Search

3-nitro-1,2,4-triazol-5-one (NTO) has been widely used as a kind of insensitive single-compound explosive owing to its excellent balance between safety and explosive energy. To reduce its possible acid corrosion and extend its application to insensitive ammunition, acid protection research on NTO-based explosives is significant. Traditionally, the acid protection effect was evaluated by metal corrosion, which is time-consuming and qualitative. An efficient and quantitative method is desirable for evaluating the acid protection effect and exploring novel protection materials. Herein, a polyimide of 4,4'-(hexafluoroisopropene)diphthalic anhydride (6FDA)/2,2-bis(trifluoromethyl)-4,4-diaminobiphenyl (TFMB) was synthesized by replacing the 4,4'-diaminodiphenyl ether (ODA) monomer with a TFMB monomer to act as an acid-protective coating material for NTO-based explosives. Compared with three other coating materials, polyvinylidene fluoride (PVDF), polyetherimide (PEI), and copolyimide (P84), the fluorinated polyimide exhibits the best acid protection effect. Moreover, a new method was constructed to obtain the pH time-dependent curve in order to evaluate efficiently the acid protection effect of the polymer materials. By the virtue of molecular dynamic simulation (Materials Studio 2023), the interfacial effects of the coating materials with NTO-based explosives were obtained. The study provides an interpretation of the acid protection effect on the molecular level, suggesting that the higher content of fluorine atoms is beneficial for stabilizing the active hydrogen atom of the NTO by forming intermolecular hydrogen bonds. [ABSTRACT FROM AUTHOR]

Production of insensitive munitions (IM) creates wastewater containing 3-nitro-1,2,4-triazol-5-one (NTO). Because NTO is an anion in neutral pH wastewaters, it can be removed via ion exchange (IX), released during IX brine recharge, and may be subsequently degraded by halophiles. IX brine regeneration through halophilic NTO biotransformation was observed over 210 cycles in a sequencing batch reactor (SBR) and averaged 64.8%±20.2% NTO removal. NTO formed 3-amino-1,2,4-triazol-5-one (ATO) under sulfate- and nitrate-reducing conditions. Variable NTO reductions were observed over four phases including anoxic enrichment (80.5%±7.7% , Cycles 0 to 41); anoxic followed by aerobic (42.2%±23.5% , Cycles 42 to 81); anoxic supplemented with nitrate (64.7%±21.5% , Cycles 82 to 177); and anoxic stress test with nitrate and perchlorate (91.0%±9.7% , Cycles 178 to 210). Sequencing results showed 69% of the genera to be halophiles and sulfate-reducing bacteria and archaea including Desulfovibrio and Halanaerobium. ATO reduction in each cycle was shown to be correlated with the abundance of genus Alkalibacterium. The presence of the potential cocontaminants in munitions wastewater IX brine, nitrate and perchlorate, were shown to either increase or not interfere with NTO transformation, respectively. The results of these studies demonstrate that NTO biotransformation by halophiles in brine solutions is feasible and could be utilized for IX brine regeneration. Explosive production and munitions manufacturing in the US creates wastewater containing explosive contaminants. Treatment of this wastewater to remove the explosives is required before the water can be released to the environment. IX can remove the explosive NTO from munitions manufacturing wastewater, but to be economical, the resins need to be reused many times. Regeneration of the IX resin for reuse generates brine that contains the explosive NTO. To remove NTO from the brine so it can be reused, salt-tolerant bacteria were grown that biodegrade NTO. The bacteria were able to biotransform NTO over for 210 cycles and over 500 days from a synthetic IX brine. After optimization of the treatment system, the bacteria were degrading 91.0%± 9.7% of the NTO in each cycle. This system, IX with brine regeneration, for munitions wastewater treatment is potentially more economical and sustainable than current wastewater treatment methods. [ABSTRACT FROM AUTHOR]

Synthesis method of nanocrystalline Barium‐Copper‐Cobalt oxide (BCC) and its composite with reduced graphene oxide (rGO) was provided. The size of nanocrystalline (∼13 nm) materials (BCC and BCC/rGO) was confirmed using powder X‐ray diffraction patterns. The effect of rGO, BCC, and BCC/rGO on the thermal decomposition of 3‐Nitro‐1,2,4‐triazol‐5‐one (NTO) and ammonium perchlorate (AP) was investigated using simultaneous thermal analysis. Non‐isothermal isoconversion method was used to calculate the activation energy of AP and NTO with and without rGO, BCC, and BCC/rGO. The thermal analysis suggests that in the presence of BCC and BCC/rGO, the thermal decomposition exotherm of NTO was lowered to ∼259, and ∼228 °C, respectively, and that of AP was lowered to 355, and 345 °C, respectively. BCC and BCC/rGO exhibit very good catalytic activity for the thermal decomposition of NTO by lowering NTO's activation energy barrier by ∼179 and 261 kJ mol−1, respectively. The activation energy calculations for low thermal decomposition and high thermal decomposition of AP (∼95 kJ mol−1 average) do not provide conclusive evidence to confirm the catalytic influence of BCC and BCC/rGO. The composition NTO+BCC has a lower activation energy barrier (∼121 kJ mol−1) than pure NTO which makes the thermal decomposition of NTO+BCC more favorable than pure NTO making its application in insensitive munitions more favorable. AP+BCC decomposes within a short temperature range and hence, it can be used in solid rocket propellants requiring faster decomposition of AP in place of pure AP. [ABSTRACT FROM AUTHOR]

Nanosize Nickel ferrite (NiF) was synthesized by the co-precipitation methods, and its effect as a 5% by mass additive was studied on the thermal decomposition of micrometer and nanometer size NTO. In the presence of a 5% NiF additive, the thermal decomposition peak temperature of NTO was decreased from 276.36 to 260.18 °C and that of nanoNTO was decreased from 261.38 to 258.89 °C (β = 10 °C min−1). The kinetics parameters confirm the catalytic activity of NiF for the thermal decomposition of NTO, and nNTO as the parameters such as activation energy (NTO = ~ 25.45% and nNTO = ~ 45.94% decrement), and pre-exponential factor (NTO = ~ 21.94% and nNTO = ~ 43.12% decrement) were decreased when 5% NiF additive was added to NTO, and nNTO. The rate of the decomposition process was increased in the presence of a 5% NiF catalyst, indicating the faster thermal decomposition of both NTO, and nNTO in the presence of a nickel ferrite catalyst. [ABSTRACT FROM AUTHOR]

[Display omitted] • Insensitive explosive NTO was electrochemically determined by a smartphone application. • Polyethyleneimine (PEI)−modified GC- and SP-electrodes created a sensing platform for NTO. • Electrostatic and hydrogen bonding interactions between PEI and NTO enhanced sensitivity. • Cobalt-amine sites formed between PEI and cobalt(II)-acetylacetonate served as electrocatalyst. • Validated method was not affected by electroactive camouflage materials and soil ions. Rapid and sensitive voltammetric methods for 3-nitro-1,2,4-triazol-5-one (NTO) determination are scarce in the literature. In the present research, we reported a crosslinked polyelectrolyte-based modified electrode decorated with gold nanoparticles that can be easily formed on the surfaces of both screen-printed electrodes (SPEs) and glassy carbon electrodes (GCEs) for the first time, as well as a voltammetric method for the electrochemical determination of NTO. Cobalt-amine sites formed between PEI and cobalt(II)-acetylacetonate (CoAcAc, an electrocatalyst) are used as a redox mediator. Electrochemical reduction of NTO in the concentration range of 1.3–13 mg L−1 was carried out by both the developed DPV method and a smartphone application. LOD and LOQ values were found to be 0.4 mg L−1 and 1.25 mg L−1 for the developed DPV method and 0.26 mg L−1 and 0.82 mg L−1 for the smartphone implementations, respectively. By taking advantage of the restricted solubility of some other nitro-explosives in water, the solvent medium and the pH of the supporting electrolyte (the pH value at which NTO exists in anionic form, not valid for other explosives) were optimized. In the presence of other nitro explosives, such as trinitrotoluene (TNT), 1,3,5-trinitro-1,3,5-triazacyclohexane (RDX), 2,4-dinitro toluene (DNT), and 1,3,5,7-tetranitro-1,3,5,7-tetraazacyclooctane (HMX), the percentage recovery values range from 90.1 to 105.2 % according to the DPV results measured in admixtures with NTO. Surface morphologies of the modified electrode were characterized using scanning electron microscopy (SEM), and Fourier-transform infrared spectroscopy (FTIR), whereas electrochemical studies were performed using cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The detection method proposed was not adversely affected by common soil ions as well as detergents, sugar, sweeteners, caffeine, and paracetamol-based painkillers as camouflage materials for explosives, the negative impacts of which were either nonexistent or eliminable. [ABSTRACT FROM AUTHOR]

Two major components of insensitive munition formulations, nitroguanidine (NQ) and 3-nitro-1,2,4-triazol-5-one (NTO), are highly water soluble and therefore likely to photo-transform while in solution in the environment. The ecotoxicities of NQ and NTO solutions are known to increase with UV exposure, but a detailed accounting of aqueous degradation rates, products, and pathways under different exposure wavelengths is currently lacking. Here, we irradiated aqueous solutions of NQ and NTO over a 32-h period at three ultraviolet wavelengths (254 nm, 300 nm, and 350 nm) and analyzed their degradation rates and transformation products. NQ was completely degraded by 30 min at 254 nm and by 4 h at 300 nm, but it was only 10% degraded after 32 h at 350 nm. Mass recoveries of NQ and its transformation products were ≥80% for all three wavelengths, and consisted of large amounts of guanidine, nitrate, and nitrite, and smaller amounts of cyanamide, cyanoguanidine, urea, and ammonium. NTO degradation was greatest at 300 nm with 3% remaining after 32 h, followed by 254 nm (7% remaining) and 350 nm (20% remaining). Mass recoveries of NTO and its transformation products were high for the first 8 h but decreased to 22–48% by 32 h, with the major aqueous products identified as ammonium, nitrate, nitrite, and a urazole intermediate. Environmental half-lives of NQ and NTO in pure water were estimated as 4 and 6 days, respectively. We propose photo-degradation pathways for NQ and NTO supported by observed and quantified degradation products and changes in solution pH. Image 1 • Aqueous NQ yielded guanidine, cyanamide, urea, cyanoguanidine, nitrate, and nitrite. • Nitrosoguanidine suspected as an intermediate in NQ photo-transformation. • NTO produced mineralized gases, nitrate and nitrite, and transient urazole. • NQ and NTO estimated to have surface environmental half-lives on the order of days. [ABSTRACT FROM AUTHOR]

Military training exercises can result in deposition of energetic residues on range soils, which ultimately can contaminate groundwater with munitions constituents. Column experiments followed by HYDRUS-1D modeling were conducted to evaluate dissolution and transport of energetic constituents from the new insensitive munitions (IM) formulations IMX-101, a mixture of 3-nitro-1,2,4-triazol-5-one (NTO), nitroguanidine (NQ), and 2, 4-dinitroanisole (DNAN), and IMX-104, a mixture of NTO, 1,3,5-hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) and DNAN. NTO and DNAN are emerging contaminants associated with the development of insensitive munitions as replacements for traditional munitions. Flow interruption experiments were performed to investigate dissolution kinetics and sorption non-equilibrium between soil and solution phases. The results indicated that insensitive munitions compounds dissolved in order of their aqueous solubility, consistent with prior dissolution studies conducted in the absence of soil. Initial elution of the high concentration pulse of highly soluble NTO and NQ was followed by lower concentrations, while DNAN had generally lower and more constant concentrations in leachate. The sorption of NTO and NQ was low, while RDX, 1,3,5,7-octahydro-1,3,5,7-tetranitrotetrazocine (HMX, an impurity in technical grade RDX), and DNAN all exhibited appreciable sorption. DNAN transformation was observed, with formation of amino-reduction products 2-ANAN (2-amino-4-nitroanisole) and 4-ANAN (4-amino-2-nitroanisole). HYDRUS-1D model, incorporating one-dimensional advective-dispersive transport with particle dissolution and first-order solute transformation was used to simulate the measured breakthrough curves. Optimized dissolution parameters varied widely but were correlated between compounds in the same formulation. Determined adsorption coefficients generally agreed with values determined from batch and column studies conducted with pure NTO and DNAN, while mass-loss rate coefficients were in better agreement with ones from batch than column studies possibly due to suppression of microbial transformation during elution of high concentrations of explosives. Even in the low organic matter soils selected in this study DNAN experienced significant retardation and transformation, indicating potential for its natural attenuation. [ABSTRACT FROM AUTHOR]

The insensitive munitions compound 3-nitro-1,2,4-triazol-5-one (NTO) was recently approved by the U.S. Army to replace cyclotrimethylene trinitramine (RDX) in conventional explosives. As its use becomes widespread, concern about the potential toxicity of NTO increases. NTO can undergo microbial reduction to 3-amino-1,2,4-triazol-5-one (ATO), which is recalcitrant in waterlogged soils. In this study, the acute toxicity of NTO and ATO towards various organisms, including microorganisms ( i.e. , methanogenic archaea, aerobic heterotrophs, and Aliivibrio fischeri (Microtox assay)), the microcrustacean Daphnia magna (ATO only), and zebrafish embryos ( Danio rerio ), was assessed. NTO was notably more inhibitory to methanogens than ATO (IC 50 = 1.2 mM, > 62.8 mM, respectively). NTO and ATO did not cause noteworthy inhibition on aerobic heterotrophs even at the highest concentrations tested (32.0 mM). High concentrations of both NTO and ATO were required to inhibit A. fischeri (IC 20 = 19.2, 22.4 mM, respectively). D. magna was sensitive to ATO (LC 50 = 0.27 mM). Exposure of zebrafish embryos to NTO or ATO (750 μM) did not cause lethal or developmental effects (22 endpoints tested). However, both compounds led to swimming behavior abnormalities at low concentrations (7.5 μM). The results indicate that the reductive biotransformation of NTO could enhance or lower its toxicity according to the target organism. [ABSTRACT FROM AUTHOR]

Technologies are needed to address contamination with energetic compounds at military installations. This research developed and evaluated novel and sustainable materials that can be used to remove munition constituents (MC) from stormwater runoff. Initial work focused on 3-nitro-1,2,4-triazol-5-one (NTO), as it is both highly soluble and ionized at environmentally relevant pH values. Screening cellulosic materials indicated that cationized (CAT) versions of pine shavings (pine, henceforth) and burlap (jute) demonstrated >70% removal of NTO from artificial surface runoff. CAT materials also demonstrated >90% removal of the anionic propellant perchlorate. NTO removal (~80%) by CAT pine was similar across initial pH values from 4 to 8.5 S.U. An inverse relationship was observed between NTO removal and the concentration of the major anions chloride, nitrate, and sulfate due to competition for anion binding sites. Sorption isotherms were performed using a mixture of the three primary legacy explosives (octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (HMX), hexahydro-1,3,5-trinitro-s-triazine (RDX), 2,4,6-trinitrotoluene (TNT)), the three insensitive MC (nitroguanidine (NQ), NTO, 2,4-dinitroanisole (DNAN)), and perchlorate. Isotherm results indicated that effective removal of both legacy and insensitive MC would best be achieved using a mixture of peat moss plus one or more of the cationized cellulosic materials. [Display omitted] • -Cationized cellulosic biopolymers effectively removed NTO from solution. • -NTO removal was unaffected by pH. • -Competitive effects were observed between NTO and other major anions. • -Peat moss was more effective for sorption of legacy explosives and DNAN. [ABSTRACT FROM AUTHOR]

Abstract: NTO·DNAZ was prepared by mixing 3,3-dinitroazetidine (DNAZ) and 3-nitro-1,2,4-triazol-5-one (NTO) in ethanol solution. The thermal behavior of the title compound was studied under a non-isothermal condition by DSC and TG/DTG methods. The kinetic parameters were obtained from analysis of the DSC and TG/DTG curves by Kissinger method, Ozawa method, the differential method and the integral method. The main exothermic decomposition reaction mechanism of NTO·DNAZ is classified as chemical reaction, and the kinetic parameters of the reaction are E a =149.68kJmol−1 and A =1015.81 s−1. The specific heat capacity of the title compound was determined with continuous C p mode of microcalorimeter. The standard mole specific heat capacity of NTO·DNAZ was 352.56Jmol−1 K−1 in 298.15K. Using the relationship between C p and T and the thermal decomposition parameters, the time of the thermal decomposition from initialization to thermal explosion (adiabatic time-to-explosion) was obtained. [Copyright &y& Elsevier]

Abstract: The geometries, lattice parameters, electronic structures, XRD spectra and optical properties of the 3-nitro-1,2,4-triazol-5-one (NTO) crystals at high pressure (2, 4, 6, 8 and 10GPa) have been studied using density functional theory within the generalized gradient approximation implemented using ultrasoft pseudo-potentials. The computational results show that with increasing pressure, the NTO lattice parameters and hydrogen bonds lengths rapidly decrease and the geometries change very little. The total energy increases by approximately 27.543eV from 0 to 10GPa. NTO becomes increasingly conductive or metallic with increasing pressure, while the XRD peaks are shifted to greater angles and the absorption coefficient α(ω) increases. [Copyright &y& Elsevier]

The single crystal of cobalt compound of 3-nitro-1,2,4-triazol-5-one (NTO) ([Co(H2O)6](NTO)2·2H2O) was prepared and the crystal structure has been determined by a four-circle X-ray diffractometer. The compound is monoclinic with space group Cc and unit cell parameters of a=2.3163 (2) nm, b=0.6451 (1) nm, c=1.4123 (1) nm, β=123.96 (1)°, V=1.7504 (3) nm3 and Z=4. Based on the thermal analysis, the thermal decomposition mechanism of [Co(H2O)6](NTO)2·2H2O has been derived. From measurements of the enthalpy of solution in water at 298.15 K, the standard enthalpy of formation, lattice enthalpy and lattice energy have been determined as -(2594.7±4.5), -2753.19, and -2718.19 kJ mol-1, respectively. [Copyright &y& Elsevier]

[Mg(H2O)6](NTO)2·2H2O was prepared by adding magnesium carbonate hydroxide to the aqueous solution of 3-nitro-1,2,4-triazol-5-one (NTO). The single crystal structure has been determined by a four-circle X-ray diffractometer. The compound is monoclinic with space group C2/c and unit-cell parameters a=2.3101(3) nm, b=0.6472(1) nm, c=1.4118(3) nm and β=124.05(1)°. From measurements of the enthalpy of solution in water at 298.15 K, the standard molar enthalpy of formation, lattice energy and lattice enthalpy have been determined as −(3015.38±4.2) kJ mol−1, −2680.7 and −2653.2 kJ mol−1. [Copyright &y& Elsevier]

We report a reactive molecular dynamic (ReaxFF-MD) study using the newly parameterized ReaxFF-lg reactive force field to explore the initial decomposition mechanism of 3-Nitro-1,2,4-triazol-5-one (NTO) under shock loading (shock velocity >6 km/s). The new ReaxFF-lg parameters were trained from massive quantum mechanics data and experimental values, especially including the bond dissociation curves, valence angle bending curves, dihedral angle torsion curves, and unimolecular decomposition paths of 3-Nitro-1,2,4-triazol-5-one (NTO), 1,3,5-Trinitro-1,3,5-triazine (RDX), and 1,1-Diamino-2,2-dinitroethylene (FOX-7). The simulation results were obtained by analyzing the ReaxFF dynamic trajectories, which predicted the most frequent chain reactions that occurred before NTO decomposition was the unimolecular NTO merged into clusters ((C2H2O3N4)n). Then, the NTO dissociated from (C2H2O3N4)n and started to decompose. In addition, the paths of NO2 elimination and skeleton heterocycle cleavage were considered as the dominant initial decomposition mechanisms of NTO. A small amount of NTO dissociation was triggered by the intermolecular hydrogen transfer, instead of the intramolecular one. For α-NTO, the calculated equation of state was in excellent agreement with the experimental data. Moreover, the discontinuity slope of the shock-particle velocity equation was presented at a shock velocity of 4 km/s. However, the slope of the shock-particle velocity equation for β-NTO showed no discontinuity in the shock wave velocity range of 3–11 km/s. These studies showed that MD by using a suitable ReaxFF-lg parameter set, could provided detailed atomistic information to explain the shock-induced complex reaction mechanisms of energetic materials. With the ReaxFF-MD coupling MSST method and a cheap computational cost, one could also obtain the deformation behaviors and equation of states for energetic materials under conditions of extreme pressure. [ABSTRACT FROM AUTHOR]

The use of insensitive munitions such as 3-nitro-1,2,4-triazol-5-one (NTO) is rapidly increasing and is expected to replace conventional munitions in the near future. Various NTO treatment technologies are being developed for the treatment of wastewater from industrial munition facilities. This is the first study to explore the potential phytoremediation of industrial NTO-wastewater using vetiver grass (Chrysopogon zizanioides L.). Here, we present evidence that vetiver can effectively remove NTO from wastewater, and also translocated NTO from root to shoot. NTO was phytotoxic and resulted in a loss of plant biomass and chlorophyll. The metabolomic analysis showed significant differences between treated and control samples, with the upregulation of specific pathways such as glycerophosphate metabolism and amino acid metabolism, providing a glimpse into the stress alleviation strategy of vetiver. One of the mechanisms of NTO stress reduction was the excretion of solid crystals. Scanning electron microscopy (SEM), electrospray ionization mass spectrometry (ESI-MS), and Fourier-transform infrared spectroscopy (FTIR) analysis confirmed the presence of NTO crystals in the plant exudates. Further characterization of the exudates is in progress to ascertain the purity of these crystals, and if vetiver could be used for phytomining NTO from industrial wastewater. [ABSTRACT FROM AUTHOR]