Ammonium Nitrate Solution Research Articles

Nitrogen‐Based Alternative Fuels: Progress and Future Prospects

AbstractWe describe and review recent research of a low‐carbon nitrogen‐based alternative fuel consisting of an aqueous solution of urea and ammonium nitrate (UAN). This fuel possesses a volumetric energy density of 4.44 MJ L−1. Conceptually, it is intriguing to think of ample atmospheric nitrogen as a future storage hub for sustainable and economic hydrogen derived from water rather than fossil fuels. First, we discuss and compare the nitrogen‐ and carbon‐based routes for chemical hydrogen storage. Second, we review recent research developments of this fuel: continuous combustion with lower NOx emissions than US regulation, computerized combustion simulations, ambient and high pressure thermal analyses, safety and stability considerations, catalytic effect on the effluent, and metal corrosion resistance at reaction and storage conditions. Aqueous UAN is found to yield about 99.9 % N2 when combusted at 25 MPa without a catalyst. Finally, future prospects and research needs are discussed.

Hygroscopicity of internally mixed multi-component aerosol particles of atmospheric relevance

The hygroscopic properties of two water-soluble organic compounds (WSOCs) relevant to urban haze pollution (phthalic acid and levoglucosan) and their internally mixtures with inorganic salts (ammonium sulfate and ammonium nitrate) are investigated using a hygroscopicity tandem differential mobility analyzer (H-TDMA) system. The multi-component particles uptake water gradually in the range 5-90% relative humidity (RH). The experimental results are compared with the thermodynamic model predictions. For most mixtures, Extended Aerosol Inorganic Model (E-AIM) predictions agree well with the measured growth factors. The hygroscopic growth of mixed particles can be well described by the Zdanovskii-Stokes-Robinson (ZSR) relation as long as the mixed particles are completely liquid. ZSR calculations underestimate the water uptake of mixed particles at moderate RH due to the partial dissolution of ammonium sulfate in the organic and ammonium nitrate solution in this RH region. The phase of ammonium nitrate in the initial dry particles changes dramatically with the composition of mixtures. The presence of organics in the mixed particles can inhibit the crystallization of ammonium nitrate during the drying process and results in water uptake at low RH (RH < 60%). These results demonstrate that certain representative WSOCs can substantially influence the hygroscopicity of inorganic salts and overall water uptake of particles. (c) 2015 Elsevier Ltd. All rights reserved.

Influence of carbon nanofiber clustering on the chemo-mechanical behavior of cement pastes

The influence of carbon nanofiber (CNF) clustering on the chemo-mechanical behavior of cement pastes subjected to a decalcifying environment was studied. Portland cement pastes with and without CNFs were exposed to a concentrated solution of ammonium nitrate to accelerate decalcification. Microstructural changes and evolution of the porosity were examined as a function of exposure duration. Changes in the flexural response of the cement paste with CNFs were studied and reviewed in relation to CNF clustering and microstructural evolution. Results showed a strong coupling between decalcification, CNF clustering, microstructural evolution, and the flexural properties of the cement paste. After 7 days of decalcification by NH4NO3, the CNF clusters acted as weak zones that reduced the flexural strength retention of the cement paste. However, after 125 days of decalcification by NH4NO3, a dissolution-filling mechanism within the clusters created a better bond with the surrounding cement paste, slowing down the loss of flexural strength and providing added ductility to the cement paste.

Investigation of the changes in microstructure and transport properties of leached cement pastes accounting for mix composition

Ca-leaching of cement-based materials induces detrimental effects on properties related to long-term durability. A better understanding of leaching degradation in terms of alterations in mineralogy, microstructure, and transport properties is important for long-term assessments of concrete and reinforced concrete structures used in nuclear waste disposal systems or in hydro structures. However, the decalcification process is not easy to study because it is extremely slow. In this study, an ammonium nitrate (NH4NO3) solution of 6mol/l was used to accelerate the leaching kinetics. The experiments were performed on cement paste samples with different water/powder (w/p) and limestone filler (LS) replacement ratios. Both the change of sample mass over time and the amount of calcium ion leached out were monitored during the test. Different post-analysis techniques including SEM/SEM-EDX, XRD/QXRD, MIP, ion chromatography, and N2-adsorption were used to characterize the microstructural and mineralogical changes. The effect of accelerated leaching on transport properties was studied by measuring the changes in water permeability and diffusivity of dissolved gases. Results showed that the square-root-time law of degradation was applicable under accelerated conditions. Both higher w/p ratios and LS replacements increased the rate of leaching propagation; the former had a more significant effect. The accelerated leaching significantly altered the microstructure of the cement paste to a material with a higher specific surface area, increased total porosity and a shift to larger pore sizes. Those changes led to a significant increase in water permeability (one to two orders of magnitude) and diffusivity (less than one order) depending on degradation state.

The Effects of Aggressive Environments on the Properties of Fly Ash based Geopolymers

This paper analyzes the effects of two different aggressive environments, concentrated ammonium nitrate solution (480 g/dm3) and sodium sulphate solution (50 g/dm3), on the structure and mechanical strength of fly ash based geopolymers. Geopolymer samples were subjected to the aggressive solutions over a period of 365 days. It was found that exposure to the NH4NO3 and Na2SO4 solutions caused small decrease in geopolymer strength (10-20%). The most valuable insight into the structural changes caused by testing of the geopolymer samples in the aggressive solutions was provided by means of 29Si MAS NMR. It was found that the immersion of geopolymer samples in the NH4NO3 solution caused breaking of Si-O-Al bonds in the aluminosilicate geopolymer gel structure. On the other hand, treatment of the geopolymer samples with the Na2SO4 solution resulted in breaking of Si-O-Si bonds in geopolymer gel structure and leaching of Si. It was concluded that the major changes in the geopolymer structure were associated with the changes in the pH values of aggressive solutions during the testing.

Corrosion of aluminum alloys Al 6061 and Al 2024 in ammonium nitrate‐urea solution

The corrosion behavior of two aluminum alloys Al 6061 T6 and Al 2024 T3 was investigated in a low carbon fuel consisting of concentrated aqueous solutions of ammonium nitrate and urea (ANU). Weight loss, potentiodynamic polarization, and electrochemical impedance spectroscopy techniques were applied to study the alloys corrosion behavior. Results obtained showed that a corrosion resistance passive film was formed on the surface of both aluminum alloys in solutions of pure ANU and ANU containing up to 1% NaCl. No flawed regions were found on the surface of either alloy after immersion in both solutions for 1500 h. However, immersion of the metals into pure 1% NaCl solution resulted in corroded regions immediately after immersion. The results received from weight loss, polarization, and impedance measurements are in excellent agreement. The high corrosion resistance of both Al alloys in the ANU solution containing up to 1 wt% NaCl support a safe usage of these materials for construction of storage containers and piping of these solutions.

Batch electrodialysis of ammonium nitrate and sulfate solutions

Batch electrodialysis of ammonium nitrate and sulfate solutions at potentiostatic conditions was investigated using the PC SA and SK membranes. The influence of the initial concentration (0.3–1.5M) and applied voltage (15, 20V) on the current efficiency, CE, and minimal diluate concentration was investigated. It was found that for both salts the average CE was comparable and was in the range 67–80%, depending on the conditions. For the concentrate concentration not exceeding 0.8M, the lowest diluate concentration was below 0.002, 0.005M for sulfate, nitrate, respectively. In the final stage of electrodialytic process, the correlation between the time dependence of the instantaneous CE and the changes of electric current and of potential drop on the membrane stack was analyzed. It was found that by estimating inflection point of these dependencies it is possible to find the moment of process when CE decreases and the energy consumption increases approximately twice. The concentration changes were fitted using the model based on the extended Nernst-Planck equation and ideal Donnan equilibrium. The results of each experiment were fitted with a very good accuracy, however, it was not possible to fit all the experimental results with one set of the model parameter values. The volume changes were satisfactorily approximated by a two parametric equation relating volume flux with electric current density and concentration difference. The effective electroosmotic coefficient referring to a membrane pair corresponds to ca. 6–8mol of water per 1F of electric charge passed through the membrane stack.

Nitrogen‐Based Alternative Fuel: Safety Considerations

AbstractDue to increasing global greenhouse gas emissions there is urgency to pursue all measures to develop carbon‐neutral energy technologies. The most attractive approach for large‐scale energy storage is perhaps in the form of synthetic fuels. In this work, a nitrogen‐based fuel consisting of an aqueous solution of urea and ammonium nitrate is evaluated for chemical stability and handling safety. The steady combustion of the fuel was demonstrated at 10 MPa. Thermal analysis under an ambient pressure dry air flow in the range of 25–500 °C showed that the monofuel does not react with atmospheric oxygen in a ventilated open system, and only endothermic thermal processes were observed in the condensed phase. Under applied pressure the fuel combusts exothermically above 300 °C, after water vaporization. The fuel described herein is an excellent gas generator with a potential effluent composition of 73.0 % H2O, 21.6 % N2, and 5.4 % CO2, which is an environmentally friendly working fluid.

Differences Between Sensitivity of Mycobiont and Photobiont of Cladonia sp. Lichens to Different Types of Nitrogen Exposure

Lichens absorb water, gases, dissolved substances, and especially pollutants by the entire surface, and they are considered to be the indicators of air quality. In our experiment, a sensitivity of Cladonia arbuscula subsp. mitis and Cladonia furcata lichens with the same photobiont Trebouxia was tested to nitrogen excess through a sensitivity of both the photobiont and mycobiont. Lichen ecophysiological parameters like chlorophyll a fluorescence, chlorophyll a integrity, the content of photosynthetic pigments, ergosterol, soluble proteins, thiobarbituric acid reactive substances, and secondary compounds were measured during two experiments that differed in time of nitrogen exposure. In the short-term experiment, also higher nitrogen concentrations were used to evaluate the dependence of different nitrogen concentrations. In the short-term experiment, lichens were soaked at the different solutions of ammonium nitrate (NH4NO3) for describing an immediate effect of range of NH4NO3 concentrations. In the long-term experiment, lichens were sprayed with low NH4NO3 concentrations for 3 months for evaluating the effect of naturally occurring low nitrogen concentrations. Results showed that lichens responded differently in spite of having the same photobiont. The mycobiont of C. arbuscula subsp. mitis was more sensitive than mycobiont of C. furcata. In higher nitrogen concentrations, the photobiont of C. furcata was more sensitive than C. arbuscula subsp. mitis photobiont. Both lichens exhibited signs of damage; therefore, we conclude that they are sensitive to nitrogen excess, while C. arbuscula subsp. mitis is more sensitive species. The secondary compound content did not change in neither of lichen species. Cladonia sp. response to nitrogen excess depends on length and nitrogen dose exposure.

Isolation of rare earth elements from ammonium salts solutions

It has been shown that nonradioactive concentrate containing up to 97–99 wt % rare earth elements (REEs) oxides after calcinations might be isolated from the strippant based on concentrated aqueous solution (275–300 g/L) of ammonium sulfate or ammonium nitrate obtained during the REE extraction from phosphogypsum or phosphoric acid. A REE loss in thorium-containing precipitate does not exceed 0.1–0.5% in the hydrolytic precipitation of thorium.

Selective extraction of In(III), Ga(III) and Zn(II) using a novel extractant with phenylphosphinic acid

A new extractant, [N,N-di(2-ethylhexyl)amino]methylphenylphosphinic acid (DEAPP), was synthesized to develop the mutual separation techniques of In(III), Ga(III) and Zn(II). The extraction selectivity for In(III), Ga(III) and Zn(II) with DEAPP was higher than that of the commercial phosphorus acid extractants such as D2EHPA and PC-88A. The extraction selectivity for metal ions in 1mol·L−1 aqueous ammonium nitrate solution with DEAPP was in the following order: In(III)>Ga(III)>Zn(II). These selective extraction behaviors indicate that the amino moiety of DEAPP plays an important role in the mutual separation of In(III), Ga(III) and Zn(II). The extraction equilibria of In(III), Ga(III) and Zn(II) with DEAPP (=HR) were expressed by the following reactions: In3++2HR¯2⇋InR3HR¯+3H+, Ga3++1.5HR¯2+NO3−⇋GaR2HRNO3¯+2H+, and Zn2++2HR¯2⇋ZnR2HR¯2+2H+. The extraction equilibrium constants of In(III), Ga(III) and Zn(II) with DEAPP were determined to be Kex,M=1.7×104 [dm3·mol−1], 4.17 [(dm3·mol−1)0.5], and 1.55 x 10−2 [–], respectively.

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.

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.

Use of Fly Ash as Soil Amendment to Offset Anion Exclusion Effect on Nitrate Transport

This study investigated the direct effect of fly ash used as a soil amendment on anion exclusion in NO3− transport in a variably saturated soil. A sandy clay soil was amended with Class F fly ash (FA) at four levels: 0, 2, 10, and 20% FA. The soils were placed in a small soil column and kept at constant saturation using a steady‐state centrifugation unsaturated flow apparatus. Three saturation ranges were investigated, 0.75 to 0.9, 0.4 to 0.45, and 0.27 to 0.29, designated as high, medium, and low saturation, respectively. Ammonium nitrate (0.7 mmol L−1) solution was passed through the soil sample, and the leachate was collected at predetermined intervals up to a total volume equivalent to 12 effective pore volumes. The leachate samples were analyzed for NO3− concentration using ion chromatography, and breakthrough curves were constructed. Experimental and modeling results showed that the amount of fly ash and saturation level had a significant effect on the hydraulic properties of the soil, reducing the hydraulic conductivity and increasing water retention. Furthermore, it was shown that the fly ash treatment slowed the transport of NO3−, especially at low saturation levels, when the effect of anion exclusion is thought to be stronger.

Research on decalcification degradation process of cement stone

An accelerated laboratory method (saturated ammonium nitrate solution immersion method) was used to analyze the degradation of cement decalcification process. By studying the changes of intensity, volume, elastic modulus, quality, pH value, the Ca/Si, and mineral phase, it could be found that the first cement decalcification degradation process was the decalcification of calcium hydroxide, and then CSH gel, AFm, etc. The secondary ettringite deposition happened and the decalcification degradation depth was proportional to the square root of time. Moreover, the corresponding strength of cement would be gradually reduced, cement rock volume shrinkage occurred, pH values decreased, the surface elastic modulus decreased down to a certain level, and slightly changed and the Ca/Si was 3.1 from the beginning and lasted down to 1.3.

Evaluation of air photoactivation at linear accelerators for radiotherapy

High-energy x-rays produced by radiotherapy accelerators operating at potentials above 10 MV may activate the air via (γ, n) reactions with both oxygen and nitrogen. While the activation products are relatively short-lived, personnel entering the accelerator room may inhale some radioactive air, which warrants internal dosimetry assessments. This work illustrates a method based on the use of ammonium nitrate solutions for the evaluation of photon-induced air activation and for the estimate of internal doses to radiotherapy personnel. Air activation and internal dosimetry assessments based on our method are presented for some widespread radiotherapy linear accelerator models. Our results indicate that the equivalent dose to the lungs of radiotherapy personnel is negligible for beam energies below 18 MeV.

Reactivity of concentrated ammonium nitrate solutions in the presence of organic impurities

Assessment of mixtures reactivity under certain conditions is essential for safe and conscious designing and improving manufacturing processes. One commonly used compound, the reactivity of which is very important, is ammonium nitrate and its solutions. The biggest influence on the reactivity of ammonium nitrate has the temperature and presence of other compounds, including impurities, that catalyze reactions leading to degradation. One of such impurities are organic compounds which impact on the ammonium nitrate has not yet been clearly described. The aim of the research was to investigate the influence of selected organic impurities on the reactivity of aqueous solutions containing up to 50 wt % ammonium nitrate, buffered with 15 wt % diammonium phosphate. The measurements were carried out using differential scanning calorimetry. Solution without organic compounds showed no reactivity up to 240 C. The addition of 8 wt % ammonium oxalate did not increase the reactivity of ammonium nitrate. It was observed an endothermic decomposition reaction of oxalic acid, beginning at 185 C. During the measurement of a solution containing 6 wt % phenidone, it was registered an exothermic complex reaction, beginning at 189 C and showing relatively small thermal effect. Addition of 6 wt % pyrogallol caused a significant increase in reactivity of ammonium nitrate solution. Strongly exothermic reaction beginning at 192 C was observed. Spectrophotometric measurement showed a clear nitrate concentration loss in the sample after calorimetric measurement. The results show that the nitrate ion selectively oxidizes certain functional groups in organic compounds.

Fabrication of long-term stable superoleophobic surface based on copper oxide/cobalt oxide with micro-nanoscale hierarchical roughness

We have demonstrated a simple and cost-effective technique for the large-area fabrication of a superoleophobic surface using copper as a substrate. The whole process included three simple steps: First, the copper substrate was oxidized under hot alkaline conditions to fabricate flower-like copper oxide microspheres by heating at a particular temperature for an interval of time. Second, the copper-oxide-covered copper substrate was further heated in a solution of cobalt nitrate and ammonium nitrate in the presence of an ammonia solution to fabricate cobalt oxide nanostructures. We applied this second step to increase the surface roughness because it is an important criterion for improved superoleophobicity. Finally, to reduce the surface energy of the fabricated structures, the surfaces were chemically modified with perfluorooctyltrichlorosilane. Contact-angle measurements indicate that the micro–nano binary (MNB) hierarchical structures fabricated on the copper substrate became super-repellent toward a broad range of liquids with surface tension in the range of 21.5–72mN/m. In an attempt to significantly improve the superoleophobic property of the surface, we also examined and compared the role of nanostructures in MNB hierarchical structures with only micro-fabricated surfaces. The fabricated MNB hierarchical structures also displays thermal stability and excellent long-term stability after exposure in air for more than 9 months. Our method might provide a general route toward the preparation of novel hierarchical films on metal substrates for various industrial applications.

Synthesis of pure-phase Sr2MgMoO6 nanostructured powder by the combustion method

Abstracts Pure-phase Sr2MgMoO6 (SMMO) nanopowder was obtained by combustion synthesis (CS) from an aqueous solution of metal nitrates, glycine and ammonium nitrate and subsequent treatment in air at 900 °C. The morphological and structural characterization was performed by X-Ray diffraction (XRD), N2 physisorption and scanning electron microscopy (SEM). This nanostructured powder presents average crystallite size of ~150 nm and a sponge-like morphology composed of highly interconnected crystallites and an effective specific area of 5.6 m2/g. EIS measurements indicate ASR values as low as 0.07 Ω cm2 at 800 °C.

Ceric ammonium nitrate oxidation of N-(p-methoxybenzyl)lactams: competing formation of N-(hydroxymethyl)δ-lactams

The ceric ammonium nitrate mediated oxidative deprotection of N-(p-methoxybenzyl) δ-lactams leads to the formation of an unexpected N-(hydroxymethyl) δ-lactam along with the Ndeprotected δ-lactam. In comparison, N-(p-methoxybenzyl) γ-lactams are completely deprotected under the same reaction conditions. Further studies indicated that addition of an aqueous solution of ceric ammonium nitrate to an acetonitrile solution of N-(p-methoxybenzyl) δ-lactams in the presence of 2-amino-2-methyl-1-propanol as an additive promoted N-deprotection. Ceric ammonium nitrate oxidation of N-(α,α-dideuterio-p-methoxybenzyl)-6-allyl-δ-lactam (8), revealed that the methylene unit of the N-(hydroxymethyl) group is derived from the benzylic methylene unit of the N-protecting group. A plausible reaction pathway for the formation of the N-(hydroxymethyl) δ-lactams from an N-acyliminium ion intermediate is proposed.