Fire Research Articles

КІНЕТИКА КОМПЛЕКСОУТВОРЕННЯ 2-МЕТОКСИФЕНОЛУ З ЙОНОМ ФЕРУМУ (III) ТА ЙОНОМ ГЕКСАЦІАНОФЕРУМУ (III)

Study of the formation of complexes of 2-methoxyphenol with ferrum (III) ion or hexacyanoferrum (III) ion. Kinetic studies have shown that the order of reaction for ferrum ion or ferrum hexacyanoion is close to one. The order of reaction for 2-methoxyphenol is 0.8 in the reaction with ferrum (III) ion and close to zero in the reaction with ferrum (III) hexacyanoion. It has been shown that the formed complexes are stable in acidic solution at pH less than 7 and rapidly decompose in alkaline solution. The complex of iron ion with 2-methoxyphenol decomposes into 2-methoxyphenol and ferrum hydroxide at pH above 8. At the same time, the rapid oxidation of 2-methoxyphenol is observed with increasing pH of the solution of the hexacyanoiron ion complex with 2-methoxyphenol. The found Kp values for the interaction of ferrum ion with 2-methoxyphenol are much higher than for the reaction with hexacyanoferrum ion.

Protective layers of zirconium alloys used for claddings to improve the corrosion resistance

Abstract Zirconium alloys are used as a cladding material for fuel elements in nuclear reactors. In the case of severe accident conditions, the possible rapid oxidation of zirconium in steam or/and air may result in intense hydrogen generation and hydrogen–oxide mixture explosion. Advanced technologies for increasing the corrosion resistance of claddings are being investigated in two directions: (a) protective coatings on Zr alloys and (b) the use of new materials for claddings. Coatings with silicon may provide a more protective barrier than the ZrO2 films formed on an alloy cladding during nuclear plant operations. These coatings may also serve as a protective barrier during high-temperature accidents. The current work aimed at developing protective coatings with silicon on zirconium alloys. Multielemental Zr–Si–Cr coatings were formed on Zry-2 alloy using the physical vapor deposition (PVD) method. Long-term oxidation tests were carried out under the following conditions: 360°C/195 bar/63 days/water-simulating PWR water. Obtained results show the protective character of formed layers. The material in the form of silicon carbide grains covered with yttrium–aluminum garnet (SiC + YAG) was prepared using the sol–gel method. The formed powder is the main component for coating formation on Zr–1Nb alloy using the method of suspension plasma spraying (SPS).

Facile preparation of arginine-based carbon dots for highly selective detection of dopamine

Arginine-based carbon dots (Arg-CDs) were synthesized through a facile one-step hydrothermal method using arginine and urea as precursors. The as-prepared Arg-CDs displayed good aqueous solubility and typical excitation-dependent emission property, with the fluorescence quantum yield of 25.47 %. The fluorescence of Arg-CDs was gradually quenched by the addition of dopamine (DA) in the alkaline solution. However, under neutral and acidic condition, the fluorescence intensity of Arg-CDs remained unchanged upon the addition of DA. The sensing mechanism was probably due to the rapid oxidation of DA to dopaquinone in alkaline condition, which could quench the fluorescence of Arg-CDs through the Inner Filter Effect (IFE). Moreover, the fluorescence change of Arg-CDs was proportional to the concentration of DA under the optimized condition. Because of the linear relationship, the detection limit of dopamine was calculated to be 0.28 μM with the detection range from 10 to 100 μM. The interference experiment was carried out to further verify the specificity of this fluorometric method. Finally, the fluorometry based on Arg-CDs has been successfully used to the determination of DA in human serum with high accuracy and satisfactory recovery.

Rapid oxidation of semiconductors at room temperature with a basic plasma cleaner

This paper shows how a simple modification of the electrodes in a basic commercial plasma cleaner allowed the oxidation of compound semiconductors (GaAs) and Si at room temperature. We explained the oxidation of the semiconductor surface by the participation of aluminum atoms evaporated from the electrode surface in the discharge, which resulting in additional ultraviolet (UV) radiation from the plasma. The UV radiation not only increases the decomposition of oxygen molecules adsorbed on the surface but also results in photoionization of GaAs with the formation of Ga and As ions at the oxide–GaAs interface. In addition to obtaining oxides on semiconductor surfaces, the modified device proved to be an effective tool for etching amorphous carbon films.

A Simulation-Based Investigation on Thermal Responses of Suspension Bridge Tower Under Different Fire Scenarios

AbstractRecords of bridge fire incidents illustrate that bridge fires can have catastrophic consequences. The severity of these fires can be influenced by various factors such as bridge type, vehicle size, and wind. Contrary to building fires that have been extensively studied, scant attention has been paid to bridge fires and more specifically fire exposure to the suspension bridges. In addition, existing bridge fire literature is mostly concentrated on fire exposure to girders or cables of suspension bridges. Therefore, this study focused on the post-fire condition of a fire-exposed suspension bridge tower using computational fluid dynamics (CFD) modeling techniques and finite element analysis (FEA). The impacts of the main bridge fire parameters including vehicle size, exposure duration, distance between the fire source and tower, and wind effects were also evaluated. Initially, fire dynamic simulator (FDS) was used to simulate 12 different fire scenarios. The time–temperature histories obtained from each scenario were transferred to the ABAQUS finite element (FE) software to conduct transient thermal analysis and obtain the temperature development within the steel tower of the bridge. The post-fire evaluation was performed with respect to the temperature-induced reduction in the yield strength of steel. The results show that fire exposure from a fuel truck in the proximity of a steel tower could significantly reduce the strength of the tower and lead to severe damage. Early control of the fuel truck fire is crucial in reducing the severity of the damage and preventing temperature development in higher areas of the tower. Although a wind toward the tower can significantly increase the fire-induced damage to the bottom parts of the tower, it considerably reduces the temperature exposure to the higher parts of the tower. Fire exposure from a normal vehicle does not put the tower at risk of failure, and an unprotected steel tower can withstand it. However, a bus fire may lead to minor damage. The thermal strengthening of the first 20 m of the tower can help in preventing the potential fire damage.

Furnace MILD combustion versus its open counterpart in hot coflow

The open jet flame in hot co-flow (JHC) has been frequently utilized for fundamental investigations of Moderate or Intense Low-oxygen Dilution (MILD) combustion due to its controllable conditions and relatively easy measurement capabilities. However, practical MILD combustion must take place within a combustor that is enclosed. Therefore, it is necessary to examine the similarity and disparity of combustion characteristics between two flame configurations. This issue is addressed currently. Specifically, we investigate the flow mixing, ignition, and combustion, as well as emission characteristics of non-premixed and premixed JHC and cylindrical furnace (FUR) flames at various values of the environmental temperature (Te) and central jet Reynolds number (Re). For the open non-premixed flames, we employ both previous single-tube JHC (SJHC) combustor and presently modified JHC (MJHC) one that uses the same nozzle configuration as the FUR burner. It is revealed that significant differences occur in flow, combustion and emission characteristics between the SJHC and FUR cases. On the other hand, both non-premixed and premixed MJHC configurations exhibit high similarity to the corresponding FUR cases in terms of upstream flow mixing and combustion features. Moreover, different CO and NOx emissions result from open JHC and close furnace flames due to different post-combustion configuration and residence time. Accordingly, future experiments on non-premixed MJHC and premixed JHC flames are highly recommended for better understanding practical MILD combustion.

Study on the fire extinguishing effect of compressed nitrogen foam on 280 Ah lithium iron phosphate battery

This study conducted experimental analyses on a 280 Ah single lithium iron phosphate battery using an independently constructed experimental platform to assess the efficacy of compressed nitrogen foam in extinguishing lithium-ion battery fires. Based on theoretical analysis, the fire-extinguishing effects of compressed nitrogen foam at different outlet pressures from foam mixture tanks were analyzed, examining factors such as battery surface temperature, flame temperature, and thermal weight loss. The results indicate that the compressed nitrogen foam can extinguish the open flame of the battery in 14 s at 0.7 MPa, with the battery's surface temperature dropping by approximately 11 % before and after the application of the extinguishing agent. Compared with other commonly used extinguishing agents, the compressed nitrogen foam demonstrates superior extinguishing efficiency, but its cooling efficiency is somewhat lower. At pressures ranging from 0.4 to 0.6 MPa, the foam displays prolonged drainage time and sustained cooling effects, rendering it more suitable for lithium-ion battery fire scenarios. To address the issue of reduced cooling performance during later stages of fire suppression by compressed nitrogen foam, an intermittent injection approach has been proposed to effectively preserve its cooling efficacy.

One-Pot Oxidative Amidation of Aldehydes via the Generation of Nitrile Imine Intermediates.

A one-pot procedure for the oxidative amidation of aldehydes via the in situ generation of reactive nitrile imine (NI) intermediates has been developed. Distinct from our progenitor processes, mechanistic and control experiments revealed that the NI undergoes rapid oxidation to an acyl diazene species, which then facilitates N-acylation of an amine. A range of substrates have been explored, including application in the synthesis of pharmaceutically relevant compounds.

Nonlinear Analysis of Steel Fiber Reinforced Recycled Aggregate Concrete under Compression, Tension, and Elevated Temperatures

In this study, we report on experiments conducted to determine the compressive behaviour of steel fibre reinforced-recycled coarse aggregate concrete (SFRCAC). Many researchers are interested in exploring the utilize of recycled aggregate in concrete for its potential to reduce environmental impact. By using recycled materials in place of natural ones, Recycled Aggregate Concrete (RAC) represents a novel environmentally friendly construction material. Processing waste concrete with a high proportion of building waste yields recycled aggregates. Natural sand & gravel reserves have been drastically depleted, and natural resources used, as a result of the expansion of the construction sector. Fire damage caused by spalling is a major issue when considering the use of such concrete in construction. SFRAC could help with this. In this research, we provide the outcomes of an investigational study into the compressive properties, particularly the compressive strength, of SFRAC cylinders subjected to extreme temperatures. Compressive mechanical characteristics of concrete were studied as a function of temperature (room temperature, 200 ℃, 400 ℃, & 600 ℃) & steel fibre volume percentage (0%, 0.5%, 1%, 1.5%). Adding steel fibres to RAC that has been heated at high temperatures greatly improves its ductility & cracking behaviour, making it more appropriate for usage in building construction since it lessens the likelihood of spalling.

Impacts of WWII bomb explosions on weathering damage of architectural heritage: Bath, England

The effects of bomb impacts, including the explosive force and combustion associated with these impacts, are preserved in only a few cities across the UK. In particular, World War Two (WWII) has left scars across a wide range of structures as a result of air raids. On immovable heritage, such as architectural structures, these impacts commonly take the form of craters, fractures and fire damage to stonework. This instantaneous damage is subsequently exposed to environmental stresses, such as moisture cycling, thermal stress and the movement of soluble elements and can thus lead to further deterioration of the stone. In this study, Rock Surface Hardness (RSH) measurements, permeametry measurements and microscopic observations were selected to capture stone deterioration data from 80-year-old bomb impacts on two walls of the Labour Exchange in Bath (UK) for spatial distribution analysis (Kriging) in Geographic Information Systems (GIS). The results show that the weathering forms that were found on the two walls can be attributed to nine different types. They can provide quantitative assessment of damage caused by bomb explosions and combustion in the war. The increase in permeability of walls and craters is shown to be primarily caused by the bomb explosion and combustion, whereas the decrease of hardness is associated with subsequent stone deterioration processes. This indicates that the interplay of initial damage likely accelerates subsequent response to environmental stress, extending the initial damage patterns from the impact crater to larger areas of stonework.

An open flame and smoke detection dataset for deep learning in remote sensing based fire detection

ABSTRACT The early warning of fires is pivotal for preventing substantial economic losses and ecological damage. However, the enhancement of fire model generalization performance still faces challenges due to limitations in existing fire datasets, such as image quantity and heterogeneity. Taking the advantage of rapid advancements in remote sensing technology and artificial intelligence, we introduce the Flame And Smoke Detection Dataset (FASDD), a pioneering collection comprising over 120,000 heterogeneous images covering various fire scenarios, aiming to promote the evolution of fire detection models. FASDD serves as a challenging benchmark for object detection tasks and features three sub-datasets: FASDD_CV, FASDD_UAV, and FASDD_RS. These sub-datasets comprise cross-domain images from ground-based, airborne, and spaceborne sensors, respectively. Extensive experiments using advanced Swin Transformer models demonstrate satisfactory fire detection performance, with mAP scores of 84.9%, 89.7%, and 74.0% on the respective sub-datasets. Notably, the application case in wildfire localization highlights the proficiency of FASDD_RS models for monitoring and tracking forest fires. Trained on FASDD_RS, FASDD_UAV, and FASDD_CV, deep learning models can be individually deployed on edge devices including satellites, drones, and terrestrial sensors, thus empowering collaborative fire warning within the space-air-ground integrated observation network. Additionally, a standardized procedure for data preparation, data procedure, and quality assurance is established, providing off-the-shelf annotations with four common configurations to facilitate machine learning model training. FASDD stands as a pivotal benchmark, providing valuable resources for training and evaluating deep learning fire detection models, especially Large Vision Models (LVM). It holds the potential to accelerate research progress in urban firefighting or forest fire detection, providing vital security measures for early fire warning and emergency response tasks.

Long-term oxidation of Ti3Al0.8Sn0.2C2 in air at 1200 °C

The addition of Sn into the raw materials is currently one of the most widely used methods to improve the purity and mechanical properties of Ti3AlC2. It follows in this work to investigate the oxidation behavior of the resulting Ti3Al0.8Sn0.2C2 at 1200 °C with the oxidation time up to 500 h. The oxidation kinetics shows that its oxidation resistance is much worse than that of common MAX phases including Ti3AlC2, Ti2AlC, and Cr2AlC. The oxide layer mainly consists of TiO2 and Al2O3, with only a small amount of SnO2 at the beginning of the oxidation stage. Cracks induced by the internal thermal stress penetrate through the entire oxide layer after only 1 h, which is an important reason for the rapid oxidation of the internal substrate layer. This work is expected to provide some inspiration and reference for Ti3Al0.8Sn0.2C2 used as the potential high-temperature structural material.

Smoke deposition and extraction in compartment fires with different ignition sources

The paper presents the experimental research findings on the characteristics of smoke emission and deposition during compartment fires with different ignition sources: an open flame, a heated surface, local heating sources and exposed electrical conductors. The research involved the interior design and construction materials typical of residential and industrial premises: wood, linoleum and cardboard. Adaptive approaches were proposed to the creation of smoke deposition conditions at incipient fire stages using limited volumes of liquid. The foaming agent emulsion was found to be very effective for smoke suppression. The efficiency of several methods of smoke extraction using supply and exhaust ventilation was investigated. Efficient combined techniques of smoke extraction and deposition were identified. Smoke extraction was found to be most efficient at an air velocity of less than 3 m/s. The alternation of intermittent activation of the spraying system and supply and exhaust ventilation system is the most efficient method of smoke removal. Mathematical equations were derived to predict the characteristics of sprinkler and ventilation systems, providing effective smoke deposition and extraction.

Advancing building fire safety through heat resistant and flame retardant hybrid silicone sealant

Rapid urbanization and population growth have led to a significant transformation in the urban landscape, characterized by the proliferation of high-rise buildings. However, this urban development has brought about new challenges, particularly in terms of fire safety. The escalating risk of disasters, especially fires, underscores the critical importance of implementing effective fire safety measures across all building types, necessitating legislative reforms. Despite their crucial role in ensuring structural integrity, sealants have often been overlooked in building safety standards, resulting in a lack of comprehensive regulations. The research addresses these challenges by focusing on the development of fire-resistant silicone sealants designed to enhance the fire resistance of building materials. These sealants were formulated independently, incorporating three fire retardants and four heat-resistant agents. While metal oxide flame retardants generally exhibited excellent performance, excessive mixing led to surface deformation and reduced workability. Optimal combinations of flame retardants and heat-resistant agents were identified, with the FR2 specimen demonstrating promising fire resistance performance. Full-scale fire performance tests conducted on FR2 revealed a maximum temperature difference of 40.6 °C between heated and unheated surfaces over a 2-h period, indicating high thermal insulation performance. These findings validate the efficacy of the proposed method and offer significant enhancements to building safety, thereby mitigating fire damage in urban environments.

Modelling the vulnerability of urban settings to wildland–urban interface fires in Chile

Abstract. Wildland–urban interface (WUI) regions are particularly vulnerable to wildfires due to their proximity to both nature and urban developments, posing significant risks to lives and property. To enhance our understanding of the risk profiles in WUI areas, we analysed seven fire case studies in central Chile. We developed a mixed-method approach for conducting local-scale analyses, which involved field surveys, remote-sensing through satellite and drone imagery, and GIS-based analysis of the collected data. The methodology led to the generation of a georeferenced dataset of damaged and undamaged dwellings, including 16 variables representing their physical characteristics, spatial arrangement, and the availability of fire suppression resources. A binary classification model was then used to assess the relative importance of these attributes as indicators of vulnerability. The analysis revealed that spatial arrangement factors have a greater impact on damage prediction than the structural conditions and fire preparedness of individual units. Specifically, factors such as dwelling proximity to neighbours, distance to vegetation, proximity to the border of dwelling groups, and distance from the origin of the fire substantially contribute to the prediction of fire damage. Other structural attributes associated with less affluent homes may also increase the likelihood of damage, although further data are required for confirmation. This study provides insights for the design, planning, and governance of WUI areas in Chile, aiding the development of risk mitigation strategies for both built structures and the broader territorial area.

Arc erosion resistance of Al2O3–Cu/35Mo composites reinforced by trace graphene oxide

In this study, Al2O3–Cu/35Mo composites were prepared by rapid hot-press sintering-internal oxidation method, and the materials were modified by adding trace amounts of graphene oxide (GO). The results show that the relative densities of the composites are above 99%, the γ-Al2O3 generated by internal oxidation is diffusely distributed on the copper matrix. The incorporation of GO produced a small number of hard MoC particles at the interface, which facilitated the interfacial bonding of the composites. In the 30 V DC, 10–30 A electrical contact test, the anode mass of the composites increases, while the cathode mass decreases. And GO reduces the total mass loss of the electric contact by 63.6%, 38.9%, 51.3% and 20.9%, respectively. A comparison of the electrical contact properties of the two materials showed that the addition of GO dispersed the concentrated erosion of the arc. At 10 A and 30 A, the arc energy is reduced by 75.5% and 12.5%, respectively. With the gradual increase in electric current, GO makes the Al2O3–Cu/35Mo composites more stable during the electric contact process, improves the anti-welding ability of the contact and reduces contact resistance.

Exploring the potential for branched chain keto-acids to inhibit the mitochondrial pyruvate carrier

Metabolism of branched-chain amino acids (BCAAs) is often dysregulated in obesity and diabetes. To be oxidized, BCAAs are first converted to branched chain keto-acids (BCKAs), which are structurally similar to pyruvic acid. Previous studies have suggested that BCKAs inhibit the mitochondrial pyruvate carrier (MPC), particularly in hepatocytes, so we sought to investigate this further. Mitochondria were isolated from mouse liver and coupled pyruvate respiration was assessed before and after addition of either 100μM keto-leucine (alpha-ketoisocaproate), keto-isoleucine, keto-valine, an equimolar mixture of the 3 BCKAs, or NaCl control. Keto-leucine and the BCKA mixture reduced respiration by ~35%, but keto-isoleucine and keto-valine had no effect. This was repeated in mouse heart mitochondria, and again, only keto-leucine or the BCKA mixture reduced pyruvate respiration by ~30%. In comparison, 1μM of the synthetic MPC inhibitor UK-5099 reduced pyruvate respiration by 80%. In hepatocytes, most pyruvate is not oxidized but is carboxylated, which is an important first step for hepatic gluconeogenesis. Isolated hepatocytes were treated with pyruvate +/- BCKAs, and while UK-5099 reduced glucose production, none of the BCKAs had any effect. This experiment was repeated with 13C-pyruvate, and while UK-5099 reduced 13C enrichment into the hepatocyte TCA cycle, gluconeogenic intermediates, and glucose in the media, again none of the BCKAs had any effect. This lack of effect on gluconeogenesis may be due to the relatively mild inhibition and the ability of hepatocytes to perform pyruvate-alanine cycling to maintain some pyruvate carbon entry into the TCA cycle. Respiration was then assessed in MPC-deficient cardiac mitochondria, and keto-leucine and the BCKA mixture were no longer able to reduce pyruvate oxidation suggesting the effect is dependent on the MPC. Keto-leucine also had no effect on pyruvate dehydrogenase (PDH) activity of cardiac mitochondrial lysates, suggesting that the reduction in pyruvate oxidation is due to MPC inhibition and not reduced PDH activity. In a bioluminescent resonance energy transfer (BRET) assay which indicates inhibitor binding and MPC conformational change, while UK-5099 increased BRET, keto-leucine had no effect. Lastly, we hypothesized that rapid oxidation of the keto-leucine could explain the relatively mild inhibition of the MPC that we observe. Therefore, we repeated mitochondrial respiration studies in mitochondria isolated from PPM1K−/− mice which is the phosphatase that regulates the branched chain keto acid dehydrogenase (BCKDH) and BCKA oxidation. As expected, PPM1K−/− mitochondria displayed enhanced BCKDH phosphorylation, suggestive of inhibited BCKA oxidation. To our surprise, while pyruvate oxidation was inhibited by keto-leucine in WT mitochondria, this inhibition was completely lost in liver or heart mitochondria from PPM1K−/− mice. Altogether, these results suggest that a downstream metabolite of keto-leucine inhibits the MPC, via a mechanism that differs from synthetic MPC inhibitors. Ongoing studies are being performed to search for this downstream metabolite responsible for MPC inhibition. Saint Louis University School of Medicine internal sponsorship. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Online headspace monitoring of volatile organic compounds using proton transfer reaction-mass spectrometry: Application to the multiphase atmospheric fate of 2,4-hexadienedial

Chemical processes in clouds have been suggested to contribute significantly to the mass of organic aerosol particles in the atmosphere. Experimental and theoretical evidence suggest that organic mass production in clouds can be substantial and depends on the concentration of organic precursor compounds available in the gas phase. The present study aims at studying the aqueous phase reactivity of one of these overlooked precursors, i.e. 2,4-hexadienedial, an important and toxic intermediate in the atmospheric oxidation of aromatic species. Cautious synthesis and purification of 2,4-hexadienedial was performed. Its effective Henry's law constant was measured using a new simple and fast method based on online flow-injection analysis. The reactivity of 2,4-hexadienedial in the aqueous phase relevant to atmospheric conditions was studied, including hydrate formation, photolysis, ∙OH- and SO4∙--oxidation as well as reaction with NH3. The results revealed a low hydration constant compared to other dicarbonyls (Khyd1 = 7 × 10−2) and no dihydrate formation, indicating in an intermediate solubility (KH = 1.0 × 104 M atm−1) and high absorption cross sections (σ278nm > 10−16 cm2 molecule−1). Compared to its gas phase photolysis, its aqueous phase photolysis showed low quantum yields (Φ290–380nm = 0.9 %), and a significant red shift of the absorbance maximum, leading to a fast aqueous photolysis kinetics (Jaq,atm = 8.7 × 10−5 s−1) under atmospheric solar radiation, but no triplet state formation was detected. Radical oxidation experiments revealed extremely rapid oxidation kinetics (k∙OH = 1.10 × 1010 M−1 s−1 and kSO4∙- = 1.4 × 109 M−1 s−1) driven by fast addition of the radicals to the unsaturated bonds. In contrast, the reaction with aqueous NH3 (kNH3 = 2.6 × 10−3 M−1 s−1) was found slower than glyoxal and 2-butenedial, likely due to the hyperconjugation of 2,4-hexadienedial. Using these new data complemented with assumed aqueous phase kinetics (for NO3, 3C* and 1O2 reactions) and previous gas-phase kinetic ones, the multiphase atmospheric fate of 2,4-hexadienedial was established under atmospheric conditions reported from previous field measurements and models. The results revealed a short day lifetime (∼1 h) and a long night lifetime (>12 h). It was shown that daytime atmospheric chemistry of 2,4-hexadienedial can be influenced by aqueous-phase reactivity during cloud events, up to ∼50 % under thick cloud conditions (Liquid Water Content >2000 g/m3), indicating that even a compound of intermediate solubility can be strongly affected by condensed-phase reactivity. Besides its fast aqueous phase reactivity towards ∙OH and photolysis, its daytime condensed-phase reactivity may be driven by reactions with dissolved triplet states (3C*), up to 35 %, highlighting the need to study further the kinetics, the nature and concentrations of dissolved 3C* under various atmospheric conditions. In addition, the molecular properties and atmospheric behavior of 2,4-hexadienedial were found different from those of glyoxal and 2-butenedial, highlighting the need for detailed atmospheric reactivity studies of polyfunctional compounds, in particular unsaturated compounds.

Ball-milled biochar-modified zero-valent aluminum activates peroxodisulfate for phenol degradation: Enhancement of catalysis by membrane-breaking effect

Zero-valent aluminum (ZVAl) is a potential activator for peroxodisulfate (PDS), yet the dense oxide film on its surface hampers electron transfer for the O−O bond cleavage of PDS. We synthesized zero-valent aluminum-biochar (BM-ZVAl@BC) composites through ball milling, which effectively disrupted the native oxide layer on BM-ZVAl@BC. Within the BM-ZVAl@BC/PDS system, biochar (BC) not only suppressed the rapid oxidation of BM-ZVAl@BC but also enhanced the dispersion and electron transfer rate of ZVAl, thereby improving the overall catalytic efficiency. Consequently, the phenol removal efficacy in the BM-ZVAl@BC/PDS system was notably improved. Optimal catalytic performance of the prepared BM-ZVAl@BC was achieved at a charcoal-to‑aluminum mass ratio of 2:1, resulting in 95.7 % phenol removal after 180 min. Quenching experiments and electron paramagnetic resonance (EPR) analysis revealed that both free radicals (SO4•−, •OH, and O2•−) and non-radical species (1O2) contributed to phenol degradation, with SO4•− and •OH playing predominant roles. In summary, the BM-ZVAl@BC/PDS system represented an effective and promising technology for the remediation of phenolic water pollutants.

Study on the secondary oxidation behavior and microscopic characteristics of oxidized coal gangue.

Spontaneous combustion of coal gangue (CG) hills has caused varieties of secondary disasters that seriously endanger the ecological environment of the world. The emission law of index gases and their oxidation kinetics during the secondary oxidation process of CG with different ranks of oxidation were studied by using the temperature programmed device and online mass spectrometer (MS). Fourier transform infrared spectroscopy (FTIR) was used to reveal the changes of the CG internal active functional groups. The results showed that the energy required for the combustion of CG with low rank of pre-oxidation was significantly lower than that of the raw sample. However, as the oxidation rank increased, due to amounts of volatile components were released in the process of oxidation reaction, the CG in the combustion process of the emission of index gases and its oxygen consumption rate gradually reduced; the rapid oxidation stage shifted to the direction of the high temperature. In this study, the risk of spontaneous combustion of CG after oxidation at 80℃ under 3% oxygen concentration was the strongest. The results of this paper are of great guiding significance for exploring the spontaneous combustion characteristics of CG hills and their prevention by traditional covering method.