Decomposition Pathways Research Articles

Mechanistic study of the influence of aluminum nanoparticles on the pressure sensitivity of 1,3,5-trinitro1,3,5-triazinane (RDX) thermal decomposition

The incorporation of Al nanoparticles (Al NPs) into 1,3,5-trinitro1,3,5-triazinane (RDX) can catalyze its thermal decomposition and reduce the pressure exponent (n) of solid propellants. However, the underlying reaction mechanism at a deeper level remains unclear. In this study, the reaction processes of Al NPs catalyzing the thermal decomposition of RDX under different initial pressures were investigated by utilizing the ReaxFF molecular dynamics (ReaxFF-MD) simulations combined with DFT calculations, and the influence mechanism of Al NPs on the pressure sensitivity of RDX thermal decomposition was revealed from various perspectives. In the initial stage of the reaction, unlike the nitro group dissociation observed in pure RDX, the incorporation of Al NPs alters the initial decomposition pathway of RDX, making it more easily adsorbed on the surface of Al and enhancing the early-stage decomposition rate. Furthermore, Al NPs exhibit higher catalytic activity in low-pressure systems. In the later stage, because of the massive adsorption of free radicals generated from RDX decomposition on the surface of Al NPs, the decomposition rate of RDX decreases significantly, especially in high-pressure systems. Consequently, Al NPs synergistically reduce the pressure sensitivity of the RDX thermal decomposition from two different perspectives. Compared to traditional experimental research or single RDX simulation studies, this work further explores the interaction between Al and RDX from a microscopic perspective, addressing the gap in the field of the influence mechanisms of Al NPs on the pressure sensitivity of RDX thermal decomposition. It also establishes a theoretical foundation for the practical application of Al@RDX fuels.

Effects of redox active agents on cyanocobalamin stability in heated milk

SummaryReducing agents and oxidizing agents have been identified as contributors to vitamin B12 losses associated with food processing and/or storage. We evaluated the effects of redox active agents on cyanocobalamin stability in heat‐treated non‐fat milk and neutral pH buffers. The largest average cyanocobalamin losses occurred in the presence of an added thiol (glutathione, cysteine, dithiothreitol and the thiamine decomposition product 2‐methyl‐3‐furanthiol) or dithionite, whereas cyanocobalamin recoveries generally increased in the presence of an added oxidizing agent. Cyanocobalamin instability in the heat‐treated, non‐fat milk (~40% loss after 90 min at 100 °C) was attributed to a combination of heat, cystine/cysteine, oxygen and a low‐level presence of transition metals, a combination also found in many other foods for which B12 instability has been reported. The proposed cyanocobalamin decomposition pathway – complexation with heat‐exposed cysteine thiolate, cobalt reduction, hydrolysis of the complex, conversion to hydroxocobalamin and irreversible oxidation – follows the sequence described by others.

Thermodynamic Analysis and Pyrolysis Mechanism of 4,4'-Azobis-1,2,4-triazole.

The nonisothermal thermal decomposition kinetics of 4,4'-azobis-1,2,4-triazole (ATRZ) at different heating rates (5, 10, 15, and 20 °C·min-1) were investigated by thermogravimetry (TG) and differential scanning calorimetry (DSC) studies. The thermal decomposition kinetic parameters such as apparent activation energy (E) and pre-exponential factor (A) were calculated by the Kissinger, Ozawa, and Šatava-Šestak methods. The E and A values calculated by the above three methods are very close, which are 391.1 kJ·mol-1/1034.92 s-1, 381.1 kJ·mol-1/1034.30 s-1, and 393.4 kJ·mol-1/1035.76 s-1, respectively. Then, the decomposition mechanism function of ATRZ is analyzed by the calculated results. The results show that the decomposition temperature of ATRZ is about 300 °C and the exothermic decomposition speed is fast. The decomposition pathway of ATRZ was analyzed by pyrolysis-gas chromatography-mass spectrometry (PY-GC-MS). The thermal decomposition kinetic equation of the ATRZ was deduced.

Exploring the impact of backbone architecture on the thermal decomposition of silicon-containing arylacetylene resins

Silicon-containing arylacetylene (PSA) resins are promising heat-resistant polymers. However, little is known about their decomposition mechanisms. A molecular dynamics (MD) study based on reactive force field (ReaxFF) was employed to investigate the thermal decomposition mechanism of two representative PSA resins containing benzene or naphthalene in the backbone. The effect of heating rate, temperature, and crosslinking degree on decomposition behavior was examined, and the temperatures of three decomposition stages were disclosed. The predicted 5% decomposition temperatures (Td5) and decomposition products are consistent with experimental findings. The ReaxFF MD simulation reveals that the Td5 is dominated by the secondary decomposition and final decomposition, in which the high molecular weight and the stable CC bond of naphthyl play a dominant role in determining high-temperature resistance of the naphthalene-containing PSA resin. We also disclose the decomposition pathways of PSA-type resin. The results gained from the present work can be a helpful guideline for designing resins with excellent heat resistance.

LED visible light assisted photo-oxidation of acetaminophen using one-step synthesis of Cu,Fe@g-C3N4 nanosheet – Activated persulfate system in aqueous solutions

In this work, the synthesis of Iron (Fe) and Copper (Cu) co-doped g-C3N4 was performed using the thermal decomposition of urea while iron nitrate and copper nitrate were used as dopant precursors. The fabricated catalyst (Fe-Cu@g-C3N4) was coupled with visible light and used for acetaminophen (APAP) degradation. The synthesized catalyst was characterized via several techniques including XRD, BET, BJH, SEM, TEM, EDX, EDS Dot mapping, DLS, and UV–Vis deflective reflectance spectroscopy. The performed characterization tests confirmed the successful synthesis of Fe-Cu co-doped g-C3N4 with high purity, nano-sheet structure and high porosity (79.93 m2/g). The complete APAP decomposition efficiency was achieved under optimal experimental conditions including pH of 11, catalyst dosage of 10 mg/L, PS dosage of 1 mM, and APAP concentration of 4 mg/L. The scavenging tests confirmed the major contribution of sulfate radicals and consequently, hydroxyl radicals for APAP removal. In addition, the kinetics of APAP degradation was studied and it revealed the pseudo first–order kinetics with 0.0698 min−1 rate constant. Finally, a plausible and tentative decomposition pathway was proposed for APAP degradation. The results of this study confirmed that the LED/catalyst (Cu, Fe@g-C3N4)/PS process could be an efficient and robust process for antibiotic-containing wastewater including hospital wastewater.

Chemical decontamination of methamphetamine and ephedrine using an activated peroxide-containing cleaning solution

Manufacture and recreational use of methamphetamine can result in widespread chemical contamination throughout a property. Hydrogen peroxide (H2O2)-based cleaning products have shown success against a number of chemical contaminants including agents of chemical warfare, and biological contaminants such as anthrax. They are considered to be environmentally friendly and economically viable and, as such, are used by many companies within the methamphetamine decontamination industry. The oxidative decontamination of methamphetamine and ephedrine hydrochloride was investigated in this current study, employing a commercially available H2O2-based decontamination product, Bio-Oxygen® Chem Decon. Methamphetamine and ephedrine were observed to degrade following pseudo-first order kinetics of (1.9 ± 0.4) × 10−2 min−1 and (2.2 ± 0.3) × 10−2 min−1, respectively. Major oxidation products identified through GC-MS analyses were phenylacetone oxime (from methamphetamine) and benzaldehyde (from ephedrine). LC-MS analysis revealed the presence of a number of N-oxygenated intermediates which allowed for the elucidation of an N-oxidation decomposition pathway reminiscent of flavin-containing monooxygenase enzymes. Using this information, further targeted research can be performed to understand the behaviour and persistence of these reaction products and accurate assessments can be achieved to estimate their impact on the exposure risks associated with chemical decontamination of amphetamine-type stimulants (ATS).

Synthesis of ZnO@VC for enhancement of synergic photocatalytic degradation of SMX: Toxicity assessment, kinetics and transformation pathway determination

Nanocomposite-based photocatalytic degradation of sulfamethoxazole (SMX) is frequently used for wastewater treatment. However, applying various nanoparticles led to different removal efficiencies and levels of environmental toxicity. Herein, we synthesized and characterized ZnO@VC to enhance the photocatalytic degradation of SMX. Effects of SMX concentration, catalyst dosage, pH, water matrix and role of reactive oxygen specious (ROS) were evaluated. Results confirmed 97.69±0.95% (5 mg L−1 SMX/0.05 g L−1 catalyst) removal efficiency followed pseudo-first-order kinetic. Higher SMX concentration and higher catalyst dosage reduced degradation efficiency because of the prevention of catalyst active-sites and limiting light availability. SMX removal efficiency was slightly reduced in synthetic wastewater (SWW) and tap water (TW) by anions scavenging ROS. Due to pH reliance of SMX anionic-density, the degradation efficiency was positively and negatively impacted by acidic and basic environment, and pH values below and over the catalyst point of zero charge (PZC), respectively. Quenching test revealed that some specious of ROS play more important role in photocatalytic degradation of SMX. Two degradation pathways of SMX photocatalytic decomposition were described. The synthesized catalyst showed good stability in terms of reusability. The results revealed that ZnO@VC with high detoxification ability (97%) could be a promising photocatalyst for treatment of antibiotics from water and wastewater.

Effect of prior processing on the decomposition of the β phase in Ti–Nb alloys during intermediate heat treatments

Metastable β-Ti alloys exhibit multiple decomposition pathways during isothermal ageing. Ages at intermediate temperatures below the α/β transus result in the formation of α or isothermal ω. The effect of prior processing on these pathways remains largely unexplored within the literature. Therefore, the role of processing on a Ti–Nb alloy was investigated in cold rolled and solutioned conditions. The solutioned sample showed evidence of recrystallisation, with shear bands remnant from the prior cold rolling that exhibited a greater degree of texture than the surrounding material. During isothermal ageing ωiso was observed outside of these bands whilst α phase precipitated within the bands and throughout the cold rolled sample. This shows that the remnant strain from the rolling process facilitated α nucleation over ωiso due to accommodation of the α/β interface. Additionally, it was seen that the magnitude of internal strains had a marked effect on the α morphology observed.

Systematic Search for Thermal Decomposition Pathways of Formic Acid on Anatase TiO2 (101) Surface**

AbstractIn this study, the reaction pathways for the thermal decomposition of formic acid on the anatase TiO2 (101) surface were systematically investigated. The investigation was carried out using a single‐component artificial force induced reaction method that combines density functional theory calculations. In order to uncover the overall mechanism at low surface coverage, we explored reaction path networks for three different conditions of the anatase TiO2 (101) surfaces: clean, protonated, and oxygen‐deficient surfaces. Previous temperature‐programmed desorption (TPD) experiments had shown that H2O desorption starts at a low temperature of about 300 K, while CO and formaldehyde desorption starts at high temperatures of about 500 K. The present reaction path networks are consistent with the overall trend observed in the TPD experiments. Using the reaction pathways extracted from these networks, the overall dissociation mechanism has been discussed.

Switching Reaction Pathway of Medium-Concentration Ether Electrolytes to Achieve 4.5 V Lithium Metal Batteries.

Pursuing high-energy-density lithium metal batteries (LMBs) necessitates the advancement of electrolytes. Despite demonstrating high compatibility with lithium metal anodes (LMAs), ether-based electrolytes face challenges in achieving stable cycling at high voltages. Herein, we propose a strategy to enhance the high-voltage stability of medium-concentration (∼1 M) ether electrolytes by altering the reaction pathway of ether solvents. By employing a 1 M lithium difluoro(oxalato)borate in dimethoxyethane (LiDFOB/DME) electrolyte, we observed that LiDFOB displays a pronounced tendency for decomposition over DME, leading to a modification in the decomposition pathway of DME. This modification facilitates the formation of a stable organic-inorganic hybrid interface. Utilizing such an electrolyte, the Li-LCO cell demonstrates a discharge specific capacity of 146 mAh g-1 (5 C) and maintains retention of 86% over 1000 cycles at 2 C under a 4.5 V cutoff voltage. Additionally, the optimized ether electrolyte demonstrated outstanding cycling performance in Li-LCO full cells under practical conditions.

Plant diversity enhanced nematode-based soil quality indices and changed soil nematode community structure in intensively-managed agricultural grasslands

Plant productivity, decomposition and nutrient cycling are controlled by plant-soil-biota interactions. However, it remains poorly understood how plant species diversity impacts belowground communities that modulate these processes in intensively-managed grassland systems. In managed grassland communities comprising species selected for agronomic performance, we investigated how plant species diversity affected the soil nematode community and associated ecological indices with a focus on assessing aboveground-belowground interactions. A total of 27 nematode taxa were identified from 61 experimental field plots in which plant species diversity was systematically manipulated from a pool of six plant species within three functional groups (FGs; grasses, legumes, herbs). In general, there were strong effects of plant species identity on the nematode community; interspecific interaction effects did not consistently occur, but where they did were best related to plant community evenness. The equi-proportional six-species plant community had a significantly higher nematode diversity, maturity index (MI), structure index (SI) and proportion of sensitive taxa (omnivore and predators) but a lower enrichment index (EI) than the individual monocultures. The two legumes (Trifolium pratense and Trifolium repens) had the highest EI but lowest abundance of fungivores and channel index, indicating a bacterial-dominated decomposition pathway. Moreover, the community structure of nematodes in the equi-proportional six-species community was significantly different from that in the monocultures. This change in community structure was associated with factors highly correlated with plant diversity, including higher aboveground biomass yield and total nitrogen in harvested biomass as well as lower biomass of weed species. Overall, our results show that multi-species forage sward mixtures that include grasses, legumes, and herbs can have a positive effect on the soil nematode community and nematode-based soil quality indices. This is of practical relevance for farmers and for EU agricultural policy targeted at sustainability, soil health and farming for biodiversity benefits.

Iron Complex Posolyte Species Possessing Low Capacity Fade Rate Combined with Large Positive Redox Potential for Aqueous Organic Flow Batteries

Redox flow batteries are promising technologies for energy storage and conversion applications. Among different types of flow batteries, iron-based redox-active materials can have cost and environmental advantages. We introduce a high-potential tris(2,2'-bipyridine-4,4'-diyldimethanol) iron dichloride compound as a posolyte species with a redox potential more than 0.5 V more positive than that of ferro/ferricyanide. The new species, abbreviated Fe(Bhmbp)3, operating at near-neutral pH, was paired with bis(3-trimethylammonio)propyl viologen tetrachloride as the negolyte species. The resulting aqueous flow battery exhibits an open-circuit voltage of 1.36 V and it shows excellent cycling stability with a capacity fade rate of 0.0007% per cycle or 0.07% per day. In comparison with previously reported organic and metalorganic compounds, Fe(Bhmbpy)3 exhibits a superior combination of high positive redox potential and low capacity fade rate. We investigated the decomposition pathways during cell cycling to an unprecedented level of depth for an aqueous posolyte. We found that the compound degrades through self-discharge, dimerization and ligand dissociation. The proposed decomposition pathways explain the capacity fade phenomena and offer opportunities for future improvement of metalorganic posolytes with high redox potential and good cycling stability

Insights into Electrolyte Reactivity and Solid Electrolyte Interphase Formation at the Li Metal Anode Surface from DFT Simulations

Solid electrolyte interphase (SEI) is a critical component of lithium ion batteries, yet is poorly characterized and not well understood. We use plane wave density functional theory simulations to perform a comprehensive study of the degradation reaction mechanisms of four electrolyte solvents and additives, ethylene carbonate (EC), propylene carbonate (PC), fluoroethylene carbonate (FEC), and vinylene carbonate (VC), at the Li (001) metal anode surface. The calculations provide fundamental insights into electrolyte decomposition and spontaneous SEI formation. Utilizing automated workflows implemented in the Schrödinger Materials Science Suite, we compute the adsorption energies and calculate the reaction energies for each decomposition pathway. Furthermore, we employ nudged elastic band calculations to compute the decomposition reaction barriers and provide mechanistic insights into the onset of SEI formation. We analyze trends in decomposition reaction energies and the relationships between the reaction energies and the activation barriers for the various electrolyte molecules as a function of applied bias potential. We find that the preferred decomposition pathways are different for the solvent molecules (EC and PC) than for the additives (FEC and VC). Calculations also suggest that applied bias reduces decomposition reaction barriers thus enhancing SEI formation. Such a comprehensive dataset of reaction energies and activation barriers provides useful benchmarks for the development and validation of reactive machine learned force fields for modeling advanced battery chemistries at a larger scale.

Design and Characterization of Azobenzene Electrolytes for Aqueous Redox Flow Batteries

Aqueous redox-flow batteries (RFBs) containing organic redox electrolytes are a promising technology for grid-scale renewable energy storage. Most electrolytes currently under consideration for these RFBs contain charge-storing molecules that are drawn from a narrow collection of molecular scaffolds, and undergo rapid decomposition, which results in high rates of capacity fade. To inform efforts at developing more stable aqueous RFB electrolytes, it is critical that the kinetics of charge carrier decomposition and its relationship to capacity fade are well understood.In this work, we explore a relatively new class of redox-active organic molecules known as azobenzenes as potential charge carriers in aqueous RFBs. The electrochemical properties and cycling performance of a range of substituted azobenzenes are characterized using cyclic voltammetry, chronoamperometry, and constant current-constant voltage cycling. Decomposition products are identified using UV-vis and proton nuclear magnetic spectroscopy, as well as mass spectrometry. We discern the influence of decomposition during flow cell cycling by combining in-line UV-vis spectroscopy with multivariate curve resolution, which allows us to quantify decomposition kinetics and estimate UV-vis spectra of intermediate species/decomposition products. These results are being used to drive de novo computational design of new azobenzene molecules that can eliminate or substantially mitigate the identified decomposition pathways.

Investigation of Gas Evolution by Operando GC/MS from SEI Forming Additives in Lithium-Ion-Batteries

Due to the chemical reactivity of the electrolyte, electrolyte decomposition often occurs at the electrode-electrolyte interface during cycling, which can lead to a loss in LIB performance. On the anode side, however, the formation of a stable Solid Electrolyte Interphase (SEI) is essential for the safe operation of Lithium-ion batteries (LIBs). The SEI layer, which is permeable for Li+ ions, protects the electroactive materials from direct contact with the electrolyte, thereby inhibiting further electrolyte decomposition. In the formation cycles of fresh cells, electrolyte degradation is primarily attributed to the SEI formation processes at the anode. Several literature reports have confirmed that the newly formed interphase consists of organic and inorganic decomposition products of the electrolyte.1 To increase battery performance, cycle life and safety, it is essential to form a stable SEI.2 A common strategy to stabilize the SEI is to use additives in the electrolyte composition. The additives should exhibit higher reduction potentials than other electrolyte components to enable preferential reduction and incorporation into the SEI. The most common SEI forming additives are fluoroethylene carbonate (FEC) and vinylene carbonate (VC). They both decompose during the formation cycle to form a polymeric layer at the electrode surface.The electrolyte decomposition reactions which lead to SEI formation are usually accompanied by gaseous side products. The evolving gas species form a complex gas mixture which can be separated by gas chromatography (GC) into their individual components and subsequently identified by mass spectrometry (MS). While operando GC/MS gives information on the volatile side products of the electrolyte decomposition reactions, X-ray photoelectron spectroscopy (XPS) can be used to identify the degradation products that form on the surface of the electrode and are incorporated into the SEI. The combination of the two techniques allows a more comprehensive picture of SEI formation processes to be drawn.In this work, operando GC/MS of Lithium-ion full cells with NMC 811 cathodes and graphite anodes was used to compare the gas species evolving during the formation reactions in an electrolyte with the composition of 1M LiPF6 in EC/DEC 1:1 with FEC and VC electrolyte additives in a ratio of 1w%, respectively. In a comparative study we present the decomposition pathways of the electrolytes with and without SEI forming additives by analysing the composition of the gas phase as a function of cell potential. We observe that the complex gas mixture consists of carbonate components originating from transesterification reactions and evaporation of the volatile electrolyte. In addition, inorganic components such as carbon monoxide and carbon dioxide are produced, which mainly stem from the degradation of cyclic carbonates. Furthermore, the gas phase consists of saturated and unsaturated hydrocarbons which can be ascribed to the linear carbonate components as well as ether and carbonyl components. We have also observed that it is possible to distinguish between volatile compounds which form during the charge and discharge processes, respectively. The increased gas evolution at the beginning of the formation cycle confirms that a substantial part of the passivation layer is formed during charge. Finally, operando GC/MS was also used to monitor the evolution of the decomposition products during battery operation at overcharge conditions.Acknowledgement:The author gratefully acknowledges the FFG (Austrian Research Promotion Agency) for funding this research within project No. 879613

Actionable insights into hazard mitigation of typical 3D printing waste via pyrolysis

3D printing waste (3DPW) contains hazardous substances, such as photosensitizers and pigments, and may cause environmental pollution when improperly disposed of. Pyrolysis treatment can reduce hazards and turn waste into useful resources. This study coupled thermogravimetric (TG), TG-Fourier transform infrared spectroscopy-gas chromatography/mass spectrometry, and rapid pyrolysis gas chromatography/mass spectrometry analysis to evaluate the pyrolytic reaction mechanisms, products, and possible decomposition pathways of the three typical 3DPW of photosensitive resin waste (PRW), polyamide waste (PAW), and polycaprolactone waste (PCLW). The main degradation stages of the typical 3DPW occurred at 320–580 °C. The most appropriate reaction mechanisms of PRW, PAW and PCLW were D1, A1.2 and A1.5, respectively. The main pyrolysis processes were the decomposition of the complex organic polymers of PRW, the breaking of the NH–CH2 bond and dehydration of –CO–NH– of PAW, and the breaking and reorganization of the molecular chains of PCLW, mainly resulting in toluene (C7H8), undecylenitrile (C11H21N), tetrahydrofuran (C4H8O), respectively. Unlike the slow pyrolysis, the rapid pyrolysis produced volatiles consisting mainly of phenol, 4,4'-(1-methylethylidene)bis- (C15H16O2) for PRW; 1,10-dicyanodecane (C12H20N2) for PAW; and ɛ-caprolactone (C6H10O2) for PCLW. These pyrolysis products hold great potential for applications. The findings of the study offer actionable insights into the hazard reduction and resource recovery of 3D printing waste.

Molecular Dynamics Investigation of the Gasification and Hydrogen Production Mechanism of Phenol in Supercritical Water

Supercritical water gasification is an efficient and clean method for converting biomass into hydrogen-rich gas. Phenol plays a crucial role as an intermediate product in biomass supercritical water gasification, and studying its reaction pathway in supercritical water is essential for understanding the chemical reaction mechanism and optimizing biomass energy conversion processes. In this paper, we investigated the conversion mechanism of phenol gasification and hydrogen production in supercritical water using a combined approach of reactive force field (ReaxFF) and density functional theory (DFT). We determined the decomposition pathways and product distribution of phenol in supercritical water. The calculation results demonstrate that in the supercritical water system, the efficiency of phenol conversion for hydrogen production is approximately 27 times higher than that of hydrogen production through gasification in the pyrolysis state. Moreover, both the carbon conversion rate and hydrogenation rate in the supercritical water system are significantly higher compared to those in the pyrolysis system. Furthermore, we found that the energy in the supercritical system is approximately half that of the pyrolysis system, favoring the ring-opening reactions of phenol and promoting hydrogen production. In contrast, the pyrolysis system produces a greater quantity of aromatic compounds, leading to tar formation and having significant implications for both the reaction process and reactor design. Additionally, we conducted comparative experiments between the supercritical water gasification process and the pyrolysis process to explore the advantages of supercritical water gasification.

Probing Catalyst Degradation in Metathesis of Internal Olefins: Expanding Access to Amine-Tagged ROMP Polymers.

Ruthenium-promoted ring-opening metathesis polymerization (ROMP) offers potentially powerful routes to amine-functionalized polymers with antimicrobial, adhesive, and self-healing properties. However, amines readily degrade the methylidene and unsubstituted ruthenacyclobutane intermediates formed in metathesis of terminal olefins. Examined herein is the relevance of these decomposition pathways to ROMP (i.e., metathesis of internal olefins) by the third-generation Grubbs catalyst. Primary alkylamines rapidly quench polymerization via fast adduct formation, followed by nucleophilic abstraction of the propagating alkylidene. Bulkier, Brønsted-basic amines are less aggressive: attack competes only for slow polymerization or strong bases (e.g., DBU). Added HCl limits degradation, as demonstrated by the successful ROMP of an otherwise intractable methylamine monomer.

Application of iron-intercalated graphite for modification of nickel foam cathode in heterogeneous electro-Fenton system: Bisphenol A removal from water at neutral pH

The presence of bisphenol A (BPA) in natural waters can be highly harmful due to its high persistence and adverse effects, raising concerns to remove this hazardous compound. Herein, an electro-Fenton system is proposed to eliminate BPA, wherein the iron source in the Fenton reaction is provided by its intercalation into the carbon layers of graphite. The produced heterogeneous catalyst was then coated onto the nickel foam serving as a cathode. The magnetic graphite intercalated compound (mGIC) and the modified cathode (before and after experiments) were characterized by FE-SEM, EDX, XPS, and XRD analyses. Some effective parameters, namely pH (3–9), current density (0–20 mA cm−2), and BPA concentration (0.5–20 mg L−1) were studied. At pH 3, the removal of BPA was 95.52%, and under neutral circumstances, the BPA and TOC removals were 85.70 and 58.12%, respectively at the initial BPA concentration of 10 mg L−1. The proposed system was also applied to several water sources spiked with BPA at the concentration of 5 mg L−1 under neutral pH, which exhibited considerable removal of 99.74%, 99.72%, and 92.70% for groundwater, municipal effluent wastewater, and tap water, respectively. The proposed system was applied for 15 consecutive cycles without showing significant changes in BPA removal, indicating its excellent stability and reusability. Furthermore, based on the analysis of intermediates, a possible decomposition pathway was proposed, indicating a reduction in overall toxicity. By using the proposed heterogeneous electro-Fenton system, iron waste is avoided, and operational costs of treatment can be reduced due to the absence of iron sludge production and catalyst loss.

Molecular dynamics study on the thermal decomposition of 1,3,5-trinitro-1,3,5-triazinane (RDX) catalyzed by aluminum nanoparticles with different contents

The mechanism of thermal decomposition of 1,3,5-trinitro-1,3,5-triazinane (RDX) catalyzed by nano-sized aluminum powder remains unclarified. In the present study, reactive molecular dynamics simulations using the parameterized reactive force field with low gradient correction (ReaxFF-lg) were conducted to study the microscale process of the RDX thermal decomposition catalyzed by different Al contents, and the density functional theory calculations were used to analyze the initial decomposition pathways of RDX on the Al surface. The thermal disintegration and the released energy of RDX are significantly facilitated by an increase in Al concentration at a lower level and the optimal value is around 35 wt%, while a higher concentration of Al will lead to an opposite effect. The dissociation of nitro group is the most probable initial reaction pathway for RDX decomposition on the Al surface. In addition, the evolutions of Al-containing clusters, key intermediates, and final products were analyzed, providing more information about this reaction. The findings suggest that the addition of Al nanoparticles improves the properties of RDX-based explosives, but the optimal amount of Al is critical for achieving the desired effects. The detailed analysis of the reaction mechanism and intermediate products provides valuable insights into the underlying mechanisms of the Al/RDX system.