CsNO3 Research Articles

Solubility of CsNO 3 in binary solvents formed by ethanol and water in the temperature range between 278.15 and 313.15 K

The solubility of cesium nitrate in binary solvents formed by ethanol and water was determined in the temperature range between 278.15 K and 313.15 K at atmospheric pressure using an isothermal method. The reliability of the measured method used in this study was checked by comparing the experimental data with published data in the literature for the CsNO 3–water system, and the method proved to be accurate. Experimental solubility data were correlated with Sechenov's equation.

Distillation Separation of Hydrofluoric Acid and Nitric Acid from Acid Waste Using the Salt Effect on Vapor–Liquid Equilibrium

This study presents the distillation separation of hydrofluoric acid with use of the salt effect on the vapor–liquid equilibrium for acid aqueous solutions and acid mixtures. The vapor–liquid equilibrium of hydrofluoric acid + salt systems (fluorite, potassium nitrate, cesium nitrate) was measured using an apparatus made of perfluoro alkylvinylether. Cesium nitrate showed a salting-out effect on the vapor–liquid equilibrium of the hydrofluoric acid–water system. Fluorite and potassium nitrate showed a salting-in effect on the hydrofluoric acid–water system. Separation of hydrofluoric acid from an acid mixture containing nitric acid and hydrofluoric acid was tested by the simple distillation treatment using the salt effect of cesium nitrate (45 mass%). An acid mixture of nitric acid (5.0 mol · dm−3) and hydrofluoric acid (5.0 mol · dm−3) was prepared as a sample solution for distillation tests. The concentration of nitric acid in the first distillate decreased from 5.0 mol · dm−3 to 1.13 mol · dm−3, and the concentration of hydrofluoric acid increased to 5.41 mol · dm−3. This first distillate was further distilled without the addition of salt. The concentrations of hydrofluoric acid and nitric acid in the second distillate were 7.21 mol · dm−3 and 0.46 mol · dm−3, respectively. It was thus found that the salt effect on vapor–liquid equilibrium of acid mixtures was effective for the recycling of acids from acid mixture wastes.

Synthesis, crystal structure and thermal decomposition of a novel environmentally friendly energetic cesium compound, [Cs2(HTNR)(OH)(H2O)

A novel energetic cesium compound based on trinitroresorein, (Cs2(HTNR)(OH)(H2O))n (H2TNR: 2,4,6- trinitroresorcinol) has been synthesized by the reaction of cesium nitrate and styphnic acid. The molecular structure was characterized by using X-ray diffraction analysis, elemental analysis and FT-IR analysis. The crystalline material is mon- oclinic with space group P2(1)/c and the empirical formula is Cs2C6H5N3O10. The unit cell parameters are: a = 6.843(1) u

Switching Kinetics in Cesium Nitrate: Poly (Vinyl Alcohol) Composite Film

The effect of pulse amplitude on the switching properties of cesium nitrate: poly (vinyl alcohol) composite film at room temperature has been studied. The switching response of the composite film was studied using the bipolar square pulses. The switching current transients were analyzed using finite grain model (FGM) and infinite grain media (IGM). The Matlab programming based upon the assumptions of FGM and IGM theories is used to fit the experimental data with the theoretical. The microscopic parameters such as effective dimensionality, switching time, nucleation rate, and domain wall velocity have been estimated. The polarization current and domain wall velocity exhibited exponential dependence on the pulse amplitude.

Combustion of diesel soot in NO/O2 presence. Cesium nitrate and gold catalysts

The diesel soot combustion was studied using catalysts prepared by impregnation with cesium nitrate and/or gold on zirconium oxide (ZrO2), hydrated zirconium oxide and silica (SiO2). Catalysts were characterized by colorimetry, elemental analysis, atomic absorption spectrophotometry, XRD, FTIR, TPR and XPS. Measurements of catalytic activity were performed in a thermobalance with air and in a fixed bed reactor with a NO/O2 feed. All catalysts containing cesium nitrate exhibit a good activity for soot oxidation and the addition of gold substantially increases the CO2 generation leading the selectivity to 100% in CO2.

Study of properties of combustion products of advanced solid plasma-generating propellant for pulsed MHD generators

1. In the national pulse MHD generators with power from 10 to 600 MW, solid plasmagenerating propellants (SPPs) are used, which contain dibasic ballistite powders with an aluminum content of up to 21% (in mass) and an easily ionized seed like cesium or potassium nitrates (1-3). New SPPs should have increased values of the energy complex σv 2 (σ is the electrical conductivity, and v is the velocity) and the heat content of combustion products, which depends on their heat capacitance at constant pressure and the calorific power of the fuel. The value of the complex σv 2 depends mainly on temperature, while the heat capacitance is related to the combustionproduct composition and their degree of dissociation, which depends on the oxidizer excess factor α. The prelimi� nary study of new SPP compositions shows the possi� bility of a substantial increase in both the complex σv 2 and the coefficient α.

Preparation of TiO<sub>2</sub> Nanoparticles Doped with Cs<sup>+</sup> and Sr<sup>2+</sup> and Their Photocatalytic Activity under Solar Light

Using cesium nitrate and strontium nitrate as doping metal ions source, Cs-doped TiO2 and Sr-doped TiO2 photocatalysts were successfully synthesized through the hydrolysis of tetrabutyl titanate by an acid-catalyzed sol-gel method. The photocatalytic activities of these catalysts prepared at 600 °C for 2 h were evaluated by the degradation of methyl orange in aqueous solution under solar light irradiation, and the as-prepared samples with higher photocatalytic efficiency were characterized by means of X-ray diffraction (XRD) and UV-Vis absorption spectroscopy. The XRD patterns indicate that the crystal structure still remains as anatase phase for the doped samples, and the average crystal size of TiO2, 0.1 at% Cs-doped TiO2 and 0.3 at% Sr-doped TiO2 is 21.3, 13.1 and 10.8 nm, respectively. The band gap absorption shows red shift to the visible region for the doped samples from the UV-Vis spectrogram. The results show that the photocatalytic activity of TiO2 nanoparticles doped with Cs+ and Sr2+ exhibits a significant improvement and their degradation efficiencies are more than 30% in comparison with those of TiO2 under the same condition, and the optimal doping concentration is determined to be 0.1 at% and 0.3 at% for Cs+ and Sr2+, respectively.

Polarization switching properties of spray deposited CsNO3: PVA composite films

The ferroelectric and switching properties of spray deposited cesium nitrate: poly (vinyl alcohol) composite films at different substrate temperatures (Ts) have been studied. The optimum value of remanent polarization was obtained in the film deposited at Ts=200°C, which may be due to larger structural distortion (c/a ratio) and less porosity as revealed by x-ray diffraction and field emission scanning electron microscope (FESEM) analysis. The switching current transients have been analyzed by nucleation limited switching model (NLS) with the Lorentzian distribution function. This model gives excellent agreement with the experimental polarization current throughout the whole time range. The switching parameters were determined in the composite films deposited at different Ts and found to be optimum at Ts=200°C. The effect of pulse amplitude on the domain switching properties has also been studied and analyzed. The peak value of polarization current exhibits an exponential dependence on the external applied field.

Study of ferroelectric properties of spray pyrolysis deposited cesium nitrate films

Cesium nitrate (CsNO 3) films were prepared by ultrasonic spray pyrolysis technique at different substrate temperatures ( T s) and their ferroelectric and switching properties were examined. The morphology of the deposited films was studied using FESEM. The ferroelectric properties were optimized based on remanent polarization as a function of substrate temperature. The switching response was studied using pulse width technique. The switching parameters such as effective dimensionality, switching time, and nucleation rate were extracted using finite grain model (FGM). The width of reading pulse shows significant effect on switching transients.

A benzocrown-6-calix[4]arene methacrylate copolymer: Selective extraction of caesium ions from a multi-component system

The synthesis and extraction properties of a copolymer comprised of a 10:1 molar ratio of methyl methacrylate (MMA) and a methacrylate functionalized benzocrown-6-calix[4]arene are reported. Under aqueous-dichloromethane liquid–liquid extraction conditions, the copolymer displayed an enhanced selectivity for caesium over sodium and potassium (in the form of their picrate salts) as compared to an appropriate small molecule analogue. Further, the copolymer was capable of removing caesium nitrate from aqueous solution in the presence of various other anionic (e.g., F−, Cl−, and SO4−) and cationic species (e.g., K+ and Na+). The ability of this polymeric system to extract inorganic caesium salts into dichloromethane from aqueous media scaled with the relative hydration energies (ΔhydG°) of each anion studied (i.e., NO3− > Br− ≫ Cl− or F−).

Topological transformation of the cesium nitrate-water-isopropanol ternary phase diagram

Phase equilibria and critical phenomena in the cesium nitrate-water-isopropanol system, where the liquid binary subsystem does not separate over the entire temperature range of its liquid state, were studied within 70–120°C using visual polythermal analysis. The temperature at which the monotectic critical tie-line appears (79.0°C) and the compositions of the solutions at critical solution points at various temperatures were determined. Isopropanol distribution coefficients between aqueous and organic monotectic phases were calculated for five temperatures. The salting out of isopropanol by cesium nitrate from aqueous solutions is enhanced by temperature elevation. The phase isotherms validated a previously reported fragment of the general scheme of the topological transformation of ternary phase diagrams for salt-binary solvent systems with salting out.

Ferroelectric and phase transition studies in cesium nitrate: poly(vinyl alcohol) composite films

The composite films of cesium nitrate (CsNO3) and poly(vinyl alcohol) (PVA) with varying composition were prepared using the solvent cast method. The hysteresis loop characteristics show optimum remnant polarization (P r ) of 2.75 μC/cm2 at 50 wt.% composition. The field emission scanning electron microscope images show a nearly homogeneous distribution of CsNO3 grains in the 50 wt.% composite film. The temperature dependence of the remnant polarization shows a diffused transition temperature range from the ferroelectric to the paraelectric phase and this has been attributed to the reduced enthalpy. The butterfly features of the dielectric constant–voltage (e–V) characteristics have been attributed to polarization switching.

Geopolymerisation kinetics. 3. Effects of Cs and Sr salts

Alternating current impedance spectroscopy (ACIS) is used to monitor in situ the kinetics of geopolymer formation by alkali silicate activation of metakaolin at 40 °C. The evolution of conductivity and resistivity as a function of time are found to correlate very well with existing models of geopolymerisation kinetics. The dissolution of metakaolin gives a rapid increase in conductivity, with a subsequent decrease due to gelation and gel ageing. After a period of curing, the resistivity of the gel network is seen to be a sensitive probe of the development of a well-formed gel structure. This enables investigation of the changes in geopolymer formation kinetics and gel structure caused by addition of various salts of interest in nuclear waste management, in particular the nitrate, sulphate and hydroxide salts of caesium and strontium. Each of the six salts studied is shown to have specific effects on the kinetics of geopolymer formation and the pore structure of the final geopolymer gel. Caesium nitrate and caesium sulphate have very similar effects, with a slight retardation of gelation followed by significant disruption of gel structure while caesium hydroxide accelerates gel formation markedly. Strontium nitrate at high concentrations interferes significantly with the pore network development, while strontium sulphate is converted gradually to carbonate salts by atmospheric carbonation.

Analysis of cesium extracting solvent using GCMS and HPLC

A high-level waste (HLW) remediation process scheduled to begin in 2007 at the Savannah River Site is the Modular Caustic Side Solvent Extraction (CSSX) Unit (MCU). The MCU will use a hydrocarbon solvent (diluent) containing a cesium extractant, a calix[4]arene compound, to extract radioactive cesium from caustic HLW. The resulting decontaminated HLW waste or raffinate will be processed into grout at the Saltstone Production Facility (SPF). The cesium containing CSSX stream will undergo washing with dilute nitric acid followed by stripping of the cesium nitrate into a very dilute nitric acid or the strip effluent stream and the CSSX solvent will be recycled. The Defense Waste Processing Facility (DWPF) will receive the strip effluent stream and immobilize the cesium into borosilicate glass. Excess CSSX solvent carryover from the MCU creates a potential flammability problem during DWPF processing. Bench-scale DWPF process testing was performed with simulated waste to determine the fate of the CSSX solvent components. A simple high performance liquid chromatography (HPLC) method was developed to identify the modifier (which is used to increase Cs extraction and extractant solubility) and extractant within the DWPF process. The diluent and triocytlamine (which is used to suppress impurity effect and ion-pair disassociation) were determined using gas chromatography mass spectroscopy (GCMS). To close the organic balance, two types of sample preparation methods were needed. One involved extracting aqueous samples with methylene chloride or hexane, and the second was capturing the off gas of the DWPF process using carbon tubes and rinsing the tubes with carbon disulfide for analysis. This paper addresses the development of the analytical methods and the bench-scale simulated waste study results.

Synthesis, Thermal Decomposition and Sensitivity Study of CsDNBF

AbstractCsDNBF (cesium 7‐hydroxy‐4,6‐dinitro‐5,7‐dihydrobenzofuroxanide) was synthesized from the sodium salt of DNBF and cesium nitrate. The thermal decomposition process has been investigated and the results show that the solid residues at 240 °C are RCOOCs, CsNCO, RNO2 and CsNO3. The sensitivity results demonstrate that CsDNBF has better properties than KDNBF, which has been widely used.

Neutron Diffraction and Simulation Studies of CsNO3 and Cs2CO3 Solutions

Neutron diffraction with isotopic substitution (NDIS) experiments and molecular dynamics (MD) simulations have been used to study the structuring in aqueous solution of two cesium salts, cesium carbonate, and cesium nitrate. As was previously found for guanidinium salts of carbonate, mesoscopic-scale clusters were seen to form in the Cs2CO3 solution both in the MD simulations and in the diffraction experiments. No such large scale ion clusters were found in the CsNO3 solutions in either the modeling or experiments. The results are dominated by the strength and geometry of the direct first-neighbor interactions, which explain the differences in the clustering behavior between the two solutions without need to refer to longer-range water-water structuring.

Confining caesium in expanded natural Perlite

We present the potential use of expanded perlite, a metastable amorphous hydrated aluminum silicate, as a permanent medium for the long-term confinement of caesium. A simple loading by mixing an aqueous caesium nitrate solution and expanded perlite at 300 K followed by thermal annealing leads to 96% sintering. The formation of pollucite, CsAlSi 2O 6, a naturally occurring mineral phase, appears as the crystalline phase embedded in a glassy phase. Leaching tests on the resulting glass-ceramics reveal a very low Cs departure of 0.5 mg m −2 day −1. This simple method seems to be a good way to permanently confine caesium issued from recycled nuclear waste.

Enhancement of DC ionic conductivity in dispersed solid electrolyte system—CsNO 3:γ-Al 2O 3

This paper reports the effect of heterogeneously doped alumina (γ-Al 2O 3) on the ionic conductivity of cesium nitrate (CsNO 3). Enhancement of conductivity is noticed to increase with mole percent (m/o) of the dispersoid. The maximum enhancement observed is about three orders of magnitude with respect to the host material. The experimental data indicating higher conductivity in dispersed system is interpreted in terms of the formation of space charge layer between the host material and dispersoid. The DSC results indicate that the addition of alumina to CsNO 3 leads to new phase boundaries at about 260 °C for the dispersed systems.

Tungsten bronze-based nuclear waste form ceramics. Part 3: The system Cs 0.3M xW 1− xO 3 for the immobilization of radio cesium

Previous studies in this series have indicated that Cs- and Sr-loaded Mo-doped hexagonal tungsten bronze (MoW-HTB) oxides, either in the form of fine grained powders, or as composite granules, can be converted to leach resistant ceramics at modest temperatures in the range 600–1200 °C. In the present study it has been shown that such waste form ceramics can also be readily prepared through very simple conventional routes involving the blending of cesium nitrate with tungstic acid and other oxide components followed by heating in air. The phase chemistry resulting from the blending of these oxides has been explored. In the Cs 0.3M x W 1− x O 3 compositional system where x = Ti, Zr, Nb and Ta the solid solution limit has been found to be where x = 0.2. For all values of x between 0 and 0.2 mixed phase materials of HTB and WO 3 were obtained and Cs was found associated with HTB phases that are both rich and depleted in M element. At temperatures above about 1000 °C, phase pure HTB compounds in the space group P63/ mcm were obtained. Even when x greatly exceeds 0.2, the additional oxide content did not interfere with the formation of the HTB phase. Durability of the Cs 0.3M x W 1− x O 3 compositions as gauged by the fractional Cs loss in de-mineralized water was lowest when M = Ti and Nb, and greatest when M = Zr. From these results the durability appears intimately linked with the unit cell a-dimension which in turn varies with M cation radius.

Bonding energetics in clusters formed by cesium salts: a study by collision‐induced dissociation and density functional theory

In relation to the interaction between (137)Cs and soil organic matter, electrospray mass spectrometry experiments and density functional theory (DFT) calculations were carried out on the dissociation of positively charged adducts formed by cesium nitrate and cesium organic salts attached to a cesium cation [Cs(CsNO(3))(CsA)](+) (A = benzoate, salicylate, hydrogen phthalate, hydrogen maleate, hydrogen fumarate, hydrogen oxalate, and hydrogen malonate ion). These mixed clusters were generated by electrospray from methanol solutions containing cesium nitrate and an organic acid. Collision-induced dissociation of [Cs(CsNO(3))(CsA)](+) in a quadrupole ion trap gave [Cs(CsNO(3))](+) and [Cs(CsA)](+) as major product ions. Loss of HNO(3) was observed, and also CO(2) loss in the case of A = hydrogen malonate. Branching ratios for the dissociation into [Cs(CsNO(3))](+) and [Cs(CsA)](+) were treated by the Cooks' kinetic method to obtain a quantitative order of bonding energetics (enthalpies and Gibbs free energies) between Cs(+) and the molecular salt (ion pair) CsA, and were correlated with the corresponding values calculated using DFT. The kinetic method leads to relative scales of Cs(+) affinities and basicities that are consistent with the DFT-calculated values. This study brings new data on the strong interaction between the cesium cation and molecular salts CsA.