Mechanism Of Thermal Decomposition Research Articles

Elucidating Thermal Decomposition Kinetic Mechanism of Charged Layered Oxide Cathode for Sodium-Ion Batteries.

The safety of the P2-type layered transition metal oxides (P2-NaxTMO2), a promising cathode material for sodium-ion batteries (SIBs), is a prerequisite for grid-scale energy storage systems. However, previous thermal runaway studies mainly focused on morphological changes resulting from gas production detection and thermogravimetric analysis, while the structural transition and chemical reactions underlying these processes are still unclear. Herein, a comprehensive methodology to unveil an interplay mechanism among phase structures, interfacial microcrack, and thermal stability of the charged P2-Na0.8Ni0.33Mn0.67O2 (NNMO) and the P2-Na0.8Ni0.21Li0.12Mn0.67O2 (NNMO-Li) at elevated temperatures is established. Combining a series of crystallographic and thermodynamic characterization techniques, the specific chemical reactions occurring in the NNMO materials during thermal runaway are clarified firstand solidly proved that Li doping effectively hinders the dissolution of transition metal ions, reduces oxygen release, and enhances thermal stability at elevated temperatures. Importantly, based on Arrhenius and nonisothermal kinetic equations, the kinetic triplet model is successfully constructed to in-depth elucidate the thermal decomposition reaction mechanism of P2-NaxTMO2, demonstrating that such thermodynamic assessment provides a new perspective for building high-safety SIBs.

Investigating the decomposition mechanism of DNAN/DNB cocrystal explosive under high temperature using ReaxFF/lg molecular dynamics simulations.

DNAN/DNB cocrystals, as a newly developed type of energetic material, possess superior safety and thermal stability, making them a suitable alternative to traditional melt-cast explosives. Nonetheless, an exploration of the thermal degradation dynamics of the said cocrystal composite has heretofore remained uncharted. Consequently, we engaged the ReaxFF/lg force field modality to delve into the thermal dissociation processes of the DNAN/DNB cocrystal assembly across a spectrum of temperatures, encompassing 2500, 2750, 3000, 3250, and 3500K. We analyzed the evolution of species, preliminary disintegration processes, and fluctuations in the quantification of terminal outcomes were examined. The findings suggest that 2,4-dinitroanisole (DNAN) undergoes a thorough phase of disassembly within a timespan of 218ps, while 1,3-dinitrobenzene (DNB) completely decomposed within 228ps, demonstrating that DNAN has lower thermal stability than DNB, but with no significant difference. The thermal dissociation of DNAN/DNB cocrystals at elevated temperatures reveals a triad of potential reaction sequences. Primordially, the denitration of DNAN transpires, succeeded by the denitration of DNB, culminating in the nitro-isomerization of the latter. This sequence implies that the nitro moieties within DNB possess inferior thermal resilience compared to their counterparts within the DNAN cocrystal matrix. An examination of the six resultant end products suggests a predominance of H2O, NO2, and H2 in comparison to the other byproducts, which may be indicative of the pyrolytic transformations occurring during the disassembly process. This study first constructed the supercell model of DNAN/DNB eutectic crystal using the Materials Studio software and optimized the geometric structure of the model through the conjugate gradient algorithm. Then, the Nosé-Hoover method was used for NPT-MD simulation to further relax the model. Subsequently, molecular dynamics simulations were carried out using the LAMMPS software and the ReaxFF/lg force field. Simulation parameters were set, and NPT ensemble molecular dynamics simulations were performed at different temperatures. The simulation results were analyzed to reveal the thermal decomposition mechanism of DNAN/DNB eutectic crystal.

Molecular dynamic simulation study on the influence of heating rate on the thermal decomposition process of 1,3,5-triamino-2,4,6-trinitrobenzene (TATB).

To clarify the effect of heating rate on the thermal decomposition process of 1,3,5-triamino-2,4,6-trinitrobenzene (TATB), this study employs molecular dynamic simulations to investigate the thermal decomposition of TATB at heating rates of 20, 40, 60, and 80K/ps. The initial temperature is uniformly set to 300K, while the final temperature is set to 3000K. Results indicate that within the temperature range of 300-3000K, the thermal decomposition rate of TATB decreases with increasing heating rate, whereas the initial decomposition temperature of TATB increases, consistent with the experimental pattern. Within the studied temperature range, a lower heating rate results in a higher number of decomposition fragments, leading to more effective collision between active fragments, facilitating more effective collisions between active species, and leading to the formation of more stable products such as H₂O, CO₂, and N₂. Conversely, higher heating rates reduce the quantities of these stable products. This study enhances the understanding of TATB's thermal decomposition mechanism, providing valuable insights for its safe handling and application. METHODS: The Gaussian09 software was used to calculate the BDEs of TATB molecules, while the MD simulation using the ReaxFF-lg force field was performed by the LAMMPS package. Visualization and postprocessing were conducted using the OVITO software, and a custom script was developed to analyze the reaction products and frequencies.

In Vitro, In Vivo, Ex Vivo Characterisation of Dihydroimidazotriazinones and Their Thermal Decomposition Course Studied by Coupled and Simultaneous Thermal Analysis Methods.

The biological and thermal properties of a class of synthetic dihydroimidazotriazinones were disclosed in this article for the first time. Molecules 1-6-as potential innovative antimetabolites mimicking bicyclic aza-analogues of isocytosine-were evaluated for their in vitro anticancer activity. Moreover, in vivo, in vitro, and ex vivo toxicity profiles of all the compounds were established in zebrafish, non-tumour cell, and erythrocyte models, respectively. Their antihaemolytic activity was also evaluated. Additionally, the thermal decomposition mechanism, path, and key thermal properties of heterocycles 1-6 were analysed. It was found that all the studied compounds revealed significant antiproliferative activities against tumour cells of the lung, cervix, ovary, and breast, as well as acute promyelocytic leukaemia cells, superior or comparable to that of an anticancer agent gemcitabine. Most of them were less toxic to non-tumour cells than this standard drug, and none had a haemolytic effect on red blood cells. All the tested heterocycles proved to be safer for zebrafish than a standard drug pemetrexed. Some exhibited the ability to inhibit oxidative haemolysis, suggesting their protective action on erythrocytes. The differential scanning calorimetry (DSC) analyses confirmed that all molecules melted within one narrow temperature range, proving their purity. The melting points depended solely on the type of substituent and increased as follows: 4 (R = 3-ClPh) < 2 (R = 4-CH3Ph) = 3 (R = 4-OCH3Ph) < 5 (R = 4-ClPh) = 1 (R = Ph) < 6 (R = 3,4-Cl2Ph). The thermogravimetry/differential thermogravimetry (TG/DTG) studies confirmed high thermal stability of all the investigated heterocycles in inert (>230 °C) and oxidising (>260 °C) atmospheres, which depended directly on the R. The pyrolysis process included one main decomposition stage and was connected with the emission of NH3, HCN, CH3CN, HNCO, alkane, alkene, aromatic fragments, CO2 (for all the compounds), and HCl (for the molecule with 3,4-Cl2Ph), which was confirmed by FTIR and QMS analyses. In turn, the oxidative decomposition process of the tested polyazaheterocycles took place in two main stages connected with the formation of the same volatiles as those observed in an inert atmosphere and additionally with the release of N2, NO, CO, and H2O. These results proved that the pyrolysis and oxidative decomposition run through the radical mechanism connected with the additional reactions between radicals and oxygen in synthetic air. The favourable biological and thermal properties of this class of dihydroimidazotriazinones imply their usefulness as potential pharmaceutics.

ANALYSIS OF THERMAL DECOMPOSITION KINETICS AND THERMAL HAZARD ASSESSMENT OF NITROBENZOIC ACID ISOMERS BY DSC AND THERMOGRAVIMETRIC METHOD

Nitroaromatic acids, ubiquitous intermediates in nitro compounds, find broad applications in pharmaceuticals and fine chemical industries, yet their safety often receives inadequate attention. This paper investigates the thermal decomposition process of three isomers of nitrobenzoic acid using differential scanning calorimetry (DSC) and thermogravimetric analysis (TG), complemented by calculations of the apparent activation energy using typical kinetic methods. The reaction type was verified using a nonlinear fitting method. Thermal safety parameters including the time to maximum rate (TMR), critical temperature of self-acceleration (TCL), and thermal risk index (TRI) were employed to elucidate the thermal hazards. The thermal decomposition mechanism was further explained using density functional theory (DFT) methods, focusing on the Mayer bond order. The findings revealed that the average apparent activation energies for p-nitrobenzoic acid (PNBA), m-nitrobenzoic acid (MNBA), and o-nitrobenzoic acid (ONBA) were 157.00, 203.43, and 131.31 kJ mol-1, respectively. A single n-order reaction characterized the thermal decomposition process. The TMR and TCL parameters indicated a decomposition tendency at high temperatures, with the thermal stability at elevated temperatures following the order: PNBA &lt; ONBA &lt; MNBA. The TRI parameter indicates the danger level of the nitrobenzoic acids. The thermal decomposition mechanism was elucidated using Mayer bond energies, offering valuable insights into storage and transportation, and contributing to developing predictive models for thermal characteristics.

Study on the effect of solar salt thermal decomposition reaction on internal and external characteristics of molten salt pump

Solar salt is the main heat storage medium for concentrated solar power plants. It will undergo thermal decomposition reactions to produce gas when the temperature is higher than 450°C. So that the thermal decomposition bubbles of solar salt are free in the molten salt pump flow channel, which have serious impacts on the internal and external characteristics of the molten salt pump. This paper takes the 16ENH-2 high-temperature molten salt pump as the research object. Based on the thermal decomposition mechanism of solar salt, we studied the influence of different thermal decomposition gas generation rates and different flow rates on the bubble coalescence and breakage phenomenon in the flow channel, and the influence mechanism on the internal and external characteristics of the molten salt pump. The research results show that the thermal decomposition gas generation rate is the key factor affecting the gas content in the first stage impeller and the bubble size distribution in the second stage impeller. The flow rate is the key factor affecting the gas phase distribution position in the first/second stage impeller and the bubble size distribution in the first stage impeller. The bubble coalescence within the first stage impeller is the main reason for the pump performance degradation. The research results can provide theoretical guidance for the efficient and stable operation of the molten salt pump.

Kinetics and mechanism of thermal decomposition of ammonium dinitramide by TG/DSC-FTIR and chip-DSC coupled with microscope

Abstract Kinetics and mechanism of ammonium dinitramide were studied by the multiple methods composed of an in-situ testing thermal analysis system, product analysis by XPS/XRD/FTIR and evolved gas analysis using TG/DSC-FTIR. A three-step model for thermal decomposition of ADN was established, which were the low-temperature reaction, the single-step decomposition process with an autocatalytic reaction, and the multi-step decomposition process. N2O and NO2 were the main gaseous products, and there was difference in the intensity of the reaction at each stage. The corresponding kinetics and mechanism were proposed based on the analysis of activation energies and the intensity changes of the gaseous products.

Study on the effect of confined environment on thermal hazard potential of composite propellants and quantitative evaluation method

The thermal decomposition and combustion characteristics of solid composite propellants can vary significantly under different environmental pressures; however, a quantitative method for assessing their thermal hazards is lacking. This study investigates the thermal decomposition mechanisms of hydroxyl-terminated polybutadiene/ammonium perchlorate/aluminium powder (HTPB/AP/Al) and hydroxyl-terminated block copolyether/AP/Al (HTPE/AP/Al) propellants in varying environments. Using an accelerating rate calorimeter, the adiabatic decomposition characteristics of the two propellants were analysed. Laser ignition and closed bomb experiments were conducted to examine ignition and combustion under different pressures. A quantitative method for evaluating thermal hazard potential (THP) was established based on delay temperature and reaction intensity. Results indicate that the sealing conditions mainly change the nucleation factors of the two propellants in the third decomposition stage, making the nucleation factors of HTPB/AP/Al and HTPE/AP/Al propellants in the third stage change from 3/2 and 5/2–4 and 4/3, respectively. The lower Tstart (264.16 ℃) and higher Pmax (1.97 MPa) of HTPB/AP/Al compared to HTPE/AP/Al (280.31 ℃ and 1.21 MPa) suggest a higher thermal hazard for HTPB/AP/Al. A THP safety threshold of 0–20 % was identified. These findings provide essential insights for improving the thermal safety of propellants in practical applications.

Neural network potential-based molecular investigation of thermal decomposition mechanisms of ethylene and ammonia

This study developed neural network potentials (NNPs) specifically tailored for pure ethylene and ethylene-ammonia blended systems for the first time. The NNPs were trained on a dataset generated from density functional theory (DFT) calculations, combining the computational accuracy of DFT with a calculation speed comparable to reactive force field methods. The NNPs are employed in reactive molecular dynamics simulations to explore the thermal decomposition reaction mechanisms of ethylene and ammonia. The simulation results revealed that adding ammonia reduces the activation energy for ethylene decomposition, thereby accelerating ethylene consumption. Furthermore, the addition of ammonia uncovers a new reaction pathway for hydrogen radical consumption, which reduces the occurrence of H-abstraction reactions from ethylene by hydrogen radicals. The inhibition effect of ammonia addition on soot formation mainly acts in two aspects: on the one hand, ammonia decomposition products react with carbon-containing species, ultimately producing C1N products, thereby decreasing the carbon numbers involved in soot formation. This significantly reduces the concentrations of C5C9 molecules and key polycyclic aromatic hydrocarbons (PAHs) precursors like C2H2 and C3H3. On the other hand, ammonia promotes the ring-opening reactions of six-membered carbon rings at high-temperature conditions, thereby reducing the formation of PAHs precursors. The results show that with the addition of ammonia, six-membered carbon rings tend to convert into seven-membered carbon rings at lower temperatures, while at higher temperatures, they are more likely to transform into three- and five-membered carbon rings. These variations in the transformation of six-membered carbon rings may also affect soot formation. The insights gained from understanding these fundamental chemical reaction mechanisms can guide the development of ethylene-ammonia co-firing systems.

Thermal decomposition and shock response mechanism of DNTF: Deep potential molecular dynamics simulations

A neural network deep potential (DP) is developed for the shock response and thermal decomposition mechanisms of 3,4-Bis(3-nitrofurazan-4-yl)furoxan (DNTF). This DP potential, trained on ab initio datasets, achieves the accuracy of density functional theory (DFT) and higher computational efficiency. The simulation results show that DNTF is anisotropic under shock loading. And the critical shock decomposition temperatures along the [100], [010], and [001] directions are 463.64 K, 451.85 K, and 486.69 K, respectively. For the first time, the low-temperature (<750 K) decomposition of DNTF is successfully simulated using molecular dynamics combined with DP model. The decomposition of DNTF begins with the O-N bond opening of the furoxan ring, followed by the breaking of the C-NO2 bond and opening of the furazan rings, under thermal conditions. The critical thermal decomposition is between 458.3 K and 562.5 K at a heating rate of 13.5 K/ps. The final products are CO2, N2, and CO, and the main intermediates are NO2, NO, and N2O. The activation energy of decomposition is 142.4 kJ/mol obtained by Ozawa method. This study not only provides a powerful tool for investigating the performance of DNTF but also offers a feasible approach for other energetic materials, advancing the field significantly.

Regulating the Performance of CO2 Adsorbents Based on the Pyrolysis Mechanism of Self-Sacrificial Templating Agents.

Previous research has proven that the pore shape and nitrogen group content of adsorbents play essential roles in determining their carbon dioxide (CO2) adsorption performance. In this article, a series of nitrogen-doped porous carbon materials were prepared for CO2 adsorption by varying the proportion of carbon nitride, the pyrolysis temperature, and the activation ratio of KOH, using chitosan as the carbon source, carbon nitride (g-C3N4 and g-C3N5) as self-sacrificing templating agents, and KOH as the activator. Among the prepared materials, T6-850-1 has the highest specific surface area (SBET) of 2336 m2/g, and T6-750-1 has the highest microporous area (Smicro) and CO2 adsorption capacity (1 bar, 298 K) of 1969 m2/g and 3.49 mmol/g, respectively. The thermal decomposition temperature and products of carbon nitride templates were characterized and tested by thermogravimetric infrared gas chromatography-mass spectrometry (TG-IR-GC-MS), and the thermal decomposition mechanisms of the two carbon nitride templates were investigated. We found that the thermal stability of the template directly affects the pore structure of the final sample as well as the type and quantity of nitrogen species.

Mechanisms of Thermal Decomposition in Spent NCM Lithium-Ion Battery Cathode Materials with Carbon Defects and Oxygen Vacancies.

Resource recovery from retired electric vehicle lithium-ion batteries (LIBs) is a key to sustainable supply of technology-critical metals. However, the mainstream pyrometallurgical recycling approach requires high temperature and high energy consumption. Our study proposes a novel mechanochemical processing combined with hydrogen (H2) reduction strategy to accelerate the breakdown of ternary nickel cobalt manganese oxide (NCM) cathode materials at a significantly lower temperature (450 °C). Particle refinement, material amorphization, and internal energy storage are considered critical success factors for the accelerated decomposition of NCM cathode materials. In our proposed approach, NCM cathode materials can develop active sites with carbon defects (Cv) and oxygen vacancies (Ov), which improve the reduction and breakdown of H2. The adsorbed H2 on the surface of NCM decomposes into H* and combines with oxygen to form OH species, which can be facilitated by Ov via the enhanced charge transfer. The introduced Cv can enhance H2 cracking and generate *C-H species to promote the thermal decomposition of NCM. The presence of defects proves to foster the preferential reduction of Mn(IV) by H2, leading to a lower activation energy for the NCM decomposition (from 139 to 110 kJ/mol) with less H2 consumption. Life cycle assessment suggests a reduction of 4.42 kg CO2 eq for the recycling of every 1.0 kg of retired batteries. This study can promote material circularity and minimize the environmental burden of mining technology-critical metals for a low-carbon transition.

Thermal properties and decomposition of perovskite energetic materials (C6H14N2) NH4 (ClO4)3

(C6N2H14) NH4 (ClO4)3 (DAP-4) have attracted an increasing focus recently as an ammoniumperchlorate-based molecular perovskite energetic material with outstanding features. Microscopy, variable temperature X-ray diffraction, in situ infrared spectroscopy, differential scanning calorimetry-thermogravimetry simultaneous thermal analysis coupled with infrared spectroscopy and mass spectrometry (DSC-TG/FTIR/MS) techniques were used to systematically investigate DAP-4 thermal properties from -40 °C to 550 °C. The results revealed that DAP-4 have two solid-solid crystallization phase transitions with a non-characteristic melting process. The generated activation energies of HCN, CO, CH2NH2, CO2 and NO2 gas products are all lower than the macroscopic decomposition's of DAP-4. This finding strongly proves that DAP-4 is easy to form these gas products during thermal stimulus. The two stages decomposition mechanism accompanying a large of CH2NH2 and NH2C2H4 gases and kinetic model of DAP-4 were proposed under the condition of high-purity argon gas. This study provides new insight into the in-depth and accurate description thermal decomposition mechanism of DAP-4 as a potential energetic material.

Study on thermal decomposition and enrichment quality of coal from Mogoin gol deposit in Mongolia

The main purpose of this study is to investigate the thermal stability and the mechanism of thermal decomposition of Mogoin gol coal, the possibility of liquefaction by pyrolysis and thermolysis, and the possibility of enriching by heavy liquids to reduce the mineral content of coal and improve its quality. Under this purpose, The Mogoin gol coal was characterized by proximate and ultimate analysis, thermogravimetry, and investigated its thermal decomposition (thermolysis and pyrolysis). Thermogravimetric analysis was performed using Japanese HITACHI TG/DTA7300 instrument and pyrolysis investigation was carried out at different heating temperatures 200–700 °C with constant heating rate 20 °C/min for 80 min. On the basis of proximate and elemental analysis results, it has been indicated that the Mogoin gol coal is high-rank coking coal. The pyrolysis of Mogoin gol coal was studied by SNOL furnace at different heating temperatures and obtained from pyrolysis products such as hard residue, tar, pyrolytic water, and gas. From pyrolysis, the yield of pyrolysis tar (6.28%) was highest at 700 °C. The experiment of thermal decomposition (thermolysis) was carried out in air closed autoclave at 350–450 °C and using hydrogen donor solvent (tetraline) with different mass ratios of coal and solvent (1:1.75; 1:1.5). In the thermolysis experiment, the yield of liquid product is highest with the coal: solvent ratio of 1:1.5 at 450 °C.

Synthesis and Characterization of 3,4-Bis[3(2-azidoethoxy)furazan-4-yl]furoxan (DAeTF): A Novel Low-Melting Insensitive Energetic Material.

The synthesis and characterization of low-melting-point insensitive energetic materials are crucial due to their increasing applications in melt-cast explosives. In this work, a furazan-derived energetic compound, 3,4-bis[3(2-azidoethoxy)furazan-4-yl]furoxan (DAeTF), exhibiting insensitive and high-energy characteristics, is rationally designed and synthesized. The structure of DAeTF is characterized by nuclear magnetic resonance spectroscopy, Fourier transform infrared spectroscopy, elemental analysis, mass spectrometry, and single-crystal X-ray diffraction. The thermal properties of DAeTF are investigated using differential scanning calorimetry, in situ FTIR spectroscopy and thermogravimetric-differential scanning calorimetry-Fourier transform infrared-mass spectrometry and thermal decomposition mechanism was elucidated in combination with bond energy calculations. The detonation performance of DAeTF is predicted by the EXPLO5 program. The results indicate that DAeTF has thermal stability (Td = 251.7 °C), high energy level (D = 7270 m/s) and significant insensitivity (IS = 60 J). Additionally, its relatively low melting point (Tm = 60.5 °C) facilitates processing and loading. These characteristics indicate that DAeTF is a promising candidate as an insensitive melt-cast explosive in future applications.

Mechanical Properties and Thermal Decomposition Mechanism of Glycidyl Azide Polyol Energetic Thermoplastic Elastomer Binder with RDX Composite.

To improve the reinforcement effect between a binder and high solid filler in a propellant formula, grafting the bonding group into the binder to form a neutral polymeric is a practically novel approach to improving the interface properties of the propellant. In this work, a glycidyl azide polyol energetic thermoplastic elastomer binder with a -CN bonding group (GAP-ETPE) was synthesized, and the mechanical and thermal decomposition mechanism of GAP-ETPE with Hexogeon (RDX) model propellants were studied. The stress-strain results indicated that the tensile strength and strain of GAP-ETPE/RDX model propellants were 6.43 MPa and 32.1%, respectively. DMA data showed that the storage modulus (E') of the GAP-ETPE/RDX model propellants could increase the glass transition temperature (Tg) values, those were shifted to higher temperature with the increase in filler RDX percentages. TG/DTG showed the four decomposition stages of the decomposition process of the GAP-ETPE/RDX model propellants, and the thermal decomposition equation was constructed. These efforts provide a novel method to improve GAP-ETPE/RDX propellants mechanical property, and the thermal decomposition behavior of GAP-ETPE/RDX propellants also provided technical support for the study of propellant combustion characteristics.

Theoretical Study on the Thermal Decomposition Mechanism of Fe(EDTA)- and Fe(EDTMP).

The decomposition mechanisms of Fe(EDTA)- and Fe(EDTMP)- complexes, widely used in various industrial applications, were investigated through a theoretical approach. Despite their structural similarities, the phosphonic acid and carboxylic acid groups in these complexes lead to vastly different decomposition behaviors. Fe(EDTA)-, stabilized by delocalized π bonds in carboxylic acid groups, exhibited higher stability than that of Fe(EDTMP)-, which has only σ bonds in phosphonic acid groups. Interaction Region Indicator (IRI) analysis revealed that the steric hindrance of Fe(EDTMP)- was stronger than that of Fe(EDTA)-. Ab initio molecular dynamics simulations revealed that Fe(EDTMP)- undergoes rapid decomposition due to the ease of breaking P-C bonds and the repulsion between phosphonic acid groups. In contrast, Fe(EDTA)- decomposes more slowly. These findings suggest the incorporation of phosphonic acid groups for easier degradation pathways when designing organic acid molecules. Understanding these mechanisms provides a basis for developing strategies for wastewater treatment in industrial settings.

Comparative analysis of enhanced adsorption and thermal decomposition of oil-borne PFAS using CeO2 nanoparticles and activated carbon

Per- and poly-fluoroalkyl substances (PFAS) are widely used as surfactants in the oil and gas industry, presenting significant environmental and health risks due to their persistence and mobility. While prevailing research primarily targets PFAS removal from aqueous environments, this study explores the efficacy of nanosized cerium oxide nanoparticles (CeO2 NPs) and traditional activated carbon (AC) in removing PFAS from organic media via adsorption and thermal degradation. Both adsorbents exhibited robust adsorption capabilities; however, their interaction mechanism with PFAS differ significantly. CeO2 NPs primarily engage in chemical adsorption with PFAS, whereas AC relies on hydrophobic interactions. Additionally, CeO2 NPs outperformed AC in thermal degradation experiments, achieving approximately 95 % decomposition of PFOS at 400 °C, compared to only 52 % with AC. Furthermore, the formation of stable Ce−F bonds at high temperatures significantly reduced fluoride ion release from CeO2 NPs, underscoring their potential to minimize environmental impact. This study is the first to apply both AC and CeO2 NPs for PFAS removal from organic media and to elucidate their distinct adsorption and thermal decomposition mechanisms, highlighting the superior performance of CeO2 NPs in environmental remediation of PFAS.

Thermal decomposition kinetics and storage life prediction of nitramine propellants with different energetic plasticizers based on model-fitting method

The research on the thermal decomposition of propellant is critical to determining its safe storage life. The thermogravimetry (TG) testing of nitramine propellants plasticized by nitroglycerin (NG), glycidyl azide polymer (GAP), 2,2-dinitropropanol hexanoate (DNPH), and N-butyl-2-nitratoethylnitramine (BuNENA) was performed under non-isothermal circumstances. The thermal decomposition mechanism of propellant was then analyzed using the model-fitting method, and the storage life was predicted based on the mechanism. The results show that when heated to the same mass loss, the temperature of GAP-NC-RDX, BuNENA-NC-RDX, and DNPH-NC-RDX is higher than that of NG-NC-RDX. GAP-NC-RDX, BuNENA-NC-RDX, and DNPH-NC-RDX propellants have superior thermal stability to that of NG-NC-RDX. The kinetic mechanism functions and equations of the propellants were calculated, and multi-step reaction models of the thermal decomposition were built. The major thermal decomposition mechanism of nitramine propellants was discovered to be composite autocatalytic decomposition (Kamal-Sourour equation), which means that the reaction of reactants and the reaction catalyzed by products occur in tandem. The decomposition depth of propellants increases as the temperature rises during the same storage time. The storage lifetimes of GAP-NC-RDX, BuNENA-NC-RDX, DNPH-NC-RDX, and NG-NC-RDX propellants at 288 K are 28.71 years, 24.49 years, 18.34 years, and 16.33 years, respectively. The inclusion of GAP, DNPH, and BuNENA in the formulation improves the storage life of propellant more than NG. This study offers an attractive strategy for analyzing the decomposition mechanism of propellant with a multi-step decomposition reaction and forecasting its storage life.

The Unimolecular Decomposition Mechanism of Trimethyl Phosphate.

Trimethyl phosphate (TMP), an organophosphorus compound (OPC), is a promising fire-retardant candidate for lithium-ion battery (LIB) electrolytes to mitigate fire spread. This study aims to understand the mechanism of TMP unimolecular thermal decomposition to support the integration of a TMP chemical kinetic model into a LIB electrolyte surrogate model. Reactive intermediates and products of TMP thermal decomposition were experimentally detected using vacuum ultraviolet (VUV) synchrotron radiation and double imaging photoelectron photoion coincidence (i2PEPICO) spectroscopy. Phosphorus-containing intermediates such as PO, HPO and HPO2 were identified. Sampling effects could successfully be obviated thanks to photoion imaging, which also showed evidence for isomerization reactions upon wall collisions in the ionization chamber. Quantum chemical calculations performed for the unimolecular decomposition of TMP revealed for the first time that isomerization channels via hydrogen and methyl transfer (barrier heights of 65.9 and 72.6 kcal/mol, respectively) are the lowest-energy primary steps of TMP decomposition followed by CH3OH/CH3/CH2O or dimethyl ether (DME) production, respectively. We found an analogous DME production channel in the unimolecular decomposition of dimethyl methylphosphonate (DMMP), another important OPC fire-retardant additive with a similar molecular structure to TMP, which are not included in currently available chemical kinetic models.