Explosive Chemical Research Articles

Infrared to terahertz identification of chemical substances used for the production of IEDs

In our modern times, improvised explosive devices (IEDs) have become more sophisticated than ever, capable of causing destruction and loss of life. The creative use of homemade substances for IEDs manufactures has led to efforts in developing sensitive detection methods that can anticipate, identify and protect against improvised attacks. Laser-based spectroscopic techniques provide rapid and accurate detection of chemicals in improvised explosives, but no single method can detect all components of all explosives. In this study, two spectroscopic methods are used for the sensitive identification of 8 explosive chemical substances in the form of powders and vapors. Absorption spectra of benzene, toluene, acetone and ethylene glycol were examined with CO2 laser photoacoustic spectroscopy. The photoacoustic signals of the samples were recorded in the CO2 laser emission range from 9.2 to 10.8 µm and a different spectral behavior was observed for each analyzed substance. Time-domain spectroscopy with THz radiation was used to analyze ammonium nitrate, potassium chlorate, dinitrobenzene, hexamethylenetetramine transmission spectra in the 0.1–3 THz range, and it was observed that they have characteristic THz fingerprint spectra. CO2 laser photoacoustic spectroscopy and THz time domain spectroscopy have met the criterion of proven effectiveness in identifying explosive components. The combination of these spectroscopic methods is innovative, giving a promising new approach for detection of a large number of IED components.

Aerobic biodegradation of HMX by Planomicrobium flavidum.

In this report, aerobic biodegradation of octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine or high melting explosive (HMX), a highly explosive chemical by Planomicrobium flavidum strain S5-TSA-19, an isolate from an explosive-contaminated soil, was investigated. The isolate S5-TSA-19 degraded 70% of HMX in 20days during which time nitrite ion was produced with the subsequent formation of metabolites, viz. methylenedintramine and N-methyl-N,N'-dinitromethanediamine with molecular weights 136Da and 149Da, respectively. The degradation mechanism was found to follow first-order kinetics with a half-life of 11.55days and formation of above intermediates indicate single nitrite elimination pathway. The proliferation of isolate S5-TSA-19 in the absence of nitramines indicates the cometabolic degradation of HMX. Isolate S5-TSA-19 can thus be used as futuristic microbe for degradation of HMX at explosive-contaminated site.

Flexible single walled nanotube based chemical sensor for 2,4-dinitrotoluene sensing

In this work, we have attempted to fabricate flexible single walled carbon nanotube based sensor for detection of 2,4-dinitrotoluene (DNT) an explosive chemical. For analyte sensing study, the flexible sensor is fabricated by vacuum filtration method. These fabricated gas sensors are characterised by SEM and Raman spectroscopy. The sensor response is investigated toward the explosive chemicals which have NO2 group in their molecular structure. The fabricated sensor is able to detect the traces of DNT at room temperature. The sensor gives 0.28–0.32% repeatable response to 0.22 ppm of DNT. The response of sensor increases with increase in the vapour concentration of the DNT vapours.

A New Type of Explosive Chemical Detector Based on an Organic Photovoltaic Cell

A new type of chemical sensor to detect explosive related compounds has been designed and fabricated with an organic photovoltaic cell as the active element. The detection of chemical molecules is performed by optically exciting the cell while its photovoltaic open-circuit voltage is continuously sampled. Upon exposure to compounds like nitroaromatics, the sensors exhibit a significant increase in open-circuit voltage. This indicates an efficient internal energy transfer between the explosive chemicals and the organic thin film surface. It is quite unique that the organic chemical sensors directly use the open-circuit voltage as a detection indicator, while the vast majority of conventional chemical sensors are based on the change in resistance. Since the open-circuit voltage can be measured without current and can also be directly sampled or amplified in the circuits, this new type of chemical sensor is very attractive for low-power application and sensor networks for the future Internet of Things.

Imidazolylmethylpyrene sensor for dual optical detection of explosive chemical: 2,4,6-Trinitrophenol

Fluorescence and colorimetric sensor with simplistic synthesis method based on 1-imidazolylmethylpyrene (IMPY) was found to be a specific recognition for an explosive chemical: 2,4,6-trinitrophenol or picric acid (PA). The sensor did not only provide highly sensitive OFF–ON fluorescence enhancement toward PA in acetonitrile, but also offered ON–OFF fluorescence quenching upon PA binding in toluene solution. In addition, the sensor IMPY provided high selectivity to 2,4,6-trinitrophenol and was shown to discriminate various phenolic compounds such as p-iodophenol, p-bromophenol, m-hydroxybenzaldehyde, o-nitrophenol, m-nitrophenol, p-nitrophenol and 2,4-dinitrophenol. Upon binding to PA, the fluorogenic change of the sensor were observed and accompanied by the noticeable chromogenic change from colorless to yellow, therefore the sensor could also serve as a “naked-eye” indicator. Finally, two different types of crystal structures of IMPY·PA complexes were successfully recrystallized and characterized, which confirmed highly interactive affinity of the host-guest molecules.

Nanoscale surface modification of Mt. Etna volcanic ashes

Ashes emitted during volcanic explosive activity present peculiar surface chemical and mineralogical features related in literature to the interaction in the plume of solid particles with gases and aerosols. The compositional differences of magmas and gases, the magnitude, intensity and duration of the emission and the physical condition during the eruption, strongly influence the results of the modification processes. Here we report the characterization of the products emitted during the 2013 paroxysmal activity of Mt. Etna. The surface features of the ash particles were investigated through X-ray photoelectron spectroscopy (XPS) and Transmission electron microscopy (TEM) allowing the analysis at nanometer scale. TEM images showed on the surface the presence of composite structures formed by Ca, Mg and Na sulphates and halides and of droplets and crystals of chlorides; nanometric magnesioferrite and metallic iron dendrites are observable directly below the surface. From the chemical point of view, the most external layer of the volcanic glassy particles (<5nm), analysed by XPS, presents depletion in Si, Mg, Ca, Na and K and strong enrichment in volatile elements especially F and S, with respect to the inner zone, which represents the unaltered counterpart. Below this external layer, a transition glassy shell (thick 50–100nm) is characterized by Fe, Mg and Ca enrichments with respect to the inner zone. We propose that the ash particle surface composition is the result of a sequence of events which start at shallow depth, above the exsolution surface, where gas bubbles nucleate and the interfaces between bubbles and melt represent proto-surfaces of future ash particles. Enrichment of Ca, Mg and Fe and halides may be due to the early partition of F and Cl in the gas phase and their interaction with the melt layer located close to the bubbles. Furthermore the formation of volatile SiF4 and KF explain the observed depletion of Si and K. The F enrichment in the external ∼50nm thick layer of the glassy particles suggests the resorption of this element during the rise from depth less than 400m below the summit vent. During the eruption, the gas/ash interaction persists inside the plume where further changes on the particle surface occurs. Gaseous S, Cl and F react causing the formation of solid Ca, Mg, Na and K compounds, while SiF4 was released as volatile phase and HF was physisorbed. Finally, in the low temperature plume zone, halides previously formed continuously react with gases producing sulfates.

Inside the 'Hurt Locker': The Combined Effects of Explosive Ordnance Disposal and Chemical Protective Clothing on Physiological Tolerance Time in Extreme Environments.

Explosive ordnance disposal (EOD) technicians are often required to wear specialized clothing combinations that not only protect against the risk of explosion but also potential chemical contamination. This heavy (>35kg) and encapsulating ensemble is likely to increase physiological strain by increasing metabolic heat production and impairing heat dissipation. This study investigated the physiological tolerance times of two different chemical protective undergarments, commonly worn with EOD personal protective clothing, in a range of simulated environmental extremes and work intensities Seven males performed 18 trials wearing 2 ensembles. The trials involved walking on a treadmill at 2.5, 4, and 5.5 km h(-1) at each of the following environmental conditions, 21, 30, and 37°C wet bulb globe temperature. The trials were ceased if the participants' core temperature reached 39°C, if heart rate exceeded 90% of maximum, if walking time reached 60min or due to volitional fatigue. Physiological tolerance times ranged from 8 to 60min and the duration (mean difference: 2.78min, P > 0.05) were similar in both ensembles. A significant effect for environment (21 > 30 > 37°C wet bulb globe temperature, P < 0.05) and work intensity (2.5 > 4 > 5.5 km h(-1), P < 0.05) was observed in tolerance time. The majority of trials across both ensembles (101/126; 80.1%) were terminated due to participants achieving a heart rate equivalent to greater than 90% of their maximum. Physiological tolerance times wearing these two chemical protective undergarments, worn underneath EOD personal protective clothing, were similar and predominantly limited by cardiovascular strain.

Thermal Hazard Evaluation of Cumene Hydroperoxide (CHP) Using Isothermal and Heating Method

Cumene hydroperoxide (CHP) is a explosive chemical in the chemical industry in Taiwan that can be identified as organic peroxide (OP). Therefore, CHP can be manufactured using cumene mixed with oxygen or air (21% O2) in the oxidation tower and can be an important chemical and hazardous chemical for dicumyl peroxide (DCPO) process, acrylonitrile-butadienestyrene (ABS) process, and phenol and acetone manufacturing plant. Since 1981-2010 in Taiwan, plenty of thermal explosion accidents of CHP were recorded and analyzed in Taiwan. Therefore, this study was applied to analyze thermal hazard of CHP using an isothermal calorimeter. The reaction order (n) was calculated to be 0.5 that can be used to simulate a thermal explosion accident and to determine thermokinetics in the CHP oxidation process. This study was applied to analyze thermal hazard of CHP in the oxidation tower using the differential scanning calorimetry (DSC) with isothermal and heating method. The temperature of an exothermic reaction of 30, 80, and 88 mass % CHP can be analyzed less than 90℃ in the oxidation tower. The critical temperature of 30, 80, and 88 mass% CHP can be evaluated less than 100℃.

Fluorescent Microporous Polymeric Microsphere: Porosity, Adsorption Performance, and TNT Sensing

Spiro(fluorene-9,9′-xanthene)-based polymeric monodisperse spheres have been prepared through a surfactant-free Suzuki coupling polymerization in a single-phase. The polymer (PSFX) exhibits permanent microporous nature with Brunauer–Emmett–Teller specific surface area up to 610 m2 g−1. Its hydrogen storage can reach to 1.20 wt% (1.0 bar and 77 K) and the uptake capacity for carbon dioxide is 11.8 wt% (1.0 bar and 273 K). PSFX is a highly hydrophobic material with good sorption capacity for toluene (887 mg g−1 at saturated vapor pressure and room temperature), which makes it show potential use in elimination of harmful small aromatic molecules in the environment. Interestingly, PSFX exhibits a remarkable fluorescent emission property in the suspension. Fluorescence detection of explosive chemical (TNT) was performed through a series of spectrofluorometric titration using the suspension of PSFX as the probe.

Safety Advantages of On-Site Microprocesses

Usually large-scale capacities are preferred in process industry because of the economics of scale. However, small capacities bring along several other advantages, which are emphasized especially in on-site production. By producing on-site, the transportation of dangerous chemicals can be avoided. Moreover, smaller on-site production processes also mean a step towards inherently safer technology. Microreactors represent a technology that efficiently utilizes safety advantages resulting from small scale. These safety advantages of microreactors in on-site production are studied in this contribution. Production of peracetic acid is used as a test case. This unstable and explosive chemical is used, e.g. in treatment of municipal wastewater and pulp bleaching. This study is based on comparison of a conventional batch process with the capacity of 170 kg/h and an on-site continuous microprocess producing 10 kg/h peracetic acid. Preliminary design of these processes was carried out. Four different methods were used to analyze the safety of the processes. It was found that the conventional methods for analysis of process safety might not be reliable and adequate for radically novel technology, such as microprocesses. This is understandable because the methods are partly based on experience, which is very limited in the connection of totally novel technology.

Reproductive and developmental effects and physical and chemical properties of pentaerythritol tetranitrate (PETN) in the rat

Pentaerythritol tetranitrate (PETN) is an explosive chemical that has been detected in environmental media. Although previous toxicology studies have shown PETN to be relatively benign, a lack of available information concerning developmental and reproductive effects from oral PETN exposure was needed. Sprague-Dawley rats were exposed to oral daily adjusted volumetric doses of 0, 100, 500, or 1,000 mg PETN/kg body mass in a corn oil vehicle for up to 56 days. Mating, duration of gestation, body weight, feed consumption, overall condition of adults, and the number, sex, and condition of pups were recorded. Histological examinations were also performed on the ovaries, testes, and epididymides of animals from the control and the highest dose groups. Other environmental criteria, water solubility, octanol/water partition coefficient, and biodegradation rates of neat PETN were also determined. Only body weights and feed consumption were affected by treatment; however, these differences may be attributed more to volumetric adjustments of vehicle in the control and high-dose groups than to PETN toxicity. No adverse effects on development or reproduction from PETN exposure were observed. Water solubility, octanol water partition coefficient, and water suspension and biodegradation rates suggest PETN is unlikely to transport or bioaccumulate in the environment to any appreciable extent. Additionally, biotic processes are most likely faster in breaking down PETN than the abiotic processes involved in dissolving PETN in water.

Theoretical maximum pressure developed in own volume by thirteen military explosives

Tetryl is an explosive chemical that was formally used as a detonator and propellant in military ordnance. While tetryl is obsolete as a military propellant, spills and discharges to waste streams have resulted in contamination of environmental media at or near installations where the compound was manufactured and/or where it was used in load, assemble, and pack (LAP) activities. Tetryl is subject to degradation by photolysis, hydrolysis, and microbiota. Toxicity studies using tetryl were performed on laboratory rodents and rabbits; no wildlife toxicity testing has been performed. Using the existing rat data, the mammalian ingested toxicity reference value (TRV) was calculated with medium confidence to be 0.142 milligrams per kilogram per day (mg/kg/day) no observed adverse effect level (NOAEL) and 1.72 mg/kg/day lowest observed adverse effect level (LOAEL) based on dose-related weight loss as the sensitive endpoint. Other wildlife TRVs were not calculated due to a lack of data.