) the roles in soil reclamation, and (iv) relevant carbon sequestration mechanisms. Finally, the future research directions regarding cotton byproduct-derived biochar mingled to soil environment are discussed. Insight derived from this work would provide scientific basis for promoting more applications of cotton byproduct-derived biochar in soil ecological restoration and carbon fixation. Graphical Abstract

The growth of eggplant (Pusa Safed Baingan-1) was studied during the semi-arid (March to June) and humid sub-tropical (July to September) seasons of New Delhi, India. The individual effects of wheat straw biomass (WSBM), wheat straw biochar (WSBC) and compost versus the combined effect of WSBM plus compost and WSBC plus compost were determined under field conditions. The amendments were made at two different application rates: 1 wt% and 2 wt%. WSBC was successfully prepared in a proprietary kachcha reactor (Indian patent no. 380921), designed using locally sourced clay. Amendments were characterized using elemental analyzer, scanning electron microscopy (SEM), transmission electron (TEM) microscopy, Fourier transform infrared (FTIR) spectroscopy and X-Ray diffraction (XRD). The field study was conducted in 11 (1x1-meter) plots with two replicates. Basic soil health parameters including pH, electrical conductivity (EC), water holding capacity (WHC), bulk density (BD), cation exchange capacity (CEC), soil total nitrogen (STN), soil available nitrogen (SAN), soil organic carbon (SOC), soil available phosphorus (SAP), microbial biomass carbon (MBC) and mineral contents are analyzed. Observable plant growth characteristics (germination percentage, height, number of leaves, fruits, and plant biomass) were also recorded. Biochar amendment was most beneficial for enhancing the majority of these parameters. With respect to the control, a 20% decrease in bulk density, a 30% increase in water holding capacity, a 122% increase in organic carbon, a 175% increase in total nitrogen, a 23% increase in available nitrogen, and a 473% increase in available phosphorus were recorded. Furthermore, with respect to the control, a 115% increase in CEC was recorded using the compost amendment vs 84% with WSBC. Synergism between biochar and compost was reflected by high germination percentage (44%), number of fruits (600%), plant biomass weight (243%) and soil microbial biomass carbon (286%). Biomass amendment failed to show any positive influence. In summary, biochar emerges as a superior choice compared to both biomass and compost when it comes to soil amendments.

Ensuring global food security under present and futuristic scenario of climate change accompanied by expanding population is of major concern worldwide. Researchers across the world are focusing on sustainable agronomic practices to combat climate change induced issues like desertification, reduction in crop yield, pest outbreaks, and reduction in soil health. Biochar has demonstrated positive effects on plant growth, development, fruit quality, carbon capture and sequestration. Studies indicate that biochar amendments to soil can enhance soil health, plant growth and development as well as help in combating abiotic stressors. Biochar has several properties that make it an attractive soil amendment, including high porosity, surface area, water-holding capacity, and the ability to increase soil microbiota, which in turn can promote nutrient uptake and reduce soil erosion. Environmentally, biochar's ability to degrade organic pollutant as well as sequester carbon makes it a very attractive addition to sustainable agriculture. Nonetheless, biochar has also been reported to have potential hazardous impacts on human health associated with possible leakage of toxic elements and particulate matter pollution. However, lack of exhaustive studies that detail all the major aspects of biochar application in agroecosystem impedes decision making on its overall usability in agriculture. There exists a need for comprehensive review that cover all the important aspects of biochar supplementation. This review provides a thorough overview of the multifaceted impacts of biochar, encompassing its positive effects on soil, plant growth, development and environment, while also exploring the limitations along with potential toxic effects associated with its application. [ABSTRACT FROM AUTHOR]