Pyrogenic Carbon Research Articles

Does micro-sized pyrogenic carbon made in lab affect earthworm mortality in restrained water content?

Micro-sized pyrogenic carbon (PyC) is expected to interact more efficiently with soil biota such as earthworms than coarse pyrogenic carbon. Little is known about whether the micro-sized PyC poses a threat to earthworms. We investigated the effects of hydrophilic micro-sized PyC on earthworm mortality in two contrasting soil substrates from young and old reclaimed soils of a successional chronosequence. These two soil substrates had different hydraulic properties, total organic carbon, pH, and nutrient status. Lower earthworm survival rates were observed in both soil substrates receiving dry micro-sized soil particles and the micro-sized PyC. Specifically, the addition of micro-sized PyC resulted in the lowest survival rate compared to the addition of micro-sized soil particles and the control from day 8 to 11. The decreased earthworm survival rate due to micro-sized PyC was more pronounced in the old soil substrate than in the young substrate. Fully moistened soil substrates containing micro-sized PyC or dry micro-sized soil substrate particles did not result in decreased earthworm survival. Micro-sized PyC turned from hydrophilic to hydrophobic when mixed with rhamnolipids, possibly hindering the uptake of dissolved oxygen by earthworm skins. Our results thus provide a new explanation for the negative effects of micro-sized PyC on earthworms and demonstrate the importance of assessing the hydraulic properties of both the micro-sized PyC and soil prior to PyC's application to soils.

Pyrogenic carbon facilitated microbial extracellular electron transfer in electrogenic granular sludge via geobattery mechanism

Electroactive pyrogenic carbon (PC) is an intriguing candidate for realizing the ambitious goals of large-scale applications of microbial electrochemical technologies (METs). In this study, PC was employed to promote the extracellular electron transfer (EET) within the electrogenic granular sludge (EGS) by acting as an electron conduit. The pecan shell-derived PC prepared at three temperatures (600, 800, and 1000 ˚C) contained rich oxygenated-functional moieties (mainly quinone) on the surface, endowing a good electron transfer capacity (EEC). The maximum current density (Jmax) of EGS with PC amendment outperformed the control EGS without PC amendment, i.e., 100-132 times higher than Jamx of EGS in the absence of PC. Among various pyrolysis temperatures, the PC derived from 600 ˚C produced the highest Jmax (0.40 A/ m2), 0.67-times, and 0.33-times higher than that of PC derived from 800 and 1000 ˚C, respectively. Furthermore, more polysaccharides were secreted in extracellular polymeric substance with PC amendments. The microbial community analysis demonstrated that the PC favored the growth of electroactive bacteria over methanogens. The metabolic pathway revealed that PC induced more functional enzymes in the quinone biosynthesis and cytochrome c and heme synthesis, resulting in an enhanced EET. The EEC of PC was responsible for the EET enhancement effect via PC acting as a geobattery to wire up the EGS and electrodes. Overall, this study pinpoints the finding of PC role in a mixed electroactive biofilm and provides a wide scenario of the PC applications in MET at large scales.

Biochar‐based land development

AbstractBiochar or pyrogenic carbon, obtained from the thermo‐chemical conversion of biomass in an anaerobic or oxygen‐limited environment, has been in use in agriculture perhaps as far back as the Neolithic. Its unique soil‐ameliorating properties render it suitable for environmental remediation as well as sustainable crop production. It improves soil physicochemical properties and plant nutrient availability, reduces toxic chemical load, facilitates biodiversity, and reduces the emission of greenhouse gases thereby subsiding global warming. The application of biochar can reduce soil erosion, improve soil hydrological properties, and help soil microbial dynamics. It has synergistic effects on plant growth, disease‐pest resistance, and crop yield per unit area and time. Due to its soil‐ameliorative effects and soil and water‐conserving ability, it can be used beneficially in organic farming, permaculture, dryland farming, conservation agriculture, and land remediation. Cheaper production cost, simple, and easy pyrolytic technologies, easy availability of feedstock and bio‐wastes in many developing countries, and its long‐term effects on soil not only build up the soil carbon pool but also help support small and marginal farmers in resource‐rich but economically deprived countries for sustainable agriculture and land development. In this review, efforts have been made to elucidate various uses of biochar, its characteristics and applications effects on soil systems, land development, and sustainable agricultural production toward achieving United Nations Sustainable Development Goals (UN‐SDGs).

Aggregation kinetics of biochar nanoparticles in aqueous environment: Interplays of anion type and bovine serum albumin

The colloidal particles, especially those at the nanoscale, are the most active part of the pyrogenic carbon (biochar). Increasingly applied biochar has resulted in a large number of biochar nanoparticles (NPs) being released into the environment. The aggregation of biochar NPs affects their environmental behavior and fate. The complex effects of anion type (Cl−, SO42−) and protein (bovine serum albumin, BSA) on the aggregation of wheat straw biochar (WB) and pinewood biochar (PB) NPs in solutions were investigated by the time-resolved dynamic light scattering method. The critical coagulation concentration (CCC) of WB and PB NPs in Na2SO4 solution was higher than their CCCs in NaCl solution, which was consistent with the Hofmeister series that SO42−, a kosmotrope anion, increased the interaction between water molecules, thus enhancing the hydrophobic interactions between biochar NPs in solution and promoting their aggregation, while Cl−, a chaotropic agent, exhibited the opposite effect. When BSA was added into the solution, BSA was adsorbed on the surface of biochar NPs and BSA corona was formed, which inhibited the aggregation of biochar NPs by inducing steric force. The enhanced stability of biochar NPs by BSA was more significant in NaCl than in Na2SO4 solution because BSA corona had a more negatively charged surface and a more steric structure in NaCl solution, thus generating stronger electrical repulsion and steric hindrance. The classical DLVO theory and the XDLVO theory incorporating the steric repulsion (in the presence of BSA) were used to interpret the aggregation and dispersion of biochar NPs. Through this study, we found that anion type indirectly affected the aggregation of biochar NPs by influencing the interaction between water molecules, while the aggregation of BSA-biochar NPs conjugates is mainly influenced by the surface charge and structure of BSA corona.

Estimating Long-Term Average Carbon Emissions from Fires in Non-Forest Ecosystems in the Temperate Belt

Research into pyrogenic carbon emissions in the temperate belt of the Russian Federation has traditionally focused on the impact of forest fires. Nevertheless, ecosystems in which wildfires also make a significant contribution to anthropogenic CO2 emissions are poorly studied. We evaluated the carbon emissions of fires in the non-forest ecosystems of the Middle Amur Lowland, in the Khabarovsk Territory of the Russian Federation. Our study is based on long-term Earth remote sensing data of medium spatial resolution (Landsat 5, 7, and 8) and expeditionary studies (2018–2021). The assessment of carbon directly emitted from wildfires in meadow and meadow–mire temperate ecosystems in the Middle Amur lowland shows that specific emissions from such ecosystems vary, from 1.09 t/ha in dwarf shrub–sphagnum and sphagnum–ledum and sedge–reed fens to 6.01 t/ha in reed–forb, forb, reed, and sedge meadows. Meanwhile, carbon emissions specifically from fires in meadow and meadow–mire ecosystems are less significant—often an order of magnitude less than carbon emissions from forest fires (which reach 37 tC/ha). However, due to their high frequency and the large areas of land burned annually, the total carbon emissions from such fires are comparable to annual emissions from fires in forested areas. The results obtained show that the inadequacy of the methods used in the automatic mapping of burns leads to a significant underestimation of the area of grassland fires and carbon emissions from non-forest fires.

Preparation and Characterization of Glass-Ceramic Foam from Clay-Rich Waste Diatomaceous Earth.

In this study, the potential use of waste diatomaceous earth from the production of diatomaceous earth for filtration purposes, as an alternative raw material for foam glass production, was explored. The chemical and mineralogical composition and the high temperature behavior of waste diatomite were studied to assess its suitability for foam glass production. Glass-ceramic foams were prepared using NaOH solution as a foaming agent, via a hydrate mechanism. The influence of different pretreatments and firing temperatures on the foam’s structure, bulk density and compressive strength was investigated. High temperature behavior was studied using TG/DTA analysis and high temperature microscopy. Phase composition was studied using X-ray diffraction analysis. Glass-ceramic foam samples of a high porosity comparable to conventional foam glass products were fabricated. The pretreatment temperature, foaming temperature and sintering holding time were found to have a significant influence on foam properties. With increased pretreatment temperature, pyrogenic carbon from the thermal decomposition of organic matter contained in the raw material acted as an additional foaming agent and remained partially unoxidized in prepared foams. The bulk densities of prepared samples ranged from 150 kg/m3 to 510 kg/m3 and their compressive strengths were between 140 and 1270 kPa.

Pyrogenic carbon decomposition critical to resolving fire’s role in the Earth system

Recently identified post-fire carbon fluxes indicate that, to understand whether global fires represent a net carbon source or sink, one must consider both terrestrial carbon retention through pyrogenic carbon production and carbon losses via multiple pathways. Here these legacy source and sink pathways are quantified using a CMIP6 land surface model to estimate Earth’s fire carbon budget. Over the period 1901–2010, global pyrogenic carbon has driven an annual soil carbon accumulation of 337 TgC yr−1, offset by legacy carbon losses totalling −248 TgC yr−1. The residual of these values constrains the maximum annual pyrogenic carbon mineralization to 89 TgC yr−1 and the pyrogenic carbon mean residence time to 5,387 years, assuming a steady state. The residual is negative over forests and positive over grassland-savannahs (implying a potential sink), suggesting contrasting roles of vegetation in the fire carbon cycle. The paucity of observational constraints for representing pyrogenic carbon mineralization means that, without assuming a steady state, we are unable to determine the sign of the overall fire carbon balance. Constraining pyrogenic carbon mineralization rates, particularly over grassland-savannahs, is a critical research frontier that would enable a fuller understanding of fire’s role in the Earth system and inform attendant land use and conservation policy. Vegetation plays an important role in the aggregate carbon balance of fires, according to a 1901 to 2010 land surface model study that, assuming steady state, shows potentially greater pyrogenic carbon production than legacy losses at global scale, due mostly to grassland adaptations to fire.

Heterogeneous compositions of oxygen-containing functional groups on biochars and their different roles in rhodamine B degradation

The reactivity of pyrogenic carbon has attracted a great deal of research attentions recently. The oxygen-containing structures are rich on the surface of biochars, and involved in accepting and donating electrons during the interactions between biochar and organic contaminants. In this work, the species and content of oxygen-containing functional groups on biochar surface were regulated through chemical modification, and batch sorption/degradation experiments were carried out for rhodamine B (RhB). Based on the comparison of surface functional groups, biochars produced below 200 °C mediated RhB degradation through phenol hydroxyl group, while semiquinone and carboxylic acid groups were the main reaction active sites for biochars produced at higher than 500 °C. Considering that various biochar properties play roles in mediating organics degradation, the strategies in manipulating biochar properties should be carefully considered.

Direct and Indirect Electron Transfer Routes of Chromium(VI) Reduction with Different Crystalline Ferric Oxyhydroxides in the Presence of Pyrogenic Carbon.

Electron transfer mediated by iron minerals is considered as a critical redox step for the dynamics of pollutants in soil. Herein, we explored the reduction process of Cr(VI) with different crystalline ferric oxyhydroxides in the presence of pyrogenic carbon (biochar). Both low- and high-crystallinity ferric oxyhydroxides induced Cr(VI) immobilization mainly via the sorption process, with a limited reduction process. However, the Cr(VI) reduction immobilization was inspired by the copresence of biochar. Low-crystallinity ferric oxyhydroxide had an intense chemical combination with biochar and strong sorption for Cr(VI) via inner-sphere complexation, leading to the indirect electron transfer route for Cr(VI) reduction, that is, the electron first transferred from biochar to iron mineral through C-O-Fe binding and then to Cr(VI) with Fe(III)/Fe(II) transformation on ferric oxyhydroxides. With increasing crystallinity of ferric oxyhydroxides, the direct electron transfer between biochar and Cr(VI) became the main electron transfer avenue for Cr(VI) reduction. The indirect electron transfer was suppressed in the high-crystallinity ferric oxyhydroxides due to less sorption of Cr(VI), limited combination with biochar, and higher iron stability. This study demonstrates that electron transfer mechanisms involving iron minerals change with the mineral crystallization process, which would affect the geochemical process of contaminants with pyrogenic carbon.

Variability in pyrogenic carbon properties generated by different burning temperatures and peatland plant litters: implication for identifying fire intensity and fuel types

Pyrogenic carbon (PyC), generated by fire, acts as a stable carbon deposit in natural ecosystems and is widely used to reconstruct fire history. Fuel type and burning temperature are the two major factors that influence PyC properties and exert variable effects on soil carbon pools, especially for peatlands. However, whether analysis of PyC can identify these two factors remains unclear. To address this knowledge gap, we selected typical peatland plant litters of seven shrub and seven herb plants in the Great Khingan Mountains, China. The properties of PyC produced at 250°C (low-intensity burning) and 600°C (high-intensity burning) without oxygen were evaluated. The results showed that the effects of burning temperature and plant type on δ13C-PyC were not significant. The differences in the initial compositions of herbs and shrubs led to more aromatic and carboxylic compounds in shrub PyC than in herb PyC. A high burning temperature led to less labile components (e.g. aliphatic compounds and acids) and higher thermal stability of high-temperature PyC compared to that of low-temperature PyC. Our results also indicate that several typical PyC chemical composition indicators (e.g. Fourier-transform infrared spectroscopy 1515/1050 ratio and 1720/1050 ratio) can potentially identify PyC sources.

Continental-scale measurements of soil pyrogenic carbon in Europe

Pyrogenic carbon (PyC), the product of incomplete biomass combustion, is a key component of soil organic carbon (SOC) because it can persist in soils for centuries to millennia. Quantifying PyC across large spatial scales remains a significant challenge in constraining the global carbon cycle. We measured PyC in topsoils across Europe using molecular marker (benzene polycarboxylic acids, BPCA) and spectroscopic techniques (Diffuse Reflectance Infrared Fourier Transform Spectroscopy, DRIFTS). We developed a calibration between BPCA and DRIFTS, but the calibration was less reliable (Y-variance explained = 0.62) than previous reports due to low soil PyC content and heterogeneity of soil matrices. Thus, we performed multiple regressions to identify drivers of PyC distribution using only the measured BPCA data. PyC content varied widely among soils, contributing 0–24% of SOC. Organic carbon was the strongest predictor of soil PyC content, but mean annual temperature, clay, and cation exchange capacity also emerged as predictors. PyC contributes a smaller proportion of SOC in European soils compared to other geographic regions. Comparing soil PyC measurements to PyC production rates in high latitude and Mediterranean regions suggests that transport, degradation, and recombustion are important mechanisms regulating soil PyC accumulation.

A Framework for Agricultural Decarbonisation: Environmental Assessment from Seed to Soil of a Cradle-To-Cradle Farm System with Industrial Hemp and Pyrogenic Carbon Capture & Storage

A Framework for Agricultural Decarbonisation: Environmental Assessment from Seed to Soil of a Cradle-To-Cradle Farm System with Industrial Hemp and Pyrogenic Carbon Capture & Storage

The Roles of Fe Oxyhydroxide Coating and Chemical Aging in Pyrogenic Carbon Nanoparticle Transport in Unsaturated Porous Media

The Roles of Fe Oxyhydroxide Coating and Chemical Aging in Pyrogenic Carbon Nanoparticle Transport in Unsaturated Porous Media

Finer Particles and Pyrogenic Carbon Fractions Regulate PAH Partitioning and Burial in a Eutrophic Shallow Lake

Finer Particles and Pyrogenic Carbon Fractions Regulate PAH Partitioning and Burial in a Eutrophic Shallow Lake

Pyrogenic Carbon Colloids Facilitate Transport and Transformation of Cr(Vi) in Soil: Steric Competition Coupling with Reduction Reaction

Pyrogenic Carbon Colloids Facilitate Transport and Transformation of Cr(Vi) in Soil: Steric Competition Coupling with Reduction Reaction

Post-Fire Forest Floor Succession in a Central European Temperate Forest Depends on Organic Matter Input from Recovering Vegetation Rather than on Pyrogenic Carbon Input from Fire

Post-Fire Forest Floor Succession in a Central European Temperate Forest Depends on Organic Matter Input from Recovering Vegetation Rather than on Pyrogenic Carbon Input from Fire

Enhanced Microbial Ferrihydrite Reduction by Pyrogenic Carbon: Impact of Graphitic Structures.

Electron-shuttling agents such as pyrogenic carbon (PC) can mediate long-distance electron transfer and play numerous key roles in aquatic and soil biogeochemical processes. The electron-shuttling capacity of PC relies on both the surface oxygen-containing functional groups and bulk graphitic structures. Although the impacts of oxygen-containing functional groups on the electron-shuttling performance of PC are well studied, there remains insufficient understanding on the function of graphitic structures. Here, we studied the functions of PC in mediating microbial (Shewanella oneidensis MR-1) reduction of ferrihydrite, a classic and geochemically important soil redox process. The results show that PC enhanced microbial ferrihydrite reduction by 20-115% and the reduction rates increased with PC pyrolysis temperature increasing from 500 to 900 °C. For PC prepared at low temperature (500-600 °C), the electron-shuttling capacity of PC is mainly attributed to its oxygen-containing functional groups, as indicated by a 50-60% decline in the ferrihydrite reduction rate when PC was reduced under a H2 atmosphere to remove surface oxygen-containing functional groups. In stark contrast, for PC prepared at higher temperature (700-900 °C), the formation of PC graphitic structures was enhanced, as suggested by the higher electrical conductivity; accordingly, the graphitic structure exhibits greater importance in shuttling electrons, as demonstrated by a minor decline (10-18%) in the ferrihydrite reduction rate after H2 treatment of PC. This study provides new insights into the nonlinear and combined role of graphitic structures and oxygen-containing functional groups of PC in mediating electron transfer, where the pyrolysis temperature of PC acts as a key factor in determining the electron-shuttling pathways.

A Review About Preparation and Properties of Biochar and Application Fields in the Environment

Biomass’ pyrolysis process is responsible for producing the biochar charcoal, this process does not incorporate the oxygen, and it is utilized as a soil enhancer for each one of the carbon sequestration, and soil health prospects. Biochar can be defined as a stabilized solid which is enriched with carbon and could remain in the soil for extended period of time. Biochar has been studied as a way of carbon sequestration, and it might be a way used for handling climate change and global warming. It happens due to the processes that are associated with pyrogenic carbon capturing and storages. This review is focused on an overview of biochar preparation and application in the environment, previous studies and Applications. Biochar is prepared from various organic materials such as miscanthus, switch grass, corn stover, and sugarcane bagasse. The method of preparation varies with different temperatures and the discharge of nitrogen gas used for a period of one hour not to mention thermal decomposition at different temperatures of heat (500, 600, 700 and 800oC). The success of its use as a adsorbent material, and in treating the soil from heavy metals, its suitability for agriculture, and the treatment of the liquid leachate from solid waste down into the groundwater, in addition to the treatment of groundwater when the topography of the region differs.

Carbon sequestration in cementitious matrix containing pyrogenic carbon from waste biomass: A comparison of external and internal carbonation approach

Cement manufacturing and concrete constructions are associated with high carbon dioxide (CO2) emission. This can be potentially reduced by sequestering CO2 through calcium carbonate mineralization using the technique of accelerated carbonation curing (ACC). This research investigates and compares the role of biochar – as-produced (BC) and CO2-saturated (SatBC), and silica fume (SF) respectively on carbon sequestration, strength and hydration of cement composites. In case of SatBC, the CO2 is pre-adsorbed in biochar pores a priori before deployment in cement matrix. The study found that addition of BC can densify the cement matrix through accelerating hydration and improving the total hydration. This leads to reduction in carbon dioxide diffusion and carbonate mineralization initially (7-day age) than control. However, the net carbonate mineralization in biochar-cement paste is similar to control and silica fume-paste after 28 days of carbonation. Accounting for the carbonate mineralization and carbon sequestered in the biochar structure, ACC of BC-CP and internal carbonation in SatBC-CP can lead to 5–6% reduction in carbon dioxide-equivalent (CO2-eq) than control. Addition of biochar yields higher carbonate mineralization from carbonation of calcium hydroxide compared to silica fume-cement (SF-CP), where more carbonate mineralization is contributed by carbonation of binder gel. This leads to 8–10% higher compressive strength and lower loss in strength (4–5% loss) in BC-CP compared to SF-CP (15% loss) at 28-day age. Application of SatBC as admixture substantially improves compressive strength compared to uncarbonated control and SF-CP at 7-day age and demonstrates similar strength as carbonated SF-CP after 28 days. The results suggest that spent biochar, previously used as industrial CO2 adsorbent, can be valorized as “green admixture” in cement-based materials. In summary, this research illustrates the potential of biochar to manufacture low carbon cementitious building materials, that can turn future cities into “carbon sinks”.

Negligible Quantities of Particulate Low-Temperature Pyrogenic Carbon Reach the Atlantic Ocean via the Amazon River.

Particulate pyrogenic carbon (PyC) transported by rivers and aerosols, and deposited in marine sediments, is an important part of the carbon cycle. The chemical composition of PyC is temperature dependent and levoglucosan is a source‐specific burning marker used to trace low‐temperature PyC. Levoglucosan associated to particulate material has been shown to be preserved during riverine transport and marine deposition in high‐ and mid‐latitudes, but it is yet unknown if this is also the case for (sub)tropical areas, where 90% of global PyC is produced. Here, we investigate transport and deposition of levoglucosan in suspended and riverbed sediments from the Amazon River system and adjacent marine deposition areas. We show that the Amazon River exports negligible amounts of levoglucosan and that concentrations in sediments from the main Amazon tributaries are not related to long‐term mean catchment‐wide fire activity. Levoglucosan concentrations in marine sediments offshore the Amazon Estuary are positively correlated to total organic content regardless of terrestrial or marine origin, supporting the notion that association of suspended or dissolved PyC to biogenic particles is critical in the preservation of PyC. We estimate that 0.5–10 × 106 g yr−1 of levoglucosan is exported by the Amazon River. This represents only 0.5–10 ppm of the total exported PyC and thereby an insignificant fraction, indicating that riverine derived levoglucosan and low‐temperature PyC in the tropics are almost completely degraded before deposition. Hence, we suggest caution in using levoglucosan as tracer for past fire activity in tropical settings near rivers.