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Biochar
Number of Followers: 1  Hybrid journal (It can contain Open Access articles)ISSN (Print) 2524-7972 - ISSN (Online) 2524-7867 Published by Springer-Verlag  [2468 journals]
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- Microbial responses towards biochar application in potentially toxic
element (PTE) contaminated soil: a critical review on effects and
potential mechanisms-
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Abstract: Soil harbors a huge diversity of microorganisms and serves as the ecological and social foundation of human civilization. Hence, soil health management is of utmost and consistent importance, aligning with the United Nations Sustainable Development Goals. One of the most hazardous contaminants in soil matrix is potentially toxic elements (PTEs), which can cause stress in soil indigenous microorganisms and severely jeopardize soil health. Biochar technology has emerged as a promising means to alleviate PTE toxicity and benefit soil health management. Current literature has broadly integrated knowledge about the potential consequences of biochar-amended soil but has focused more on the physical and chemical responses of the soil system than microbiological attributes. In consideration of the indispensable roles of soil microbials, this paper first introduces PTE-induced stresses on soil microbials and then proposes the mechanisms of biochar’s effects on soil microbials. Finally, microbial responses including variations in abundance, interspecific relationships, community composition and biological functions in biochar-amended soil are critically reviewed. This review thus aims to provide a comprehensive scientific view on the effect of biochar on soil microbiological health and its management. Graphical
PubDate: 2023-09-15
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- Synthesis of Mg–K-biochar bimetallic catalyst and its evaluation of
glucose isomerization-
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Abstract: Highly efficient isomerization of glucose to fructose is essential for valorizing cellulose fraction of biomass to value-added chemicals. This work provided an innovative method for preparing Mg-biochar and Mg–K-biochar catalysts by impregnating either MgCl2 alone or in combination with different K compounds (Ding et al. in Bioresour Technol 341:125835, 2021, https://doi.org/10.1016/j.biortech.2021.125835 and KHCO3) on cellulose-derived biochar, followed by hydrothermal carbonization and pyrolysis. Single active substance MgO existing in the 10Mg–C could give better catalytic effect on glucose isomerization than the synergy of MgO and KCl crystalline material present in 10Mg–KCl–C. But the catalytic effect of 10Mg–C was decreased when the basic site of MgO was overloaded. Compared to other carbon-based metal catalysts, 10Mg–KHCO3–C with 10 wt% MgCl2 loading had excellent catalytic performance, which gave a higher fructose yield (36.7%) and selectivity (74.54%), and catalyzed excellent glucose conversion (53.99%) at 100 °C in 30 min. Scanning electron microscope–energy dispersive spectrometer and X-Ray diffraction revealed that the distribution of Mg2+ and K+ in 10Mg–KHCO3–C was uniform and the catalytic active substances (MgO, KCl and K2CO3) were more than 10Mg–C (only MgO). The synergy effects of MgO and K2CO3 active sites enhanced the pH of reaction system and induced H2O ionization to form considerable OH− ions, thus easily realizing a deprotonation of glucose and effectively catalyzing the isomerization of glucose. In this study, we developed a highly efficient Mg–K-biochar bimetallic catalyst for glucose isomerization and provided an efficient method for cellulose valorization. Graphical
PubDate: 2023-09-08
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- Biochar contributes to resistance against root rot disease by stimulating
soil polyphenol oxidase-
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Abstract: Biochar has been considered an effective approach as soil amendment for decreasing incidences of disease and regulating microbial populations in continuous-cropping soil. Although researches have extensively focused on changes of soil microbes and unbalance of nutrition in continuous-cropping soil, the relationship between soil properties and pathogens by biochar application remains poorly understood. In this study, we applied ITS ribosomal RNA gene profiling to analyze tobacco root microbiota of biochar and non-biochar treatment in a 3-year continuous-cropping tobacco field, comparing firstly planting tobacco as control. We found that biochar application decreased the relative abundance of the soil fungal pathogens (Ceratobasidium and Monosporascus), which are the prime pathogens of tobacco root rot in continuous-cropping soil. Using RDA, co-occurrence and PLS-PM approaches, we provided evidence that there was a negative correlation between fungal genera (especially for Ceratobasidium and Monosporascus) and soil polyphenol oxidase (PPO) activity (R2incidence rate = − 0.930, R2disease index = − 0.905, both p < 0.001). The PPO was up-regulated by different biochar treatment intensities. Together, we demonstrated that biochar in continuous-cropping soil regulated the soil PPO activity to suppress pathogens, and further decrease incidence of root rot. Notably, biochar application forward continuous cropping was more effective for the continuous-cropping soil improvement than the other treatments. The data should help in appropriate timing of biochar application for alleviating continuous-cropping obstacle. Graphical abstract
PubDate: 2023-09-07
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- Enhanced phenol removal by permanganate with biogas residue biochar:
catalytic role of in-situ formation of manganese dioxide and activation of
biochar-
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Abstract: Increased biogas residue related to the rapid development of anaerobic fermentation has become an urgent environmental problem. The pyrolysis of biogas residue into biochar is one of the most promising treatments. In this study, biochar derived from biogas residue was prepared, and the degradation efficiency of phenol by permanganate (KMnO4) increased from 25.3% to 73.4% in 60 min in the presence of biogas residue biochar (BRB). KMnO4 reacted with BRB to produce intermediate manganese dioxide (MnO2), while BRB was activated. The specific surface area increased by 132.25%, and the oxygen-containing functional groups C=O, C−O, and COOH increased after the reaction. The generated MnO2 complexed with BRB to form MnO2@BRB. The newly formed MnO2@BRB catalyzed KMnO4 to remove phenol, which explains the high removal efficiency of phenol. A significant removal rate was also observed for antibiotics and chlorophenols, which suggested that the KMnO4/BRB system has a relatively high ability to oxidize organic pollutants. In addition, the co-existing metal ions and the natural environment had little influence on the removal efficiency of the KMnO4/BRB system. This work provides a novel technology for the resource utilization of biogas residue and improved organic pollutant removal efficiency of KMnO4 in the presence of BRB. Graphical abstract
PubDate: 2023-09-05
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- Geo-environmental and mechanical behaviors of As(V) and Cd(II)
co-contaminated soils stabilized by goethite nanoparticles modified
biochar-
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Abstract: Goethite nanoparticles modified biochar (FBC) could address the weak effectiveness of conventional biochar commonly to process heavy metal(loids) (HMs) co-contamination with different charges. However, few studies have focused on the change of soil mechanical properties after stabilization. In this study, FBC was synthesized to stabilize simultaneously arsenic (As (V)) (anions) and cadmium (Cd (II)) (cations) in co-contaminated soils. Batch adsorption, leaching toxicity, geotechnical properties and micro-spectroscopic tests were comprehensively adopted to investigate the stabilization mechanism. The results showed that FBC could immobilize As (V) mainly through redox and surface precipitation while stabilizing Cd (II) by electrostatic attraction and complexation, causing soil agglomeration and ultimately making rougher surface and stronger sliding friction of contaminated soils. The maximum adsorption capacity of FBC for As (V) and Cd (II) was 31.96 mg g−1 and 129.31 mg g−1, respectively. Besides, the dosages of FBC required in contaminated soils generally were approximately 57% higher than those in contaminated water. FBC promoted the formation of small macroaggregates (0.25–2 mm) and the shear strengths of co-contaminated soils by 21.40% and 8.34%, respectively. Furthermore, the soil reutilization level was significantly improved from 0.14–0.46 to 0.76–0.83 after FBC stabilization according to TOPSIS method (i.e., technique for order preference by similarity to an ideal solution). These findings confirm the potential of FBC in immobilizing As (V) and Cd (II) of co-contaminated soils and provide a useful reference for green stabilization and remediation of HMs co-contaminated sites. Graphical
PubDate: 2023-09-04
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- Engineered biochar improves nitrogen use efficiency via stabilizing soil
water-stable macroaggregates and enhancing nitrogen transformation-
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Abstract: The use of inorganic nitrogen (N) fertilizers has increased drastically to meet the food requirements of the world's growing population. However, the excessive use of chemical nitrogen fertilizer has caused a series of soil and environmental problems, such as soil hardening, lower nitrogen use efficiency (NUE), nitrate pollution of water sources, nitrous oxide emissions, etc. In this review, we aimed to elaborate and discuss the role of engineered biochar in inducing the stability of water-stable macroaggregates, improving inorganic N transformation, and utilization efficiency to address the current uncertainties of nitrogen loss and maintaining soil and water quality. Firstly, we elucidated the characteristics of engineered biochar in improving biochar quality to work as a multifunctional player in the ecosystem and promote resource utilization, soil conservation, and ecosystem preservation. Secondly, we discussed how the engineered biochar modulates the stability of water-stable macroaggregates and soil inorganic nitrogen transformation to enhance plant response under various toxic or deficient nitrogen conditions in the soil. Thirdly, the role of engineered biochar in biological nitrogen fixation, mediating nirK, nirS, and nosZ genes to promote the conversion of N2O to N2, and decreasing denitrification and N2O emission was reviewed. Altogether, we suggest that engineered biochar amendment to soil can regulate soil water-stable macroaggregates, reduce N input, improve nitrogen metabolism, and finally, NUE and crop growth. To the best of our knowledge, this is the first time to evaluate the combined interactions of "engineered biochar × soil × NUE × crop growth,” providing advantages over the increasing N and water utilization and crop productivity separately with the aim of enhancing the stability of water-stable macroaggregates and NUE together on a sustainable basis. Graphical abstract
PubDate: 2023-09-01
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- Application of magnesium and biosurfactant functionalized biochar
composite in treating cyanobacteria in phosphorus and crude oil
contaminated water-
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Abstract: Various human activities have led to multiple contamination of natural water systems. The present study investigated the effect of a novel multifunctional biochar to treat nutrients, oil, and harmful algae in water. Specifically, magnesium (Mg) and biosurfactant rhamnolipid (RL) were incorporated into biochar, including Mg-biochar, RL-biochar, and Mg-RL-biochar. Their adsorption efficiency on phosphate and total petroleum hydrocarbons (TPH) was evaluated in separate batch studies. Also, the inhibition effect of RL-modified biochars on cyanobacteria was investigated. The results showed that Mg-impregnated biochar showed high adsorption capacity on phosphate (118 mg g−1), while RL-modified biochar significantly reduced TPH (especially aromatic and light aliphatic fraction) with adsorption capacity of 44.4 mg g−1. The inhibition effects of biochar composites on algae in water without contaminants were in order of Mg-RL-biochar > RL-biochar > biochar with biomass reduction ranging 61–64%. Overall, Mg-RL-biochar was suggested based on this study due to its ability to remove PO43− and TPH, and inhibit the growth of toxic algae. Graphical abstract
PubDate: 2023-08-24
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- Investigation on the mechanism of structural reconstruction of biochars
derived from lignin and cellulose during graphitization under high
temperature-
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Abstract: The structural reconstruction mechanism of lignin and cellulose-derived biochars during direct graphitization under ultra-high temperatures was intensively investigated. It was demonstrated that cellulose-derived char was almost composed of carbon microcrystallites, whereas lignin-derived char reserved some of its skeleton structures, and such structural difference played a vital role in the morphology of formed graphitic layers. The results illustrated that the graphitized lignin-derived sample under 2800 ℃ had graphitic degree of 89.53%, interlayer spacing of 0.3363 nm and electronic conductivity of 104.6 S cm−1, while cellulose-derived sample had graphitic degree of 76.74%, layer distance of 0.3374 nm, and electronic conductivity of only 48.8 S cm−1. Combined with the results of structural analysis of the chars derived from lignin and cellulose, it was inferred that the stable and aromatic ring containing skeleton structure in lignin was beneficial to the ring-enlarging reconstruction and the formation of large areas of continuous graphitic layers during graphitizing process, leading to high electronic conductivity. Meanwhile, the interwoven microcrystallites in cellulose-derived char strongly restricted the expanding of continuous lamellar graphitic areas even at such ultra-high temperature, causing the formation of turbostratic structure with numerous structural defects as well, and finally resulting in relatively lower electronic conductivity. This work is expected to provide theoretical guidance for preparing high-performance functional carbon materials from lignocellulosic biomass. Graphical
PubDate: 2023-08-24
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- Spatial and temporal changes of charosphere hotspots with or without
nitrogen additions-
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Abstract: The charosphere is a thin soil one surrounding the biochar with highly active biochemical functions. Yet, little is known about the spatial and temporal distribution of charosphere hotspots. In this study, repacked soil cores were incubated with a central layer of biochar (pristine or acid-modified) with or without nitrogen (N) additions for 30 days and sliced at the millimeter scale for analyzing soil pH, mineral N, bacterial and fungal communities as well as the putative functions. We aimed to determine gradient distributions (in millimeter scale) of charosphere affected by biochar under different N additions. Our results showed narrower gradient changes (3 mm) of microbial community composition and wider shifts (6 mm) in pH and inorganic N contents in charosphere. The pristine biochar increased the soil pH up to 1.5 units in the charosphere, and subsequently boosted the relative abundance of Proteobacteria, Acidobacteria, and Zygomycota. With N addition, both the biochar site and charosphere were observed with decreased complexity of microbial networks, which might imply the limited microbial functionality of charosphere. These results will advance the understanding and prediction of biochar’s environmental impacts in soil. Graphical abstract
PubDate: 2023-08-18
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- Biochar-mediated Cd accumulation in rice grains through altering chemical
forms, subcellular distribution, and physiological characteristics-
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Abstract: Biochar can change the availability and morphology of soil Cd. However, the influence of biochar on Cd chemical form and subcellular fraction in rice is poorly understood, particularly under different irrigation methods. A pot experiment of biochar application combined with two irrigation methods (continuous flooding and intermittent irrigation, CF and II) was conducted. The Cd accumulation, chemical form and subcellular fraction in rice organs and the associated physiological responses were examined. Biochar significantly reduced soil available Cd (30.85–47.26% and 32.35–52.35%) under CF and II but increased the Cd content (30.4–63.88% and 13.03–18.59%) in brown rice. Additionally, the Cd content in shoots/grains under II was higher than that under CF. Biochar elevated the Cd soluble fraction in roots while lowered the cell wall fraction under both irrigation methods, whereas the opposite result was observed in leaves. Biochar increased water-, ethanol-, and NaCl-extractable Cd in roots meanwhile increased ethanol-extractable Cd in leaves under both irrigation methods. Moreover, the total amount of water-, ethanol-, and NaCl-extractable Cd in rice roots was higher under II than under CF. Related hormones and antioxidant enzymes may also be involved in biochar-mediated Cd accumulation in rice grains. Thus, changes in Cd chemical form and subcellular fraction in the root and leaf are the main mechanisms of biochar-induced rice grains Cd accumulation. Graphical
PubDate: 2023-08-09
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- Gas permeability and emission in unsaturated vegetated landfill cover with
biochar addition-
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Abstract: Plant–biochar interaction has been recognized to affect the hydraulic properties of landfill cover soils, while its influence on landfill gas emission is rarely studied. This study investigated the coupled effects of biochar and vegetation on gas permeability and emission in unsaturated landfill cover through an integrated theoretical modelling and laboratory investigation. First, a gas permeability model was developed for vegetated coarse-grained soils with biochar addition. Then, a well-instrumented laboratory column test and two tests from the literature, considering bare, grass, biochar and grass + biochar conditions, were used for model validation. Finally, a numerical parametric study was conducted to investigate the influence of root growth and drought conditions on the gas emission rate. Results showed that the developed model can satisfactorily capture the gas permeability of unsaturated soils at various degrees of saturation. The lowest water retention capacity, the highest gas permeability and gas emission rate after 24 months of growth were observed in the grassed column. However, adding biochar in vegetated soils can maximize the water retention capacity and decrease the gas permeability, resulting in the lowest gas emission rate. The measured gas emission rates for the four cases meet the recommended value by the design guideline. The parametric study showed that the increased root depth from 0.2 m to 0.4 m improved the gas emission rate by 170% in the grass case but decreased by 97% in the grass + biochar case. Under the severe drought condition with soil suction around 500 kPa, the gas emission rate in the grassed case exceeded the design value by 18%, while those in the biochar cases were far below the allowable value. Therefore, peanut shell biochar should be considered to amend the grassed landfill cover using coarse-grained soils as it can significantly improve engineering performance in reducing gas emissions under extreme drought conditions. Graphical abstract
PubDate: 2023-08-03
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- Construction of the hierarchical porous biochar with an ultrahigh specific
surface area for application in high-performance lithium-ion capacitor
cathode-
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Abstract: Biochar with a highly accessible specific surface area can display a higher performance when it is used as the cathode of lithium-ion capacitors. Facing the complex composition and diversity of biomass precursors, there is a lack of a universally applicable method to construct hierarchical porous biochar controllably. In this work, a multi-stage activation strategy combining the feature of different activation methods is proposed for this target. To confirm the porous characteristic in prepared samples, N2 adsorption–desorption and transmission electron microscope were used. As the optimal sample, BC-P3K4S had the highest specific surface area of 3583.3 m2 g−1. Evaluated as the electrode for a lithium-ion capacitor, BC-P3K4S displayed a capacity of 139.1 mAh g−1 at 0.1 A g−1. After coupling it with pre-lithiated hard carbon, the full device exhibited a high energy density of 129.3 W h kg−1 at 153 W kg−1. The work outlined herein offers some insights into the preparation of hierarchical porous biochar from complex biomass by multistep activation method. Graphical
PubDate: 2023-07-24
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- Sustained and efficient remediation of biochar immobilized with
Sphingobium abikonense on phenanthrene-copper co-contaminated soil and
microbial preferences of the bacteria colonized in biochar-
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Abstract: Immobilized microbial technology has been widely used in wastewater treatment, but it has been used less frequently for soil remediation, particularly in sites that are co-contaminated with organic compounds and heavy metals. In addition, there is limited knowledge on the efficiency of remediation and microbial preferences to colonize the immobilized carriers. In this study, biochar immobilized with Sphingobium abikonense was introduced to remediate soils that were co-contaminated with phenanthrene (PHE) and copper (Cu), and the mechanisms of microbial assemblage were investigated. The immobilized microbial biochar maintained a degradation rate of more than 96% in both the first (0–6 d) and second (6–12 d) contamination periods. The addition of biochar increased the proportion of Cu bound to organic matter, and Fe–Mn oxide bound Cu in the soil. In addition, both Cu and PHE could be adsorbed into biochar pellets in the presence or absence of immobilized S. abikonense. The presence of biochar significantly increased the abundance of bacteria, such as Luteibacter, Bordetella and Dyella, that could degrade organic matter and tolerate heavy metals. Notably, the biochar could specifically select host microbes from the soil for colonization, while the presence of S. abikonense affected this preference. The autonomous selection facilitates the degradation of PHE and/or the immobilization of Cu in the soil. These results provide a green approach to efficiently and sustainably remediate soil co-contaminated with PHE and Cu and highlight the importance of microbial preference colonized in immobilized carriers. Graphical
PubDate: 2023-07-21
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- Biochar application in remediating salt-affected soil to achieve carbon
neutrality and abate climate change-
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Abstract: Salt-affected soils urgently need to be remediated to achieve the goals of carbon neutrality and food security. Limited reviews are available on biochar performance in remediating salt-affected soils in the context of carbon neutrality and climate change mitigation. This work summarized the two pathways to achieve carbon neutrality during remediating salt-affected soils using biochars, i.e., biochar production from sustainable feedstock using thermal technologies, application for promoting plant productivity and mitigating greenhouse gas (GHG) emission. Converting biomass wastes into biochars can reduce GHG emission and promote carbon dioxide removal (CDR), and collection of halophyte biomass as biochar feedstocks, development of biochar poly-generation production systems with carbon neutrality or negativity could be promising strategies. Biochar can effectively improve plant growth in salt-affected soils, showing that the grand mean of plant productivity response was 29.3%, via improving physicochemical characteristics, shifting microbial communities, and enhancing plant halotolerance. Moreover, biochar can mitigate GHG emission via inducing negative priming effect, improving soil properties, changing microbial communities associated with carbon and nitrogen cycle, direct adsorption of GHG. However, biochar also may pose negative effects on plant growth because of stress of toxic compounds and free radicals, and deterioration of soil properties. The promoted GHG emission is mainly ascribed to positive priming effect, and provision of labile carbon and inorganic nitrogen fractions as microbial substrates. Finally, this review pointed out the gaps in the current studies and the future perspectives. Particularly, the development of “carbon neutral” or “carbon negative” biochar production system, balancing the relationship of biochar effectiveness and functionality with its environmental risks and costs, and designing biochar-based GHG adsorbents would be important directions for remediating salt-affected soils to achieve carbon neutrality and abate climate change. Graphical
PubDate: 2023-07-21
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- Co-incorporation of hydrotalcite and starch into biochar-based fertilizers
for the synthesis of slow-release fertilizers with improved water
retention-
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Abstract: The unsatisfactory nutrient slow-release and water-retention performance of traditional biochar-based compound fertilizers (BCF) severely limit their practical application. Herein, a new type of slow-release fertilizer with high water retention was fabricated via the incorporation of hydrotalcite and starch into BCF, named as HS-BCF. The water-retention and nutrient releasing performance of the prepared HS-BCF and related nutrient slow-release mechanism were investigated. The results showed that the incorporation of hydrotalcite and starch into BCF could increase the soil water-retention ratio by 5–10% points. The accumulated N, P, and K leaching amounts of HS-BCF in soil within 30 days were 49.4%, 13.3%, and 87.4% of BCF at most, respectively. Kinetic analysis indicated that the release of nutrients from HS-BCF was attributed to the coupling of the diffusion-controlled and relaxation-controlled mechanism. Moreover, hydrotalcite could bind with P in HS-BCF, contributing to the enhanced durability of P in HS-BCF. Finally, pot experiments showed that the N–P–K utilization efficiencies of HS-BCF were all higher than those of BCF due to a better synchronization between the nutrient release of HS-BCF and the uptake of tomato plants. Overall, the study may provide a promising strategy for simultaneously improving the water-retention and slow-release performance of traditional biochar-based fertilizers. Graphical
PubDate: 2023-07-21
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- Biochar-based materials in environmental pollutant elimination, H2
production and CO2 capture applications-
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Abstract: Biochar and biochar-based materials have been studied extensively in multidisciplinary areas because of their outstanding physicochemical properties. In this review article, biochar and biochar-based materials in the removal of environmental pollutants, hydrogen generation and carbon dioxide capture were summarized and compared. The interaction mechanisms were discussed from the experimental results and characterization analysis. The high porous structures, active surface sites, (co)doping of single metals/nonmetals, and incorporation of metal oxides or other materials improved the high activity of biochar-based materials in their applications. However, there are still some challenges such as: (1) the fact that H2 generation with high selectivity or the produced syngas to meet the real application requirement in industrial is the main challenge in H2 production; (2) the fact that the selective capture of CO2 with high stability, high adsorption capacity and recyclability at low-cost should be considered and focused on; (3) the sorption-(photo)degradation of the organic chemicals; and (4) the fact that the sorption-reduction-extraction/solidification of metals/radionuclides are efficient methods for the elimination of environmental pollutants. In the end, the perspectives, challenges and possible techniques for biochar-based materials’ real application in future were described. Graphical
PubDate: 2023-07-20
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- Biochar and zero-valent iron sand filtration simultaneously removes
contaminants of emerging concern and Escherichia coli from wastewater
effluent-
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Abstract: Advanced treated municipal wastewater is an important alternative water source for agricultural irrigation. However, the possible persistence of chemical and microbiological contaminants in these waters raise potential safety concerns with regard to reusing treated wastewater for food crop irrigation. Two low-cost and environmentally-friendly filter media, biochar (BC) and zero-valent iron (ZVI), have attracted great interest in terms of treating reused water. Here, we evaluated the efficacy of BC-, nanosilver-amended biochar- (Ag-BC) and ZVI-sand filters, in reducing contaminants of emerging concern (CECs), Escherichia coli (E. coli) and total bacterial diversity from wastewater effluent. Six experiments were conducted with control quartz sand and sand columns containing BC, Ag-BC, ZVI, BC with ZVI, or Ag-BC with ZVI. After filtration, Ag-BC, ZVI, BC with ZVI and Ag-BC with ZVI demonstrated more than 90% (> 1 log) removal of E. coli from wastewater samples, while BC, Ag-BC, BC with ZVI and Ag-BC with ZVI also demonstrated efficient removal of tested CECs. Lower bacterial diversity was also observed after filtration; however, differences were marginally significant. In addition, significantly (p < 0.05) higher bacterial diversity was observed in wastewater samples collected during warmer versus colder months. Leaching of silver ions occurred from Ag-BC columns; however, this was prevented through the addition of ZVI. In conclusion, our data suggest that the BC with ZVI and Ag-BC with ZVI sand filters, which demonstrated more than 99% removal of both CECs and E. coli without silver ion release, may be effective, low-cost options for decentralized treatment of reused wastewater. Graphical
PubDate: 2023-07-19
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- Biochar addition to tea garden soils: effects on tea fluoride uptake and
accumulation-
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Abstract: Long-term consumption of tea with high fluoride (F) content has a potential threat to human health. The application of different amounts of biochar to reduce F accumulation in tea leaves has been little studied. In this study, a pot experiment was conducted to investigate the effect of biochar amounts (0, 0.5%, 2.5%, 5.0%, 8.0%, and 10.0%, w/w) on tea F content during the tea plant growth. Changes in tea quality, soil F fraction, and soil properties caused by biochar and the relationship with tea F accumulation were also considered. The results showed that the application of biochar amendment significantly reduced water-soluble F contents in tea leaves compared to CK (without biochar), especially in the 8.0% treatment (72.55%). Overall, biochar contributed to improving tea polyphenols and caffeine, but had no significant impact on free amino acids and water leachate. Compared with CK, 5.0–10.0% biochar significantly increased soil water-soluble F content due to the substitution of F− with OH− under high pH. Additionally, biochar applied to tea garden soil was effective in decreasing the soil exchangeable aluminum (Ex-Al) content (46.37–91.90%) and increasing the soil exchangeable calcium (Ca2+) content (12.02–129.74%) compared to CK, and correlation analysis showed that this may help reduce F enrichment of tea leaves. In general, the application of 5.0–8.0% biochar can be suggested as an optimal application dose to decrease tea F contents while simultaneously improving tea quality. Graphical
PubDate: 2023-07-15
DOI: 10.1007/s42773-023-00220-2
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- Topological defects strengthened nonradical oxidation performance of
biochar catalyzed peroxydisulfate system-
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Abstract: Nonradical oxidation based on peroxydisulfate (PDS) activation has attracted increasing attention for selective degradation of organic pollutants. Herein, topological defects were introduced into biochar (BC) via removing N atoms in N-doped BC (NBC) in an attempt to improve the nonradical catalytic performance. Compared to the pristine BC and NBC, the introduction of topological defects could achieve up to 36.6- and 8.7-times catalytic activity enhancement, respectively. More importantly, it was found that the catalytic activity was dominated by topological defects, which was verified by the significant positive correlation between the pseudo-first-order rate constants and the content of topological defects. Theoretical calculations suggested that topological defects enhanced the electron-donating ability of BC by reducing the energy gap, which made the electrons transfer to PDS molecules more easily. As a result, holes were generated after the carbon defects lost electrons, and induced a nonradical oxidation process. Benefiting from the merits of nonradical oxidation, the developed BC/PDS system showed superior performance in removing electron-rich contaminants in the presence of inorganic anions and in the actual environments. This study not only provides a potential avenue for designing efficient biochar-based catalysts, but also advances the mechanism understanding of nonradical oxidation process induced by carbon defects. Graphical
PubDate: 2023-07-12
DOI: 10.1007/s42773-023-00243-9
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- Biochar filler in MEX and VPP additive manufacturing: characterization and
reinforcement effects in polylactic acid and standard grade resin matrices
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Abstract: The development of sustainable and functional biocomposites remains a robust research and industrial claim. Herein, the efficiency of using eco-friendly biochar as reinforcement in Additive Manufacturing (AM) was investigated. Two AM technologies were applied, i.e., vat photopolymerization (VPP) and material extrusion (MEX). A standard-grade resin in VPP and the also eco-friendly biodegradable Polylactic Acid (PLA) in the MEX process were selected as polymeric matrices. Biochar was prepared in the study from olive trees. Composites were developed for both 3D printing processes at different biochar loadings. Samples were 3D-printed and mechanically tested after international test standards. Thermogravimetric Analysis and Raman revealed the thermal and structural characteristics of the composites. Morphological and fractographic features were derived, among others, with Scanning Electron Microscopy (SEM) and Atomic Force Microscopy (AFM). Biochar was proven to be sufficient reinforcement agent, especially in the filament MEX process, reaching more than 20% improvement at 4 wt.% loading in tensile strength compared to the pure PLA control samples. In the VPP process, results were not as satisfactory, still, a 5% improvement was achieved in the flexural strength with 0.5 wt.% biochar loading. The findings prove the strong potential of biochar-based composites in AM applications, too. Graphical
PubDate: 2023-07-04
DOI: 10.1007/s42773-023-00238-6
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