Hydrazine Nitrate Research Articles

Experimental Investigations of Combustion: (95 WT.-%) HAN–Water Solution with High-SSA Activated Carbons

ABSTRACTThe thermal decomposition of hydroxylamine nitrate (HAN) 95% water solution, a “green” alternative of fuel/oxidizer formulation to hydrazine nitrate, as a rocket propellant in the presence of the high-specific surface area (SSA)-activated carbons was investigated. It was shown that the linear burning rate increased for the system of HAN 95% water solution admixed with activated carbons compared to that of the 95% water solution HAN alone. Also, decomposition of the mixture (HAN spiked with rice husk (RH)-derived activated carbons by 1 mass %) was monitored by electron ionization–mass spectrometry (EI–MS) at different heating rates (from 16 to 128 K/min). EI MS analysis of the formation of major gas products (NO, NO2 and N2O) at the HAN decomposition in presence carbon particles shown various results.

Preparation of Powdered Uranium Oxides by Denitration of Nitric Acid Uranium Solutions Using UHF Radiation

Denitration of nitric acid uranium solutions under the action of UHF radiation in ambient and reducing atmosphere in the presence of organic reductants containing amino groups (carbohydrazide, acetohydroxamic acid, aminoacetic acid, hydrazine nitrate) and without them to obtain a mixture of uranium oxides was studied. The conditions of thermal transformation of the initially formed mixture of uranium oxides into uranium dioxide powder under the action of UHF radiation were determined. The characteristics of UO2 powders meet the requirements of TU (Technical Specification) 95414–2005 to ceramic-grade powders.

Detonation properties of hydrazine nitrate

The results of investigation of the detonation waves structure, the critical diameter, detonation parameters and the dependence of detonation velocity on the charge diameter for pressed hydrazine nitrate (HN) charges in the density range of 1.40–1.68 g/cm3 are presented. It was found that the critical diameter drops with the initial density decrease. Under steady-state detonation conditions at an initial density of 1.68 g/cm3, a high detonation velocity of 8.92 km/s is observed in HN charges. The change of the detonation velocity with variation of the initial density is not monotonous, but has a characteristic s-shape.

Nickel-based catalysts for hydrogen evolution by hydrolysis of sodium borohydride: from structured nickel hydrazine nitrate complexes to reduced counterparts

Nickel complexes have recently been presented as prospective catalytic materials for hydrogen H2 evolution by hydrolysis of sodium borohydride NaBH4. An attractive complex is nickel hydrazine nitrate [Ni(N2H4)3][NO3]2 for which little variations in the synthesis procedure result in different morphologies like hexagonal plates, clews and discs. In our conditions, the clews have the better catalytic activity owing to more defects and more active sites. There is an effect of the morphology on the catalytic activity. However, the H2 evolution curves (regardless the initial morphology) show an induction period during which the complex (purple violet in color) evolves into a catalytically active form (fine black powder). The evolution is featured by changes in morphology and chemical state of nickel. The catalytically active form is even more active than the pristine complex: it shows a higher H2 generation rate (three times higher in the best case). The starting complexes and the “reduced” counterparts have been then characterized (e.g. SEM, FTIR, XRD, XPS) to better understand the aforementioned evolutions. One of our main conclusions is that there are some marked analogies between our nickel-based catalysts and the much-investigated cobalt-based catalysts.

Investigation of Preparation, Solubility and Stability Properties of Nickel Hydrazine Nitrate (NiHN)

AbstractFollowing an initial, brief, review of the environmental problems associated with the use of lead based primers, and also some of their potential replacements, this study investigated the preparation of the promising, lead free, energetic material nickel hydrazine nitrate by different methods. All three methods trialed produced the same, analytically indistinguishable, compound but with minor changes in visual appearance. The solution properties governing the precipitation process were investigated in a controlled pH titration experiment. Product solubility in a number of common solvents was investigated. Aqueous ammonia and hydrazine hydrate proved the best “non‐destructive solvents” for the solid. UV spectroscopy and conductivity of the solutions obtained was used as an indicator of the processes involved in the solubility. Using the critical pH conditions for precipitation from aqueous solutions of hydrazine and nickel nitrate the formation constant for the tris hydrazine complex was determined. Also using the solubility of the tris‐hydrazine complex in concentrated hydrazine hydrate an equilibrium constant for the formation of the soluble hexa‐hydrazine complex from insoluble tris hydrazine complex was determined. These values were compared with similar values for nickel hydrazine complexes with other anions. The origins of these differences were discussed. Further work on controlling and measuring the particle size of the NiHN produced should be considered.

Shock Wave and Detonation Properties of Pressed Hydrazine Nitrate

AbstractIn this work, the structure of the steady‐state detonation waves, the critical diameter, detonation parameters and the dependence of detonation velocity on the charge diameter for pressed hydrazine nitrate (HN) charges in the density range of 1.40–1.68 g/cm3 were investigated by VISAR interferometer. It was found that the critical diameter drops with the initial density decrease. Under steady‐state detonation conditions at a maximum initial density of 1.68 g/cm3, a high detonation velocity of 8.92 km/s is realized in HN charges. The change of the detonation velocity with variation of the initial density is not monotonic, but has a characteristic s‐shape. Experiments on the determination of Hugoniot data and initiation of detonation under shock wave action for HN were carried out with samples of maximum density. The results of the conducted experiments show the low shock wave sensitivity, which is much lower than that of TNT. A noticeable reaction rate behind the front of the initiating shock wave in charges of maximum density is observed only at a pressure above 20 GPa.

Thermal decomposition of energetic MOFs nickel hydrazine nitrate crystals from an ab initio molecular dynamics simulation

We report the initiation mechanisms and subsequent chemical decompositions of energetic metal-organic frameworks (MOFs) nickel hydrazine nitrate (NHN) crystal at high temperatures and high temperatures coupled with high pressures by ab initio molecular dynamics simulations. The initial decomposition step is the collapse of the MOF cage at 518 K and 518 K coupled with 1, 2, and 3 GPa. But their cleavage steps are different. It is found that the pressure decelerates the initial decomposition of the NHN crystal. The decomposition mechanisms of the NHN crystal at 518 K coupled with 20.2 GPa are much different from those at 518 K coupled with low pressures. The results indicate that the temperature is the foremost factor that affected the decomposition of the NHN crystal. At 4000 K and 4000 K coupled with 20.2 GPa, the initial decomposition mechanisms of NHN are both the cage collapse by several NiN bond breaking. The variation tends and the release times of H2O are similar at the two cases. In the early decomposition stage, NHN decomposed very fast and drastically. But the later decomposition was slow. During 1.0 ps, there are ten H2O released fast at the two extreme conditions. Then the population of H2O keeps nearly stable during the later decomposition stage. At 7.959 ps, last one H2O was formed. Our results may provide useful information for understanding the chemical decompositions of energetic metal-organic frameworks compounds.

Research on the thermal performance and storage life of series of high-energy hydrazine nitrate complexes

The thermal performance of high-energy hydrazine nitrate complexes [Zn(N2H4)2(NO3)2]n, [Cd(N2H4)2(NO3)2]n, [Co(N2H4)3](NO3)2 and [Ni(N2H4)3](NO3)2 (signed as ZnHN, CdHN, CoHN and NiHN) was researched systematically. The thermal behavior, kinetics, thermal safety and storage life of them were investigated by the DSC, TG and dynamic pressure measuring thermal analysis method. The thermal decomposition of CdHN and ZnHN with NO3 − as ligand is more complicated than CoHN and NiHN with NO3 − as counterion indicating that similar structures have some influence on the thermal properties, but there is no necessary relationship. DSC curves and TG mass-loss stages of CdHN and ZnHN are similar but their thermal decomposition mechanism is quite different.

Evaluation of consequence due to higher hydrazine content in partitioning stream of PUREX process

Abstract Hydrazine nitrate is being used as a stabilizer for U(IV) as well as Pu(III) during partitioning of Pu in PUREX process by scavenging the nitrous acid present along with nitric acid. As hydrazine hydrate as well as its salts have been successfully used for scrubbing of degradation products of TBP to aqueous phase, experiments were conducted to evaluate the consequence of hydrazine content during Pu partitioning. It was observed that higher amount of hydrazine nitrate along with uranous nitrate in the partitioning stream of PUREX process leads to build up of DBP in aqueous phase and resulted in precipitation of Pu.

The Development and Testing of the New Flowsheets for the Plutonium Purification Cycle of the Purex Process

In order to improve the extraction flowsheet of RT-1 Plant two versions of plutonium purification unit flowsheet were developed: a flowsheet with stabilization of Pu(IV)-Np(IV) valence pair and Pu, Np co-recovery, and a flowsheet with stabilization of Pu(IV)-Np(V) valence pair and Pu recovery. The task related to stabilization of the valence pair of the target components in the required state was solved with the use of reactants already applied at RT-1 Plant, namely, hydrogen peroxide, hydrazine nitrate and catalyst (Fe). Both flowsheets were adapted for the plant purification facility with minimum modifications of the equipment, and passed the full scale industrial testing. As a result of this work, reduction in volume and salt content of the raffinate was achieved.

硝酸肼镍废水的处理和回收利用

介绍了用母液循环、分解、沉淀分离等方法处理和回收利用硝酸肼镍废水。实践证明：利用“母液循环”工艺制备硝酸肼镍可大量减少废水产生、节约水量，并且能提高产品质量；利用分解、沉淀分离的方法可回收硝酸镍，处理后的废水符合国家规定排放标准。 This paper introduces using the methods of liquor cycle, decomposition, precipitation, separation to treat and recycle the waste water of nickle hydrazine nitrate. Practice proved that: using the technology of liquor cycle to prepare the nickle hydrazine nitrate can greatly reduce waste water generation, conserve water and improve product quality; the use of decomposition and precipita-tion separation could recover nickle nitrate and the treated waste water is in line with the nation emission standards.

Catalytic reduction of U(VI) to U(IV) using hydrogen with platinum loaded on alumina and silica

During the reprocessing of spent nuclear fuel, uranium (U) and plutonium (Pu) are together extracted by employing tri-n-butyl phosphate (TBP)/dodecane mixture and their partitioning is achieved by adding uranous nitrate. The partitioning agent, uranous is conventionally produced by the electrolytic reduction of uranyl nitrate. An alternate route for the reduction of U from (VI) to (IV) using hydrogen (H2) as reductant was developed using platinum (Pt) based catalyst. Improvements in the development of the catalyst have been carried out in order to reduce the requirement of Pt without affecting the reduction performance. Experiments using 2 wt% Pt loaded on alumina beads and alumina powder have been performed and results are discussed. As the catalyst supported on alumina was found to be unstable in acidic environment, Pt loaded on silica powder has also been developed. Pt loaded on alumina and silica substrates have been tried to envisage the reduction behaviour using H2 as reductant in presence of hydrazine nitrate which acts as U(IV) stabiliser as well as reductant. Parametric studies have been carried out to optimise the process parameters namely pressure, temperature, U concentration, free acidity, hydrazine concentration and catalyst to U (C/U) ratio. 2 wt% Pt loaded on silica has been selected for further scale up studies for making uranous.

Solidification Behavior of the Hydrazine Nitrate‐Nitroguanidine Eutectic System

AbstractIn an attempt to better understand the properties of energetic eutectic materials, the eutectic mixture of hydrazine nitrate (HN) and nitroguanidine (NQ) was prepared by a melt crystallization method. The melting temperature and fusion enthalpy of the pure components and the eutectic were determined using differential scanning calorimetry. The structure of the HN‐NQ title compound was characterized by infrared spectroscopy (IR), X‐ray diffraction (XRD), and scanning electron microscopy. Thermodynamic functions such as excess Gibb’s energy, excess enthalpy, and excess entropy of the title mixture were calculated using activity coefficient data. The intermolecular interactions of different molar ratios of the HN‐NQ eutectic were determined by density functional theory (DFT) methods. The results of the excess thermodynamic functions and computer simulations indicate that the eutectic is not a mechanical mixture. IR spectroscopic and XRD studies confirm that there is some interaction between the components during the formation of the eutectic mixture. Moreover, the microstructure of the eutectic mixture at a molar ratio of 3 : 2 was more uniform than others, which was proved by DFT calculations. The Jackson’s roughness parameter was found to be greater than 2, suggesting a faceted, irregular morphology. These results could pave a way for further investigation of the energetic eutectic system aiming to supersede TNT.

Extractants selection for hyphenated electrothermal atomic absorption method

Abstract The theoretical approach for extractants selection during hyphenated atomic absorption determination of highly volatile metals (Pb, Cd), hydride- (Sb, Bi) and carbide-forming (Cr) metals using thermodynamic modelling was proposed. The calculated parameter — maximum pyrolysis temperature — can be used for selection of the extractants and chemical modifiers. Using this approach the antimony extract with Brilliant green was modified for which the 1.8-fold sensitivity and 2.6-fold repeatability decreasing while extract sampling in graphite furnace was observed. A chemical modifier — mixture of hydrazine nitrate with the palladium(II) complex with Xylenol orange — was theoretically selected and experimentally tested, which allowed to enhance the maximum pyrolysis temperature on 200°C, to eliminate extract matrix influence. Using this modifier two-fold increasing in sensitivity and 3-fold decreasing in relative standard deviation was achieved while extraction atomic absorption determination.

Reduction of uranium (VI to IV) by hydrogenation using Adams’ catalyst

Plutonium uranium reduction extraction using U(IV) as universal reductant for Pu partitioning is the only technology practiced internationally to recover U and Pu from spent nuclear fuels. Uranous requirement of Indian reprocessing plants is met by the electrolytic reduction of uranyl nitrate with 50–60% conversion. Though the current requirement can be met with this method, it increases the load on uranium purification cycle. In addition, it is a batch process with slow kinetics. In order to achieve higher conversion of uranyl nitrate to uranous nitrate, catalytic reduction method using hydrogen in presence of Adams’ catalyst (PtO2) was tried. Parametric studies have been performed in an autoclave to evaluate the effect of U(VI) concentration, the role of hydrazine nitrate and pressure. It is observed that kinetics is improved at higher pressures. The studies revealed that near total conversion of uranium from (VI to IV) can be achieved by the catalytic reduction route.

Low Temperature Synthesis of N-Doped TiO<SUB>2</SUB> Nanocatalysts for Photodegradation of Methyl Orange

N-doped TiO2 nanoparticles were synthesized using a hydrazine-assisted liquid method at low temperatures, owing to the additional heat provided by the decomposition of hydrazine nitrate, which was formed by reaction of hydrazine with nitric acid. Different crystal phases of N-doped TiO2 were studied by varying the nitric acid concentration, and calcination temperature and time. These photocatalysts were characterized using a transmission electron microscope, UV-vis photometer, X-ray diffractometer, and nitrogen adsorption. Photocatalytic performance of the N-doped TiO2 was studied by testing the degradation of methyl orange under visible irradiation. It was observed that N-doped TiO2 demonstrated much higher photocatalytic performance than commercial TiO2 (P-25) and exhibited excellent reusability.

Reduction of uranyl nitrate ions in a continuous flow electrochemical reactor

In a contemporary salt-free flowsheet of nuclear fuel reprocessing, uranous ions are used as a reducing agent to accomplish the separation of uranium and plutonium from each other which is normally produced electrochemically. In the present study, continuous mode electrochemical reduction of uranyl ions in nitric acid medium and in the presence of hydrazine nitrate was carried out in a divided cell at three different feed flow rates and cathodic current densities for the purpose of optimizing the process conditions for better conversion efficiency. A correlation function is described as a mathematical model in which, mass transfer parameter is expressed as a function of current density and flow rate. From the multivariable nonlinear regression of the experimental data, rate parameter was determined. The electro reduction of uranyl ions was not influenced by the initial acidity. The maximum conversion rate of 87 % was obtained for the electro-reduction of 100 g/l U(VI) in 3 M nitric acid with feed flow rate as 0.3 l/h and current density as 15 mA/cm2. The results for the reduction of 100 g/l uranyl ions indicate that an optimum flow rate of about 0.5 l/h and 15 mA/cm2 as cathodic current density may suffice for the conversion with efficiency better than 60 %. The calculated steady state concentrations for U(IV) were found to be in good agreement with the experimental results.

Electrochemical oxidation of oxalic acid and hydrazinium nitrate on platinum in nitric acid media

Several studies in the literature have investigated the electrochemical effects of oxalic acid and hydrazine on various materials in neutral (pH buffered to 7), basic or weakly acidic media (pH 6). The present work proposes electrochemical techniques that allow for the study of the electrochemical behavior, on a Pt electrode, of oxalic acid and hydrazinium nitrate to better understand their oxidation mechanisms in a nitric acid medium at a pH below 1; in addition, some experiments were carried out to define an electrochemical method that would allow for the simultaneous detection of these species when present within process effluent in very acidic solutions. Some physical data regarding oxalic acid and hydrazinium nitrate were also determined: anodic oxidation of hydrazinium nitrate and oxalic acid were observed at 0.2V and 0.7V (vs. Ag/AgCl), respectively. The diffusion coefficients of hydrazinium nitrate and oxalic acid were found to be 5.2×10−6 and 2.9×10−7cm2s−1, respectively. An experimental design approach demonstrated the influence of nitric acid concentrations on the diffusion coefficients of these species.

Validation of the flow-sheet proposed for reprocessing of AHWR spent fuel: counter-current studies using TBP

ABSTRACT A solvent extraction based flow-sheet, for reprocessing of spent fuel arising from Advanced Heavy Water Reactor (AHWR) for separation of uranium, plutonium and thorium using 5% TBP in n-dodecane, has been tested using laboratory scale mixer-settlers. Simulated feed solution containing thorium, uranium and plutonium in the concentration levels expected in feed solutions of AHWR spent fuel reprocessing is prepared using plutonium, natural uranium and thorium nitrate. Quantitative extraction of uranium and plutonium is achieved under experimental conditions leaving bulk of thorium in the raffinate. Co-extracted thorium from the organic phase is scrubbed using 3.00 M HNO3. Separation of plutonium from uranium is achieved by chemical reduction employing a mixture of hydroxylamine nitrate and hydrazine nitrate in nitric acid. Results show quantitative partitioning. Uranium from the plutonium lean organic phase is stripped using 0.01 M HNO3. The results clearly established the validity of the proposed f...

Studies on testing and evaluation of platinum plated titanium electrode for production of uranous nitrate

Partitioning of plutonium from uranium is an important step in the reprocessing of spent fuel by PUREX process of solvent extraction using 30% TBP-dodecane. This is achieved by selectively reducing the Pu in solution to least extractable trivalent state by uranous nitrate as the reductant. The latter is conventionally produced by electrolytic reduction of uranyl ion in presence of hydrazine nitrate as uranous nitrate stabilizer using Pt-coated titanium as the anode. The anode plating wears out after period of operation thus affecting the process efficiency and hence the quality control testing of platinum plated electrode becomes important. This article describes the use of Beta backscattering method with strontium-90 radioisotope as non-destructive testing tool for measuring the coating thickness of the sample Ti electrode. The surface characteristics and coating morphology were also examined by scanning electron microscope and the micrographs are presented.