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Under the circumstances of serious environmental challenges and energy crises, it is of utmost importance to produce fuels and chemicals from renewable biomass and organic wastes. Biochar as a bioproduct from thermochemical conversion of biomass has attracted exponential research interest in recent years due to the abundance of its precursor (biomass resources) and its adaptability in different chemical reaction systems. Undoubtedly, it is essential to attain an in-depth understanding of the physiochemical properties and functionalization of biochar catalysts to further improve their catalytic activity, selectivity and stability in the reactions. However, until now, only a few reports are accessible on the use of biochar as a catalytic support material and/or a standalone catalyst in thermochemical biomass conversion to produce high-quality biofuels. Thus, the key objective of this review article is to summarize and discuss the latest progress in biochar production, modification, activation and functionalization by understanding its physical chemistry, composition and application in catalytic processes. This review article provides insights into the thermochemical and hydrothermal production of biochar as well as the engineering and process optimization aspects for value-added biofuel production and decarbonization. [Display omitted] • Effects of biomass composition and process conditions on biochar are reviewed. • Systematic discussion on biochar functionality as bio-based catalyst support is made. • Insights into the modification of biochar targeting optimal performance are shown. • Comparative analysis of biochar-based catalytic pyrolysis, gasification and liquefaction. • The significance of activation of biochar for enhanced functionality is justified. [ABSTRACT FROM AUTHOR]

The study explores the synthesis and utilization of biochar (BC) and multi-layer MXene to MXene/biochar (MB) composites for wastewater treatment. Simultaneously, it also investigates their energy generation potential through biomass and soil property assessments. The integrated column and batch treatments have shown significant results, elevating total dissolved solids from 63.7 to 125.5 mg L−1 with column treatment, while reducing them to 6.37 % and 1.35 % with BC and MB treatment, respectively. BC with high carbon content, demonstrated increased hydrophobicity, which was amplified by the integration of MXene, thereby enhancing its potential for advanced wastewater treatment. Treated wastewater exhibited elevated nutrient concentrations (Ca, Cu, Fe, K, Na, and NH 4 +), promoting the growth of Pennisetum purpureum. WW_B shows promising energy potential, with a higher heating value of 25.03 MJ kg−1 and a lower heating value of 23.57 MJ kg−1. They demonstrated high volatile matter exceeding 70.9 wt %, and a fixed carbon from 10.02 to 27.53 wt %, signifying their potential for efficient conversion and bio-oil yield during pyrolysis. The ultimate analysis emphasized significant carbon, with oxygen content ranging from 43.42 to 47.78 wt %., influencing combustion characteristics. MT_B exhibited its suitability for energy production through thermochemical conversion, underlined by its high flammability and low volatile ignition values. In the absence of BC, the E a ranged from 24.77 to 77.88 kJ mol−1 in wastewater and from 21.67 to 69.6 kJ mol−1 in MB treated wastewater. Meanwhile, when soil contained BC and was irrigated with wastewater, the E a varied from 24.66 to 80.91 kJ mol−1. In the case of MB treated wastewater, it ranged from 25.01 to 75.79 kJ mol−1. The research thereby affirms the potential of MB composites to advance water and energy sustainability setting us for broader nexus-based applications. [Display omitted] • Wastewater reclamation within the context of sustainable energy generation was studied. • Pennisetum purpureum exhibited promising bioenergy production potential using MT_B. • Crops, with WW_B having even higher VM, exhibited high VM exceeding 70.9 %. • WW_B's high HHV (25.03 MJ kg − 1 ) and LHV (23.57 MJ kg − 1 ) indicate promising energy potential for thermochemical conversion. [ABSTRACT FROM AUTHOR]

[Display omitted] • Efficient co-valorization of waste cooking oil into biofuel and carbon nanotubes. • Natural biochar shows excellent deoxygenation performance and good stability. • Correlation between AAEM in biochar and selectivity of A&E and HCs in bio-oil. • Potential for obtained biofuel to serve as a precursor for jet fuel. • Feasibility and profitability of integrated production process demonstrated. Valorizing renewable precursors into high-quality biofuel and functional carbon nanomaterials can considerably improve the economic viability. Here, we propose a process for integrated production of high-quality biofuel and carbon nanotubes from waste cooking oil via catalytic pyrolysis coupling with chemical vapor deposition (CVD) technology. The natural biochar catalyst demonstrates excellent deoxygenation performance and good stability in catalytic pyrolysis process. The alkali/alkaline earth metal species (AAEMs) content in biochar catalysts has a strong correlation with the selectivity of esters and hydrocarbons in bio-oil. The biofuel obtained under optimal conditions exhibited potential as a precursor for jet fuel. The CVD process convert pyrolysis gas into carbon nanotubes with yield of 2.13%. The technical–economic analysis demonstrated the feasibility of the integrated process, projecting profitability and substantial total profit over a ten-year period. Overall, this study improves the economic viability of the waste cooking oil pyrolysis process and supports its wider commercial application. [ABSTRACT FROM AUTHOR]

Hydrothermal carbonization (HTC) is a process for enhancing energy content of biomass through deoxygenation reactions, effectiveness of which depends on composition of biomass. Thermal pretreatment could induce structural change of biomass and thus affects the chemical inertness/reactivity in HTC. This was investigated herein by HTC of the pine needles, thermally treated at 250 or 350 °C with/without presence of 11.5% O 2 , at 250 °C for 10 h. The results showed that pretreatment at 250 °C could increase overall yield of hydrochar in subsequent HTC, due to the enhanced aromatization and the resistance towards fragmentation in HTC. Nonetheless, the HTC worked on biochar formed at 250 °C, facilitating deoxygenation to remarkably decrease O/C ratio. In comparison, the pretreatment at 350 °C removed substantial amount of volatile fractions, significantly increasing chemical inertness of resulting char-350 during the followed HTC. Oxygen presence induced oxidation reactions in pretreatment, forming more bio-oil/gases and making resulting hydrochar more hydrophilic. Especially, oxidation at 250 °C formed more aliphatic structures that could be easier removed during followed HTC, enhancing thermal stability of resulting hydrochar. Although a portion of cellulose retained in the biochar obtained from pretreatment at 250 °C, the elimination of aliphatics suppressed formation of spheric structures of hydrochar, while retained original fibrous structures from pine needles. [Display omitted] • Pine needle pretreated at 250°C is more inert in HTC, generating more hydrochar. • HTC barely works the sample pretreated at 350°C, due to removing most of volatiles. • Pretreatment at 250°C retains cellulose crystals, which are removed at 350°C. • O2-pretreatment makes hydrochar thermally more stable via removing more aliphatics. • Pretreatment at even 250°C suppresses formation of hydrochar of spheric structures. [ABSTRACT FROM AUTHOR]

Enormous annual sewage sludge (SS) volumes pose global environmental challenges owing to contamination and significant greenhouse gas emissions. Here, we investigated the economic viability of co-pyrolyzing SS and biomass waste to produce biofuels (bio-oil and gas) and biochar. Net present worth (NPW) analysis, the sale product break-even price, and sludge handling price (SHP) were used to determine the profitability of co-pyrolysis compared with SS pyrolysis alone and conventional treatment methods. In this study, the sale prices of biochar based on quality (i.e., stability, carbon sequestration effectiveness, and heavy metal content) were estimated to be 2.24, 1.44, and 0.98 CAD/kg for high-, medium-, and low-grade biochar. The bio-oil prices, estimated based on the higher heating values of bio-oil and diesel, ranged from 0.80 to 1.22 CAD/kg. Sawdust (SD) and wheat straw (WS) were the chosen co-pyrolysis feedstocks, with four mixing ratios (20, 40, 60, and 80 wt%). Economically, SD (40 wt% mixing ratio) co-pyrolysis achieved the best performance, with a maximum NPW of 8.71 million CAD. SD single and co-pyrolysis were the only profitable scenarios. Moreover, SS single pyrolysis and WS co-pyrolysis exhibited higher profitability than conventional SS treatment methods, with SHPs of 65 and 40 CAD/1000 kg dry sludge, respectively. Sensitivity analysis highlighted the dependence of economic performance on biochar and bio-oil market value. This study offers the first economic analysis of this approach and enhances our understanding of the potential of co-pyrolysis for biofuel and biochar production, providing innovative solutions for the environmental challenges of SS disposal. [Display omitted] • Cost, operating expenses, and energy recovery of a pyrolysis plant were evaluated. • Co-pyrolyzing SS with sawdust SS showed the highest NPW of 8.71 million CAD. • All single and co-pyrolysis cases showed higher revenue than SS disposal methods. • Economic feasibility was dependent on bio-oil and biochar quality and sales price. [ABSTRACT FROM AUTHOR]

As the most promising anode material for ultra-high specific capacity lithium-ion batteries, Si has been hindered from widespread use by large volume effects and limited electrical conductivity during cycling. In this study, NiO nanoflowers were coated onto the exterior of Si NPs by hydrothermal method. Si@NiO was then mixed and annealed with natural biomass gel extracted from moldy wheat to produce Si@NiO@Biochar ternary composites, which were prepared. Si NPs are the source of high specific capacity of anode materials. The carbon layer minimizes the electrode bulk effect and enhances cycling stability, while the NiO flowers expand the lithium-ion transport channel and reduce Si NPs bulk effect. Furthermore, the N element from wheat protein in the carbon layer enhances the electrical conductivity of the material. After 100 cycles at 0.1 A g−1 and 1000 cycles at 1 A g−1, the capacity of the electrode rose to 952.12 mAh g−1 and 1098.05 mAh g−1, respectively. The Si@NiO@Biochar material showed remarkable electrochemical stability at various current densities and the thickness grew by just 27.97% after 500 cycles. It can also be utilized in lithium-sulfur batteries because of its microporous structure and capacity to transport sulfur. The reversible capacity was 388.21 mAh g−1 after 70 cycles at 1 C. Biomass carbon from biomass gels coated on Si@NiO reduces biomass energy waste. This research is a significant step for commercializing Si anode materials and providing an eco-friendly new method for storing energy. [Display omitted] • Nitrogen-doped biochar is made from the recycling of mouldy wheat. • The simple preparation process and excellent results. • The volume expansion of the silicon is well limited. • The composite has low internal resistance and high cycle life. • It can be used in two scenarios: lithium batteries and lithium- sulfur batteries. [ABSTRACT FROM AUTHOR]

Grass silage and cattle slurry are the most abundant feedstocks for biogas in an Irish context. This work describes how to optimize their biomethane yield. Hydrolysis and biomethane yields from co-digestion of grass silage and slurry were enhanced in a biochar-supplemented two-stage digestion process. Biochar addition at the optimal dosage of 10 g/L in batch two-stage digesters led to the highest methane yield of 253 L per kilogram (kg) volatile solid (VS), which was 24% higher than that from two-stage digesters without biochar supplementation. For a batch single-stage digester, the biomethane yields were lower than the two-stage but 10 g/L biochar addition led to an increase to 218 L/kg VS as compared to 198 L/kg VS for the group without biochar supplementation. Volatile fatty acid accumulation increased with the enhancement of biomethane production in the biochar-supplemented two-stage reactors. The addition of biochar in single-stage and two-stage anaerobic digesters presented positive effects on the electrochemical properties of the digester contents, reflected by the increased charge storage capacity, reduced solution resistance and improved digester content conductivity. The methane yields in two-stage anaerobic digestion were shown to be strongly correlated (R2 = 0.92) with the concentration of extracellular polymeric substances. This evidenced that the interlaced conductive network established by extracellular polymeric substances and biochar was essential for direct interspecies electron transfer and biomethane production. This study demonstrated that biochar-supplemented two-stage anaerobic digestion is an optimal route for energy recovery from grass silage and cattle slurry. [Display omitted] • Co-digestion of on-farm feedstock was enhanced in a two-stage process with biochar. • Biochar at 10 g/L in two-stage digestion maximized CH 4 yield at 253 L/kg VS. • Biochar at 10 g/L in single-stage digestion achieved a CH 4 yield of 218 L/kg VS. • Biochar improved sludge conductivity to facilitate interspecies electron transfer. • CH 4 yield highly correlated with extracellular polymeric substances concentration. [ABSTRACT FROM AUTHOR]

Involving biomass in the energy sector is a way to replace fossil fuels with renewable and CO 2 -neutral raw materials, reducing the negative impact on the environment. The energy application of agro-industrial waste is of particular interest, allowing one not only to obtain biofuel, but also to utilize by-products. The present work considers pine nut shells from a candy factory in relation to microwave processing into solid and gaseous fuels. The aim is to study the features of pine nut shells microwave pyrolysis, including the initiation mechanism and process behaviour, as well as the composition and characteristics of the resulting products. The study included experimentation in combination with application of high-speed video recording of the process and gas analysis, study of dielectric characteristics of raw materials, proximate and ultimate analysis of the obtained solid and gaseous products. At microwave pyrolysis, the conversion degree into liquid and gaseous products (76.9%) is much higher than, for example, at slow fixed bed pyrolysis (65.5%). The radiation absorption by the sample is nonlinear throughout the process and increases during the organic part degradation with the appearance of liquid and gaseous products. The gas obtained at microwave processing has a low ballast (share of CO 2 =3.5%) and a high hydrogen content (share of H 2 =19.3%) that results in a high heat of combustion (21.8 MJ·m−3), which is probably connected with interaction of pyrogenetic water and fuel carbon during plasma-chemical reactions. • Microwave pyrolysis of pine nut shells is caused by electric discharges. • Microwave radiation absorption by pine nut by shells is nonlinear over process time. • Microwave radiation absorption grows with increasing the yield of volatile products. • Interaction of pyrogenetic water and carbonaceous residue leads to high H 2 content. • Pyrolysis gas has a high heat of combustion (21.8 MJ·m–3) and low CO 2 content (< 3.5%). [ABSTRACT FROM AUTHOR]

Fossil fuels-related environmental issues, such as global climate change and soil and water acidification, are driving countries to develop biomass energy sources. As a second-generation biofuel with a significant spatiotemporal availability for global consumption, Ganoderma lucidum (GL) calls for the characterization and multi-objective optimization of its pyrolytic performance and byproducts. The GL pyrolysis was divided into three stages, with the main stage occurring between 205 and 630 °C. The activation energy for the main stage was estimated at 221.23 kJ/mol and 222.83 kJ/mol according to the FWO and KAS methods, respectively. The primary volatile products of the GL pyrolysis between 200 and 600 °C included H 2 O, CH 4 , CO 2 , CO, C O, C-O(H), C C, and NH 3. The multi-objective optimization indicated that the GL pyrolysis between 650 and 750 oC jointly led to maximum energy yield and minimum gas emission. Biochar produced from GL (GLB) between 400 and 600 °C enhanced its aromaticity and stabilized the functional groups in the carbon structure. GLB obtained exhibited an increased number of porous structures and decreased aromaticity. These results provide a theoretical and practical basis for enhancing and volarizing the comprehensive circularity of GL biomass. [Display omitted] • The pyrolysis behavior of GL was characterized through thermogravimetric analysis. • The activation energy for the main stage was based on the FWO and KAS methods. • The gaseous products and emission patterns were identified and quantified. • The production and properties of GL-derived biochar were explored. • A multi-objective optimization of energy yield and gas emissions was employed. [ABSTRACT FROM AUTHOR]

This overview addresses the formation of solid trash and the various forms of waste from a variety of industries, which environmentalists have embraced. The paper investigates the negative effects on the environment caused by unsustainable management of municipal solid trash as well as the opportunities presented by the formal system. This examination looks at the origins of solid waste as well as the typical treatment methods. Pyrolysis methods, feedstock pyrolysis, and lignocellulosic biomass pyrolysis were highlighted. Explain in detail the various thermochemical processes that take place during the pyrolysis of biomass. Due to its carbon content, low cost, accessibility, ubiquitousness, renewable nature, and environmental friendliness, biomass waste is a unique biochar precursor. This study looks at the different types of biomass waste that are available for treating wastewater. This study discussed a wide variety of reactors. Adsorption is the standard method that is used the most frequently to remove hazardous organic, dye, and inorganic pollutants from wastewater. These pollutants cause damage to the environment and water supplies, thus it is important to remove them. Adsorption is both simple and inexpensive to utilize. Temperature-dependent conversions explain the kinetic theories of biomaterial biochemical degradation. This article presents a review that explains how pyrolytic breakdown char materials can be used to reduce pollution and improve environmental management. [Display omitted] • Sources, synthesis and modification techniques of biochar are discussed. • Conversion of biomass into energy is more effective after being torrefied. • Appraisals on the activation energies during biochar preparation are made. • Torrefied biomass has environmental applications which are critically surveyed. [ABSTRACT FROM AUTHOR]

On-farm feedstocks such as grass silage and cattle slurry present recalcitrant characteristics that can limit microbial conversion in biofuel production. Introducing a biochar supplement in two-stage anaerobic digestion may facilitate feedstock hydrolysis and improve energy yields in biohydrogen and biomethane production. The biomethane potentials were first investigated in batch trials without biochar supplement; results indicated a biomethane yield of 230 L per kilogram (kg) volatile solid (VS) in single-stage digestion and 275 L/kg VS in two-stage digestion. In continuous trials, operated at an organic loading rate of 4.0 g VS/L/d, the second-stage digester in two-stage digestion showed a methane yield of 237 L/kg VS with 10 g/L biochar addition; this was 7% higher than the second-stage digester without biochar addition. At the same loading rate of 4.0 g VS/L/d, the biomethane yield in continuous single-stage digestion with 10 g/L biochar addition was 212 L/kg VS; this was 3% higher than the single-stage digester without biochar addition. Biochar was found to enhance the hydrolysis of recalcitrant solid components in the hydrogen-producing phase, promote biomethane production in methanogenesis, and stabilize the digestion process. The highest energy yield of 8.5 MJ hydrogen and methane per kg VS was achieved in the two-stage digestion with 10 g/L biochar addition at a loading rate of 4.0 g VS/L/d. The results demonstrated that the application of a biochar supplement could effectively enhance gaseous biofuel production in two-stage anaerobic digestion. [Display omitted] • Co-digestion of silage and cattle slurry was compared in single and two stage. • Biochar enhanced hydrolysis and acidification in continuous two-stage process. • 10 g/L biochar enhanced CH 4 production and stabilized continuous digestion process. • Two-stage digestion increased H 2 and CH 4 production as compared to single stage. • The highest energy yield was 8.5 MJ/kg VS at 4.0 g VS/L/d in second-stage digestion. [ABSTRACT FROM AUTHOR]

This work investigates the feasibility of extracting biofuels from general wastes, with significant non-recyclable and inorganic components, through the novel thermo-catalytic reforming (TCR®) technology. Two forms of general waste (Up-Sieve Material and Grey Compost) supplied by Risorse Ambiente Palermo (RAP) are studied. Each feedstock is shredded, pelletised and characterised. Analyses of the feedstock materials show the Up-Sieve Material has a higher heating value (HHV) of 17.6 MJ kg−1 with an ash content of 19.60% (by weight), while the Grey Compost has a HHV of 11.5 MJ kg−1 and an ash content of 40.16%. The results of the TCR® experiments on both feedstock materials show they can be thermochemically converted into energy carriers in significant quantities. The characterisation results of the oil and char from the Up-Sieve Material show they have HHVs of 38.2 MJ kg−1 and 13.6 MJ kg−1 respectively, while the oil and char from the Grey compost have HHVs of 37.0 MJ kg−1 and 5.7 MJ kg−1 respectively. In addition, the biogases produced from both feedstock materials are rich in hydrogen (up to 30% by volume each). Hence, apart from the chars and the reaction product water, the products can be further processed into biofuels due to their fuel-grade properties. Therefore, the successful extraction of biofuels from general waste is an important step in renewable energy harnessing, waste management and environmental protection. • Thermo-catalytic reforming involves intermediate pyrolysis and catalytic reforming • General waste converted to biofuels using this technology • Two types of general waste studied: up-sieve material and grey compost • Both produce biochars with high ash contents and biooils with high heating values • Both produce biogases with high hydrogen fractions, compared to gasification and pyrolysis [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Three types of biochar can efficiently activate hydrogen peroxide. • Biochar/H 2 O 2 systems exhibited high tetracycline degradation efficiency. • Catalytic property of biochar depends on the amounts of PFRs. • Biomass types and its compositions were crucial for the formation of PFRs. • Electron transfer pathways could be the catalytic mechanisms of biochar. Abstract Biochar, a green material that possesses high catalytic potential due to its persistent free radicals (PFRs), has attracted increasing attention in the removal of refractory pollutants from water. The influences of biomass types (bamboo, corn stalk, and pig manure) and its compositions (metals and phenolic compounds) on the formation of PFRs in biochar were investigated by electron paramagnetic resonance (EPR). It was found that the amounts of PFRs in biochar would decrease sharply with the decrease of the initial metals and phenolic compounds existed in biomass, and the effect of metals contents on PFRs formation was much greater than that of phenolic compounds contents. This finding was supported by the results obtained from elemental analysis and molar H/C analysis of three types of biochar, which suggested that pig-manure biochar (PM500) had the highest concentrations of PFRs of 14.13 × 1018 spins·g−1 due to the high content of metals and phenolic compounds in pig manure. The EPR trapping experiment and Linear sweep voltammetry (LSV) measurements in biochar/H 2 O 2 systems showed that OH was the dominant reactive radical and electrons transfer pathways might be responsible for the activation of H 2 O 2 by biochar. Possible degradation pathways of the tetracycline in biochar/H 2 O 2 systems were also proposed. Besides, high degradation efficiency and good stability were observed in real wastewater application of the PM500/H 2 O 2 system. These findings would provide a clearer insight into the formation mechanisms of PFRs in biochar, and also present a better strategy for biochar preparation and application in Fenton-like system. [ABSTRACT FROM AUTHOR]

Highlights • Economic feasibility of portable systems to utilize forest residues was investigated. • Forest residues were processed into raw and torrefied briquettes and biochar. • Minimum selling price (MSP) of biochar was estimated to $1044/ODMT. • MSP of raw and torrefied-briquettes were $162 and $274/ODMT respectively. • MSPs could be reduced by at least 50% with improved portable systems. Abstract Wildfires are getting extreme and more frequent because of increased fuel loads in the forest and extended dry conditions. Prevention of wildfire by fuel treatment methods will generate forest residues in large volumes, which in addition to available logging residues, can be used to produce biofuels and bioproducts. In this study, the techno-economic assessment of three portable systems to produce woodchips briquettes (WCB), torrefied-woodchips briquettes (TWCB) and biochar from forest residues were evaluated using pilot-scale experimental data. A discounted cash flow rate of return method was used to estimate minimum selling prices (MSPs) for each product, to conduct sensitivity analyses, and to identify potential cost-reduction strategies. Using a before-finance-and-tax 16.5% nominal required return on investment, and a mean transport distance of 200 km, the estimated delivered MSPs per oven-dry metric ton (ODMT) of WCB, TWCB, and biochar were $162, $274, and $1044 respectively. The capital investment (16–30%), labor cost (23–28%), and feedstock cost (10–13%) without stumpage cost were the major factors influencing the MSP of solid biofuels and biochar. However, the MSPs of WCB, TWCB, and biochar could be reduced to $65, $145, and $470/ODMT respectively with technologically improved portable systems. In addition, the MSPs of solid biofuels and biochar could be further reduced by renewable energy and carbon credits, if the greenhouse gas (GHG) reduction potentials are quantified and remunerated. In conclusion, portable systems could be economically feasible to use forest residues and make useful products at current market prices while simultaneously reducing potential wildfires and GHG emissions. [ABSTRACT FROM AUTHOR]

Abstract This work investigated the optimization of process parameters in the upgrading of the oil extracted from Scenedesmus obliquus microalgae using a novel nickel-impregnated biochar catalyst. The effects of temperature, dodecane-to-oil mass ratio and pressure on the upgraded liquid-phase biofuel yield were evaluated and optimized by central composite design of the response surface methodology (RSM). The model equation generated from RSM showed that dodecane-to-oil mass ratio and pressure, as well as the quadratic effects of all the three factors, were significant model terms in predicting the yield of upgraded liquid-phase biofuel. Maximum liquid biofuel yield was attained at 246.89 °C, 3.72 (w/w) dodecane-to-oil mass ratio, 3.84 MPa hydrogen pressure and 6 h processing time. Validation runs resulted in an upgraded biofuel yield of 69.4%, which was in close agreement with predicted values generated by RSM. The upgraded biofuel comprised of 100% green liquid hydrocarbons containing 94% alkanes and 6% alkenes. Its main fuel properties, such as heating value (43.78 MJ kg−1), elemental composition, density, and viscosity, exceeded those of the fatty acid methyl ester standard and were found comparable to those of petroleum diesel. More importantly, the results of the ultimate analysis and confirmed by the findings from Fourier transform infrared and gas chromatography – mass spectroscopy analyses, showed significantly low oxygen and nitrogen content and absence of sulfur in the upgraded biofuel. Graphical abstract Image Highlights • Novel catalyst was synthesized from rice hull biochar. • The catalyst was used to upgrade Scenedesmus obliquus oil to high-quality biofuel. • Response surface methodology was used to optimize biofuel yield. • High optimum biofuel yield at 69.4 wt. % was obtained. • The biofuel consisted of 100% green liquid hydrocarbons and HHV of 43.78 MJ kg−1. [ABSTRACT FROM AUTHOR]

Highlights • Uncertainty in market prices drives financial outcomes. • Monte Carlo simulation allows uncertainty to be quantified. • Biochar-only production offers a potentially profitable venture. • Biofuel-biochar coproduction requires RINs to achieve financial success. Abstract A comparative techno-economic analysis of two different thermochemical biomass conversion pathways was conducted to examine the effects of fuel price and other variables on project financial performance. Monte Carlo simulation was used to quantify the effects of uncertainty and volatility of ten critical variables: biofuel, biochar and feedstock prices, discount rate, capital investment, labor cost, loan terms, feedstock drying, and biofuel and biochar conversion rates. Market prices for biofuel and biochar have the largest impact on net present value (NPV) of any variable considered, due in part to the high levels of uncertainty associated with future prices of both. Across the ranges of input values for these variables in simulation analysis, hearth-based pyrolysis biochar production had the highest likelihood of profitability with a mean NPV of $41.5 million and only 20% of outcomes resulting in a net loss, while 68% of outcomes for auger-based biochar-biofuel coproduction represented a financial loss, including a mean NPV of -$24.2 million. However, when additional revenue from Renewable Identification Numbers (RINs) credits generated by biofuel production is considered, financial outcomes of biochar-biofuel coproduction improve to 50% likelihood of experiencing a net loss. Findings of the very strong impact of market prices on financial outcomes, relative to other important technical and economic variables, can inform effective targeting of future renewable energy policy, as well as the design of future techno-economic analyses, which do not currently focus on the effect of market prices on profitability. [ABSTRACT FROM AUTHOR]

This study investigates the effect of feedstock drying on the emissions of polycyclic aromatic hydrocarbons (PAHs) associated with the particulate matter (PM) produced during the co-generation of biochar and bioenergy. Raw pyrolysis volatile mixtures were generated from the pyrolysis of rice husk at 400, 500, 600, 700, and 800 °C using a laboratory-scale continuous pyrolysis-combustion system and combusted at 850 °C. PM samples from the combustion were collected and analysed for 15 priority PAH species with a gas chromatography/mass spectrometer (GC/MS). It was found that the utilization of the as received (AR) rice husk resulted in significantly greater energy-based yields of PM 10 (1.2 times at 400 °C and 1.6 times at 800 °C) than the dried rice husk. The majority of the increase was of the PM 2.1-10 size fraction. The PM-bound PAH concentration was found to be 2.1 and 2.8 times higher for the AR rice husk at 400 and 800 °C, respectively. This resulted in a significant increase in the energy-based yield of PAHs over the entire volatile production temperature range for the AR rice husk. Nevertheless, the majority of the PM-bound PAH species generated from the AR rice husk consisted of 2 and 3 ring PAHs (naphthalene, acenapthylene, and acenaphthene) with relatively low toxicity. The concentration of 4, 5, and 6 ring PAHs was generally lower than that generated from the dried rice husk. This resulted in the benzo( a )pyrene-equivalent toxicity of the PM generated from the AR rice husk being lower than the dried counterpart. [ABSTRACT FROM AUTHOR]

The effect of three operating parameters (peak temperature, pressure, and pyrolysis atmosphere) during the slow pyrolysis of three biomass sources (corn stover, vine shoots, and two-phase olive mill waste) was extensively analyzed. A 2-level full factorial design of experiments was adopted to assess the effect of the above-mentioned factors on the potential stability of biochar as well as the yields of the main pyrolysis products. To evaluate the effect of the biomass feedstock, the design was divided into three blocks (one per biomass feedstock). Results from the statistical analyses indicated that the properties of biochar related to its potential stability were mainly affected by the peak temperature and, to a lesser extent, the biomass feedstock. A significant increase in the yield of produced gas was observed when pressure was raised. This increase in the total gas yield was in part due to a higher release of CO, CH 4 , and H 2 . Using a pyrolysis atmosphere of CO 2 (instead of N 2 ) did not result in any remarkable change in neither the distribution of the pyrolysis products nor the potential stability of biochar. However, when CO 2 was used as carrier gas, a significant increase in the yield of CO, at the expense of produced CO 2 , was observed. The findings reported herein suggest that processing biomass through pressurized slow pyrolysis under CO 2 atmosphere is interesting to simultaneously obtain two valuable products: a biochar with an appropriate carbon sequestration potential, and a produced gas with an appropriate composition for energy recovery purposes. [ABSTRACT FROM AUTHOR]

Highlights • Biomass origin and structure affect composition and yield of pyrolysis biochar. • Operating conditions of thermal treatment affect composition and yield of pyrolysis biochar. • Further pyrolysis reactions modify young biochar structure and release gas products. • A predictive kinetic mechanism of biomass pyrolysis accounts for all these effects. • Large collection of literature experimental data supports the validation of the kinetic mechanism. Abstract Biomass is increasingly being recognized as a promising carrier for both heat, energy and chemicals production. However, several aspects still require intense research activity towards a better design and optimization of industrial combustors, gasifiers and pyrolyzer. The objective of this work is to update the CRECK kinetic mechanism of biomass pyrolysis, allowing a better prediction of both yield and composition of the solid residue (biochar). Moreover, further model modifications allow to better describe the variability of hemicellulose in different biomass. To this end, a large set of literature experimental data is collected and organized into a database, which is used to further tune and validate the proposed kinetic mechanism. Although the kinetic model maintains the previous agreement in respect of the rate of biomass pyrolysis, formation and distribution of gas and tar products, the novelty of this work is the greater attention to the predictions of biochar yield and composition, in a wide range of operative conditions. The model describes the solid residue as a mixture of pure carbon together with lumped metaplastic compounds, which represent the whole range of oxygenated and hydrogenated groups bonded to the carbonaceous matrix. These metaplastic species are released to the gas phase with their own kinetics and describe the change of both mass loss and elemental composition of the biochar. These comprehensive predictions of biochar composition are crucial for an accurate description of the successive oxidation and gasification processes. [ABSTRACT FROM AUTHOR]

Highlights • Compared to pyrolysis temperature feedstock types has obviously effects on biochar physical properties and inorganic N holding ability. • High pyrolysis temperature significantly enhanced CEC,pH,C and organic matter content but decreased nutrient element content. • Biochar derived from herbaceous biomass had relatively lower yield and C content compared with that of wooden biomass at the same pyrolysis temperature. Abstract Biochar not only provides an important way to utilize agricultural and forestry waste, but also plays an important role in soil improvement and soil carbon sequestration. This study mainly investigated the effect of pyrolysis temperatures(300, 500 and 650 °C) and feedstock types including Banana Leaf (BL), Banana Stalk (BS), Banana Pseudo stem (BP), Sugarcane Leaf (SL), Sugarcane Stalk (SS), Cassava Stem (CS), Mulberry Stalk (MS), and Eucalyptus Branches (EB) on the biochar properties an its inorganic N holding ability. The results showed that the physical properties of biochar were more affected by agricultural and forestal residues types e.g.; herbaceous feedstock materials resulted in lower surface area (2–70 m2/g) while woody materials obtained relatively higher surface area (200-380 m2/g). However, the chemical properties of biochar were affected by pyrolysis temperature, as results indicated that BL biochar obtained pH 10.0 at 650 °C, while 8.45 at 300 °C, BS got highest CEC value 13.79 cmol kg−1 at 650 °C, while 6.83 cmol kg−1at 300 °C. NH 4 +-N sorption amount was ranging from 609.59 to 2040.40 mg/kg by different biochars, BS biochar adsorbed the highest amount of NH 4 +-N (1668.11 to 2040.4 mg/kg) among all the feedstock materials. Biochar derived from herbaceous biomass had relatively lower yield and C content as compared with that of wooden biomass. However, herbaceous biochars showed relatively better chemical properties than that of wooden biochars. The inorganic nitrogen holding ability of biochar was significantly affected by feedstock resources. [ABSTRACT FROM AUTHOR]

Highlights • Optimal biochar (∼39%) and bio-oil (∼19%) yields were obtained at 500 °C. • Basic functional groups on biochar surface were increased with higher temperature. • Acidic and carboxyl groups drastically reduce in biochar at HHT (700 °C). • Biochar produced at high temperature with fine particle size has higher stability. • Cost-benefit analysis showed the economic viability of biochar saleable system for all scenarios. Abstract In this study, the slow pyrolysis of rice husk was conducted by using a split-tube furnace under a nitrogen environment to investigate the influence of various pyrolysis conditions and biomass particle sizes on products yield distribution as well as physicochemical characteristics and surface chemistry of produced biochars. Results revealed that temperature has a more pronounced influence on products yield compared to the other operational conditions. The biochar yield decreases from 57.13 ± 5.37% to 37.19 ± 2.05% and gaseous phase yield increase from 25.64 ± 0.93% to 42.50 ± 4.58% with temperature increase from 300 °C to 700 °C. The surface chemistry of produced biochar varies widely as the distribution of different functional groups on its surface influenced by operational conditions and biomass particle size; above 500 °C the intensity of FTIR vibrational peaks reduces abruptly. FTIR, SEM, elemental composition and surface area results indicate that biochar synthesized under higher pyrolysis temperature, extended retention time and, lower heating and gas flow rates with fine biomass particle size has utility as a potential C-sequestration and remedial agent to mitigate global climate change and adsorption of environmental pollutants, respectively. Furthermore, biochar has potential application as a renewable solid bio-fuel source due to higher calorific values. A cost-benefit analysis indicates that the viability of biochar saleable product system is more economical with an annual profit of 138,533$ for the low scenario, when the presumed unit processes 2500 tons y−1 of biomass. In a comparison to other presumed scenarios, this system is more feasible in areas where low-cost RH biomass waste is available abundantly such as in rice production and processing areas. The profitability of this system increases further by accounting pyrolysis-gas energy value that reduces operational cost. For the optimization of biochar economical yield with desired properties, this work provides insight knowledge. [ABSTRACT FROM AUTHOR]

This paper presents the results regarding the parametric optimization and characterizations on codensification of Eucommia ulmoides Oliver stem using biochar and bio-oil as additives. The results reveal that the relative importance of different parameters contributing to the pellet physical stability follows the order of: particle size > bio-oil content > biochar content > pressure > bio-oil type, and smaller particles size (0.1–0.3 mm) is critical for the formation of durable pellets. The biochar functioned as the fuel promoter and improved the higher heating value and energy density, however, caused poor physical stability by secondary size reduction during densification. The apple tree branch pyrolysis oil acted as an effective binder, improved the surface morphology and enabled strong interlocking of the particles, therefore, enhanced the physical stability. Above all, codensification of Eucommia ulmoides Oliver stem with biochar and bio oil generated pellets with excellent physical stability and moisture resistance. The pellets also showed better fuel characteristics than the Eucommia ulmoides Oliver stem pellets, and the cost is significantly lower than the char pellets. With comprehensiveness, these results can guide the future industrial implementation of codensification technology for the production of clean, sustainable, and efficient fuel with low cost. [ABSTRACT FROM AUTHOR]

The versatility of several N-doped biochar-supported metal catalysts (M/N-BioC) derived from vineyard pruning waste, to promote circular bioeconomy, was evaluated in catalytic transfer hydrogenation (CTH) of furfural (FF), electrocatalytic oxygen reduction and evolution reactions (ORR and OER). The CTH of FF to prepare high valuable chemicals was performed in the presence of formic acid as hydrogen donor at 160 °C, reaching high conversion (up to 80 %) and selectivities towards furfuryl alcohol (ca. 88 %), establishing a promising catalytic route to valorise a biomass platform molecule using 3d-transition metal-based catalysts in absence of molecular hydrogen. The prepared materials also demonstrated moderate ORR electrocatalytic performance in alkaline medium with diffusion-limiting current densities between − 3.48 (Co/N-BioC) and − 1.27 mA cm−2 (Cu/N-BioC) and potential onset values of 0.88 ≥ E onset ≥ 0.66 V vs. RHE. Additionally, the materials tested showed selectivity towards indirect pathway in which O 2 is reduced to H 2 O 2 and then further reduced to water with the number of electrons transferred per O 2 molecule ranging from 2.1 to 3.6 electrons. The materials also presented moderate OER electrocatalytic performances in alkaline medium, with overpotential values between 0.48 (Co/N-BioC) and 0.63 V vs. RHE (Fe/N-BioC) and maximum current densities between 0.28 (BioC) and 42.60 mA cm−2 (Co/N-BioC). This research contributes to the development of a new type of promising (electro)catalyst based on biomass residue for biomass valorisation and energy conversion as a promising contribute to the future of biorefineries implementation. [Display omitted] • Novel metal-supported N-doped biochar catalysts obtained from vineyard pruning waste (VPW). • Selective production of the industrially valuable furfuryl alcohol from furfural without external H 2. • Metal-supported N-doped biochar were successfully applied as ORR and OER ECs. • (Electro)catalysts from VPW for biomass valorisation and energy conversion for future biorefineries. [ABSTRACT FROM AUTHOR]

Biochar is the carbon-rich solid product derived from thermochemical processing of biomass. Its application to soil can sequester atmospheric carbon, leading to negative net emissions, while also improving agricultural yield. Biochar-based carbon management networks thus have the potential for scalable contributions to climate change mitigation efforts. However, it is necessary to allocate biochar of suitable quality to appropriate sinks, based on contaminant tolerance limits of soil. In this work, the network is modelled as a bi-objective mixed integer linear programming model, with profit and carbon sequestration as the objective functions. The model calculates the optimum allocation of biochar such that their prescribed limits for the contaminants are met. A Philippine case study is solved under different scenarios to illustrate the practical use of the developed model. The results provide useful insights for the rational decision-maker to arrive at the most preferred solution among the Pareto optimal choices. Comparison of the two scenarios substantiate the significance of unique sequestration factor as an additional parameter in the model to account for the interactions between the soils and biochars so that the maximum sustainable potential of biochar in climate change mitigation can be properly assessed. [ABSTRACT FROM AUTHOR]

New analytical tools that enable analytical laboratories to quantitatively and qualitatively analyze alternative and renewable solid biofuels are needed. Fourier transform infrared (FTIR) spectroscopy was applied in combination with a two-step multivariate modelling procedure. In the first instance, a C&RT (classification and regression trees) model was developed and validated for use in distinguishing different biomass origins and possible sources of contamination. Once the solid fuels were correctly identified, the model was used to predict the concentrations of individual components using partial least squares regression (PLSR) models. The first C&RT model differentiated between the different classes of biofuel origins. Using the absorption intensity in the wavenumber range of 1800–400 cm −1 , the prediction had a recovery of between 92% and 99%. The second C&RT model differentiated between the possible sources of contamination, which could be predicted with a recovery between 76% and 91% based on the FTIR results. Accuracy profiles based on the analysis results of validation samples were then calculated to prove the reliability of the developed regression models. The developed spectroscopic methods rapidly and adequately determined (qualitative analysis) the origin of the biofuels and indicated the possible source of contamination. The effects of two spectral data pre-processing methods (PQN & SNV) were also compared based on the accuracy of the developed models. [ABSTRACT FROM AUTHOR]

Abstract: This work evaluated the novel application of biochars derived from potassium (K)-rich feedstock (banana peels (BB) and cauliflower leaves (CB)). The sorptive property of the produced biochars was evaluated with multi-element [Copper (Cu(II)), Cadmium (Cd(II)) and Led (Pb(II))] sorption experiments. Morphologies of the pre- and post-sorption samples were characterized using SEM/EDS and XRD spectra analyses. The produced biochar was further subjected to mono-element sorption studies to explore the effect of the pH value of the sorbate solution on the removal efficiency of Cu(II), Cd(II) and Pb(II) ions. Biochar productivity was noticeably high (61.44 and 64.66% for BB and CB, respectively) due to the catalytic action of K during the pyrolytic conversion of the feedstock. K-minerals were the predominant on the XRD patterns of both biochars. Metal sorption capacity of BB was much greater than that of CB due to its higher electrostatic attraction, which was the predominant mechanism governed sorption process. Sorption of metal ions onto BB and CB was pH-dependent as the sorption capacity increased significantly with the increase of the pH value of sorbate solutions (6.0 with Cu(II), Pb(II) and 8.0 with Cd(II)). Dynamics of metal ions sorption onto biochars showed competitive sorption following the order: Pb(II) > Cu(II) > Cd(II). [ABSTRACT FROM AUTHOR]

Cement production contributes over 5% of global greenhouse gas (GHG) emissions. Heavy manufacturing industries like cement production continue to rely primarily on fossil fuels for primary energy production and have limited renewable energy options. This study used life cycle assessment (LCA) to quantify the potential environmental benefits of substituting bio oil and biochar from mobile fast pyrolysis of forest harvest residues for fossil fuels in an average cement plant in Québec, Canada. Bioenergy Pathways for cement production showed reductions in non-biogenic GHG emissions as high as 50% relative to the Reference Pathway for energy provision in the plant. The use of bio oil and biochar from mobile pyrolysis units increased the share of renewable energy in the cement plant energy mix from just under 15% in the Reference Pathway up to 47% and 73% in the Bioenergy Pathways, depending on the scale of fuel substitution. Bioenergy Pathways also led to decreases in potential acidification, ozone depletion, respiratory effects, and eutrophication impacts, with slightly higher contributions to smog-forming emissions. The environmental and socioeconomic sustainability of fast pyrolysis units are strongly linked to the availability of, and proximity to, sufficient forest harvest residues, such that regional-level analysis of feedstock availability is needed prior to wide-scale deployment of these systems. [ABSTRACT FROM AUTHOR]

[Display omitted] • A new technique was developed to measure the kinetics of fast pyrolysis up to 380 K/s. • The decomposition activation energy was greatly reduced in fast pyrolysis conditions. • TGA-derived kinetic parameters failed to represent the fast pyrolysis process. • Fast pyrolysis enhanced bio-oil products by minimizing secondary reactions. • Fast pyrolysis slightly increased pore volume and surface area of biochar product. Converting algal biomass to clean energy via a thermochemical pathway is an emerging technique for tackling environment and energy issues. Traditional kinetic studies on biomass pyrolysis employ a thermogravimetric analyzer (TGA) which heats the biomass sample at a rate of 0 ∼ 2 K s−1, so TGA could only replicate the thermal behavior of the biomass sample in a fixed bed reactor. However, biomass samples can be heated at a rate over ∼102 K s−1 in industrial reactors, including fluidized beds, spouted beds, or rotary kilns due to the direct contact between biomass samples and the solid heat carriers, thus TGA is incapable to reproduce these thermal behaviors. In view of the limitation of TGA in fast heating cases, this study has developed a fast-heating thermo-balance consisting of wire-mesh and wireless power supply technique to investigate the kinetics of fast pyrolysis. Seaweed is fast-growing and can be considered a promising feedstock for biofuel production. Therefore, this study selected seaweed as representative biomass waste and compared the pyrolysis behaviors under both slow and fast pyrolysis conditions. A key finding was the TGA-derived kinetic parameters were unable to describe the pyrolysis rate under fast pyrolysis conditions with significant overestimation. When compared to slow pyrolysis, fast pyrolysis can increase bio-oil yield by about 3–17%, but the N- and S-containing compounds in the bio-oil increase by about 1.1% and 0.15% respectively at a final temperature of 700 °C. Fast pyrolysis produced about 16–53% more CO 2 than slow pyrolysis above a final temperature of 500 °C. The polarity of compounds in biochar was reduced with increasing temperature and the presence of CaO was only found in biochar at a high temperature of 700 °C. The specific surface area of biochar was higher under fast heating pyrolysis (5.534–7.469 m2 g−1) than that under slow heating pyrolysis (4.076–6.414 m2 g−1). [ABSTRACT FROM AUTHOR]

• Co-pyrolysis is an eco-friendly sewage sludge treatment process. • Mixing co-feed biomass with sewage sludge reduced the environmental burden. • All examined scenarios reduced the global warming potential. • All scenarios achieved positive energy balance with product energy recovery. • Transportation distance significantly affects scenarios' environmental outcome. To address the gaps in current research on sewage sludge (SS) pyrolysis, this study examined the feasibility of the environmental and energy demands of co-pyrolysis as an SS treatment process. The analyses included a cradle-to-gate life cycle assessment, carbon emission and credit assessment, energy recovery calculations, and sensitivity analysis. Sawdust (SD) and wheat straw (WS) were chosen as co-feeds for the co-pyrolysis scenarios; four mixing ratios (20, 40, 60, and 80 wt%) were examined for each co-feed. The functional unit was 1000 kg of bio-oil. Mixing the co-feed biomass with SS reduced the overall environmental burden by 58–83 %; WS/SS co-pyrolysis performed better than SD/SS in this respect. All examined scenarios reduced the global warming potential (GWP) and achieved a net positive energy balance; SD/SS co-pyrolysis was more desirable owing to high energy recovery. The additional gas turbine operation generated a process energy demand of 23–224 %. GWP and terrestrial ecotoxicity potential are indicators that are significantly affected by co-feed material transportation. Sensitivity analysis revealed that the transportation of feedstock and pyrolysis products should be prioritised to limit the environmental burden of the process. Co-pyrolysis is an eco-friendly SS treatment method, and its economic viability should be further investigated. [ABSTRACT FROM AUTHOR]

Inorganic minerals are important compositions in biochars, but their roles in biochar functions are investigated limitedly, which restricted our understanding on biochar applications. This study applied different biomasses to produce biochars. Their properties as well as sorption to bisphenol A (BPA) were studied, with a major focus on the role of inorganic compositions. Oxalates, carbonates, as well as KCl crystals were observed in the produced biochars depending on the feedstocks and temperatures. Oxalates and KCl formed at relatively low temperature (200–300 °C), while carbonates generally formed at pyrolysis temperature above 400 °C. The separated insoluble crystal particles and the dissolved salts have limited contribution to the apparent BPA sorption, but ash content removal altered BPA sorption. The potential impact of inorganic composition to BPA sorption should be resulted from biochar properties. Based on biochar characterization and sorption comparison before and after ash removal, we proposed that the formation of inorganic mineral compositions in biochar particles may have blocked the inner pores, which limited the significance of these sorption sites. As a result, the interactions of BPA and biochars were mostly determined by biochar surface functional groups. The acid treatment removed most of the inorganic compositions, and exposed more sorption sites, which consequently increased BPA sorption. Biochar sorption capacity may be further increased if the accessibility of the inner pores could be enhanced. [ABSTRACT FROM AUTHOR]

Hydrothermal carbonisation was used to upgrade fuels from two types of agro-industrial wastes: olive tree trimmings and olive pulp. Hydrochar yield, elemental and proximate analyses, thermal stability, higher heating value (HHV), and energy yield at different reaction temperatures (120, 150, 180, 200, 220, 235 and 250 °C) and solid load (biomass to water ratios − B/W − equal to 7, 10, 15 and 25%) were assessed for a fixed reaction time of 30 min. HHV varied linearly with hydrochar mass yield and reaction temperature in the temperature range 180–250 °C. Solid load proved to be a crucial parameter in determining the energy properties of hydrochars. The higher B/W, the higher were the degree of carbonisation (in terms of fixed and total carbon), the hydrochar HHV, and the hydrochar yield. Elemental analysis showed that during HTC, olive pulp samples underwent a greater degree of carbonisation when compared to the corresponding olive tree trimmings residues. High solid load and high reaction temperature promoted secondary char formation. Secondary char showed a sphere-like structure formed by overlapping layers. EDS microanalysis showed that secondary char is characterised by a significantly higher carbon content than parent primary char, thus confirming its contribution towards enhancing the HHV of hydrochars. [ABSTRACT FROM AUTHOR]

Energy recovery via waste utilization in gasification process is an attractive alternative energy source which is expected to supersede part of the energy from fossil fuels. To enhance the H 2 -rich syngas production from residual biomass mixed with polymeric waste, a dual stage process involving catalytic steam gasification and tar cracking was integrated as a promising alternative technology for clean fuel production. Generally, the presence of tar causes syngas degradation and has been identified as one of the major impurities from the gasification process. This study shows the results obtained from an integrated process with optimization process conditions to enhance H 2 -rich syngas yield. Nickel and dolomite were used as cheap and effective catalysts in fluidized and fixed bed gasifiers respectively, which resulted in high-quality syngas production with a maximum hydrogen yield of 284.1 g H2 kg −1 feedstock and carbon conversion efficiency (CCE) of 92.4 wt%. Furthermore, the study eventuates the upgrading of the bio-char to carbon nano-tubes (CNT). In fact CNT could be further employed either in gasification process or as electrocatalyst supporting materials for low-temperature fuel cells. [ABSTRACT FROM AUTHOR]

Dedicated bioenergy crops grown on marginal lands such as reclaimed mine lands and other non-arable lands are auspicious cellulosic sources for sustainable bioenergy production. In this study, characterization of pyrolysis products were documented for two dedicated bioenergy crops grown on reclaimed coal-mine lands in West Virginia. Two clonal varieties (Private and Public varieties) of Miscanthus ( Miscanthus x giganteus ) and two varieties (Bomaster and Kanlow varieties) of Switchgrass ( Panicum virgatum L ) were used in this study. The oven-dried samples were pyrolyzed in a fixed-bed batch reactor under an inert condition and at a temperature of 500 °C to produce biochar and bio-oil (vapor condensate). The pyrolysis product, energy and carbon conversion yields were calculated. Additionally, biochar and bio-oil were characterized for elemental composition, volatile, ash and calorific values. Results showed that there was no significant difference in the biochar yields (about 30.00% yield) obtained from the clonal varieties of Switchgrass and Miscanthus. The bio-oil yields were in the range of 45.00–51.00% with the Miscanthus (Private variety) having the highest bio-oil yield of 50.61%. The carbon content of the biomass, biochar and bio-oil were found to be 46.80–48.02%, 77.72–80.23% and 54.68–59.68%, respectively. Average calorific values were found to be 19.49 MJ/kg, 29.01 MJ/kg and 24.98 MJ/kg for the biomass, biochar and bio-oil, respectively. Results for the surface chemistry of the biochars showed carbon and oxygen to be the major chemical constituents of the surfaces of the biochars. Carbon dioxide (CO 2 ), nitrogen (N 2 ) and carbon monoxide (CO) were found to be the major components of the non-condensable gas and the CO:CO 2 ratio showed that the non-condensable gas cannot be used as a fluidizing medium. [ABSTRACT FROM AUTHOR]

The catalytic and non-catalytic fast pyrolysis process for converting Kraft pulp paper waste into bio-oil and biochar was studied. Catalysis free pyrolysis of untreated Kraft pulp resulted on good yields of bio-oil (39% at 400 °C), showing a relative high concentration of levoglucosan, while phosphoric acid-pretreated pulp produced lower yields of bio-oil (max. value 14% at 350 °C) being levoglucosenone the main component. The catalytic pyrolysis of pretreated pulp employing silica led to a high yield of the liquid fraction (57% at 400 °C) with a high selectivity to levoglucosan. The biochar produced from as received pulp could be envisaged for soil amendment. It displayed a relatively high specific surface area, showing micro and mesoporosity. Besides, no phytotoxic effect of the biochar obtained at 350 °C was recorded. [ABSTRACT FROM AUTHOR]

Biochar derived from orchid tree leaves is utilised as the fuel of a direct carbon solid oxide fuel cell (DC-SOFC), with yttrium stabilized zirconia (YSZ) as electrolyte and cermet of silver and gadolinium doped ceria (Ag-GDC) as the material of both cathode and anode, operating without any liquid medium or feeding gas. The performance of the DC-SOFC operated on the leaf char is higher than that operated on the best reported carbon fuel for DC-SOFCs, Fe-loaded activated carbon. XRD, Raman spectroscopy, SEM and EDX are applied to characterize the leaf char. It turns out that the leaf char is with porous structure and there is much Ca along with some K and Mg uniformly distributing in the leaf char. The effects of the naturally existing alkaline earth metal and alkaline metal and their distribution on the performance of the DC-SOFCs operated on the leaf char are analyzed in detail. [ABSTRACT FROM AUTHOR]

It is a thorny issue to properly handle heavy metals-contaminated livestock manure. The transformation of the heavy-metals-contaminated livestock manure into valuable carbonaceous material has motivated our curiosity. Herein, this study provided a new concept of valorizing the contaminated manure into heavy metals-containing biochar catalysts for catalytic fast pyrolysis/gasification of biomass to manufacture phenols-enriched biofuel and H 2 -rich gas. The versatile Cu, Pb, and Zn-containing cow manure biochar catalysts were newly prepared from Cu, Pb, and Zn-contaminated livestock manure through a single-step energy-efficient thermal process. Cu and Pb-containing biochar catalysts prepared at 500 °C were more favorable for the production of bio-oil and organic phase, and up to 41.20% of phenolics was found in the bio-oil by using the Pb-containing biochar catalyst. The highest gas yield (51.55 wt%), equaling to 550 NmL/g WS , was observed in the presence of Cu-containing biochar catalyst prepared at 500 °C. Meanwhile, the H 2 concentration was elevated to 35.85 vol%, and the H 2 yield was correspondingly promoted to 197 NmL/g WS. Additionally, a deep knowledge of the reaction mechanisms regarding the catalytic fast pyrolysis/gasification of biomass over heavy metals-containing biochar catalysts was elucidated. Overall, this study provided a novel way to valorize heavy metals-contaminated livestock manure into effective biochar catalysts for catalytic fast pyrolysis/gasification of biomass to produce phenols-enriched bio-fuel or H 2 -rich gas. [Display omitted] • A new concept of valorizing heavy metals-contaminated manure into biochar catalysts. • Cu, Pb, and Zn-containing manure biochar catalysts were prepared at 500 °C and 800 °C. • Pb/CMBC-500 and Cu/CMBC-500 favored the production of bio-oils and liquid organics. • Up to 41.20% of selectivity toward phenolics was obtained by using Pb/CMBC-500. • The highest gas yield (51.55 wt%), i.e., 550 NmL/g WS , was gained over Cu/CMBC-500. [ABSTRACT FROM AUTHOR]

Two different pathways for utilizing Miscanthus giganteus biochar were evaluated, namely, for the production of sustainable solid biofuels and as a precursor of high surface area activated carbons. Biochars were produced through a simple thermochemical conversion method via pyrolysis at 400, 500, 600, and 800 °C. The obtained biochars and raw biomass were characterized in detailed by proximate and ultimate analyses. The thermal behaviour and structural and strength properties were evaluated. The chemical composition (cellulose, hemicellulose, and lignin content) of raw Miscanthus giganteus was investigated. The biochars afforded a sufficient higher heating value (HHV) of up to 32 MJ kg−1. Activated carbon was obtained via chemical activation with KOH at 800 °C. The effect of the pyrolysis temperature on the surface properties of the activated carbons was investigated over a wide temperature range. The resulting activated carbons were characterised by N 2 adsorption–desorption at −196 °C and by determining the pH of aqueous extracts. As a potential application, the obtained activated carbon series was used for the adsorptive removal of isoproturon from aqueous media. The adsorption capacity was as high as 384 mg g−1 and depended on the pore size distribution of the activated carbons. The conducted study follows the current trend of search for novel energy sources and water purification. [Display omitted] • Miscanthus giganteus biochar was produced by pyrolysis at 400–800 °C. • Pyrolysis temperature affected properties of biochar and activated carbon. • The higher heating value of biochar pyrolysed at 600 °C was 32.8 MJ kg−1. • Biochar was used as precursor of activated carbon with high specific surface area. • Activated carbon efficiently adsorbed isoproturon from aqueous solution. [ABSTRACT FROM AUTHOR]

Biochar, i.e. pyrolysed biomass, as a soil conditioner is gaining increasing attention in research and industry, with guidelines and certifications being developed for biochar production, storage and handling, as well as for application to soils. Adding water to biochar aims to reduce its susceptibility to become air-borne during and after the application to soils, thereby preventing, amongst others, human health issues from inhalation. The Bagnold model has previously been modified to explain the threshold friction velocity of coal particles at different moisture contents, by adding an adhesive effect. However, it is unknown if this model also works for biochar particles. We measured the threshold friction velocities of a range of biochar particles (woody feedstock) under a range of moisture contents by using a wind tunnel, and tested the performance of the modified Bagnold model. Results showed that the threshold friction velocity can be significantly increased by keeping the gravimetric moisture content at or above 15% to promote adhesive effects between the small particles. For the specific biochar of this study, the modified Bagnold model accurately estimated threshold friction velocities of biochar particles up to moisture contents of 10%. [ABSTRACT FROM AUTHOR]

Bio-char, produced from biomass pyrolysis, can be pelletized to improve its undesirable characteristics, such as low bulk and energy densities, poor transportation and storage properties, and troublesome to co-fire with coal. In this study, rice husk char was compressed into pellets with four kinds of binders (lignin, starch, calcium hydroxide and sodium hydroxide). The compressive process, mechanical strength, basic fuel properties, and combustion characteristics were investigated to elucidate the effect of binders on the properties of bio-char pellets. Results showed that starch pellets had good hydrophobicity, but low volume density and poor mechanical strength. The softening and morphological transition of lignin during compression may account for the high elastic modulus and good bonding of lignin pellets. The low saturated moisture content of Ca(OH) 2 pellets is mainly ascribed to its hydration. NaOH pellets showed the highest compressive strength among all pellets, and also exhibited the highest moisture uptake that may worsen the handling and storage treatment of bio-char. Compared with raw bio-char, bio-char pellets had a lower ignition temperature, wider temperature interval, and higher oxidation activity according to the thermogravimetric analysis. The lignin and Ca(OH) 2 pellets showed lower compression energy consumption and moisture uptake, enhanced mechanical strength and promoted combustion performance, which demonstrated more desirable properties for utilization as biofuels. [ABSTRACT FROM AUTHOR]

Severe environmental and ecological problems have resulted due to the unharvested Miscanthus lutarioriparius biomass in Dongting Lake, the largest miscanthus production hub in the world. Pyrolyzing the miscanthus biomass to produce biochar is a win–win strategy for abandoned miscanthus biomass utilization and Cd-polluted paddy restoration in Hunan. However, the sorption efficiency of biochar requires improvement by modification. It is theoretically possible that biological modification by fungi and bacteria as well as a modification technique using Fe will increase the Cd sorption capacity. Thus, the current study used two biomass biomodification techniques, FB (fungal decomposition) and BB (bacterial digestion), and one biochar Fe-modification technique (by NH 3 ·H 2 O–FeCl 3), and determined their ability to improve biochar quality. The results showed that the biomass modification by FB and BB increased the Cd sorption capacity of the derived biochar. The Cd sorption capacity of FB-derived biochar (36.4 mg g−1) was significantly greater as compared to BB-derived biochar (30.2 mg g−1) and the unmodified control (14.8 mg g−1). This improvement can be further optimized by Fe-modification, with an average potential of 22.2% (13.5–32.3%). The increased Cd sorption capacity is attributed to (in descending order of importance) the increased amount of ash, specific surface area, amount of alkaline functional groups and phenolic hydroxyl groups, and the pH of the biochar after modification. The Fe-FB-derived biochar pyrolyzed under 650 °C was tested and exhibited the highest Cd sorption capacity, at 64.9 mg g−1. Biomodification of M. lutarioriparius biomass and its subsequent pyrolysis to produce biochar will simultaneously provide economic and ecological benefits. This approach provides a model for the integrated production of food and energy from biomass. [Display omitted] • Biomass modification strongly increases the Cd sorption capacity of biochar. • Fungal decomposition and bacterial digestion are effective modification techniques. • The Cd sorption capacity of biochar can be further optimized by Fe modification. [ABSTRACT FROM AUTHOR]

Renewable energy sources such as biomass have been proven to be one of the promising sustainable alternatives to fossil fuels. However, using biomass directly as a fuel is less attractive due to its high moisture content, poor grindability, low bulk density, and low energy density nature. Hence biomass can be converted into biochar to overcome these challenges. In this study, biochar was derived from citrus peels biomass by slow pyrolysis over the temperature range of 300–700 °C. The effect of pyrolysis temperature on the quality of citrus peels-derived biochar was examined based on the physical and chemical properties obtained from various analyses. The citrus peels biomass and biochar were characterized by means of higher heating value (HHV) analysis, field emission scanning electron microscopy with energy dispersive X-ray spectroscopy (FESEM-EDX), Fourier transform infrared ray (FTIR) analysis, proximate and thermogravimetric analysis. Based on the characterization results, the potential usage of the derived biochar as a solid fuel was discussed. Results obtained from the pyrolysis experiments indicated that a lower pyrolysis temperature produced a higher char yield. The carbon content and energy content of biochar were found to be increasing with pyrolysis temperature. Biochar produced at 500 °C presented the best fuel properties by having the highest value of HHV and carbon content. The results from this study provided great insights into biomass waste reutilisation to generate value-added biochar for renewable energy production in Malaysia. [Display omitted] • Promising potential for citrus peels biomass to biochar for energy conversion. • Higher heating value of citrus peels biochar comparable to sub-bituminous coal. • Carbon and energy content increased with increasing pyrolysis temperature. • Better combustion stability for biochar of higher pyrolysis temperature. [ABSTRACT FROM AUTHOR]

Biochar additions have been suggested to influence soil microbial communities that, through a cascade effect, may also impact soil fauna. In turn, any direct biochar effects on fauna can influence microbial communities through grazing, physical fragmentation of organic debris (and biochar) and modifying soil structure. If biochar creates a favorable environment for soil microorganisms, it is also plausible for fauna to be attracted to such microbially enriched habitats. However, how soil fauna respond to biochar addition to soil and what are the main factors that drive their behavior has rarely been experimentally addressed. Therefore, the behavior of two mesofauna species was assessed as a result of corn stover biochar (slow pyrolysis at 600 °C) additions to a loamy temperate soil, after preincubation for 2, 17, 31 and 61 d, and related to variations in microbial biomass and activity. Microbial biomass increased by 5–56% and activity by 6–156% with increasing biochar rates for the different preincubation times. Over the incubation time, microbial biomass did not change or increased at most 15% with the different biochar rates, while in turn microbial activity decreased steadily (around 70–80% at day 61). Enchytraeids generally did not show avoidance or preference to biochar when provided with an alternative unamended soil, while collembolans often showed avoidance responses. However, collembolan avoidance to biochar decreased or disappeared in biochar mixtures with higher microbial biomass and water extractable NH 4 -N content, agreeing with the plausible role of microorganisms to potentially attract soil fauna after biochar applications. Avoidance response was mainly explained by environmental preferences of the test species and not by any toxic effect of the biochar in this study. However, avoidance after the application of biochar may still need to be considered due to the potential negative impacts of individuals’ migration on soil ecosystem functioning. [ABSTRACT FROM AUTHOR]

This paper explores the viability of producing energy and agricultural soil conditioners with biochars and bio-oils from the pyrolysis of biomasses that in some cases are potential environmental pollutants. This approach addresses the need to develop sustainable production systems that minimize pollution and soil degradation, and meet the demand for renewable fuels. Large volumes of biomass from different sources are available in Brazil, including Eucalyptus crop residues (CE), castor meal (CM), coconut pericarp (CP), sugarcane bagasse (SB), and water hyacinth (WH). CM char and SB bio-oil are good prospects for energy generation. Characterization using DRIFT, 13 C NMR, and van Krevelen diagrams indicated that after carbonization, aromatic structures were predominant in the biochars produced from the CP, CE, and SB biomasses, while aliphatic groups were abundant in the biochars from CM and WH. Analysis using EPR showed that unpaired electrons were preferentially located on carbon atoms in the case of the CP, CE, and SB biochars, with EPR g values around 2.0030, while the CM and WH biochars presented g values around 2.0035, indicating that the unpaired electrons were closer to oxygen atoms. In terms of bio-oil chemical composition, the most abundant compounds were 3-pyridinol and furans (WH), phenols (CP), and hexadecanoic, octadecanoic, 9,12-octadecenoic (z,z), 3-docosenoic, and 5-docosenoic acids (present only in the CM bio-oil). The bio-oils from SB and CE were quite similar and the main compound was 1,2,6-hexanetriol. The biomass sources studied produced reasonable amounts of bio-oil, and could compete as suitable raw materials for biofuel production. [ABSTRACT FROM AUTHOR]

This work focuses in the application of the hydrothermal carbonization (HTC) technology as a possible moist agro-industrial waste management treatment. Through this technique, olive mill, canned artichoke and orange wastes (OMW, CAW and OJW, respectively) were carbonized in a lab-scale high pressure reactor at different temperatures (200–250 °C) and durations (2, 4, 8 and 24 h) in order to obtain useful bioenergy feedstocks. The effect of the residence time and temperature on the properties of the bio-char obtained was studied through different characterization techniques. Material and energy balances were also performed to determine the potential energy saving of hydrothermal carbonization versus dry thermal treatments like torrefaction (TF). It is found that the moisture content of HTC-hydro-chars decreases as the temperature and duration increase, which implies that wet biomass can be upgraded and, at the same time, dewatered through HTC. The best results are found for the OMW, whose moisture content decreases from over 70% to less than 30% for the experiments carried out under the more severe conditions. Consequently, it is be possible to reach energy savings over 50% by using HTC instead of TF technologies. Regarding the hydro-char properties, the hydrothermal carbonization of the three organic wastes treated leaded to hydro-chars that present carbon contents and heating values closed to those of brown coal and great energy densifications, depending on the type of waste. Accordingly, it can be concluded that it is feasible to manage moist agro-industrial wastes via HTC, which is ostensibly more efficient than TF in terms of energy consumption. [ABSTRACT FROM AUTHOR]

Biochar, also known as black carbon, is a byproduct of biomass pyrolysis. As a low-cost, environmental-friendly material, biochar has the potential to replace more expensive synthesized carbon nanomaterials (e.g. carbon nanotubes) for use in future supercapacitors. To achieve high capacitance, biochar requires proper activation. A conventional approach involves mixing biochar with a strong base and baking at a high temperature. However, this process is time consuming and energy inefficient (requiring temperatures >900 °C). This work demonstrates a low-temperature (<150 °C) plasma treatment that efficiently activates a yellow pine biochar. Particularly, the effects of oxygen plasma on the biochar microstructure and supercapacitor characteristics are studied. Significant enhancement of the capacitance is achieved: 171.4 F g −1 for a 5-min oxygen plasma activation, in comparison to 99.5 F g −1 for a conventional chemical activation and 60.4 F g −1 for untreated biochar. This enhancement of the charge storage capacity is attributed to the creation of a broad distribution in pore size and a larger surface area. The plasma activation mechanisms in terms of the evolution of the biochar surface and microstructure are further discussed. [ABSTRACT FROM AUTHOR]

Biochar obtained from the pyrolysis of corn cob is used as the fuel of a direct carbon fuel cell (DCFC) employing a composite electrolyte composed of a samarium doped ceria (SDC) and a eutectic carbonate phase. An anode layer made of NiO and SDC is utilized to suppress the cathode corrosion by the molten carbonate and improves the whole cell stability. The anode off-gas of the fuel cell is analyzed with a gas chromatograph. The effect of working temperature on the cell resistance and power output is examined. The maximum power output achieves 185 mW cm −2 at a current density of 340 mA cm −2 and 750 °C. An anode reaction scheme including the Boudouard reaction is proposed. [ABSTRACT FROM AUTHOR]

Highlights: [•] Conventional and microwave pyrolysis of biomass has been compared. [•] Conventional pyrolysis produces higher gas yield. [•] Microwave pyrolysis produces more char. [•] Two stages of gas release are seen, first CO & CO2 and second CH4 & H2. [Copyright &y& Elsevier]

Highlights: [•] Properties of products properties obtained during co-pyrolysis were studied with polypropylene addition. [•] Were observed synergistic effects to the product yield from biomass co-pyrolysis process with polypropylene addition. [•] Describe differences in properties of products obtained during co-pyrolysis with polypropylene addition. [•] Were observed relationship among of polypropylene addition and differences in the high heats of products. [ABSTRACT FROM AUTHOR]

Highlights: [•] The performance of HTC and LTP was compared to produce solid fuel from waste biomass. [•] Fuel qualities of the biochars produced from HTC and LTP were investigated. [•] Ash problem related metal contents in two biochars were analyzed. [•] Combustion characteristics of two biochars were determined. [•] Hydrothermally prepared biochar is suitable for use as a solid fuel. [ABSTRACT FROM AUTHOR]