Papers by Keyword: TNT

Abstract: The 2, 4, 6-trinitrotoluene (TNT) vapor detection by quartz crystal microbalance (QCM) coated with 18-crown-6 ether film is introduced. The film acts as selective or sensitive layer for detecting TNT molecule. The frequency shift response is depend on the amount of mass of molecule adhere on the coated film surface. In this study, the concentrations of TNT vapor which is related to responses are studied. It shows that the TNT vapor concentration is related to the time for steady state condition and the frequency shift response. The high concentration vapor will increase the frequency shift response but increase the steady state time.

Abstract: This work deals with the numerical simulation of unsteady compressible turbulent flow past a circular cylinder. Turbulent flow is modeled by two different methods. The first method is based on the system of URANS equations closed by the two equation TNT model or modified EARSM model. Second method is based on the X-LES model, which is a hybrid RANS-LES method. Numerical solution is obtained by the finite volume method. Presented results are for the sub-critical turbulent flow characterized by Re=3900.

Abstract: Intermolecular interaction of mononitrotoluenes (MNs) plasticizer with 2,4,6-trinitrotoluene (TNT) and 1,3,5-trinitrohexahydro-1,3,5-triazine (RDX) was experimentally and theoretically investigated. The basis set superposition error (BSSE) and interaction energy of TNT, RDX and plasticizers were computed at MP2/6-311++G** levels. Compared with the weak E_inter between RDX and TNT (−1.586 kJ/mol), E_inter between the o-nitrotoluene and TNT and RDX can increase to −131.557 kJ/mol and −48.487 kJ/mol, indicating there is strong intermolecular-interaction. SEM imagines also show that mononitrotoluene could form layered deposits in TNT and closely surround RDX crystalline. MD simulation results indicate that tensile modulus of (100) TNT and (100) RDX increases when introducing mononitrotoluene plasticizers separately, which agree with the experimental phenomenon of Brazilian disk test.

Abstract: The solubility of TNT and RDX was measured in supercritical carbon dioxide fluid at 303.0, 308.0, 323.0, 338.0 K, and over the pressure range from 10.0 MPa to 50.0 MPa. This study examined the influences of extraction temperature, extraction pressure and support effect (SE) between molecules of TNT and RDX on their solubility in the TNT/RDX/SC-CO₂ system. The results show that solubility of TNT and RDX in TNT/RDX/SC-CO₂ ternary system is much higher than that in binary system. The values of SE of RDX and TNT increase first and decrease then with the pressure changing. The pressure turning point occurred over the pressure range from 25 MPa to 28 MPa for TNT and from 13 MPa to 20 MPa for RDX.

Abstract: In this paper, we fabricated the 4-aminobenzenethiol modified gold nanoparticles onto polymer spheres as SERS substrate to selectively detect 2,4,6-trinitrotoluene (TNT) explosives. The gold nanoseeds were fixed on polymer surface by reduction of HAuCl₄·3H₂O with sodium citrate. About 60~100nm nanoparticles were formed from the previous seeds and self-assembled by 4-aminobenzenethiol. The functionalized gold nanopartilces aggregation coated on large polymer sphere surface not only absorbed more TNT molecules via conjugation system, but also generated numerous "hot spots". It was demonstrated that this substrate displayed high SERS activity for TNT detection. It could also be anticipated that the aforementioned material would be used for fast and sensitive SERS detection of TNT in real-world situation. Keywords: gold nanopartilces, SERS, TNT, functionalization

Abstract: Wastewater from the munitions decomposing process typically contains the widely used explosive-trinitrotoluene (TNT), which is also toxic and mutagenic. Commonly used technologies for degradation of TNT,such as activated carbon adsorption and chemical oxidation, are proved to be feasible but not cost-effective. In this study, the effectiveness of biodegradation of TNT by co-metabolism was evaluated in a hybrid hydrolysis acidification and aerobic membrane bioreactor. After six weeks acclimatization, over 90% TNT was removed with influent TNT concentration ranging between 70-85mg/L. Simultaneously remarkable MLSS concentration increase from 1.4 g/l to 6.9 g/l was observed, which indicated that the acclimatization and incubation of biomass was successful. The membrane effectively prevented loss of sludge and kept large biomass in the reactor, which made the system maintained in a high volume loading rate and low sludge loading rate. The experiment results showed that addition of carbon source was an essential factor in biodegradation of TNT wastewater.

Abstract: In order to clarify the characteristic behavior such as shockwave propagation, dispersion of sand and the crater depth due to explosive ordnance disposal, the finite element models of soil, surrounding air and explosive have been constructed based on HyperWorks-RADIOSS (®Altair) software. By conducting a series of numerical simulations, it has been observed the effect of explosion on the crater depth and diameter, overpressure exerted on sand and the surrounding air. These results based on the computational mechanics are useful data for setting the evacuation area and its distance associated with an explosive ordnance disposal.

Abstract: In order to investigate the afterburning effect of TNT in an open space, a double-layer container (DLC) which can be filled with different gases and enhance the afterburning effect of underoxidized explosives was designed. The charges were located in the inner container, and the outer container was filled with different gases (air, oxygen or nitrogen). The experiments were conducted under water. After initiation, the DLC cracks and provides gas for the detonation products. Underwater static pressure transducer was the main diagnostic. It is shown that pressure and impulse histories for explosions in oxygen and air are greater than those recorded for explosions in nitrogen. Moreover, the afterburning energy was calculated. Results show that the afterburning energy increases with the increase of the amount of oxygen, but cannot reach the theoretically maximum value even though there is excessive oxygen. Finally, two-dimensional numerical simulations were performed by the explicit finite element program ANSYS AUTODYN. The Miller energy release model was used to describe the afterburning process. Results demonstrate that computed pressure histories agreed with measured pressure histories well in terms of initial peak pressure, waveforms and total impulse.

Abstract: By XRD, UV-Vis, and X-ray absorption spectroscopy, it seems that copper is inserted in the framework of TiO2 nanotube (Cu-TNT), which was prepared for photocatalytic splitting of H2O. The Cu-TNT has light absorption extended into the visible range (400-550 nm) and decreased the band gap to 2.95 eV. Under UV/Vis light irradiation for six hours, H2 yielded from photocatalytic splitting of H2O on the Cu-TNT is greater than that on the TNT by 2-3 times.

Abstract: AC/TiO₂ composite particles were prepared by sol-gel method in normal temperature. Three kinds of particles were obtained by adding Phytic Acid (ab. PA), Benzoyltrifluoroacetone (ab. BTA) and SnCl4 during the preparation. The photo catalytic activity and adsorptive capability of different particles were compared. Raman analysis showed TiO₂ grain on the surface of the AC carrier was anatase. FE-SEM photos showed particles with PA were homogeneously coated by TiO₂, but more fine TiO₂ particles were formed with BTA. The results showed that the adding of PA and BTA helped to get fine grains. The degradation ratio of the TNT solution showed that the photo catalyses activity and adsorptive capability of all composite particles were higher than that of single AC, and the accumulated degradation ratio of TNT solution reached 99.3 % (repeated by 20 times). The degradation of single AC to TNT solution is thought mainly by physical adsorption, but for other composite particles the degradation is by both of the adsorption and photo catalysis. The interface between AC carrier and TiO₂ crystal may be affected by PA or BTA, and helping to form synergic effect of AC and TiO₂.