|
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  [2467 journals]
|
- Adsorption of methane on biochar for emission reduction in oil and gas
fields-
Free pre-print version: Loading...
Abstract: To contribute to the reduction of methane emissions, using low-cost biochar as adsorbents for capturing and storing methane in oil and gas fields is investigated. This work presents results of methane adsorption on four biochars made from forestry wastes in comparison with the results of three commercial activated carbons. Although the adsorption capacity of the biochars is lower by over 50% than that of the activated carbons, thelow-cost and potential environmental benefits provide the incentive to the investigation. Moreover, it is shown that biochar can store more methane than vessels of compressed gas up to the pressure of 75 bar, suggesting the possibility of avoiding high-pressure gas compression and heavy vessels for cost savings in oil and gas fields. The thermodynamic and kinetic behaviors of the adsorption are studied and implications for the targeted application are discussed. Graphical
PubDate: 2023-03-20
-
- Tri-functional lanthanum-based biochar for efficient phosphorus recovery,
bacterial inhibition, and soil fertility enhancement-
Free pre-print version: Loading...
Abstract: Excess phosphorus (P) in water can lead to eutrophication and upset ecological balance. In this study, biochar with ultrathin two-dimensional nanosheets from the natural mesocarp of shaddock was chosen as the carrier. The highly dispersed and small particle size of La(OH)3 on the surface of the nanosheets (MSBL3) was successfully achieved using chemical impregnation for the adsorption of P in aqueous solution, and the maximum adsorption capacity was 260.0 mg P g−1 [La]. The differences in surface crystallization of La(OH)3 on biochar at different La loadings were analyzed using the high-precision characterization methods. After six adsorption–desorption cycles, MSBL3 retained 76.7% of its initial performance in terms of the P adsorption capacity. The preparation of 1 g of MSBL3 costs about RMB 1, and it could reduce the P concentration in 2.6 ton of Laoyu River water to below the eutrophication threshold; and the inhibitory effect of MSBL3 on the eutrophication of water bodies was confirmed by the growth state of water hyacinth. Furthermore, 0.1 M MSBL3 could inhibit Escherichia coli and Staphylococcus aureus up to 98.7% and 85.0%, respectively, which indicates that MSBL3 can be used to recover P from water and also to improve water quality. In addition, the growth of the maize seedlings verified that the P-absorbed MSBL3 waste is a good soil fertilizer and can solve the problem of post-treatment of the adsorbent. In conclusion, MSBL3 prepared in this study is a promising P sorbent for application. Graphical
PubDate: 2023-03-20
-
- Insights into the mechanisms underlying the biodegradation of phenanthrene
in biochar-amended soil: from bioavailability to soil microbial
communities-
Free pre-print version: Loading...
Abstract: The dynamic effect of biochar amendment in contaminated soil on the bioavailability of polycyclic aromatic hydrocarbons (PAHs) and microbial communities and how it comprehensively affects PAH biodegradation remain unclear. This study investigated the effects of wheat straw-derived biochars obtained at 300 and 500 °C at different amendment levels (0.03% and 0.3%) on the mineralization kinetics of phenanthrene with different initial concentrations (2 and 20 mg kg−1) in soil by indigenous microorganisms. The results revealed that the addition of biochar inhibited both the rates and extents of mineralization in low-concentration phenanthrene-contaminated soil (PLS) by 38.9–78.3% and 23.9–53.6%, respectively. This was because biochar amendment in the PLS greatly reduced the bioavailable fraction of phenanthrene for degradation owing to its strong sorption and also decreased that to specific degrading bacterial genera, which hindered their growth and reduced their abundances by 1.37–36.6%. However, biochar addition into the soil contaminated with high concentrations of phenanthrene (PHS) resulted in its effective mineralization and enhanced mineralization rates and extents at high amendment levels by 32.4–86.7% and 32.0–44.7%, respectively. This was because biochar amendment in the PHS significantly promoted the abundances of the total bacterial communities (29.9–80.4%) and potential degrading genera (1.89–25.9%) by providing nutrients and stimulated the specific PAH-degradative nidA gene abundance by 1–2 times. These findings will guide the use of biochar to remediate soils with different PAH pollution levels based on the two roles that they play (i.e., immobilizing PAHs or facilitating PAH degradation). Graphical
PubDate: 2023-03-17
-
- Regulated adsorption sites using atomically single cluster over biochar
for efficient elemental mercury uptake-
Free pre-print version: Loading...
Abstract: Carbon-based materials have been widely used in gaseous pollutant removal because of their sufficient surface functional groups; however, its removal efficiency for elemental mercury (Hg0) is low. In this study, we fabricated biomass using a chelated coupled pyrolysis strategy and further constructed the regulated adsorption sites for gaseous Hg0 uptake. A series of Mnδ-N2O2/BC with different manganese cluster sizes demonstrated that manganese clusters anchored on biochar acted as highly active and durable adsorbents for Hg0 immobilization, which increased the adsorption efficiency of Hg0 by up to 50%. Shrimp- and crab-based biochar adsorbents exhibited excellent Hg0 removal because of their chitosan-like structure. In particular, small Mn clusters and oxygen species around the defect led to a boost in the Hg0 adsorption by carbon. The results of density functional theory calculation revealed that the presence of oxygen in the carbon skeleton can tune the electrons of small-sized Mn clusters, thereby promoting the affinity of mercury atoms. The newly developed Mnδ-N2O2/BCshrimp had an adsorption capacity of 7.98–11.52 mg g−1 over a broad temperature range (50–200 °C) and showed a high tolerance to different industrial flue gases (H2O, NO, HCl, and SO2). These results provide novel green and low-carbon disposal methods for biomass resource utilization and industrial Hg0 emission control. Graphical
PubDate: 2023-03-14
-
- A bibliographic study reviewing the last decade of hydrochar in
environmental application: history, status quo, and trending research
paths-
Free pre-print version: Loading...
Abstract: Hydrothermal carbonization (HTC) technology has increasingly been considered for biomass conversion applications because of its economic and environmental advantages. As an HTC conversion product, hydrochar has been widely used in the agricultural and environmental fields for decades. A CiteSpace-based system analysis was used for conducting a bibliometric study to understand the state of hydrochar environmental application research from 2011 to 2021. Researchers had a basic understanding of hydrochar between 2011 and 2016 when they discovered hydrochar could apply to agricultural and environmental improvement projects. Keyword clustering results of the literature published in 2017–2021 showed that soil quality and plant growth were the major research topics, followed by carbon capture and greenhouse gas emissions, organic pollutant removal, and heavy metal adsorption and its bioavailability. This review also pointed out the challenge and perspective for hydrochar research and application, namely: (1) the environmental effects of hydrochar on soils need to be clarified in terms of the scope and conditions; (2) the influence of soil microorganisms needs to be investigated to illustrate the impact of hydrochar on greenhouse gas emissions; (3) combined heavy metal and organic contaminant sorption experiments for hydrochar need to be conducted for large-scale applications; (4) more research needs to be conducted to reveal the economic benefits of hydrochar and the coupling of hydrochar with anaerobic digestion technology. This review suggested that it would be valuable to create a database that contains detailed information on how hydrochar got from different sources, and different preparation conditions can be applied in the environmental field. Graphical
PubDate: 2023-03-13
-
- Multifaceted applications of biochar in environmental management: a
bibliometric profile-
Free pre-print version: Loading...
Abstract: Biochar is a carbon-containing material prepared through thermal treatment of biomass in limited supply of oxygen, and used for an array of applications including waste management, climate change mitigation, soil fertility improvement, bio-energy production, and contaminant remediation. The data related to biochar, its production, and the wide applicability were collected using Web of Science Core Collection Database (on 25/10/2022), while bibliometric network analysis was performed using VOSviewer software to analyse year-wise, author-wise, country-wise, and journal-wise publication trends, construct keyword co-occurrence maps, and identify research areas receiving greater focus. Further, the applications of biochar were reviewed and mechanistic insights were provided. Some of the findings include: > 50% of documents (> 13,000) getting published in the past 3 years, > 90% of documents (> 21,000) being research articles, ~ 50% of publications (> 10,000) being related to environmental sciences, pyrolysis being the most widely used (~ 40% articles) production technique (followed by carbonization, gasification, combustion, and torrefaction), China being the most active country in terms of publications (> 11,000), and biochar being mostly used for removing contaminants (followed by soil improvement, waste management, energy production, and climate change mitigation). Various strengths, weaknesses, opportunities, and threats (SWOT analysis) of biochar production and wide-ranging applicability were identified. Lastly, gaps were identified including the need for performing elaborate life cycle assessments, exploring machine learning and artificial intelligence for upgrading conversion technology and producing application-specific biochar, and investigating mechanistic aspects of soil-biochar interactions and nano-scale transformation of biochar. The study covers a broad spectrum of biochar applicability to identify areas receiving lesser attention, which could guide the future researchers for augmenting biochar research. Graphical
PubDate: 2023-03-13
-
- Experimental and numerical investigations of biochar-facilitated Cd2+
transport in saturated porous media: role of solution pH and ionic
strength-
Free pre-print version: Loading...
Abstract: The nanoscale biochar (N-BC) generated during the production and weathering of bulk biochar has caused significant concerns for its cotransport with contaminants spreading the contamination. In this study, the cotransport behaviors of N-BC with Cd2+ under variable solution chemistry were investigated for the first time, which can pose environmental contamination risks but have received little attention. The column experiment results showed that increasing ionic strength (IS) or decreasing pH retarded the transport of N-BC but promoted the transport of Cd2+ in their individual transport. In cotransport scenarios, Cd2+ facilitated the deposition of N-BC on the quartz sand with increasing IS or decreasing pH by providing additional sorption sites and led to the ripening of N-BC via cation bridging. N-BC retarded the transport of Cd2+ under all conditions. However, lower pH and higher IS could facilitate the release of Cd2+ from the immobile N-BC. The cotransport modeling results demonstrated that the Cd2+ adsorption on and desorption from the immobile N-BC controlled the retention and release of Cd2+ under variable pH and IS, while the influence of mobile N-BC on Cd2+ transport was minor. This study provided new insight for evaluating the potential contamination-spreading risks and suggested that rational use of biochar with great caution is necessary. Graphical
PubDate: 2023-03-06
-
- Biochar-derived dissolved organic matters influencing bacterium
characteristics during biodegradation of sulfamethoxazole and
chloramphenicol under alternation of visible and avoiding light-
Free pre-print version: Loading...
Abstract: The influence of biochar-released dissolved organic matter (BDOM) on the transcription of gene (DEG) in Pseudomonas stutzeri and Shewanella putrefacien during sulfamethoxazole (SMX) and chloramphenicol (CAP) biodegradation under visible light was investigated in this study. The results indicated that BDOM components would be nutrients for bacterial amplification and growth under the culture conditions of xenon lamp irradiation and avoiding light, especially BDOM from low temperatures. Additionally, visible light irradiation would improve the saturated fatty acid by stimulating the cell membrane of the microorganism, thus promoting the biodegradation of antibiotics through altering P. stutzeri and S. putrefaciens reoxidative and catabolism processes and significantly inhabiting the copy number of their genes. Moreover, the upregulated genes and enzymes related to SMX and CAP-metabolic and catabolic processes were enriched, which were involved in the pathways of biodegradation, further improving biodegradation efficiency. In particular, interaction network analysis between the top 100 dominant functional genes from P. stutzeri and S. putrefaciens and the molecular types of BDOM, e.g., CHO, CHON, and CHOS (p < 0.05), indicated that the genes of molecular function showed a high positive or negative correlation with the CHO type of BDOM. The results revealed that the CHO type of BDOM affected the functional genes of molecular function, cellular component, and biological process from P. stutzeri and S. putrefaciens, influencing the biodegradation of SMX and CAP. This study provided an basis for BDOM playing a role in antibiotic removal from the aqueous solution using biochar combined with photobiodegradation. Graphical
PubDate: 2023-02-21
-
- A novel strategy for a reinforced anammox process with iron-modified
Enteromorpha prolifera biochar-
Free pre-print version: Loading...
Abstract: Modified biochar with higher electron transport and adsorption capabilities could significantly improve the performance of anaerobic ammonia oxidation (anammox). However, there are few related investigations on the reinforcement of anammox through iron-modified Enteromorpha prolifera biochar (IMEPB). In this study, with the addition of the IMEPB in the anammox system, the enhancing process of anammox performance was studied, the improving feasibility of anammox was evaluated, and the reinforcing mechanism of anammox was elucidated. The results showed that the optimal iron−charcoal ratio (Fe:C) and IMEPB dosage were 1:10 and 10 g L−1, respectively. Under the optimal conditions, when the nitrogen loading rate gradually increased to 0.557 (kg m−3 day−1), the nitrogen removal efficiency and nitrogen removal rate of the anammox process supplemented with IMEPB increased by 11%, and the specific anammox activity increased by 23.8%. Compared with the control, the secretion of extracellular polymeric substances (EPS) of anammox bacteria supplemented IMEPB increased by 24.4%, greatly improving the stability of the anammox system. Meanwhile, EPS secretion further promoted the microbial activity of anammox bacteria, achieving a 19% increase in the abundance of Candidatus Brocadia. These findings demonstrate the potential mechanism of IMEPB in improving anammox, provide new insights into recycling E. prolifera, and provide a novel reinforcement strategy for anammox. In the future, adding IMEPB may be a vital measure for the practical application of anammox in coastal areas. Graphical
PubDate: 2023-02-15
-
- Synthesis of biochar/clay mineral nanocomposites using oil shale semi-coke
waste for removal of organic pollutants-
Free pre-print version: Loading...
Abstract: Due to the poor surface/interfacial interaction and the large gaps in the size and microstructure between biomass and clay mineral, it was difficult to adjust the structure and performance of biochar/clay mineral composites at the molecular level. Herein, oil shale semi-coke composed of multi-minerals and organic matters was used as a promising precursor to prepare biochar/clay mineral nanocomposites via phosphoric acid-assisted hydrothermal treatment followed by KOH activation for removal of organic pollutants from aqueous solution. The results revealed that the nanocomposites presented well-defined sheet-like morphology, and the carbon species uniformly anchored on the surface of clay minerals. With the changes in the pore structure, surface charge and functional groups after two-step modification, the nanocomposites exhibited much better adsorption property toward organic pollutants than the raw oil shale semi-coke, and the maximum adsorption capacities of methylene blue, methyl violet, tetracycline, and malachite green were 165.30 mg g−1, 159.02 mg g−1, 145.89 mg g−1, and 2137.36 mg g−1, respectively. The adsorption mechanisms involved electrostatic attraction, π–π stacking and hydrogen bonds. After five consecutive adsorption–desorption, there was no obvious decrease in the adsorption capacity of malachite green, exhibiting good cyclic regeneration performance. It is expected to provide a feasible strategy for the preparation of biochar/clay mineral nanocomposites with the excellent adsorption performances for removal of organic pollutants based on full-component resource utilization of oil shale semi-coke. Graphical
PubDate: 2023-02-09
-
- Bibliometric analysis of biochar research in 2021: a critical review for
development, hotspots and trend directions-
Free pre-print version: Loading...
Abstract: As a bioproduct from the thermal decomposition of biomass, biochar has various applications in diversified field. In this study, a bibliometric analysis was conducted to visualize the current research status and trends of biochar research. A total of 5535 documents were collected from the Web of Science Core Collection and subjected to visualization analysis for the biochar field's development in 2021 with CiteSpace software. The visual analysis results demonstrate that the number of publications expanded dramatically in 2021, and the growth trend would continue. China and USA were the most contributing countries in biochar research in terms of the number of publications. Based on the keyword co-occurrence analyses, “Biochar for toxic metal immobilization”, “Biochar-based catalyst for biofuel production”, “Biochar for global climate change mitigation”, “Biochar for salinity and drought stress amelioration”, “Biochar amendment in composting”, and “Biochar as additives in anaerobic digestion” were the main research trends and hotspots in this field in 2021. This indicates that the biochar research was multidisciplinary. Regarding the research hotspots, the employment of biochar as heterogeneous catalysts for biofuel production gained great attention in 2021. On the contrary, bioremediation using functional bacteria immobilized on biochar and biochar-assisted advanced oxidation process were well-studied but with less frequency than other topics in 2021. Furthermore, the future research was proposed for green and sustainable applications of biochar. This review provides a comprehensive overview of the research frontiers, the evolution of research hotspots, and potential future research directions in the biochar field. Graphical
PubDate: 2023-01-18
-
- Synthesis, characterization, safety design, and application of NPs@BC for
contaminated soil remediation and sustainable agriculture-
Free pre-print version: Loading...
Abstract: Biochar (BC) and nanoparticle-decorated biochar (NPs@BC) have emerged as potential high-performance function materials to facilitate simultaneous soil remediation and agricultural production. Therefore, there is an urgent need to incorporate environmental sustainability and human health targets into BC and NPs@BC selection and design processes. In contrast to extensive research on the preparation, modification, and environmental application of BC to soil ecosystems, reports about the adapted framework and material selection strategy of NPs@BC under environmental and human health considerations are still limited. Nevertheless, few studies systematically explored the impact of NPs@BC on soil ecosystems, including soil biota, geochemical properties, and nutrient cycles, which are critical for large-scale utilization as a multifunctional product. The main objective of this systematic literature review is to show the high degrees of contaminant removal for different heavy metals and organic pollutants, and to quantify the economic, environmental, and toxicological outcomes of NPs@BC in the context of sustainable agriculture. To address this need, in this review, we summarized synthesis techniques and characterization, and highlighted a linkage between the evolution of NPs@BC properties with the framework for sustainable NPs@BC selection and design based on environmental effects, hazards, and economic considerations. Then, research advances in contaminant remediation for heavy metals and organic pollutants of NPs@BC are minutely discussed. Eventually, NPs@BC positively acts on sustainable agriculture, which is declared. In the meantime, evaluating from the perspective of plant growth, soil characterizations as well as carbon and nitrogen cycle was conducted, which is critical for comprehending the NPs@BC environmental sustainability. Our work may develop a potential framework that can inform decision-making for the use of NPs@BC to facilitate promising environmental applications and prevent unintended consequences, and is expected to guide and boost the development of highly efficient NPs@BC for sustainable agriculture and environmental applications. Graphical
PubDate: 2023-01-18
-
- Optimizing biochar addition for vermicomposting: a comprehensive
evaluation of earthworms’ activity, N2O emissions and compost quality-
Free pre-print version: Loading...
Abstract: Biochar addition has been widely used in the field to mitigate soil nitrous oxide (N2O) emissions, and can be considered as a potential method to reduce N2O emissions during vermicomposting. However, excessive biochar addition may inhibit earthworms’ activity. Thus, it is crucial to clarify the optimum addition volumes of biochar during vermicomposting. This study evaluated the impact of addition of various amounts of biochar (0, 5, 10, 15, 20 and 25% of total amount of feedstock) on earthworms’ (Eisenia fetida) activity, N2O emission and compost quality during vermicomposting. Compared with the treatment without biochar added, 5% of biochar application significantly increased earthworm total biomass (from 177.5 to 202.2 g pot−1), and cumulative burrowing activity (from 47.0% to 52.2% pixel per terrarium). The increased earthworms activity stimulated the vermicomposting process and led to the best quality of compost, which showed the highest total nutrient content (5.38%) and a significantly higher germination percentage of seeds (88%). Although N2O emissions were slightly increased by 5% biochar addition, a non-significant difference was found between the treatment with 5% biochar and the treatment without biochar added. On the contrary, 20% and 25% biochar addition not only lowered N2O emissions, but also significantly decreased the quality of compost. The results suggest that 5% biochar application is an appropriate amount to improve the quality of compost without significant N2O emissions. Graphical
PubDate: 2023-01-17
-
- Effects of biochar carried microbial agent on compost quality, greenhouse
gas emission and bacterial community during sheep manure composting-
Free pre-print version: Loading...
Abstract: Although composting is a very effective way to dispose agricultural wastes, its development is greatly limited by the low compost quality and greenhouse gas emissions. At present, there is a lack of effective means to solve these two problems simultaneously. Here, the effects of three additives of compound microbial agent, biochar and biochar carried microbial agent on the composting performance, nitrogen transformation, greenhouse gas and ammonia emissions, and bacterial communities were investigated in sheep manure composting during 28 days. Results showed that biochar carried microbial agent prolonged the thermophilic stage and promoted compost maturity. At the same time, it was confirmed by the increase of the decomposition of organic nitrogen and the transformation of NH4+-N to NO3−-N. Besides, adding biochar carried microbial agent decreased CH4, NH3 and N2O emissions by 65.23%, 42.05% and 68.64%, respectively. The gas emissions were mainly correlated to Chloroflexi, Myxococcota, Acidobacteriota, Firmicutes, and Gemmatimonadota. Redundancy analysis showed that EC and TKN were closely related to bacterial community. Therefore, biochar carried microbial agent is recommended as an effective additive to enhance compost quality and reduce gas emissions during sheep manure composting. Graphical
PubDate: 2023-01-16
-
- Nanobiochar for the remediation of contaminated soil and water: challenges
and opportunities-
Free pre-print version: Loading...
Abstract: Although research on biochar has received increasing attention for environmental and agricultural applications, the significance of nanobiochar for environmental pollutant remediation is poorly understood. In contrast to bulk biochar, nanobiochar has superior physicochemical properties such as high catalytic activity, unique nanostructure, large specific surface area and high mobility in the soil environment. These unique characteristics make nanobiochar an ideal candidate for pollution remediation. Thus far, the research on nanobiochar is still in its infancy and most of the previous studies have only been conducted for exploring its properties and environmental functions. The lack of in-depth summary of nanobiochar’s research direction makes it a challenge for scientists and researchers globally. Hence in this review, we established some key fabrication methods for nanobiochar with a focus on its performance for the removal of pollutants from the environment. We also provided up-to-date information on nanobiochar’s role in environmental remediation and insights into different mechanisms involved in the pollutant removal. Although, nanobiochar application is increasing, the associated drawbacks to the soil ecosystem have not received enough research attention. Therefore, further research is warranted to evaluate the potential environmental risks of nanobiochar before large scale application. Graphical
PubDate: 2023-01-13
-
- Synergy effect between tetracycline and Cr(VI) on combined pollution
systems driving biochar-templated Fe3O4@SiO2/TiO2/g-C3N4 composites for
enhanced removal of pollutants-
Free pre-print version: Loading...
Abstract: Biochar-coupled Fe3O4@SiO2/TiO2/g-C3N4 composites were successfully constructed through simple sol–gel and calcination methods. The composites efficiently removed high-concentration toxic tetracycline (TC) by means of ·OH and · \({\rm O}_2^{-}\) , whose removal rate exhibited 91.88% during 3 h, and the degradation rate constant reached up to 0.0068 min−1. The excellent performance can be attributed to the high specific surface area, enhanced visible light response, the introduction of magnetic nanoparticles and biochars expediting charge transfer, Z-scheme heterojunction enhancing the spatial separation of photo-generate carriers and, importantly extraordinary adsorption capacity of 147.96 mg g−1. Moreover, the composites showed the most excellent efficiency under the calcination temperature of 450 ℃, and exhibited good stability with tolerance to a wide range of pH and anions. Interestingly, a synergistic photocatalytic effect was discovered in the TC/Cr(VI) combined pollution systems, resulting in significantly improved removal of Cr(VI). Besides, the photocatalytic mechanism and degradation path of tetracycline were also elucidated. All these findings suggested the as-synthesized catalyst was an excellent photocatalyst for removal of TC/Cr(VI)-contaminated water. Graphical
PubDate: 2023-01-03
DOI: 10.1007/s42773-022-00197-4
-
- Biochar–microbe interaction: more protist research is needed
-
Free pre-print version: Loading...
Abstract: Biochar applications have an enormous impact on the soil microbial community and functionality. However, the majority of the knowledge on biochar–microbe interaction derives almost exclusively from bacterial and fungal studies, while the vast majority of eukaryotic diversity, protists, are mostly neglected. Protists play important roles in the soil ecosystem as microbial predators, decomposers, photoautotrophs, pathogens, and parasites and they are essential for a healthy soil ecosystem. Toward a comprehensive understanding of the effects of biochar application, we need more studies on protists across the full breadth of eukaryotic diversity. The aim of this article is to highlight the research needs and discuss potential research ideas on biochar–protist interaction, which would advance our knowledge of biochar–microbe interaction. Highlights Biochar–microbe interaction is almost exclusively studied for bacteria and fungi. Only a few studies are available on how soil protists react to biochar application. More research on biochar–protist is needed for a better understanding of biochar–microbe interaction.
PubDate: 2022-12-30
DOI: 10.1007/s42773-022-00195-6
-
- Pyrolytic synthesis of graphene-encapsulated zero-valent iron
nanoparticles supported on biochar for heavy metal removal-
Free pre-print version: Loading...
Abstract: Biochar (BC)-supported graphene-encapsulated zero-valent iron nanoparticle composites (BC-G@Fe0) are promising engineering nanocomposites that can be used to scavenge heavy metal from wastewater. However, the production of BC-G@Fe0 through carbothermal reduction using biomass as a carbon source remains challenging because of biomass pyrolysis complications. Here, we examined two carbothermal reduction routes for preparing BC-G@Fe0 using bamboo as the carbon source. The first route impregnated Fe ions (Fe2+/3+) into unpyrolyzed bamboo particles initially, followed by carbonization at 600–1000 °C. This process produced BC-G@Fe0 dominated by iron carbide (Fe3C), which led to low heavy metal removal efficiency (i.e., Cu2+ capacity of < 0.3 mmol g−1). In the second route, bamboo particles were pyrolyzed (600 °C) to biochar first, followed by impregnating this biochar with Fe ions, and then carbonized at 600–1000 °C. This route produces zero-valent iron nanoparticles, which resulted in high heavy metal removal capacities (i.e., 0.30, 1.58, and 1.91 mmol g−1 for Pb2+, Cu2+, and Ag+, respectively). The effects of carbonization temperature (600–1000 °C), iron source (i.e., iron nitrates, iron sulfate, ferrous chloride, and ferric chloride), and iron loading (5–40%) on the morphology, structure, and heavy metal ion aqueous uptake performance of BC-G@Fe0 were also investigated. This study revealed the formation mechanisms of BC-G@Fe0 through biomass carbothermal reduction, which could guide the application-oriented design of multifunctional iron-BC composites for water remediation. Graphical
PubDate: 2022-12-28
DOI: 10.1007/s42773-022-00196-5
-
- The influencing mechanism of O2, H2O, and CO2 on the H2S removal of food
waste digestate-derived biochar with abundant minerals-
Free pre-print version: Loading...
Abstract: Hydrogen sulfide (H2S) removal has been a significant concern in various industries. In this study, food waste digestate-derived biochar (DFW-BC), a by-product of food waste treatment with abundant minerals, was assessed for removing H2S from different simulated biogas containing oxygen (O2) and carbon dioxide (CO2) and under different moisture (H2O) contents (0% and 20%) of biochar. The influencing mechanisms of the gas conditions combined with the moisture contents were also investigated. The results showed an H2S removal of 1.75 mg g−1 for dry biochar under pure H2S, 4.29 mg g−1 for dry biochar under H2S + O2, 5.29 mg g−1 for humid biochar under H2S, and 12.50 mg g−1 for humid biochar under H2S + O2. For dry DFW-BC, the high Fe content was responsible for the O2 enhancement. In contrast, O2 + H2O activated the catalytic H2S oxidation of the less reactive minerals (mainly Ca). The inhibition of CO2 on H2S adsorption was not obvious for dry DFW-BC; the specific pore structure may have provided a buffer against the physisorption competition of CO2. However, when H2O was present on DFW-BC, the changes in critical biochar properties and sulfur speciation as opposed to that without H2O implied an evident occurrence of CO2 chemisorption. This CO2 chemisorption partially hindered O2 + H2O enhancement, decreasing the H2S removal capacity from 12.50 to 8.88 mg g−1. The negative effect was ascribed to mineral carbonation of CO2, neutralizing the alkaline surface and immobilizing metal oxides, which thus reduced the acceleration in H2S dissociation and activation in catalytic H2S oxidation by O2 + H2O. Graphical
PubDate: 2022-12-28
DOI: 10.1007/s42773-022-00199-2
-
- Simultaneous dissipation of trichloroethene and arsenic from
co-contaminated groundwater by coupling biodechlorination and
biodetoxification with assistance of biochar-
Free pre-print version: Loading...
Abstract: Co-contamination of groundwater with trichloroethene (TCE) and arsenic (As) is a widespread problem in industrial sites. The simultaneous biological removal of As and TCE has not yet been developed. This study incorporated biochar into anaerobic dechlorination system to achieve a greatly accelerated dissipation and co-removal of TCE and As. Biochar eliminated microbial lag (6 days) and achieved a 100% TCE removal within 12 days even at a relatively high initial concentration (TCE: 30 mg L−1; As(V): 4 mg L−1), while without biochar, only 75% TCE was removed until day 18. Biochar adsorbed TCE and the intermediate products allowing them to be degraded on its surface gradually, maintaining a high metabolic activity of microbes. Biochar facilitated the preferential colonization of its surfaces by dechlorinating microorganisms (Clostridium and Dehalococcoides) and suppressed hydrogen-competing microorganisms (Desulfovibrio) in water. Biochar itself cannot adsorb As, however, separation of biochar carrying the As-laden microorganisms achieved 50–70% As-removal from groundwater. The biochar-amended incubations were found to be enriched with microbes possessing more crucial As-transforming genes (K00537-arsC and K07755-AS3MT), and upregulated amino acid metabolism, thus enhancing the self-detoxification ability of microorganisms to transform As(V) to As(III) or volatile organic As. This study proposes a strategy of regulating microbes’ metabolic activity by biochar to achieve simultaneous removal of coexisting contaminations, which is an important step prior to examining the feasibility of biochar application for enhanced bioremediation. Graphical
PubDate: 2022-12-22
DOI: 10.1007/s42773-022-00193-8
-
