Ammonium Nitrate Concentrations Research Articles

Impacts of ammonium nitrate on survival of tadpoles of the common skittering frog (Euphlyctis cyanophlyctis)

Amphibians are sensitive to agricultural chemicals such as pesticides and fertilizers. Data on responses of anuran species commonly found in agricultural areas of Pakistan to chemical pollution are lacking. We studied the effects of ammonium nitrate on survival of tadpoles of common skittering frog (Euphlyctis cyanophlyctis). Tadpoles were collected from seasonal shallow water ponds formed during rainy season in the vicinities of Rawalpindi and Islamabad cities. Tadpoles were treated with ammonium nitrate at either 62.5, 125, 250, 500 or 1000 mg nitrate / l, and compared with a control group. Individual survival was significantly affected by increased ammonium nitrate treatments (P < 0.05), with survival rates after 18 days of exposure ranging from 83% at 62.5 mg NO3- / l to complete mortality at the highest ammonium nitrate concentration. The logistic regression model with individual survival as a binomial outcome variable and fertilizer concentration as independent variable explained 87% of the variance in survivorship (Nagelkerke R2), and correctly classified 94.0% of the cases (χ2 = 259, 5 d.f., P < 0.0005). Our lab-based findings suggest that ammonium nitrate at high concentrations may affect anuran species of Pakistan in croplands with extensive nitrogen-based fertilizer use.

Application of Response Surface Methodology for Xanthan Gum and Biomass Production Using Xan-thomonas campestris

Xanthan gum is an extracellular polysaccharide produced by various Xanthomonas species such as X. campestris. The objective of present study was to investigate the influence of different carbon and nitrogen sources on xanthan gum production by X. campestris. Using an ex- perimental Response Surface Methodology (RSM) complemented with a Central Composite De- sign (CCD), the impact of peptone, lactose, glucose and ammonium nitrate in medium were esti- mated for their individual and interactive effects on biomass and xanthan gum production. The optimal concentrations of peptone, lactose, glucose and ammonium nitrate for xanthan gum yield and biomass production was determined as 9.25 g/l, 53.37 mmol, 29.31 mmol and 4.58 g/l for xan- than gum yield and 6.77 g/l, 52.65 mmol, 38.12 mmol and 3.54 g/l for biomass production. Under the optimum experimental conditions, the xanthan gum yield reached to its maximum value (8.42 g/l). The results provide the support data for xanthan gum production on a large scale.

Modelling the future distribution of ammonium nitrate concentrations in The Netherlands for 2020: The sensitivity to meteorological parameters

We present a parameterization developed to simulate Ammonium particle (NH4+) concentrations in the Operational Priority Substances (OPS) source-receptor model, without the necessity of using a detailed chemical scheme. By using the ratios of the main pre-cursor gases SO2, NO2 and NH3, and utilising calculations performed using a chemical box-model, we show that the parameterization can simulate annual mean NH4+ concentration fields to within ∼15% of measured values at locations throughout the Netherlands. Performing simulations for different decades, we find a strong correlation of simulated NH4+ distributions for both past (1993–1995) and present (2009–2012) time periods. Although the total concentration of NH4+ has decreased over the period, we find that the fraction of NH4+ transported into the Netherlands has increased from around 40% in the past to 50% for present-day. This is due to the variable efficiency of mitigation practises across economic sectors. Performing simulations for the year 2020 using associated emission estimates, we show that there are generally decreases of ∼8–25% compared to present day concentrations. By altering the meteorological fields applied in the future simulations, we show that a significant uncertainty of between ∼50 and 100% exists on this estimated NH4+ distribution as a result of variability in the temperature dependent emission terms and relative humidity. Therefore, any projections of future NH4+ distributions should be performed using well chosen meteorological fields representing recent meteorological situations.

English

Graft copolymerization of acrylonitrile onto torch ginger cellulose was carried out in an aqueous medium with ceric ion redox initiator. The optimum grafting parameters such as temperature, reaction time, ratio of monomer to cellulose addition and ceric ammonium nitrate (CAN) concentration were determined and a maximum graft yield of 40% was recorded. The graft copolymer was characterized and compared with untreated cellulose. A new absorption peak corresponding to the nitrile group of acrylonitrile was recorded by FTIR at 2244 cm-1 on the grafted cellulose. The morphology studies showed that the diameter and the surface roughness of grafted cellulose had increased as compared with the untreated cellulose. On the contrary, the grafting had resulted in lowering the crystallinity of the cellulose from 63 to 53%. The grafted cellulose produced a new derivative TG peak at 420°C and higher residual percentage than the untreated cellulose.

Effects of Snow Cover and Atmospheric Stability on Winter PM2.5 Concentrations in Western U.S. Valleys

AbstractMany populated valleys in the western United States experience increased concentrations of particulate matter with diameter of less than 2.5 μm (PM2.5) during winter stagnation conditions. Further study into the chemical components composing wintertime PM2.5 and how the composition and level of wintertime PM2.5 are related to meteorological conditions can lead to a better understanding of the causes of high PM2.5 and aid in development and application of emission controls. The results can also aid in short-term air-pollution forecasting and implementation of periodic emission controls such as burning bans. This study examines relationships between PM2.5 concentrations and wintertime atmospheric stability (defined by heat deficit) during snow-covered and snow-free conditions from 2000 to 2013 for five western U.S. urbanizations: Salt Lake City, Utah; Reno, Nevada; Boise, Idaho; Missoula, Montana; and Spokane, Washington. Radiosonde data were used where available to calculate daily heat deficit, which was compared with PM2.5 concentration for days with snow cover and days with no snow cover. Chemically speciated PM2.5 data were compared for snow-cover and snow-free days to see whether the chemical abundances varied by day category. Wintertime PM2.5 levels were highly correlated with heat deficit for all cities except Spokane, where the airport sounding does not represent the urban valley. For a given static stability, snow-cover days experienced higher PM2.5 levels than did snow-free days, mainly because of enhanced ammonium nitrate concentrations. Normalizing average PM2.5 to the heat deficit reduced year-to-year PM2.5 variability, resulting in stronger downward trends, mostly because of reduced carbonaceous aerosol concentrations. The study was limited to western U.S. cities, but similar results are expected for other urban areas in mountainous terrain with cold, snowy winters.

On-site semi-quantitative analysis for ammonium nitrate detection using digital image colourimetry

Digital image colourimetry was successfully applied in the semi-quantitative analysis of ammonium nitrate using Griess’s test with zinc reduction. A custom-built detection box was developed to enable reproducible lighting of samples, and was used with the built-in webcams of a netbook and an ultrabook for on-site detection. The webcams were used for colour imaging of chemical reaction products in the samples, while the netbook was used for on-site colour analysis. The analytical performance was compared to a commercial external webcam and a digital single-lens reflex (DSLR) camera. The relationship between Red-Green-Blue intensities and ammonium nitrate concentration was investigated. The green channel intensity (IG) was the most sensitive for the pink-violet products from ammonium nitrate that revealed a spectrometric absorption peak at 546nm. A wide linear range (5 to 250mgL−1) with a high sensitivity was obtained with the built-in webcam of the ultrabook. A considerably lower detection limit (1.34±0.05mgL−1) was also obtained using the ultrabook, in comparison with the netbook (2.6±0.2mgL−1), the external web cam (3.4±0.1mgL−1) and the DSLR (8.0±0.5mgL−1). The best inter-day precision (over 3days) was obtained with the external webcam (0.40 to 1.34%RSD), while the netbook and the ultrabook had 0.52 to 3.62% and 1.25 to 4.99% RSDs, respectively. The relative errors were +3.6, +5.6 and −7.1%, on analysing standard ammonium nitrate solutions of known concentration using IG, for the ultrabook, the external webcam, and the netbook, respectively, while the DSLR gave −4.4% relative error. However, the IG of the pink-violet reaction product suffers from interference by soil, so that blank subtraction (|IG-IGblank| or |AG-AGblank|) is recommended for soil sample analysis. This method also gave very good accuracies of –0.11 to −5.61% for spiked soil samples and the results presented for five seized samples showed good correlations between the various imaging devices and spectrophotometer used to determine ammonium nitrate concentrations. Five post-blast soil samples were also analysed and pink-violet product were observed using Griess’s test without zinc reduction indicating the absence of ammonium nitrate. This demonstrates significant potential for practical and accurate on-site semi-quantitative determinations of ammonium nitrate concentration.

Temporal variations of PM1 major components in an urban street canyon.

Seasonal changes in the levels of PM1 and its main components (organic carbon (OC), elemental carbon (EC), SO4 (2-), NO3 (-) and NH4 (+)) were studied in an urban street canyon in southeastern Spain. Although PM1 levels did not show an evident seasonal cycle, strong variations in the concentrations of its major components were observed. Ammonium sulfate, the main secondary inorganic compound, was found to be of regional origin. Its formation was favored during summer due to increased photochemical activity. In contrast, the concentrations of particulate ammonium nitrate, which is thermally unstable, were highest in winter. Although traffic emissions are the dominant source of EC in the city, variations in traffic intensity could not explain the seasonal cycle of this component. The higher EC concentrations during the cold months were attributed to the lower dispersion conditions and the increase in EC emissions. Special attention has been given to variations in organic carbon levels since it accounted for about one third of the total PM1 mass. The concentrations of both total OC and secondary OC (SOC) were maxima in winter. The observed seasonal variation in SOC levels is similar to that found in other southern European cities where the frequency of sunny days in winter is high enough to promote photochemical processes.

Fischer–Tropsch synthesis: Effect of ammonia in syngas on the Fischer–Tropsch synthesis performance of a precipitated iron catalyst

The effect of ammonia in syngas on the Fischer–Tropsch synthesis (FTS) reaction over 100Fe/5.1Si/2.0Cu/3.0K catalyst was studied at 220–270°C and 1.3MPa using a 1-L slurry phase reactor. The ammonia added in syngas originated from adding ammonia gas, ammonium hydroxide solution, or ammonium nitrate (AN) solution. A wide range of ammonia concentrations (i.e., 0.1–400ppm) was examined for several hundred hours. The Fe catalysts withdrawn at different times (i.e., after activation by carburization in CO, before and after co-feeding contaminants, and at the end of run) were characterized by ICP-OES, XRD, Mössbauer spectroscopy, and synchrotron methods (e.g., XANES, EXAFS) in order to explore possible changes in the chemical structure and phases of the Fe catalyst with time; in this way, the deactivation mechanism of the Fe catalyst by poisoning could be assessed. Adding up to 200ppmw (wt. NH3/av. Wt. feed) ammonia in syngas did not significantly deactivate the Fe catalyst or alter selectivities toward CH4, C5+, CO2, C4-olefin, and 1-C4 olefin, but increasing the ammonia level (in the AN form) to 400ppm rapidly deactivated the Fe catalyst and simultaneously changed the product selectivities. The results of ICP-OES, XRD, and Mössbauer spectroscopy did not display any evidence for the retention of a nitrogen-containing compound on the used catalyst that could explain the deactivation (e.g., adsorption, site blocking). Instead, Mössbauer spectroscopy results revealed that a significant fraction of iron carbides transformed into iron magnetite during co-feeding high concentrations of AN, suggesting that oxidation of iron carbides occurred and served as a major deactivation path in that case. Oxidation of χ-Fe5C2 to magnetite during co-feeding high concentrations of AN was further confirmed by XRD analysis and by the application of synchrotron methods (e.g., XANES, EXAFS). It is postulated that AN oxidized χ-Fe5C2 during FTS via its thermal dissociation product, HNO3. This conclusion is further supported by reaction tests with co-feeding of similar concentrations of HNO3. Additional oxidation routes of iron carbide to magnetite by HNO3 and/or by its thermal decomposition products are also considered: Fe5C2+NOx (and/or HNO3)→Fe3O4. In this study, ion chromatography detected that 50–80% HNO3 directly added or dissociated from AN eventually converted to ammonia during or after its oxidation of iron carbide, resulting from the reduction of NOx (NOx+H2+CO→NH3+CO2+N2+H2O) by H2 and/or CO.

Modeling the red pigment production by Monascus purpureus MTCC 369 by Artificial Neural Network using rice water based medium

Abstract The study investigates the application of Artificial Neural Network (ANN) in modeling a Liquid State Fermentation (LSF) for red pigment production by Monascus purpureus MTCC 369. A neural network model was characterized by the three fermentation parameters as neurons in the input layer and pigment yield as one neuron in the output layer. The input neurons included incubation period of 6–18 days, pH of rice water as substrate (3.0–5.0) and concentration of ammonium nitrate as nitrogen source (0.0–2.0%). The model was trained and validated to predict the red pigment yield (abs 500 nm /mg dry fungal biomass). The results showed a good fit between predicted and experimental values for the model. The maximum red pigment yield (20.44 U abs 500 nm /mg dfb) was obtained with substrate pH of 4.0 without any ammonium nitrate as N-source after 12 days of incubation. The developed ANN model can be used to predict the effects of fermentation parameters on red pigment production with a high correlation.

Establishment of new monoxenic culture systems for root-knot nematodes, Meloidogyne spp., on axenic water spinach roots

To establish optimal monoxenic culture systems for Meloidogyne spp., in vitro axenic culture methods of water spinach and tomato roots and monoxenic reproduction of the nematodes were assessed on six different media (MS-I to MS-VI), based on the standard Murashige and Skoog (MS) medium. The concentrations of the major elements of MS medium were amended, and the main differences among these media were concentrations of iron salts, hormone and ammonium nitrate in the macroelements. Both water spinach and tomato successfully produced roots on MS-I to MS-V media (with ammonium nitrate), but not on MS-VI (without ammonium nitrate). Water spinach produced many more roots than tomato, especially on MS-I (without hormones). Meloidogyne incognita was successfully established on in vitro roots of the two plants on MS-I to MS-V media. It was also possible to culture M. javanica and M. arenaria on water spinach root on MS-I medium. In addition, water spinach root tissues could be maintained for 8 months on MS-II and MS-V media.

Modified medium for micropropagation of recalcitrant potato cv. Kufri Jyoti

Experiments were conducted to devise an efficient micro-propagation medium for mass multiplication of a high yielding but recalcitrant potato cv. Kufri Jyoti using nodal explant with different concentrations and combinations of NHNOGAand NAA. Virus-indexed nodal cuttings established in full-strength Murashige and 43, 3 Skoog (1962) basal salts and vitamins, supplemented with 0.29 μM GA3 and 0.05 μM NAA was used as explants for the experiment. Among the various media tested, MS medium with increased level of ammonium nitrate (25.79 mM) supplemented with GA3 (0.58 μM) and NAA (0.1 μM) was found to be optimum as it significantly improved the shoot length, number of leaves, number of nodes and inter nodal length after 21 days of sub culturing. The next higher concentration of ammonium nitrate (30.94 mM) supplemented with GA3 (0.58 μM) and NAA (0.1 μM) also exhibited statistically at par response in most of the morphological characters but higher concentration (41.25 mM) retarded all the parameters studied.

Studies on AC Electrical Conductivity and Dielectric Properties of PVA/NH&amp;lt;sub&amp;gt;4&amp;lt;/sub&amp;gt;NO&amp;lt;sub&amp;gt;3&amp;lt;/sub&amp;gt; Solid Polymer Electrolyte Films

Solid polymer electrolytes have been extensively studied due to wide applications in various elec- trochemical devices (1)-(3). Most of the solid polymer electrolytes consist of polymer as a host material to provide strength and good mechanical stability and an inorganic salt that supplies io- nic carriers to cause electrical conductivity. In our studies, we prepared PVA/NH4NO3 polymer electrolyte films by solution casting method. The prepared films with varied Ammonium Nitrate concentration from 0 - 20 wt% are characterized by XRD & FTIR spectroscopy. XRD results show that amorphous nature increases as the amount of the Ammonium Nitrate salt in PVA is increased. IR-spectra confirm the polymer salt complexes in the range of 3700 - 712 cm −1 . Conductance anal- ysis reveals that polymer electrolyte films containing 20 wt% of NH4NO3 exhibit the highest ionic conductivity of 1.01 × 10 −7 S/cm while pure PVA films give the lowest ionic conductivity of 2.10 × 10−11 S/cm. It was evident from this study that the increase of ionic conductivity depended on the Ammonium Nitrate salt concentration. The dielectric constant exponentially decreases with in- crease of frequency for pure PVA and NH4NO3 doped PVA film composites. The temperature de- pendent studies of AC conductivity and dielectric constant also included to understand the con- ducting property. The results obtained by these studies are reported in this work.

Ammonium nitrate and iron nutrition effects on some nitrogen assimilation enzymes and metabolites in Spirulina platensis.

The effect of various concentrations of ammonium nitrate (5-60 mM), an economical nitrogen source, on the growth, nitrate-ammonium uptake rates, production of some pigments and metabolites, and some nitrogen assimilation enzymes such as nitrate reductase (NR), nitrite reductase (NiR), glutamine synthetase (GS), and glutamate synthase (GOGAT) in Spirulina platensis (Gamont) Geitler was investigated. Ten millimolars of ammonium nitrate stimulated the growth, production of pigments and the other metabolites, and enzyme activities, whereas 30 and 60 mM ammonium nitrate caused inhibition. In the presence of 10 mM ammonium nitrate, different concentrations of iron were tried in the growth media of S. platensis. After achieving the best growth, levels of metabolite and pigment production, and enzyme activities in the presence of 10 mM ammonium nitrate as a nitrogen source, different iron concentrations (10-100 µM) were tried in the growth medium of S. platensis. The highest growth, pigment and metabolite levels, and enzyme activities were determined in the medium containing 50 µM iron and 10 mM ammonium nitrate. In this optimum condition, the highest dry biomass level, chlorophyll a, and pyruvate contents were obtained as 55.42 ± 3.8 mg mL(-1) , 93.114 ± 7.9 µg g(-1) , and 212.5 ± 18.7 µg g(-1) , respectively. The highest NR, NiR, GS, and GOGAT activities were 67.16 ± 5.1, 777.92 ± 52, 0.141 ± 0.01, and 44.45 ± 3.6, respectively. Additionally, 10 mM ammonium nitrate is an economical and efficient nitrogen source for nitrogen assimilation of S. platensis, and 50 µM iron is optimum for the growth of S. platensis.

Optimization of Ammonium Nitrate Thermal Decomposition in a Fluidized Bed Reactor Using Differential Evolution (DE) Method

Ammonium nitrate thermal decomposition in a fluidized bed reactor (FR) is considered a suitable chemical-free disposal option for the aqueous waste nitrate stream. In this study, operating conditions of ammonium nitrate thermal decomposition are optimized via differential evolution (DE) method to minimize the concentration of ammonium nitrate at the outlet of the reactor. The model, which is based on the two-phase theory of a bubbling fluidized bed, predicts an axial concentration profile of all components in the emulsion and bubble phases as well as an axial temperature profile of the gas phase. In addition, the model predictions are in agreement with the experimental data presented by Bhowmick et al. (2012). The optimization results show that ammonium nitrate concentration decreases gradually along the reactor with increasing temperature and gas velocity. This study demonstrates the superiority of an optimized fluidized bed reactor (OFR) compared to a FR owing to the OFR for achieving a remarkably lower concentration of ammonium nitrate (approximately 20% of the time) at the outlet point of the reactor.

Enhanced Bioremediation of Field Agricultural Soils Contaminated with PAHs and OCPs

Effect of different concentrations of ammonium chloride (NCL) and ammonium nitrate (NN)and surfactants such as Tween-80, HPCD and rhamnolipids on the bioremediation of PAHs and OCPs wasinvestigated. The results showed that the best optimum concentration of NCL and NN was 50 g·kg-1, and thePAHs degradation rate during 60 days of remediation was enhanced to 64.6% and 62.8% for NCL and NN,respectively, which was approximately 45, 17, 10% higher than those in the control group, soil only addedmicroorganism, soil added microorganism and tourmaline. OCP removal rates were 51.7% and 50.4 % for NCLand NN, respectively, which was 34% higher than the control group, 14% higher than the soil only addedmicroorganism, 9% higher than the soil added microorganism and tourmaline. The best dose of Tween-80,HPCD and rhamnolipids was 2, 0.5 and 0.2 g·kg-1. When they were applied, the PAHs degradation rate during60 days of remediation was enhanced to 69, 70.4 and 71.5%, respectively, which was approximately 52, 24and 17% than those in the control group, soil only added microorganism, soil added microorganism andtourmaline. Similarly, OCP removal rate was 42, 26 and 16% higher than those in the control group,microorganism -added soil alone, soil added microorganism and tourmaline. Additionally, nutrients and surfactantscan promote the generation of soil hydrogen peroxidase and invertase enzyme. Hence, the present studyprovides a promising combination remediation technology for the remediation of field soils contaminated byPAHs and OCPs.

Nitrogen-Phosphorous Fertilizers on the Base of Concentrated Ammonium Nitrate Solution and Central Kyzylkum Phosphate Raw Material

Abstract This article presents obtaining of nitrogen-phosphate fertilizers by reacting ordinary phosphate powder from Central Kyzylkum (Uzbekistan) with 70-90% ammonium nitrate solution at 100ºС. Chemical composition of the fertilizers was determined fully. Relevant consistence of acceptable forms of Р2О5 and СаО in the product extremely decreased by the increase of amount of phosphate raw material (PRM) in reaction mixture. The addition of phosphate additive into ammonium nitrate solution significantly increases toughness of ammonium nitrate granules and their growth velocity proportionally by phosphate powder added. Herewith, initial concentration of ammonium nitrate did not effect practically on the granule’s toughness. It is described that, phosphate additive decreases the speed of solubility of ammonium nitrate granules almost up to 1.83 times. On our opinion, decrease of fertilizer solubility is the result of growing phosphorite share in the products. The more is the phosphorite share, the more slowly dissolution process of the fertilizer granule does occur.

DNA damage caused by inorganic particulate matter on Raji and HepG2 cell lines exposed to ultraviolet radiation

Epidemiological studies have correlated exposure to ultraviolet-irradiated particulate matter with cardiovascular, respiratory, and lung diseases. This study investigated the DNA damage induced by two major inorganic particulate matter compounds found in diesel exhaust, ammonium nitrate and ammonium sulfate, on Burkitt's lymphoma (Raji) and hepatocellular carcinoma (HepG2) cell lines. We found a dose-dependent positive correlation of accumulated DNA damage at concentrations of ammonium nitrate (25μg/ml, 50μg/ml, 100μg/ml, 200μg/ml, 400μg/ml) with ultraviolet exposure (250J/m2, 400J/m2, 600J/m2, 850J/m2), as measured by the comet assay in both cell lines. There was a significant difference between the treated ammonium nitrate samples and negative control samples in Raji and HepG2 cells (p<0.001). Apoptosis was shown in Raji and HepG2 cells when exposed to high concentrations of ammonium nitrate (200μg/ml and 400μg/ml) for 1h in samples without ultraviolet exposure, as assessed by the comet assay. However, the level of apoptosis greatly diminished after ultraviolet exposure at these concentrations. Over a 24h period, at intervals of 1, 4, 8, 12, 18, and 24h, we also observed that ammonium nitrate decreased viability in Raji and HepG2 cell lines and inhibited cell growth. Ammonium sulfate-induced DNA damage was minimal in both cell lines, but there remained a significant difference (p<0.05) between the ultraviolet radiation treated and negative control samples. These results indicate that the inorganic particulate compound, ammonium nitrate, induced DNA strand breaks at all concentrations, and indications of apoptosis at high concentrations in Raji and HepG2 cells, with ultraviolet radiation preventing apoptosis at high concentrations. We hypothesize that ultraviolet radiation may inhibit an essential cellular mechanism, possibly involving p53, thereby explaining this phenomenon. Further studies are necessary to characterize the roles of apoptosis inhibition induced by DNA damage caused by inorganic particulate matter.

Optimization of preparation process for allylamine-bacterial cellulose via graft copolymerization by response surface methodology

In order to improve the efficiency of new adsorbent, grafting-allylamine bacterial cellulose(al-BC), response surface methodology(RSM) was used for the optimization of preparation process. Three factors affecting the yield of grafting reaction are the amount of allylamine, the concentration of ceric ammonium nitrate(CAN) and the concentration of nitric acid. Based on the regression coefficient analysis in the Box-Behnken design, a relationship between the preparation variable and grafting yield was obtained. Square error analysis on main factors, and multi-variable interactions were employed for studying grafting yield. The results show that at the conditions of CAN of 23.00 mmol/L CAN, 0.17 mol/L nitric acid, adding an amount of grafting-allylamine bacterial cellulose of 26.49 mL/L made grafting rate reach maximum of 24.25% at 40 °C after the reaction for 4 h. The experimental results are in good agreement with the calculation values via proposed regression equation, indicating that the equation could be used to predict and optimizate the preparation of grafting al-BC.

CO sensor based on thick films of 3D hierarchical CeO2 architectures

Hollow CeO2 microspheres, having 3D architectures on their surface, were prepared by a microwave-assisted coprecipitation method. By this method, ceric ammonium nitrate was diluted in formic acid. The application of microwave irradiation produced the precipitation of a white powder, with the simultaneous emission of NO2. At low temperature, cerium formate was formed; whereas from 400°C, CeO2 with cubic crystal structure was identified. The morphology of the samples calcined from 170 to 600°C was of hollow microspheres, with size between 1.5 and 10μm. Their surface displayed unique 3D architectures, which consisted of ramifications formed by the assembly of nanograins and nanoporous. Microwave irradiation played a key role in the formation of 3D hollow architectures. The effect of the concentration of ceric ammonium nitrate on the particle morphology was also investigated. Thick films were prepared by depositing a suspension of the CeO2 powder on alumina substrates. The electrical characterization in gases was performed in alternating current (AC). The films exhibited a reliable and quantitative detection of carbon monoxide from 250°C. The effect of the applied frequency and the operating temperature was analyzed.

Surface-Enhanced Raman Scattering Detection of Ammonium Nitrate Samples Fabricated Using Drop-on-Demand Inkjet Technology

The United States Army and the first responder community are increasingly focusing efforts on energetic materials detection and identification. Main hazards encountered in theater include homemade explosives and improvised explosive devices, in part fabricated from simple components like ammonium nitrate (AN). In order to accurately detect and identify these unknowns (energetic or benign), fielded detection systems must be accurately trained using well-understood universal testing substrates. These training substrates must contain target species at known concentrations and recognized polymorphic phases. Ammonium nitrate is an explosive precursor material that demonstrates several different polymorphic phases dependent upon how the material is deposited onto testing substrates. In this paper, known concentrations of AN were uniformly deposited onto commercially available surface-enhanced Raman scattering (SERS) substrates using a drop-on-demand inkjet printing system. The phase changes observed after the deposition of AN under several solvent conditions are investigated. Characteristics of the collected SERS spectra of AN are discussed, and it is demonstrated that an understanding of the exact nature of the AN samples deposited will result in an increased ability to accurately and reliably "train" hazard detection systems.