Pyrolysis Temperature Research Articles

Uncertainty in determining carbon dioxide removal potential of biochar

Abstract A quantitative and systematic assessment of uncertainty in life-cycle assessment is critical to informing sustainable development of carbon dioxide removal (CDR) technologies. Biochar is the most commonly sold form of CDR to date, and it can be used in applications ranging from concrete to agricultural soil amendments. Previous analyses of biochar rely on modeled or estimated life-cycle data and suggest a cradle-to-gate range of 0.20–1.3 kg CO2 net removal per kg of biomass feedstock, driven by differences in energy consumption, pyrolysis temperature, and feedstock sourcing. Herein, we quantify the distribution of CDR possible for biochar production with a compositional life-cycle inventory model paired with scenario-aware Monte Carlo simulation in a “best practice” (incorporating lower transportation distances, high pyrolysis temperatures, high energy efficiency, recapture of energy for drying and pyrolysis energy requirements, and co-generation of heat and electricity) and “poor practice” (higher transportation distances, lower pyrolysis temperatures, low energy efficiency, natural gas for energy requirements, and no energy recovery) scenarios. In the best-practice scenario, cradle-to-gate CDR (which is representative of the upper limit of removal across the entire life cycle) is highly certain, with a median removal of 1.4 kg of CO2e / kg biomass and results in net removal across the entire distribution. In contrast, the poor-practice scenario results in median net emissions of 0.090 kg CO2e / kg biomass. Whether this scenario emits (66% likelihood) or removes (34% likelihood) carbon dioxide is highly uncertain. The emission intensity of energy inputs to the pyrolysis process and whether the bio-oil co-product is used as a chemical feedstock or combusted are critical factors impacting the net carbon dioxide emissions of biochar production, together responsible for 98% of the difference between the best- and poor-practice scenarios.

Enhanced fischer-tropsch synthesis performance on Co@SiO2 catalyst with core-shell structure

Energy is of great importance for the development of modern society, which is mostly dependent on crude oil. Due to the severe pollution caused by using crude oil and the diminishing of crude oil reserves, it is urgent to look for clean oil from alternative resource other than crude oil. Currently, Coal-to-Liquid (CTL) or Biomass-to-Liquid (BTL) technology is an important way to produce clean liquid fuels through Fischer-Tropsch Synthesis (FTS) of syngas. For FTS process, catalyst is a main factor for affecting on syngas conversion and product distribution. For traditional oxides-supported catalysts, the mutual constraint between active metal loading and dispersion at high metal loading is hard to overcome, which will hinder the synthesis of high-performance FTS catalysts. In this paper, a new type of Co@SiO2-T (CS-T) and Co@SiO2-X (CS-X) catalysts with core-shell structure were prepared by using polyvinyl pyrrolidone (PVP) as the structural stabilizer, hexadecyl trimethyl ammonium Bromide (CTAB) as the templating agent and tetraethyl orthosilicate (TEOS) as the silica source. The effects of hydrothermal temperature and pyrolysis temperature on the catalyst physical-chemical properties and FTS performance were investigated. The results showed that increasing the hydrothermal temperature favored the formation of the core-shell structure of the catalysts. With the increase of pyrolysis temperature, the catalyst particle size decreased from 0.54 μm to 0.23 μm. The FTS activities of the catalysts showed a volcano trend with hydrothermal and pyrolysis temperatures.

Mesoporous silica-modified metal organic frameworks derived bimetallic electrocatalysts for oxygen reduction reaction in microbial fuel cells

The design of cost-effective oxygen reduction reaction (ORR) catalysts in microbial fuel cells (MFCs) remains a challenge. Herein, a mesoporous silica (mSiO2) assisted protection strategy is developed to synthesize highly dispersed CuCo nanoalloys embedded in nitrogen doped carbon Cu/Co-NC@mS catalyst using zeolitic imidazolate framework (ZIF) as carbon and nitrogen sources. The results revealed that the mSiO2 protection holds the potential to inhabit CuCo nanoalloys from aggregation and thus promotes the formation of highly dispersed small CuCo nanoparticles. The obtained catalyst with pyrolysis temperature (T) of 800 °C (Cu/Co-NC@mS-800) achieves the best ORR performance among Cu/Co-NC@mS-T catalysts, yielding a maximum power density of 1000 mW m−2 when employed as air cathode MFCs. The significantly enhanced ORR performance of Cu/Co-NC@mS-800 could be attributed to following aspects: a) highly dispersed small CuCo nanoalloy particles, improved mesoporous surface area and volume owing to mSiO2 protection; (b) the formation of concave regular dodecahedron mesoporous structure with thin graphtic carbon layer as support; (c) the synergetic effect between CuCo nanoalloys. This work provides a facile strategy for the preparation of highly dispersed bimetal nanoalloys with enhanced electrocatalytic performance for energy-related applications.

High-performance electromagnetic absorbing Ni/C composites derived from Ni-MOF materials: Effects of organic ligands and pyrolysis temperatures

Magnetic carbon-based materials derived from nickel organic framework (Ni-MOF) are considered to be a kind of electromagnetic wave (EMW) absorbing materials with great potential and application value. However, the precise design of Ni-MOF-derived magnetic carbon-based materials remains a huge challenge. In the present work, through the modulation of organic ligand and pyrolysis temperature, Ni/C composites with excellent electromagnetic absorption properties are obtained due to their improved multiple loss and optimized impedance matching. Specifically, the organic ligand and pyrolysis temperature affect the degree of graphitization of the carbon frame and the specific surface area of the Ni/C composites, thus changing the conductivity, magnetic properties and electromagnetic parameters. In particular, the sample Ni/C-2-500 using H2BPDC as the organic ligand and calcined at 500 °C gives an RLmin of –50.37 dB and an EAB of 6.0 GHz at a packing rate of 30 wt% and a thickness of 2.5 mm, which covers the entire Ku band. In addition, Ni/C-2-500 exhibits good thermal conductivity. Therefore, this study provides an idea for exploring MOF materials and their derivatives with tunable EMW absorbing properties and heat conduction advantages prepared by different organic ligands.

Adsorption of crystal violet from wastewater using alkaline-modified pomelo peel-derived biochar

The purpose of this study is to investigate the optimal preparation conditions for alkali-modified pomelo peel biochar and to clarify its adsorption process towards crystal violet (CV). The pyrolysis temperature and the alkali-to-carbon ratio of pomelo peel raw materials with varying epidermal layers were evaluated and optimized. Several characterization techniques demonstrated that alkaline modification enhances the adsorption performance of biochar by modifying its pore structure and functional group composition. Notably, the biochar, derived from the outer epidermis of pomelo, modified with an alkali-to-carbon ratio of 2:1 at 900 °C (KC2), exhibited significant adsorption capacity through mechanisms such as pore filling, hydrogen bonding, π-π interactions, electrostatic interactions, and functional groups including CC and COC. The Freundlich isotherm and the pseudo-second-order kinetic model were determined to be the most appropriate for describing the equilibrium data. Accordingly, KC2 exhibited a maximum adsorption capacity of 805.69 mg/g, which significantly exceeded that of biochar derived from pomelo peel with a basic outer epidermis pyrolyzed at 900 °C (BC-GOP900, 586.7 mg/g). This study ultimately concluded that utilizing pomelo peel biochar, particularly KC2, represents an innovative strategy to address pollution caused by CV while effectively repurposing agricultural waste.

Biochar-bacteria coupling system enhanced the bioremediation of phenol wastewater-based on life cycle assessment and environmental safety analysis

The efficient treatment of phenol wastewater is of great necessity since it induces serious pollution of water and soil ecosystems. Using biochar-immobilized functional microorganisms can innovatively and sustainably deal with the existing problem. In this study, we utilized response surface methodology (RSM) combined with life cycle assessment (LCA) to improve phenol biodegradation rate through a novel separated alkali-resistant and thermophilic strain Bacillus halotolerans ACY. Bioinformatic analysis revealed the genetic foundation of ACY to adapt to harsh environments. The characteristics of pig manure biochar (PMB) produced at varying pyrolysis temperatures (300-700 ℃) and adsorption experiment were investigated, immobilization of the phenol-degrading ACY on PMB600 under alkaline and high pollution load promoted phenol removal and extreme environment resistance, and the phenol removal rate reached 99.5% in 7d in actual phenol wastewater, which increased compared with those achieved by PMB (50.6%) and free bacteria (80.5%) alone. Scanning Electron Microscope (SEM) and Fourier transform infrared spectrometry (FTIR) observations indicated the successful bacterial immobilization on PMB600. Reusability and economic cost study further demonstrated PMB600 as an excellent carrier for wastewater treatment. LC-MS, toxicology and carbon footprint analyses demonstrated that bacterial metabolism exerted synergy with adsorption for phenol removal, while biodegradation exerted the predominant impact on the immobilized bacterial system. This study provides an eco-friendly and effective approach to treat phenol wastewater.

Pomelo peel biochar supported nZVI@Bi0 as a persulfate activator for the degradation of acetaminophen: Enhanced performance and degradation mechanism

Due to the contradiction between superior reaction kinetics and imperfect reproducibility of nanoscale zero-valent iron (nZVI) in persulfate oxidation systems, how to improve the reusability of nZVI while highly guaranteeing efficiency is an important but challenging matter. Hence, we took a hydrothermal-assisted carbon reduction to synthesize nZVI encapsulated with Bi being loaded on pomelo peel biochar (nZVI@Bi0/PPBC), and the results indicated that the presence of Bi could improve the reproducibility of nZVI and facilitate the removal of acetaminophen (ACE) in the persulfate (PDS) system. The degradation rate constant of the nZVI@Bi0/PPBC800 composite for ACE was approximately 1.5 times higher than that of the nZVI/PPBC800. nZVI exhibited synergistic effects with Bi on PDS activation through electron transfer. Interestingly, the Bi(0) became increasingly pure as the pyrolysis temperature increased, and the catalytic performance of ZVI@Bi0/PPBC became better. In addition,electron spin resonance and quenching experiments revealed that 1O2 and O2·− were the predominant reactive oxygen species in nZVI@Bi0/PPBC/PDS system.The nZVI@Bi0/PPBC/PDS system showed excellent oxidation ability across a broad pH range (3.0–9.0) and resisted interference from certain anions. This work reveals the possible role of Bi(0) in nZVI based PDS system, and provides an idea for the protection of nZVI.

MOF-derived phase-selective synthesis of ln2O3 with appropriate surface atomic arrangement for CO2 photoreduction

Crystal phase engineering emerges as a powerful strategy to enhance photocatalytic activity, yet controlled phase-selective synthesis and phase-dependent performance understanding remain challenging. In this study, we introduce a novel method for synthesizing phase-engineered In2O3 via the pyrolysis of metal–organic frameworks (MOFs). We demonstrate that the functional groups and pyrolysis temperatures of MOFs are critical for phase-selective synthesis. Specifically, pyrolysis of MIL-68(ln)–NH2 at optimal temperatures yields In2O3 with rhombohedral (rh-In2O3), cubic (c-In2O3), and rhombohedral/cubic heterophase (rh/c-In2O3) structures. Our photocatalytic CO2 reduction tests reveal that c-In2O3 outperforms rh-In2O3 and rh/c-In2O3, achieving a CO production rate of 29.19 μmol g-1h−1 with 94.47 % selectivity. Spectroscopic and theoretical analyses show that c-In2O3 has superior charge transfer efficiency and lower reaction energy barriers, particularly for the rate-determining *CO intermediate, which exhibits a lower Gibbs free energy on its surface. This work provides a significant advancement in optimizing photocatalytic CO2 reduction efficiency through precise phase engineering, underscoring the vital role of phase control in enhancing catalytic performance.

Hydrogen-rich gas generation from enhanced catalytic cracking of biomass tar and related model compounds on Ni-Fe/ASA@HZSM-5 catalyst: Pathways and mechanisms

This study focused on the design of complex tar model compounds (CTMC) and synthesized a highly efficient aluminum dross (ASA) combined with HZSM-5 molecular sieve co-loaded bimetallic Ni-Fe catalyst (Ni-Fe/ASA@HZSM-5), comprehensively evaluated the catalytic cracking of real tar and its model compound by adjusting the injection amount and injection state of tar, and catalyst types to obtain hydrogen-rich gas with high H2 and low CO2 content. The results showed under the conditions of the injection amount of 0.6 mL/min, pyrolysis temperature of 600 °C, reforming temperature of 800 °C in the liquid phase, Ni-Fe/ASA@HZSM-5 displays excellent catalytic cracking performance with CTMC conversion efficiency of 87.80 % (79.46 % of gas yield and 34.20 vol% of H2 yield). The possible cracking paths between different components of CTMC in the Ni-Fe catalytic system were summarized by the experimental data and product distribution, the catalytic mechanism of Ni–Fe based catalysts can be attributed to the formation of a Ni-Fe alloy and the synergistic effect of ASA and HZSM-5 co-carrier. Further, the catalytic cracking pathway of CTMC was enhanced in the gas phase, the higher CTMC conversion efficiency of 93.68 %, gas yield (a mass fraction of 82.51 %) and H2 (a volume fraction of 33.59 %) were obtained from catalytic cracking of CTMC, the liquid yield decreased by 12.39 %, significantly improved the cracking degree and gas production capacity of CTMC. The real tar showed the same catalytic pyrolysis path and product distribution. Under the same cracking conditions, the yields of gas, liquid and char were 84.85 %, 12.00 % and 3.15 % respectively, and obtained the hydrogen yield of 55.29 mL/g. The CTMC simplifies the cracking process and reduces polymerization, provides insights into the cracking mechanisms of heavy components in biomass tar. Furthermore, the synergy of Ni and Fe contributed to greater activity for CTMC and real tar cracking, ASA combined with HZSM-5 molecular sieve co-loaded bimetallic Ni-Fe catalysts have a promising application potential as highly efficient catalysts for tar removal and reutilization.

Co-pyrolysis of coal-derived sludge and low-rank coal: Thermal behaviour and char yield prediction

Coal-derived sludge, a solid waste produced by the coal industry, offers potential opportunities for resource recovery due to its high organic matter. However, its products face challenges related to low utilization efficiency and economic value. Effective and clean treatment of coal-derived sludge is essential for sustainable development. Herein, we studied the co-pyrolysis treatment of coal-derived sludge and low-rank coal at different temperatures (500 °C−900 °C) and pretreatment methods (mechanical mixing and hydrothermal co-treatment). The co-pyrolysis of sludge and coal could increase the pyrolysis char yield and H2 yield, as well as reduce CO2 emissions. The hydrothermal co-treatment significantly improved the cleanliness of the co-pyrolysis treatment. Then we conducted a comprehensive analysis of the properties of the pyrolysis char using different characterization techniques. In order to better evaluate the distribution of co-pyrolysis product yield, six machine learning models were developed to predice co-pyrolysis char yield. The best model-predicted values showed excellent predictive performance when compared to the experimental values at high pyrolysis temperatures (≥700 °C). This study provided a new perspective on the resource utilization of coal-derived sludge and low-rank coal.

One-step pyrolysis of ZIF-8 after recovering rare earth elements from mining wastewater as a functional fenton-like catalyst

The management of rare earth elements (REEs) from mining wastewater has consistently a key issue. Our previous research has demonstrated the selective adsorption of REEs in mining wastewater by ZIF-8. Herein, one-step pyrolysis of ZIF-8 after recovering REEs from mining wastewater as a high-value product was further proposed. The resulting REEs-based magnetic nanoporous carbon materials (REEs-MPC) was utilized for the activation of peroxymonosulfate (PMS) in the removal of bisphenol A (BPA). Experimental results indicate substantial BPA removal efficiencies of 74.62 %, 83.57 %, and 70.06 % with REEs-MPC synthesized at different pyrolysis temperatures (700 °C, 800 °C, and 900 °C). The detailed characterizations reveal the REEs-MPC at 800 °C was obtained (REEs-MPC/800) exhibit prominent graphitic and defective characteristics. In addition, electrochemical analysis revealed that the REEs-MPC/800 demonstrate elevated conductivity and superior capacitive current, with Tafel slopes as high as 294 mV/dec. Functional theory (DFT) calculations demonstrate that the presence of graphitic-N and REEs-N species significantly enhance PMS activation. Finally, a neural network model constructed through machine learning techniques provided a comprehensive overview of the structure–property relationship. Overall, the proposal to synthesize a high-value product using mining wastewater has been put forward. This initiative is expected to contribute to the advancement of the green economy within the rare earth mining industry.

Bridging sodium storage behavior and microstructure in broad-leaf lignin hard carbon for sodium-ion batteries

Hard carbon (HC) has emerged as the most promising anode material for the sodium ion battery because high theoretical capacity and cost-effective properties. However, unsatisfactory specific capacity and initial Coulombic efficiency (ICE) significantly impede its further advancement. Moreover, the correlation between the microstructure and electrochemical performance has been not thoroughly elaborated. Here, a straightforward approach to regulate the closed nanopore and defect structure in the hard carbon matrix by adjusting the pyrolysis temperatures. Higher pyrolysis temperature will promote the growth of a long carbon chain and further fold and shrink generating more closed nanopores, which was beneficial to improve the Na+ plateau capacity. The long-range ordered turbostratic graphite domain structure should be avoided, as it can lead to a reduction in reversible capacity. Through detailed analysis of the hard carbon microstructure evolution and electrochemical performance, the relationship of which has been established. Simultaneously, the optimized hard carbon pyrolyzed at 1500 °C displays a remarkable reversible specific capacity of 338 mAh g-1 at 0.1 C with a high ICE of 87%. Based on the detailed analysis, a microstructure-dependent mechanism ‘adsorption-intercalation-filling’ was proposed for a comprehensive understanding of the sodium ion storage behavior. More significantly, fabricated 18650 cylindrical batteries demonstrate a high reversible capacity of 1175 mAh at 0.1 C with outstanding cycle stability (82.9% after 225 cycles at 0.5 C), outperforming commercial hard carbon counterparts. Our work provides deep insight into the rational design of the hard carbon structure and provides the possibility of building practical SIBs with high performance.

Evolution of Electrothermal Heating and Dielectric Properties of Phenolic Resins During Pyrolysis

AbstractElectrothermal heating generated via radio frequency (RF) fields is used to probe the transformation of phenolic resin to a carbon matrix during pyrolysis. Phenolic resin is a single‐stage thermoset that is popular due to its heat resistance, chemical resistance, high strength, and low creep properties. When phenolic resin is subjected to high‐temperature, low‐oxygen treatment (pyrolysis), it is converted to a carbon material useful for many structural applications. Here, neat phenolic resin is pyrolyzed at different temperatures, and the heating response of the newly formed carbon material is tracked when exposed to an RF field. The electrical conductivity of the matrix increased with increasing pyrolysis temperature, with ≈10−4 S m−1 for the neat sample prior to pyrolysis, and ≈102 S m−1 for the sample pyrolyzed at 850 °C. The material's electrothermal response to applied RF fields increases as the material pyrolyzes and becomes conductive; however, at high pyrolysis temperatures, the material becomes sufficiently conductive such that the RF fields are reflected rather than absorbed, and the heating response decreases. The findings of this work show that heating response to RF fields can be used as a quick and easy characterization technique for tracking structural changes associated with phenolic pyrolysis.

Insights into the interactions between cellulose and hemicellulose during pyrolysis for optimizing the properties of biochar as a potential energy vector

Cellulose and hemicellulose, the main components of biomass, undergo noticeable interactions during biomass pyrolysis. In this study, biochar was produced by the co-pyrolysis of cellulose and hemicellulose. Three co-pyrolysis parameters, namely, pyrolysis temperature (400–800 °C), residence time (5–30 min), and percentage of cellulose (0–100 %), were investigated to optimize the properties of biochar, including the application of response surface methodology in the experimental study. The analysis revealed that co-pyrolysis interactions could improve the biochar yield by up to 41.37 % (567.74 °C, 19.52 min, 50 % cellulose percentage). The co-pyrolysis interactions specifically enhanced the fixed carbon content, elemental carbon content, and higher heating value of the biochar, with the most significant enhancements being 0.87 %, 3.60 %, and 3.85 %, respectively, while simultaneously decreasing the volatile content, [H]/[C] ratio, and [O]/[C] ratio of the biochar, with the most significant reductions of −9.30 %, −10.81 %, and −26.71 %. Based on the observed decrease in the intensity ratio of the D-band and G-band of biochar in the Raman spectra, greater co-pyrolysis interactions increased the graphitization degree of the biochar. The analysis of X-ray photoelectron spectroscopy (XPS) investigations revealed that the interactions enhanced the contents of the C-C, C-O/C-O-C, aromatic, and OH functionalities while reducing the number of COO-, COOH, and CO functional groups. The results of this work indicate that the co-pyrolysis interaction between cellulose and hemicellulose contributes to optimizing the properties of biochar as a potential energy vector.

Effect of inorganic component of biochar on lead adsorption performance and the enhancement by MgO modification.

Biomass-derived biochar has enormous potential for sustainable and low-cost treatment of lead-contained wastewater. In this study, corncob and cow dung-derived biochar were prepared. The increase in pyrolysis temperature could improve the porous structures, surface area, functional groups and alkalinity, and further provide a higher Pb2+ capacity in both biochars. Cow dung biochar performed better than corncob for its higher inorganic mineral content and more alkaline surface. Among them, CDB-600 performed the Langmuir maximum capacity of 357.1 mg/g, with a high surface area of 144.3 m2/g; ion exchange and precipitate were the main adsorption mechanisms. After further MgO modification, the M-CDB displayed a high surface area of 166 m2/g, and ion exchangeability and precipitate-promoting effects were improved. M-CDB performed a Langmuir maximum capacity of 833.3 mg/g. The pHpzc was found to be 10 and the adsorbents portray a very good Pb2+ adsorption selectivity among coexisting ions in the solution. The adsorption process was found to be endothermic, feasible, spontaneous and chemisorption. The fixed lead on CDB-600 was stable in water. The immobilized lead could be desorbed by acid wash. CDB-600 performed better in terms of sustainability in use, which could support its continuous application ability.

Effect of Biochars Derived from Different Agricultural Wastes Under Different Pyrolyzing Temperatures on Microbial Properties of a Loam-Clay Soil During Plant Growing Season

ABSTRACT A two-season experiment to identify an efficient strategy for the optimized soil microbial activity using biochar from four agricultural residues subjected to two different pyrolyzing temperatures (300°C and 500°C) was conducted in greenhouse conditions. The biochar types were identified according to the final pyrolyzing temperature as vineyard pruning biochar-300°C (VB300), vineyard pruning biochar-500°C (VB500), tomato biochar-300°C (TB300), tomato biochar-500°C (TB500), clove biochar-300°C (CB300), clove biochar-500°C (CB500), banana biochar-300°C (BB300) and banana biochar-500°C (BB500). The experimental design consisted of a randomized complete block design with five replications and 9 treatments including the control with a total of 45 pots. Soil samples were taken after biochar applications at two-week intervals (0, 2nd, 4th, 6th and 8th week) during the growth period of lettuce (Lactuca sativa var. Crispa) and analyzed for chemical (pH and EC) and biological parameters (urease, alkaline phosphatase, β-glucosidase, dehydrogenase, nitrification, denitrification activities and bacterial count). Biochar applications were found to have an impact on enzyme activities in various degrees. Selected biochar treatments increased pH, EC, urease, alkaline phosphatase, β-glucosidase and nitrification activities but not the bacterial count in the first growing period. However, no significant difference was found among treatments in the second growing period (except β-glucosidase). Overall evaluation of the data suggested that, under the experimental conditions, feedstock type, rather than pyrolyzing temperature, appeared to be more influential on the biological parameters monitored and banana biochar was found to be the most effective one in the short term.

N, P Co-Doped Hard Carbon Anodes for High-Performance Lithium-Ion Batteries with Enhanced Capacity Retention and Cycle Stability.

Compared to the traditional graphite anode, heteroatom-doped polymer carbon materials have high capacity retention due to their high porosity and porous structure. Therefore, they have great potential for application in lithium-ion battery (LIB) anodes. In this work, an N, P co-doped precursor polymer material (MBPp), synthesized via a one-pot method using bisphenol-A (C-source), melamine (N-source), and 9,10-Dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (P-source). The resulting N, P-co-doped hard carbon materials (MBPs) were prepared at various pyrolysis temperatures, yielding microporous, mesoporous, and macroporous structures. MBP materials demonstrated excellent electrochemical performance as LIB anodes. Notably, MBP-900 achieved a reversible capacity of 262 mAh g-1 at 1000 mA g-1 (in 0.005-2.0 V voltage range) with a capacity retention rate of 97.1 % after 1000 cycles. These findings highlight the significance of MBP materials, which possess numerous defects, large layer gaps, and excellent cycle stability, in advancing the development of polymer anode materials for LIBs.

Impact of operational parameters on degradation of nitroglycerin using biochar doped with nano zerovalent iron

Wastewater from munition manufacturing facilities contains nitro compounds amenable to reductive degradation. Nanosized zero-valent iron (nZVI) offers a cost-effective solution but tends to agglomerate, reducing its efficacy. Biochar (BC), a sustainable carbon material derived from organic waste, improves nZVI’s performance by dispersing the nanoparticles and providing more active sites. This study explores the influence of reagent synthesis and reaction conditions on a rice hull biochar-supported nZVI (nZVI-RBC) system for removing nitroglycerin (NG) from untreated munitions wastewater. Key parameters examined included biochar pyrolysis temperature, iron-to-biochar ratio (Fe:BC), reagent dosage, and initial pH. The nZVI-RBC system removed over 99 % of NG within 30 minutes under base conditions (Fe:BC=1:1, (Fe:BC=1:1, [nZVI_RBC400]=1 g/L, unadjusted pH), significantly outperforming pristine nZVI, which removed only 57 %. Biochar improved the working pH range of nZVI particles so that nZVI-RBC was efficient over a wide pH range of 3–9; even in extreme alkaline condition (pH 11) it removed 94 % of NG. This remarkable efficacy was observed in an open system, which is especially notable. NG treated with nZVI-RBC underwent a series of sequential reductive cleavage and denitration of the nitro groups. A degradation pathway is proposed with glycerol and ammonium being the major end-products. The reaction predominantly involved surface-mediated reductive degradation. All degradation byproducts were quantified, and carbon and nitrogen mass balances were established. The carbon mass balance was closed within 5 % deviation. Nitrogen mass balance remained partially closed due to the adsorption of ammonium on the surface of biochar and ammonia volatilization.

Converting plastic-contaminated agricultural residues into fit-for-purpose biochar soil amendment: an initial study

Addressing agricultural plastic pollution is vital for ecosystem sustainability. Shifting from traditional waste treatments to a sustainable pathway presents both challenges and opportunities for global plastic management. This study investigated the properties and environmental applications of biochar derived from honeydew melon vines contaminated with plastic hanging ropes, pyrolyzed at temperatures of 300, 500, and 700 °C. The resulting biochars were evaluated for their ability to remove Pb and Cd from aqueous solutions. Additionally, a Chinese cabbage pot experiment was conducted to assess the impact of biochar on Pb and Cd immobilization and plant growth in contaminated soil. Results revealed that the properties of biochar varied with pyrolysis temperature. Specifically, incomplete carbonization of plastic ropes was observed at 300 °C, while biochar produced at 500 °C (BC500) showed a higher yield and contained higher levels of available P and K compared to the biochar produced at 700 °C (BC700). The presence of polycyclic aromatic hydrocarbons (PAHs) in biochars increased with temperature but remained within recommended limits. BC500 exhibited the highest adsorption capacities for Pb and Cd at 127 mg g−1 and 36 mg g−1, respectively. Soil amendment with BC500 and BC700 significantly improved soil pH, increased the availability of nutrients and microbial biomass, and effectively immobilized Pb and Cd in the soil. Consequently, the biomass yield of Chinese cabbage was enhanced by 119 % and 86 % under BC500 and BC700, respectively. Moreover, the Pb and Cd content in cabbage decreased by more than 80 % and 29 %, respectively. However, PAHs levels in cabbage leaves increased from 9.2 ng g−1 in the control to 20.8 ng g−1 and 30.4 ng g−1 under BC500 and BC700, respectively, remaining below China’s standard for benzo(a)pyrene. This study suggests pyrolyzing plastic-contaminated crop residues at 500 °C is a feasible strategy for waste recycling.Graphical

The Effect of the Pyrolysis Temperature of a Leather-Textile Mixture from Post-Consumer Footwear on the Composition and Structure of Carbonised Materials.

This paper presents an investigation into the use of pyrolysis to valorise solid waste in the form of post-consumer footwear uppers. A heterogenous leather and textile mixture is studied, produced by crushing some representative samples of post-consumer footwear uppers. The waste has a low ash content and a high net calorific value, which translates into the high gross calorific value of the material. In addition, it contains relatively little S and Cl, which is promising for its use in the process of pyrolysis. The effect of the pyrolysis temperature on the efficiency of carbonising leather and textile mixtures, their physico-chemical parameters, elemental composition, and structure, as well as the development of a specific surface, is investigated. The research results imply that as the pyrolysis temperature grows, the carbonisation efficiency declines. The produced materials consist primarily of C, O, N, and H, whose contents depend on the pyrolysis temperature. Moreover, all the carbonised materials display the presence of two G and D bands, which is typical for carbon materials. Based on the peak intensities of the bands, ID/IG coefficients are calculated to assess the organisation of the materials' structures. As the pyrolysis temperature rises, the structural organisation declines, contributing to an increased material porosity and, thus, a greater specific surface of the carbonised materials. This study contributes data on the thermal management and pyrolysis of leather and textile waste into useful carbonised materials. Investigating the applicability of carbonised materials is projected as the next stage of research work.