Pyrolysis Conditions Research Articles

Biochar from Co-Pyrolyzed Municipal Sewage Sludge (MSS): Part 2: Biochar Characterization and Application in the Remediation of Heavy Metal-Contaminated Soils.

The disposal of municipal sewage sludge (MSS) from wastewater treatment plants poses a major environmental challenge due to the presence of inorganic and organic pollutants. Co-pyrolysis, in which MSS is thermally decomposed in combination with biomass feedstocks, has proven to be a promising method to immobilize inorganic pollutants, reduce the content of organic pollutants, reduce the toxicity of biochar and improve biochar's physical and chemical properties. This part of the review systematically examines the effects of various co-substrates on the physical and chemical properties of MSS biochar. This review also addresses the effects of the pyrolysis conditions (temperature and mixing ratio) on the content and stability of the emerging pollutants in biochar. Finally, this review summarizes the results of recent studies to provide an overview of the current status of the application of MSS biochar from pyrolysis and co-pyrolysis for the remediation of HM-contaminated soils. This includes consideration of the soil and heavy metal types, experimental conditions, and the efficiency of HM immobilization. This review provides a comprehensive analysis of the potential of MSS biochar for environmental sustainability and offers insights into future research directions for optimizing biochar applications in soil remediation.

Rapid humification of cotton stalk catalyzed by coal fly ash and its excellent cadmium passivation performance.

Due to industrialization, soil heavy metal pollution is a growing concern, with humic substances (HS) playing a pivotal role in soil passivation. To address the long duration of the compost humification problem, coal fly ash (CFA) in situ catalyzes the rapid pyrolysis of the cotton stalk (CS) to produce HS to address Cd passivation. Results indicate that the highest yield of humic acid (HA) (8.42%) and fulvic acid (FA) (1.36%) is obtained when the CS to CFA mass ratio is 1:0.5, at 275 ℃ for 120min. Further study reveals that CFA catalysis CS humification, through the creation of alkaline pyrolysis conditions, Fe2O3 can stimulate the protein and the decomposition of hemicellulose in CS, and then, through the Maillard and Sugar-amine condensation reaction synthesis HA and FA. Applying HS-CS&CFA in Cd-contaminated soil demonstrates a 26.69% reduction in exchangeable Cd within 30days by chemical complexation. Excellent maize growth effects and environmental benefits of HS products are the prerequisites for subsequent engineering applications. Similar industrial solid wastes, such as steel slag and red mud, rich in Fe2O3, can be explored to identify their catalytic humification effect. It could provide a novel and effective way for industrial solid wastes to be recycled for biomass humification and widely applied in remediating Cd-contaminated agricultural soil.

In Situ Pyrolysis of ZIF-67 to Construct Co2N0.67@ZIF-67 for Photocatalytic CO2 Cycloaddition Reaction.

The development of heterogeneous catalysts with abundant active sites is pivotal for enhancing the efficiency of photothermal CO2 conversion. Herein, we report the construction of Co2N0.67@ZIF-67 through the in situ pyrolysis of ZIF-67 under low-temperature pyrolysis conditions. During the pyrolysis process, the crystal structure of ZIF-67 is predominantly preserved concurrently with the formation of Co2N0.67 nanoparticles (NPs) within the ZIF-67 pores. The optimal catalyst Co2N0.67@ZIF-67(450,2) not only possesses high photothermal efficiency but also can efficiently activate CO2. Benefiting from these characteristics, Co2N0.67@ZIF-67(450,2) exhibited significant catalytic activity in the photocatalytic cycloaddition of CO2 and epichlorohydrin. The yield of (chloromethyl)ethylene carbonate reached 95%, which is more than 4 times higher than that of ZIF-67 under visible light irradiation (300 W·m2 Xe lamp, 3 h). This study could offer an alternative approach to enhance the photocatalytic activity of MOFs through low-temperature pyrolysis.

An in situ exploration of how Fe/N/C oxygen reduction catalysts evolve during synthesis under pyrolytic conditions

In pursuing cheap and effective oxygen reduction catalysts, the Fe/N/C system emerges as a promising candidate. Nevertheless, the structural transformations of starting materials into Fe- and N-doped carbon catalysts remains poorly characterized under pyrolytic conditions. Here, we explore the evolution of Fe species and track the formation of Fe–N4 site development by employing diverse in-situ diagnostic techniques. In-situ heating microscopy reveals the initial formation of FeOx nanoparticles and subsequent internal migration within the carbon matrix, which stops once FeOx is fully reduced. The migration and decomposition of nanoparticles then leads to carbon layer reconstruction. Experimental and theoretical analysis reveals size-dependent behavior of FeOx where nanoparticles below 7 nm readily release Fe atoms to form Fe–N4 while nanoparticles with sizes >10 nm tend to coalesce and impede Fe–N4 site formation. The work visualizes the pyrolysis process of Fe/N/C materials, providing theoretical guidance for the rational design of catalysts.

Char formation during pyrolysis of torrefied cellulose: Role of potassium catalysis and torrefaction pretreatment

Torrefaction is an efficient pretreatment technology for large-scale and high-value utilization of biomass fuel. This study aims to enhance the understanding of the thermochemical conversion of torrefied biomass by delineating the role of potassium and torrefaction on primary/secondary charring reactions during pyrolysis of torrefied cellulose. Celluloses with varying potassium loading levels were torrefied at temperatures ranging from 200 to 320 °C and subsequently pyrolyzed at 1000 °C. Two contrasting pyrolysis conditions, i.e., limiting and enhancing transport resistance, were employed to tune the occurrence of secondary reactions, thereby determining the role of torrefaction and potassium on primary and secondary charring reactions. Potassium content, torrefaction severity, and pyrolysis conditions both profoundly affects char formation during pyrolysis of torrefied cellulose, resulting in a wide range of pyrolysis char yields from 1.95 wt% to 64.35 wt%. The structural changes induced by torrefaction, including the depolymerization of the carbohydrate structure and the formation of crosslinking structures, promote the char formation. Potassium enhances the char formation of torrefied cellulose in two ways: i) by catalyzing the transformation of the carbohydrate structure into the crosslinking structure during torrefaction, and ii) by catalyzing the charring reactions of both the carbohydrate and the crosslinking structures during pyrolysis. Raman spectral analysis of the char carbon structure indicates that increased potassium loading level and torrefaction severity enlarge the aromatic system of the char. The findings highlight the potential of optimizing biomass pyrolysis through controlled torrefaction and potassium, paving the way for more efficient biofuel production and high-quality biochar applications.

Highly efficient and eco-friendly process for selective recovery of copper from waste printed circuit boards via pyrolysis and ammoniacal solvoleaching

This study proposes a process combining pyrolysis and ammoniacal solvoleaching to selectively recover Cu from waste printed circuit boards (WPCBs). Optimal pyrolysis conditions were determined by investigating parameters such as temperature, heating rate, N2 flow rate, holding time and particle size. Under the conditions: 500 °C temperature, 20 °C/min heating rate, 0.3 L/min N2 flow rate, 10 min time and +9.50 mm particle size, ∼25% of weight loss was obtained. The pyrolyzed mass underwent further physical separation process involving impact crushing, magnetic- and gravity separations to enrich metals into a concentrate. Copper in the resulting concentrate was selectively extracted using a one-stage ammoniacal leaching and solvent extraction process (ammoniacal solvoleaching), employing an oxime-based organic extractant, LIX 84-I with a small volume of NH4OH. Ammoniacal solvoleaching was optimized by considering parameters such as stirring speed, time, LIX 84-I concentration, volume of aqueous ammonia, temperature and pulp density. Under the following conditions: 500 rpm, 0.3/0.3/10 (g/mL/mL) of sample/NH4OH/LIX 84-I (0.8 M), 3 h time and 25 °C temperature, quantitative Cu dissolution was achieved after two-stage solvoleaching. Cu solvoleaching followed the Avrami model, with an activation energy of 28.95 kJ/mol in the temperature range 15–45 °C (298–318 K) for the mixed control mechanism. LIX 84-I could be recycled without loss of extraction performance. Cu concentration was further enriched during stripping stage using H2SO4. A flowsheet for the sustainable metal recovery from WPCBs was developed.

Combined effect of thermal hydrolysis process and low-temperature pyrolysis on the classification and bioavailability of phosphorus in sewage sludge

Existing phosphorus (P) resources are becoming increasingly scarce, so it is necessary to recover P from potential sources. This paper is based on thermal hydrolysis process (THP) at 140–180 °C, coupled with low-temperature pyrolysis at 300 °C, to study its effect on the recovery and conversion of P from sewage sludge. Most significant change was observed in apatite P, which increased from 3.43 ± 0.48 mg/g in raw sludge to 30.17 ± 1.17 mg/g in biochar (BTHP-180-4-300) during optimal process (THP condition: 180 °C, 4 h; pyrolysis condition: 300 °C). Reactions between phosphates and metal ions became more complete during this combined process. Unstable forms of P were converted into more stable forms, with transformations from Al-P and Fe-P toward Ca-P compounds like Ca3(PO4)2, Ca3Mg3(PO4)4, Ca2P2O7, and Ca(H2PO4)2, making P less degradable and more suitable as slow-release fertilizers. Additionally, P characteristics of actual THP in a sewage treatment plant were similar to those of laboratory THP.

Impact of biochar produced at different pyrolysis conditions on heavy metal contaminated soil.

This study aimed to assess the effectiveness of urban derived biochars such as Sugarcane bagasse (SB), Brinjal Stem (BS), and Citrus Peel (CP) produced at two different pyrolysis conditions (450 and 600°C for 60min) for soil heavy metal bioremediation potential. An ex-situ study was conducted to remediate single heavy metal-contaminated SoilRite with lead (Pb), copper (Cu), chromium (Cr) and cadmium (Cd), with biochars applied at different rates. Heavy metal status in soilrite was evaluated using various extraction methods (water-soluble, exchangeable, TCLP (Toxicity Characteristic Leaching Procedure), and PBET (Physiologically Based Extraction Tests)) to determine the biochar treatments' efficacy. The findings show that SB biochar at 450-60 are more effective in immobilizing heavy metals in water-soluble (Cd-100% Pb and Cu-70%), exchangeable (Pb:91%, Cd and Cu by 70-80%) and PBET-extracted forms (Cd-91%, Pb-80%, and Cu-75%), whereas biochar derived from BS (84%) and CP (90%) at 600-60 are more effective in immobilizing TCLP-extracted form of Pb and Cu. Urban derived biochars significantly reduced the toxicity of Pb, Cu, and Cd in various extractable forms and can stabilize and convert them into less accessible forms except for Cr. These extraction methods aid in evaluating environmental risks and influencing remediation strategies for soil heavy metal pollution. Urban biochar, as a cost-effective and eco-friendly solution, significantly solves this issue, facilitating sustainable waste management.

Study of products derived from the microwave-assisted thermal degradation of high-moor peat

Peat reserves are of great interest for various industries (energy, fuel, chemical, etc.). It is common practice to use pyrolysis to process such solid carbon-containing resources with the subsequent yield of fuel and valuable products. One of the environmentally and energetically favorable ways to degrade carbon-containing feedstock that is currently under development is microwave-assisted pyrolysis. Microwave radiation provides volumetric heating of the material, which significantly increases heating uniformity across the volume of the irradiated sample, providing greater efficiency of heat transfer and avoiding local overheating on the reactor surface. In the conducted study, a system was designed for the microwave processing of organic materials. The structural elements of the system are described, and a schematic showing pyrolysis product separation is presented. A prototype of the developed reactor was used to conduct experiments on degrading high-moor sphagnum peat of the Greko-Ushakovskoe deposit under mild pyrolysis conditions induced by microwave radiation. The component composition of reaction products was analyzed via chromatography-mass spectrometry and compared with the results of previous experiments using conventional thermal pyrolysis. More advanced processing of peat is performed under the conditions of microwave-assisted mild pyrolysis with a high yield of valuable products due to a more efficient heat transfer, uniform heating of the material, and the optimal reaction rate. The developed technology is shown to produce raw materials for a wide range of high-tech industrial productions. The prospects for the industrial use of the proposed microwave-assisted peat processing technology are discussed, specifically for the production of efficient hydrophobic sorbent.

Predicting and refining acid modifications of biochar based on machine learning and bibliometric analysis: Specific surface area, average pore size, and total pore volume

Acid-modified biochar is a modified biochar material with convenient preparation, high specific surface area, and rich pore structure. It has great potential for application in the heavy metal remediation, soil amendments, and carrying catalysts. Specific surface area (SSA), average pore size (APS), and total pore volume (TPV) are the key properties that determine its adsorption capacity, reactivity, and water holding capacity, and an intensive study of these properties is essential to optimize the performance of biochar. But the complex interactions among the preparation conditions obstruct finding the optimal modification strategy. This study collected dataset through bibliometric analysis and used four typical machine learning models to predict the SSA, APS, and TPV of acid-modified biochar. The results showed that the extreme gradient boosting (XGB) was optimal for the test results (SSA R2 = 0.92, APS R2 = 0.87, TPV R2 = 0.96). The model interpretation revealed that the modification conditions were the major factors affecting SSA and TPV, and the pyrolysis conditions were the major factors affecting APS. Based on the XGB model, the modification conditions of biochar were optimized, which revealed the ideal preparation conditions for producing the optimal biochar (SSA = 727.02 m2/g, APS = 5.34 nm, TPV = 0.68 cm3/g). Moreover, the biochar produced under specific conditions verified the generalization ability of the XGB model (R2 = 0.99, RMSE = 12.355). This study provides guidance for optimizing the preparation strategy of acid-modified biochar and promotes its potentiality for industrial application.

Extraction and volatilization mechanism of germanium (Ge) during lignite pyrolysis

Germanium is a critical strategic metal that plays an important role in various industries. Currently, the combustion method is the main method for extracting germanium from germanium-containing lignite, however, its extraction rate of germanium is low, with the form of SiO2-GeO2 solid solution due to covolatilization of both germanium and arsenic. To address these problems, this paper proposes to activate and enrich germanium in lignite through pyrolysis. The results show that the pyrolysis temperature and time are positively correlated with the volatilization rate of germanium, and the optimal pyrolysis conditions are at temperature of 1100°C with the time of 360 min. The volatility of germanium can reach up to 96.85%, and its grade in germanium-rich product is 25.51%, while arsenic content is 0.71%. The germanium-rich product is primarily present as GeS, with no SiO2-GeO2 solid solution, which is conducive to the subsequent chlorinated distillation. The kinetics and thermodynamics of the pyrolysis process are investigated, and the volatilization of germanium during lignite pyrolysis is modeled. These results verify the feasibility of germanium extraction from lignite by pyrolysis, which anticipates to realize the high-grade enrichment of germanium in lignite and the high-value utilization of lignite resources.

Exploring the potential of chemical recycling of waste medium-density fiberboards (MDF) under oxidative and pyrolytic conditions

Medium-density fiberboards (MDFs) have been widely used to replace natural wood in structural and non-structural applications (mostly in furniture). On the positive side, the use of MDF has certainly reduced the level ofdeforestation. However, there is a need to develop a safe and effective treatment method for waste MDF as the presence of chemical additives in MDF and the generation of fine wood dust pose environmental and health challenges. Thermal decomposition of MDF taps into the “waste-to-energy” approach that has been broadly utilized in the disposal of organic-based wastes. Along this line of inquiry, this study entails three aims; (i) to compute thermodynamics and kinetic functions that govern the decomposition of MDF at conditions encountered at real pyrolytic and combustion conditions in waste incinerators; (ii) to acquire the temperature-dependent profiles of decomposition products; and (iii) to report ultimate and proximate analyses of MDF. Under both pyrolytic and combustion conditions, the thermal decay of MDF exhibits three stages that reflect its structural composition. Pertinent thermo-kinetic parameters were computed using model-fitting and iso-conversational formalisms. The nitrogen content in MDF peaked at 6.3%; significantly higher than that of natural wood (i.e., 1%) and originated from the use of urea formaldehyde resin. Chemical analysis indicates that nitrogenated (i.e., N,N-Dimethylacetamide) and oxygenated (i.e., catechol) products dominate the composition of the non-condensable fraction upon pyrolysis and oxidation of MDF. Such a finding calls for the importance of a post-treatment catalytic process that converts N- and O-containing products into pure hydrocarbons. The high nitrogen content in char of MDF indicates its potential utilization as soil nutrients. Values and insights reported herein are to establish a technical foundation for a biorefinery or a thermal facility that uses waste MDF as a feedstock.

Effect of Heat Treatment on the Supramolecular Structure of Copolymers Based on Poly(propylene glycol fumarate phthalate) with Acrylic Acid

Previous studies investigating the thermal decomposition of p-PGFPh:AA copolymers in an inert atmosphere have provided only a general understanding of the changes that occur during thermolysis. Comprehensive studies are required to gain a better understanding of these processes [1]. The most comprehensive information on the influence of various factors on both the kinetics and the supramolecular structure of the resulting products can be obtained by combining the method of thermal analysis with IR, mass spectrometry, and scanning electron microscopy. The compounds studied have two different compositions, namely p‑PGFPh:AA 6.77:93.23 mol % and p-PGFPh:AA 86.67:13.33 mol %. These compounds were then subjected to a thermolysis process, which resulted in the emission of gases and a decrease in sample weight. The degradation process can be divided into three stages: 1) Depolymerization of the main chain; 2) Depolymerization of the side chain; 3) Final decomposition. These processes occur sequentially at different temperature ranges. According to TG- and DTG studies, complete decomposition of p-PGFPh:AA copolymers occurred at Tterm = 340–350 °C. In this temperature range, a slight loss of sample mass (less than 10 wt %) was observed along with a slight gas evolution. The main gaseous products from the transformation of the studied samples were CO and CO2. This was supported by IR-CO (2000–2200 cm−1) and CO2 (2310–2370 cm−1) as well as mass spectrometric observations. The final products resulting from the thermolysis of p-PGFPh:AA copolymers were examined under an electron microscope. The results showed a similar morphological pattern of mesostructures with sizes ranging from 0.3–1.5 μm, which were observed depending on the porous structure of the initial polymer material. Based on the experimental data, it can be concluded that the p-PGFPh:AA copolymers (in proportions of 6.77:93.23 mol % and 86.67:13.33 mol %) have a relatively high degree of resistance to heating and do not undergo any changes in chemical composition, particle size and shape. In conclusion, the results clearly indicate that the selection of conditions for pyrolysis plays a crucial role in increasing the thermal stability of polymeric materials. This method allows for purposeful changes in the structure and properties of polymers.

Co-pyrolysis of cellulose and lignin: Effects of pyrolysis temperature, residence time, and lignin percentage on the properties of biochar using response surface methodology

Cellulose, hemicellulose, and lignin constitute the basic components of biomass. Knowledge of the interactions between cellulose and lignin during pyrolysis is crucial for unraveling the pyrolysis characteristics of biomass. In this study, for the co-pyrolysis of cellulose and lignin to produce biochar, three influencing factors were selected: pyrolysis temperature (400–800 °C), residence time (5–30 min), and lignin percentage (0–100 %). Pyrolysis experiments were conducted in a vertical tube furnace and the impact of these three factors on the characteristics of biochar was comprehensively explored employing response surface methodology. The results revealed obvious differences between actual values and theoretical values. Specifically, the results showed that the interaction between cellulose and lignin increased the biochar yield, oxygen content, volatile content, and ash content by 6.14 %, 22.85 %, 30.95 %, and 46.75 %, respectively. In contrast, the carbon content, fixed carbon content, and HHV of biochar were relatively reduced by 9.38 %, 11.80 %, and 3.3 %, respectively. Furthermore, Raman spectra of biochar showed that the actual value of graphitization degree of biochar was higher than the theoretical value. This was further corroborated by XPS analysis, wherein owing to the interactions between cellulose and lignin, the actual C-C bond content decreased in contrast to the theoretical value. However, the contents of C-O, CO, COOH functional groups, and aromatic rings increased. Finally, the summary of the co-pyrolysis rules of cellulose and lignin provided a reference for optimal pyrolysis conditions and understanding the mechanism of co-pyrolysis.

Structural and magnetic properties of nitrogen-doped carbon materials derived from an ionic liquid precursor

In this report, effects of pyrolysis conditions on the structure and magnetic properties of nitrogen-doped graphitic carbon materials prepared from 1-Buthyl-3-methyl imidazolium tricyano methanide ( [BMIm] [TCM]) ionic liquids(ILs) were investigated. It was found that nitrogen-containing graphitic carbon was formed under pyrolysis temperature of 400 °C or higher. Under the experimental conditions, the maximum nitrogen content of the obtained sample was C4N1.10 at a pyrolysis temperature of 400 °C and it was found that the nitrogen content in the obtained samples decreased with increasing pyrolysis temperature. Ferromagnetism was not observed in all the obtained samples to 2 K. From the value of the orbital diamagnetic susceptibility and XRD, it was found that the obtained sample had the structural characteristics of soft carbon.

Carbon nanotube interweaved Fe7Se8 nanosheet/nanorod hybrids on expanded graphite for high-performance sodium storage

The construction of nano-micro scale hybrid structures by carbon materials is an effective strategy to address the issues of metal chalcogenides when used as anodes of sodium-ion batteries. Herein, we develop a carbon nanotube (CNT)-interweaved Fe7Se8/expanded graphite (EG) composite by means of a facile one-step gas-phase pyrolysis route with ferrocene, selenium and EG as the starting materials. The ex-situ monitoring of the pyrolysis process indicates that the selenium as a promoter facilitates the formation of CNTs and the carbon coated Fe7Se8 nanosheet/nanorod mixture. A competing reaction between CNT growth and the evolution of Fe7Se8 nanostructures occurs, which could be dominated by the concentration of selenium vapor. By optimizing the feeding ratio and the pyrolysis condition, the nanocomponents are homogeneously deposited on the surface of the EG matrix to realize a well-developed nano-micro hybrid configuration. The constructed three-dimensional conductive network, rich mesopores and high specific surface area (107.1 m2 g−1) contribute to substantially enhanced sodium-storage performance in ester electrolyte. Remarkably, the optimized composite electrode exhibits high reversible capacity retention of 97.5 % after 1000 cycles at 1.0 A g−1 and improved rate performance of 325 mAh g−1 at 2.0 A g−1. This study provides new avenues to develop high-performance metal chalcogenide electrodes for electrochemical energy storage.

Adsorption of cobalt isotope from liquid radioactive waste by carbon nanostructured materials of thermochemical activation of sludge-lignin

One of the urgent problems of modern industry is the accumulation of waste. Waste from the nuclear industry is liquid radioactive waste, pulp and paper industry is sludgelignin. To solve the problem of waste accumulation in these industries, a method of selective purification of liquid radioactive waste by waste products of the pulp and paper industry is proposed. Pyrolysis is an effective way of processing sludge-lignin, as a result of the activation of the pyrolysis product by alkaline reagents, activated carbons were obtained in laboratory conditions, which presumably can selectively extract isotopes of radionuclides from liquid radioactive waste. In the conducted study, the ability of carbon nanostructured materials of thermochemical activation of sludge-lignin to extract the isotope Со27 59 in the form of an ammonia complex was studied. The influence of the pyrolysis conditions: temperature (T), time (T) and dosage of the activator (D) on the response functions: monolayer capacity, heat of adsorption, the value of the maximum adsorption and the characteristic adsorption energy, which can be used to judge the porous structure of activated carbon. The method of the planned experiment is applied — rotatable central composite plan. For clarity, response surfaces are constructed based on experimental data. The analysis made it possible to develop practical recommendations for conducting the pyrolysis process in order to obtain a marketable product — activated carbons from sludge–lignin.

Thermal properties and grey correlation degree analysis of tar-rich coal under cryogenic and pyrolysis condition

The thermal properties of coal are important factors that influence the heat and mass transfer during the pyrolysis process. Therefore, thermal properties were investigated for two tar-rich coal under cryogenic temperature and pyrolysis condition using laser flash analyzer. Gray correlation analysis and chemical composition analysis are combined to analyze the impact of chemical properties on thermal properties. With decreasing temperature, the thermal diffusivity of coal experiences a significant increase by 108.9–121.4 %, while the specific heat capacity decreases by 57.9–65.9 %. The volatile matter and fixed carbon content in tar-rich coal have the highest correlation with thermal properties (∼0.9), followed by moisture content (∼0.62), while the ash content has the lowest correlation with thermal properties (∼0.5). The thermal diffusivity of tar-rich coal increases with increasing volatile matter content. Furthermore, within the range of −100 °C to 300 °C, the thermal diffusivity of tar-rich coal decreases with increasing carbon content, while the specific heat capacity increases with increasing carbon content. The results indicate that under low-temperature cryogenic conditions, the internal heat transfer capability of tar-rich coal is significantly improved.

Optimization of Operational Parameters Using Artificial Neural Network and Support Vector Machine for Bio-oil Extracted from Rice Husk.

Bio-oil production from rice husk, an abundant agricultural residue, has gained significant attention as a sustainable and renewable energy source. The current research aims to employ artificial neural network (ANN) and support vector machine (SVM) modeling techniques for the optimization of operating parameters for bio-oil extracted from rice husk ash (RHA) through pyrolysis. ANN and SVM methods are employed to model and optimize the operational conditions, including temperature, heating rate, and feedstock particle size, to enhance the yield and quality of bio-oil. Additionally, ANN modeling is utilized to create a predictive model for bio-oil properties, allowing for the efficient optimization of pyrolysis conditions. This research provides valuable insights into the production and properties of bio-oil from RHA. By harnessing the capabilities of ANN and SVM, this research not only aids in understanding the intricate relationships between process variables and bio-oil properties but also provides a means to systematically enhance the production process. The predictive results obtained from the ANN were found to be good when compared with the SVM. Several models with different numbers of neurons have been trained with different transfer functions. R values for the training, validation, and test phases are around 1.0, i.e., 0.9981, 0.9976, and 0.9978, respectively. The overall R-value was 0.9960 for the proposed network. The findings were considered acceptable, as the overall R-value was close to 1.0. The optimized operational parameters contribute to the efficient conversion of RHA into bio-oil, thereby promoting the use of this sustainable resource for renewable energy production. This approach aligns with the growing emphasis on reducing the environmental impact of traditional fossil fuels and advancing the utilization of alternative and environmentally friendly energy sources.

Pyrolysis of shenmu coal to prepare blue-coke used as reductant

Blue-coke is a form of granular char prepared by medium-low temperature pyrolysis of low-rank coal. As a reductant, it has been widely used in calcium carbide production, ferroalloy, copper pyro refining, and ferrosilicon production in China due to the abundant reserves of raw coal and its excellent performance. However, there is little research on the pyrolysis process of granular coal to produce blue-coke and its characteristics as a reductant. Thus, the effects of pyrolysis temperature, heating rate, particle size and holding time at the final temperature on blue-coke preparation were investigated in a rotary kiln reactor. The quality index of blue-coke as a reductant and its properties, including the element composition, surface function groups, carbon forms, reactivity and lower heating value under different pyrolysis temperatures, were analyzed in detail. It is demonstrated that the pyrolysis temperature had a more significant impact on the quality of blue-coke compared to other pyrolysis conditions. With the rise of pyrolysis temperature, the blue-coke’s C/O and C/H increased. With the particle size and heating rate increased, the temperature gradients developed within the granular coal during the pyrolysis process led to the volatile release shifting to higher temperature zone and more secondary reaction occurrence. Nevertheless, the secondary reaction was restrained in the rotary kiln with good heat and mass transfer. The indexes of blue-cokes as reductants were met by the chars produced at temperatures from 550 oC to 750 oC with a holding time 60 min at this temperature and a heating rate of 10 oC/min. As the key index of blue-coke, the electrical resistivity decreased with the increase of pyrolysis temperature. It was found to be closely related to the removal of H and O heteroatom at the pyrolysis temperature below 700 °C. While at the higher temperature, the development of graphitized carbon structure took a major role on it. Nonetheless, the crystallite sizes of the blue-coke obtained under this low temperature pyrolysis were small and the carbon forms were turbostratic. These resulted in the blue-coke's high combustion reactivity, which would gradually decline with the rise of pyrolysis temperature.