Small Amount Of NH Research Articles

Analysis of thermal decomposition of acidified sediments in gold plants and harmless disposal of it

In the present work, thermal decomposition of ASs in air was characterized by a combination of TG-DSC, XRD, and TG-FTIR. The treatment of generated toxic (CN)2 gas was investigated as well. The result showed that the decomposition of Zn2Fe(CN)6 in ASs preferentially reacted with CuSCN leading to the early decomposition of ASs, in which a part of CuSCN decomposed into Cu5FeS4 or Cu2S followed by being oxidized to sulfates and oxides as the temperature increased to 420 °C. For Zn2Fe(CN)6·3H2O in ASs, the decomposition products below 500 °C include ZnS, ZnSO4, CuxFeySz, iron oxides and Zn(CN)2; instead, Fe3O4, ZnSO4 and ZnFe2O4 were formed. The FTIR and chemical quantitative analysis showed that nitrogen-containing gaseous products predominately contained (CN)2, HCN and small amounts of NH3 and NOx. In view of toxic gases released, catalytic oxidation employing in-situ generation of roasting slag at 600 °C (AS1) can be effectively used for the conversion of (CN)2 to N2 under the optimal conditions of airflow rate of 0.7 L/min and AS1/ASs mass ratio of 0.5. Significantly, the ZnFe2O4 phase in AS1 completely disappeared and was converted to ZnSO4 after the experiment, which facilitated the subsequent acid leaching, thereby achieving the synergistic treatment of exhaust gases and slag.

Reburning of Animal Waste Based Biomass with Coals for NOx Reduction, Part II: Dairy Biomass (DB) and Coal–DB Blends

Concentrated animal feeding operations (both slaughter and dairy cattle) lead to land, water, and air pollution if waste storage and handling systems are not effectively managed. At the same time, cattle biomass (CB), which includes both slaughter/feedlot biomass (FB) and dairy biomass (DB), have the potential to be a source of green energy at coal-fired power plants. Part I presented results on NOx reductions with pure FB or Coal: FB blends as reburn fuels. Part II deals with results from reburning with pure DB or Coal: DB blends as reburn fuels. A mixture of NG with a small amount of NH3 was used to generate the baseline NOx of 400–420 ppm (or 185–194 g/GJ). NOx emissions were found to be reduced by as much as 96% when reburning with FB. The effects of reburn fuel type, equivalence ratio (ERRBZ) in the reburn zone, vitiated air, several injection configurations of reburn fuel and initial NO concentrations on NOx emissions were investigated. The ERRBZ shows a significant effect on the NOx reduction. The 20% heat input by reburning was the better operating condition for the long-term operation due to its ash production. The results reveal that reburn with DB fuels is an effective technology for NOx emission control when the initial NOx emission is higher than 275 ppm (or 127 g/GJ or 0.3 lb/MMBtu).

Toward homogenous AlN via reaction of Al nanoparticles with N2 and NH3: Reactive molecular dynamics simulation

AbstractIn this study, reactive molecular dynamics simulations were implemented to study the initial events in synthesizing AlN via aluminum nanoparticles (ANPs) with N2/NH3. The dissolution and diffusion behavior of N and H atoms in ANPs is elaborated. Without sufficient N2 supply and lower temperatures (below 2000 K), AlN nucleates and grows in an island shape, and the phase separation occurs through N atoms diffusion. The increase in N2 density accelerates the dissolution of N atoms through the nitride film to the core. In the NH3 atmosphere, H atoms generated by the cleavage of NH3 on ANPs surface dominate inward penetration, while N atoms are at a disadvantage in competition. ANPs have a large number of internal stress and form interwoven dislocations in the combustion. The number and distribution of dislocations are affected by temperatures and reaction time. ANPs not only expand in volume but also have local voids generated by hot spots at high temperatures. In the analysis of ANPs/NH3 species, the instability of the N‐H bond causes aluminum‐containing substances to spill out. Furthermore, N2 atmosphere together with a small amount of NH3 can loosen the nitride film and promote the diffusion of N atoms into the ANPs core. A homogeneous AlN could be tuned and fabricated under an optimal ratio of N2/NH3 (∼6:1).

Preparation and properties of lowest eutectic mixture MTNP/TNAZ

ABSTRACT In this work, DSC tests were performed on 1-methyl-3,4,5-trinitropyrazole (MTNP) and 1,3,3-trinitroazetidine (TNAZ) binary eutectic systems with different molar ratios, and we drawn the T-X and H-X phase diagrams. We get the ratio of MTNP/TNAZ eutectic system by phase diagram, and the eutectic of the two were characterized by Energy spectrum analysis(EDS), X-ray diffraction(XRD), fourier transform infrared spectroscopy (IR), X-ray photoelectron spectroscopy (XPS), thermodynamic analysis, thermo gravimetric mass spectrometry (TG-MS), thermal sensitivity test, mechanical sensitivity test and detonation performance calculation. The results show that the ratio of MTNP/TNAZ eutectic system is 46.3/53.7, and the melting point is 72.58°C. EDS shows that there is no impurities in the lowest eutectic mixture. XRD indicates that there is some intermolecular force between the lowest eutectics mixture, which changes the diffraction peak. IR shows that the raw MTNP and raw TNAZ do not react with each other after forming the lowest eutectic mixture. Thermodynamic analysis indicates that the thermal decomposition reaction of the lowest eutectic mixture requires endotherm, and the entropy value of the reaction is decreased. Thermo gravimetric mass spectrometry (TG-MS) shows that the main decomposition products of the lowest eutectic mixture are CH4, N2O, CO2, H2, H2O, and only a small amount of NH3, and thermal decomposition of it is more complete than raw materials. Then the mechanical sensitivity of the raw MTNP, TNAZ and the lowest eutectic were tested, and the detonation performance were also calculated, the results show that the lowest eutectic has good mechanical sensitivity and detonation performance. Finally, the thermal sensitivity test was carried out on the raw materials and the lowest eutectic mixture, and it was found that the lowest eutectic mixture had the lowest activation energy, which is more conducive to thermal decomposition.

Analysis of Chemical Reaction Process after Pentaerythritol Tetranitrate Hot Spot Ignition.

In this paper, ReaxFF force field combined with molecular dynamics method was used to study the ignition, deflagration, and detonation of pentaerythritol tetranitrate (PETN) induced by hot spots. The hot spot is 5.6% of the total volume. When the hot spot temperature is 1000 K, the deflagration and detonation of PETN cannot be observed in the simulation time of 200 ps. When the hot spot temperature is 2000 K, it corresponds to the heating time of 20 to 50 ps, deflation and detonation were observed. During hot spot ignition, the products of decomposition of the condensed phase PETN are dominated by NO2 and HONO. The energy required for the C–C bond and C–ONO2 bond cleavage in PETN is high, resulting in only a small amount of CH2O and NO3 during the reaction. Small nitrogen-containing molecules (such as NO2, NO3, HONO, HNO3, etc.) mainly exist during thermal equilibrium, while the number of N2 increases sharply during the thermal runaway stage, and a small amount of NH3 and NH2 are also produced. H2O molecules are formed before CO2 and N2 are produced, and the number always dominates. During the thermal runaway, the entire system can maintain a spontaneous reaction, resulting in a sharp rise in temperature of about 2500 K in 20 ps. During this phase, the catalytic effect of H2O accelerates the formation of CO2 and N2 due to the near Chapman–Jouguet point in the crystal. PETN is a weak oxygen balance explosive that results in a small amount of CO and H2 production during the thermal instability phase. When the reaction is balanced, the relative molecular mass is close to or exceeds that of PETN. The product is only less than 1% of the total mass fraction, while the small molecule product is as high as 78%, and some relative molecular masses are [75,225]. The intermediates account for about 21%. Rapid and complex reaction events make it difficult to accurately predict the structure of these intermediates by existing experiments and calculations, which will be the focus of future research.

Nanometer Ammonium Perchlorate and Ammonium Nitrate Prepared with 2D Network Structure via Rapid Freezing Technology.

Nanometer (nano) ammonium perchlorate (AP) and ammonium nitrate (AN) were prepared with 2D network structures by the ultra-low temperature spray method. Scanning electron microscopy (SEM), X-ray diffractometry (XRD), differential scanning calorimetry (DSC) and thermogravimetric analysis/infrared spectrometry (TG-IR) were employed to probe the micron structure, crystal phase, and thermal decomposition of nano AP and nano AN. SEM images revealed that the sizes of nano AP and AN were in the nanometer scale (<100 nm) in one dimension. XRD patterns showed that the crystal phases of nano AP and AN were in accordance with those of raw AP and raw AN, respectively. DSC traces indicated that the thermal decomposition process of AP depended on its particle size, while the thermolysis of AN was independent of the particle size of AN. TG-IR analyses illustrated that the decomposition products of nano AP were NO2, N2O, HCl and H2O, with a small amount of NOCl, and the main decomposition products of nano AN were N2O and H2O, with a small amount of NH3. The results of mechanical sensitivity tests indicated that nano AP was more sensitive than raw AP and both nano AN and raw AN were very insensitive to impact and friction stimuli.

A full-scale integrated-bioreactor with two zones treating odours from sludge thickening tank and dewatering house: performance and microbial characteristics

A full-scale integrated-bioreactor consisting of a suspended zone and an immobilized zone was employed to treat the ordours emitted from a wastewater treatment plant. The inlet concentrations of H2S and NH3 were 1.6–38.6 mg∙m–3 and 0.1–6.7 mg∙m–3, respectively, while the steady-state outlet concentrations were reduced to 0–2.8 mg∙m–3 for H2S and 0–0.5 mg∙m–3 for NH3. Both H2S and NH3 were eliminated effectively by the integrated-bioreactor. The removal efficiencies of H2S and NH3 differed between the two zones. Four species of microorganisms related to the degradation of H2S and NH3 were isolated. The characteristics and distributions of the microbes in the bioreactor depended on the inlet concentration of substrates and the micro-environmental conditions in the individual zones. Product analysis indicated that most of the H2S was oxidized into sulfate in the immobilized zone but was dissolved into the liquid phase in the suspended zone. A large amount of NH3 was converted into nitrate and nitrite by nitration in the suspended zone, whereas only a small amount of NH3 was transferred to the aqueous phase mainly by absorption or chemical neutralization in the immobilized zone. Different microbial populations dominated the individual zones, and the major biodegradation products varied accordingly.

Developments in understanding the nucleation of AlN on silicon by MOCVD and its effects on defects

We have studied the process of AlN nucleation on silicon by metal-organic chemical vapor phase deposition. We have shown that for our reactor, which incorporates a chlorine-based chamber clean, we require similar growth conditions to those shown to be optimum by molecular beam epitaxy, that is to say a small amount of NH3 followed by tri-methyl aluminum (TMAl). When TMAl was introduced first, the resulting layers were low quality and cracked. Furthermore, we have shown that for the highest quality layers, with longer TMAl injection, we have an increased density of “inverted pyramid” defects in the layer which can impact electrical device performance. As we have shown that wafer bow becomes increasingly concave with reduced crystalline quality of the GaN layers, a compromise should be achieved between layer quality and morphology to produce wafers which can be processed into large area, high power transistors. We have been able to produce wafers with a low vertical leakage current density 900 V for test structures up to 12 mm2, with a total nitride structure of 3.6 μm on silicon, resulting in a bow less than <50 μm on the 200 mm wafer.

Online Study on the Catalytic Pyrolysis of Bituminous Coal over HUSY and HZSM-5 with Photoionization Time-of-Flight Mass Spectrometry

Pyrolysis is considered to be a simple and effective method for the clean conversion of coal. In this work, catalytic pyrolysis of bituminous coal over two commercial available zeolites, i.e., HZSM-5 and HUSY, was investigated with newly constructed pyrolysis photoionization time-of-flight mass spectrometry (Py–PI–TOFMS) in real time. The fragment-free mass spectra of coal pyrolysis products at different pyrolysis temperatures were measured. Products such as alkanes, alkenes, dienes, phenols, aromatics, and small amounts of NH3 and H2S could be detected. The abundant products at a relatively low temperature (500–600 °C) are phenols. With the presence of zeolites, the product distribution could be observed from the mass spectra. Temperature effects for pyrolysis products show some different tendencies with and without HZSM-5 and HUSY as a result of different acidities and pore sizes of the catalysts. Time-evolved profiles of major products were also measured during the pyrolysis processes. The temperature ...

Optimization of a non-arsenic iron-based superconductor for wire fabrication

We report on the optimization of synthesis of iron selenide-based superconducting powders and the fabrication of selenide-based wire. The powders were synthesized by an ammonothermal method, whereby Ba is intercalated between FeSe layers to produce Bax(NH3)yFe2Se2, with tetragonal structure similar to AFe2X2 (X: As, Se), ‘122’, superconductors. The optimal Tc (up to 38 K) and Meissner and shielding superconducting fractions are obtained from the shortest reaction time (t) of reactants in liquid ammonia (30 min). With the increase of t, a second crystalline 122 phase, with a smaller unit cell, emerges. A small amount of NH3 is released from the structure above ∼200 °C, which results in loss of superconductivity. However, in the confined space of niobium/Monel tubing, results indicate there is enough pressure for some of NH3 to remain in the crystal lattice, and thermal annealing can be performed at temperatures of up to 780 °C, increasing wire density and yielded a reasonable Tc ≈ 16 K. Here, we report of the first successful wire fabrication of non-arsenic high-Tc iron-based superconductor. Although bulk materials are estimated to carry critical current densities >100 kA cm−2 (4 K, self-field), the current transport within wires need to be optimized (Jc ∼ 1 kA cm−2).

The concentration of geothermal brines with iodine content by membrane distillation

The concentration of Zabłocka Thermal Brine that contains iodine was studied in order to prepare a concentrated solution of the curative salts. The membrane distillation process was used for the concentration of brines with two kinds of polypropylene Accurel PP membranes. The solutions were concentrated from 34 to 310gNaCl/L, and the iodine concentration increase up to 1gI−/L was achieved. The mineral composition of concentrated solutions, including the iodine content was determined using an ion chromatography method. The obtained rejection of solutes was close to 100%, but the small amounts of NH3 and I2 also diffused together with water vapor through the membrane. However, the concentration of brines using the membrane distillation process allows achieving significantly lower losses of iodine in comparison to the traditional evaporation methods. An increase in the solute concentration (to 310gNaCl/L) caused a 30–50% drop in the yield of water evaporation through the membrane. Moreover, an intensive membrane scaling was observed, especially during the initial period of feed concentration.

G071025 アンモニアの基礎燃焼特性の評価([G071-02]エンジンシステム部門,一般セッション(2))

Burning velocity and NOx formation in the combustion of NH_3 mixed with H_2 at different air-fuel equivalence ratios and different H_2/NH_3 ratio were experimentally studied in this research. NH_3 burning velocity increased with increase of amount of H atom in the flame with the addition of H_2. Burning velocity of H_2/NH_3-air changed with the H_2/NH_3 ratio, and it seemed to be highest at the H_2/NH_3 of 0.67. The nitrogen in NH_3 converted to N_2 during the combustion. Small amount of NH_3 converted to NOx and its concentration increased with the increase of H_2/NH_3 ratio.

Proton transfer chains in cold plasmas of H2with small amounts of N2. The prevalence of NH4+

The ion-molecule chemistry of the astronomically relevant H(3)(+), N(2)H(+), and NH(4)(+) ions has been investigated in the weakly ionized cold plasmas formed in glow discharges of H(2) with small amounts of nitrogen. The concentrations of neutrals and ions were determined by means of mass spectrometry, and electron temperatures and densities were measured using Langmuir probes. A kinetic model was used for the interpretation of the results. The selection of experimental conditions allowed the generation of ion distributions with different relative weights of the mentioned protonated species and the model calculations showed that the observed ion distributions can be explained by the occurrence of a very efficient H(3)(+) → N(2)H(+) → NH(4)(+) proton transfer chain. The NH(4)(+) ion, which is dominant in most of the cases studied, is ultimately derived from the small amount of NH(3) produced at the reactor walls. NH(4)(+) tends to be preponderant in the ion distributions even for NH(3) density ratios as low as 1%. Due to the high proton affinity of ammonia, this molecule is readily transformed into NH(4)(+) upon collision with H(3)(+) or N(2)H(+). It is conjectured that these results can be extrapolated to most of the small molecules predominant in the interstellar medium, which also have proton affinities lower than that of NH(3). The results support the predictions of astrochemical models indicating that NH(4)(+) could be a preponderant ion in some warm environments like hot cores, where NH(3) molecules have desorbed from the grains.

Characteristic features of the molecular dynamics and phase transitions of mixed [(NH4)1−xRbx]3H(SO4)2 (x=0, 0.8, and 1) crystals using 1H and 87Rb NMR

Abstract In this study, we grew [(NH4)1−xRbx]3H(SO4)2 (x = 0, 0.8, and 1) mixed crystals using a slow evaporation method and determined their lattice constants by X-ray diffraction. We investigated the molecular dynamics and phase transition temperatures of the crystals using 1H and 87Rb nuclear magnetic resonance (NMR) relaxation and differential scanning calorimetry. When a fraction of rubidium ions in the pure Rb3H(SO4)2 crystal is partial replaced by ammonium ions, we compared the physical properties of the three types of crystals. A small amount of NH 4 + added to Rb3H(SO4)2 led to a change in the physical properties, bringing about a shift in phase transition temperatures and showed a superprotonic phase transition.

Desalination of geothermal water by membrane distillation

Membrane distillation process was used for desalination of hot (333 K) geothermal water, which was applied in the plant producing heating water. The investigated water contained 120 g salts/dm3, mainly NaCl. The mineral composition was studied using an ion chromatography method. The obtained rejection of solutes was closed to 100%, but the small amounts of NH3 also diffused through the membrane together with water vapour. However, the composition of obtained distillate allowed to use it as a makeup water in the heating water system. The geothermal water under study was concentrated from 120 to 286 g NaCl/dm3. This increase in the solution concentration caused the permeate flux decline by a 10-20%. The geothermal water contained sulphates, which was subjected to two–fold concentration to achieve the concentration 2.4-2.6 g SO4 2−/dm3 and the sulphates then crystallized in the form of calcium sulphate. As a results, an intensive membranes scaling and the permeate flux decline was observed. The XRD analysis indicated that beside the gypsum also the NaCl crystallites were deposited on the membrane surfaces. The fresh geothermal water dissolved the mixed CaSO4 and NaCl deposit from the membrane surface. This property can be utilized for self-cleaning of MD modules. Using a batch feeding of MD installation, the concentration of geothermal water was carried out over 800 h, without significant performance losses.

Study on the thermal degradation of high performance fibers by TG/FTIR and Py-GC/MS

The thermal degradation behaviors of Kevlar 49, Kevlar 129 (Poly(p-phenylene terephthamide), Nomex (polyisophthaloyl metaphenylene diamine), and PBO(poly(p-phenylene benzobisoxazole)) fibers were measured by TG/FTIR and Py-GC/MS. The characteristic temperatures of the fibers in air were obtained by TG. It indicated that the initial degradation temperature of the PBO is the highest. The initial degradation temperature of Nomex fiber is the lowest, but the end decomposition temperature of Nomex is the highest. The gases released by the pyrolysis in air were mainly CO2, CO, H2O, NO, and HCN, also containing a small amount of NH3, and the absorption peaks of CO2 were the strongest. The results of Py-GC/MS showed that CO2 and benzene were the most pyrolysis fragment. With the change of pyrolysis temperature, the chromatogram and mass spectra results take a large variety. The pyrolysates can help us to study the pyrolysis process of high performance fibers.

A guided-ion beam study of the reactions of Xe+ and Xe2+ with NH3 at hyperthermal collision energies

We have measured the absolute cross sections for reactions of Xe(+) and Xe(2+) with NH(3) at collision energies in the range from near-thermal to ∼34 and ∼69 eV, respectively. For Xe(+), the cross section for charge transfer, the only exothermic channel, decreases from ∼200Å(2) below 0.1 eV to ∼12Å(2) at the highest energies studied. The production of NH(3) (+) is the only channel observed below 5 eV, above which a small amount of NH(2) (+) is also formed. In Xe(2+) reactions, the main products observed are NH(3) (+) and NH(2) (+). The charge transfer cross section decreases monotonically from ∼80 to ∼6Å(2) over the studied energy range. The NH(2) (+) cross section is similar to the charge transfer cross section at the lowest energies, and exhibits a second component above 0.4 eV, with a maximum of 65Å(2) at 0.7 eV, above which the cross section decreases to ∼30Å(2) at the highest energies studied. At energies above 10 eV, a small amount of NH(+) is also observed in Xe(2+) collisions. Product recoil velocity distributions were determined at selected collision energies, using guided-ion beam time-of-flight methods.

The muonic He atom and a preliminary study of the reaction

The muonic atom He4μ has the composition α++μ-e-, and is formed by stopping negative muons in He doped with a small amount of NH3 (or Xe). It may be regarded as a unique heavy H-atom isotope with a mass of 4.1 amu. As such, the study of its chemical reaction rates and comparison with those of the well-known light Mu atom (0.113 amu) allows unprecedented tests of kinetic isotope effects over a range of 36 in mass. As a first example, and one which is of most fundamental interest, we have begun kinetics studies of the Heμ+H2→HeμH+H reaction in the gas phase. The first measurements, at 295 K, give a rate constant of kHeμ=4.1±0.7×10-16cm3molec-1s-1. In comparison, variational transition state calculations give a value of 2.46×10-16cm3molec-1s-1, somewhat below the measurement, despite the large error bar, raising the possibility that the calculations, on an essentially exact potential energy surface, have underestimated the amount of quantum tunneling involved, even for this heavy H-atom isotope.

Recovery of visible-light photocatalytic efficiency of N-doped TiO 2 nanoparticulate films

Bare TiO 2 and N-doped TiO 2 nanoparticulate films in anatase phase were prepared on glass substrates by laser ablation of titanium target in O 2, N 2/O 2 and NH 3/N 2/O 2 atmospheres, respectively. The nitrogen dopant concentration increased notably when a small amount of NH 3 was added into the N 2/O 2 mixture. The film prepared in NH 3/N 2/O 2 exhibited enhanced photoabsorption and photocatalytic ability in the visible-light region as compared with that produced in N 2/O 2. However, for all films, rapid deactivations were observed with operating time, leading to a poor reusability of the catalysts. With a simple and effective approach of mild heat treatment, the photocatalytic efficiency was completely recovered and the reusability of the film was greatly improved.

Hydrogen storage properties of 2LiNH 2 + LiBH 4 + MgH 2

We have investigated the ternary mixture of complex hydrides with stoichiometry 2LiNH 2 + LiBH 4 + MgH 2, and have identified a set of novel hydrogen storage reactions. One of these reactions involves the known reversible reaction Mg(NH 2) 2 + 2LiH ↔ Li 2Mg(NH) 2 + 2H 2. Previous studies have shown that initiating this reaction from the binary mixture 2LiNH 2 + MgH 2 results in poor hydrogen desorption kinetics and a small amount of NH 3 release. In contrast to this behavior, here we demonstrate that by starting from the ternary mixture 2LiNH 2 + LiBH 4 + MgH 2, the above reaction can proceed at lower temperatures and with improved kinetics, while maintaining reversibility. The advantage of starting with the ternary mixture can be traced to the subsequent formation, melting, and reaction of Li 4BH 4(NH 2) 3 with MgH 2 to form the mixed imide phase Li 2Mg(NH) 2, which acts as a seed for the reversible reaction, and is at least partly responsible for the improved kinetic response.