White Fuming Research Articles

Bicyclic ammonium ionic liquids as dense hypergolic fuels

1-Aza-bicyclo[2.2.2]octane/1,4-diazabicyclo[2.2.2]octane-based dicyanamide possesses higher densities (1.06–1.31 cm−3) than the corresponding pyrrolidinium and imidazolium-based isomers, besides hypergolicity with white fuming nitric acid.

Hypergolic fuels based on water-stable borohydride cluster anions with ultralow ignition delay times

A series of [B12H12]2−, [B10H10]2− and [B6H7]− salts were prepared with excellent hydrolytic and thermal stabilities (Td > 200 °C), especially ultra-fast ignition delay times (as low as 1 ms) upon contact with white fuming nitric acid or N2O4, which is a superior ignition performance.

Cyanotetrazolylborohydride (CTB) anion-based ionic liquids with low viscosity and high energy capacity as ultrafast-igniting hypergolic fuels.

A series of hypergolic cyanotetrazolylborohydride (CTB) anion-based ionic liquids have been synthesized by a straightforward N-hydroboration of tetrazole followed by a salt metathesis reaction, which exhibited remarkably low viscosity (<20 mPa s), high density (often >1.1 g cm-3), and ultra-short ignition delay time (as short as 1.4 ms) upon contact with white fuming nitric acid (WFNA).

Synthesis and testing of hypergolic ionic liquids for chemical propulsion

Synthesis of new highly energetic ionic liquids (ILs) is described, and their hypergolic ignition properties are tested. The synthesized ILs combine the advantages of conventional rocket propellants with the energy characteristics of acetylene derivatives. To this end, N-alkylated imidazoles (alkyl = ethyl, butyl) have been synthesized and alkylated with propargyl bromide. The desired ionic liquids have been produced by metathesis using Ag dicyanamide. Modified hypergolic drop tests with white fuming nitric acid have been performed for N-ethyl (IL-1) and N-butyl propargylimidazolium (IL-2) ionic liquids. In the modified drop tests, high-speed shadowgraph imaging is used to visualize the process, and the temperature rise due to ignition is monitored with a two-color photodetector. It is shown that the ignition delay is shorter for IL-1 as compared to IL-2. The ignition of IL-1 occurs in two stages, whereas the combustion of IL-2 proceeds smoothly without secondary flashes.

Hypergolic ignition by head-on collision of N,N,N′,N′−tetramethylethylenediamine and white fuming nitric acid droplets

Hypergolic ignition by the head-on collision of a smaller N,N,N′,N′−tetramethylethylenediamine (TMEDA) droplet and a larger white fuming nitric acid (WFNA) droplet was experimentally investigated by using a droplet collision experimental apparatus equipped with a time-resolved shadowgraph, a photodetector and an infrared detector. The investigation was focused on understanding the influence of droplet collision and mixing, which vary with the collisional Weber number (We = 20−220) and the droplet size ratio (Δ = 1.2−2.9) while have a fixed Ohnesorge number (Oh = 2.5×10−3), on the hypergolic ignitability and the ignition delay times. The hypergolic ignition was found to critically rely on the heat release from of the liquid-phase reaction of TMEDA and nitric acid, which is subsequent to and enhanced by the effective mixing of the droplets of proper size ratios. Consequently, the ignitability regime nomogram in the We-Δ space shows that the hypergolic ignition favors small Δs and large Wes; the ignition delay times tend to decrease with either decreasing Δ, or increasing We, or both. A non-monotonic variation of the ignition delay times with We was observed and attributed to the non-monotonic emergence of jet-like mixing patterns that enhance the droplet mixing and hence the liquid-phase reaction.

Ab Initio Investigation of Cation Proton Affinity and Proton Transfer Energy for Energetic Ionic Liquids.

Protonation of the anion in an ionic liquid plays a key role in the hypergolic reaction between ionic liquids and oxidizers such as white fuming nitric acid. To investigate the influence of the cation on the protonation reaction, the deprotonation energy of a set of cations has been calculated at the MP2 level of theory. Specifically, guanidinium, dimethyltriazanium, triethylamine, N-ethyl-N-methyl-pyrrolidinium, N-ethyl-pyridinium, 1,4-dimethyl-1,2,4-triazolium, 1-ethyl-4-methyl-1,2,4-triazolium, and 1-butyl-4-methyl-1,2,4-triazolium were studied. In addition, the net proton transfer energies from the cations to a set of previously studied anions was calculated, demonstrating an inverse correlation between the net proton transfer energy and the likelihood that the cation/anion combination will react hypergolically with white fuming nitric acid. It is suggested that this correlation occurs due to a balance between the energy released by the proton transfer and the rate of proton transfer as determined by the ionicity of the ionic liquid.

Towards Safer Rocket Fuels: Hypergolic Imidazolylidene‐Borane Compounds as Replacements for Hydrazine Derivatives

Currently, toxic and volatile hydrazine derivatives are still the main fuel choices for liquid bipropellants, especially in some traditional rocket propulsion systems. Therefore, the search for safer hypergolic fuels as replacements for hydrazine derivatives has been one of the most challenging tasks. In this study, six imidazolylidene-borane compounds with zwitterionic structure have been synthesized and characterized, and their hypergolic reactivity has been studied. As expected, these compounds exhibited fast spontaneous combustion upon contact with white fuming nitric acid (WFNA). Among them, compound 5 showed excellent integrated properties including wide liquid operating range (-70-160 °C), superior loading density (0.99 g cm(-3) ), ultrafast ignition delay times with WFNA (15 ms), and high specific impulse (303.5 s), suggesting promising application potential as safer hypergolic fuels in liquid bipropellant formulations.

Assessing the Bioaccumulative Impact of Four Heavy Metals on the Endocrine System of Tilapia rendalli Fish Species in the Kafue River

The term, “heavy metals” (HMs) refers to a group of metals with atomic density greater than 4g/cm3. HM contamination is a major environmental problem worldwide today, especially in growing cities of developing countries mainly due to pollution. High levels of HMs can cause health problems in an organism, despite their various uses. Their biotoxic effects come into play once accumulation levels in organisms go beyond maximum permissible limits. Thus, this study aimed at assessing the bioaccumulative impact of cadmium (Cd), copper (Cu), nickel (Ni) and Lead (Pb) on the endocrine system of Tilapia rendalli fish in Kafue River. Water samples were collected in 2 x 500 mL polypropylene bottles, refrigerated at about 8 oC, then put at room temperature before filtering for analysis. Tissues (blood, gills, liver and muscle) were extracted per fish from 93 samples collected from upper, middle and lower sites of the river; KUP, ITT and SH respectively. Gills, livers and muscles were cleaned in distilled water, oven dried at 110 oC, weighed and transferred into digestion flasks. 10 mL of 55 % nitric acid and 5 mL of 70 % perchloric acid (ANALAR) were added into digestion flasks. Samples were digested at about 200 – 250 oC on a hot plate to a transparent solution after disappearance of initial brown fumes. White fumes indicated completion of digestion. Solutions were cooled and diluted to 20 mL using distilled water. The samples were assayed for Cd, Cu, Ni and Pb using Flame Atomic Absorption Spectrophotometric method (FAAS), Varian AAS 220 instrument. Blood samples were thawed at room temperature, centrifuged at 2016 x g (3000 rpm) for 10 minutes to collect supernatant serum. Serum was assayed for Estradiol (E2) and Testosterone (T) using the ELISA method and concentrations of unknowns determined from standard curves by interpolation using Graphpad prism 6.01. Hormone levels varied significantly among the fish samples. This difference was significantly related to variations in HM levels in fish tissues from the respective study sites. Highest mean levels of T (13.58±2.8 ng/mL) and E2 (774.33±66.98 pg/mL) were measured in SH while lowest mean levels of T (5.78±0.69 ng/mL) and E2 (63.75±45.39 pg/mL) were measured in ITT. The study further showed that low levels of Cd, Cu, and Ni in SH correlated significantly to high hormone levels recorded in fish at SH while high levels of Cu in livers and muscles, 496.73 ±184.96 mg/kg and 43.68±18.32 mg/kg respectively; recorded in ITT correlated negatively to low hormone levels in fish. Study also observed a positive correlation between hormone levels and Pb concentrations in tissues, indicating biphasic mechanisms of Pb and other metals on E2 and T levels in fish. Therefore, HM bioaccumulation affects expression levels of sex hormones in fish and this may be extrapolated to humans who are major consumers of fish along trophic levels. Since HM levels were high in internal organs than in muscle (flesh), high public awareness should be emphasized on the risk benefit of consuming fish with…

Effect of alkali metal salts on decomposition of ionic liquid like organic salt

N1,N1,N2,N2-tetramethylethane-1,2-diamine-based ionic salts (TMEDA), N1,N1,N1,N2,N2,N2-hexamethylethane-1,2-diaminium dicyanamide (HMEDA-(DCA)2) were prepared following the quaternization and subsequent ion exchange. The chemical structure of the HMEDA-(DCA)2 was confirmed using 13C NMR spectrum and elemental analysis. The corresponding viscosity of its 60 wt% solution was found to be lower than 5 cP at room temperature, which was critical for propellant application. The ignition delay of 40 wt% HMEDA-(DCA)2 solution was decreased to 20–30 ms dramatically using alkali metal salts, Li(CH3COO), Mg(CH3COO)2, and Ca(CH3COO)2 as a co-catalyst when white fume nitric acid was utilized as an oxidizer.

Recovery of Antimony Trioxide Flame Retardants from Lead Refining Residues by Slag Conditioning and Fuming

AbstractBottom‐up process design is performed for a new antimony white fuming approach from antimony‐rich lead refining residues. Thermochemical modelling is used to evaluate process boundaries regarding temperature and slag composition allowing the fuming of qualified antimony white from mentioned residues. Two methods are evaluated in laboratory scale to test possibilities of preconditioning for the fuming process. The first one is based on a more selective oxidation during lead softening; the second one on carbothermic reduction of the slag. Antimony enrichment is successfully proven under laboratory scale conditions.

Characterization of Ethylenediamine Bisborane as a Hypergolic Hybrid Rocket Fuel Additive

A boron-based catalytic and energetic fuel additive is explored as a mechanism to enhance performance of hybrid motors using nitric-acid-based oxidizers. Ethylenediamine bisborane is highly hypergolic with nitric acid, thereby eliminating the need for a separate ignition system and providing the potential for restart. Ignition delays of for ethylenediamine bisborane powder and for ethylenediamine bisborane/hydroxyl-terminated polybutadiene combinations have been measured using white fuming nitric acid as the oxidizer. Theoretical specific impulse values higher than any other nitric-acid-based hypergolic hybrid combination tested are obtained; in addition, ethylenediamine bisborane is air stable and not toxic. Also presented is a method of manufacturing large quantities of high-purity ethylenediamine bisborane.

Amine-boranes: green hypergolic fuels with consistently low ignition delays.

Complexation of amines with borane converts them to hypergols or decreases their ignition delays (IDs) multifold (with white fuming nitric acid as the oxidant). With consistently low IDs, amine-boranes represent a class of compounds that can be promising alternatives to toxic hydrazine and its derivatives as propellants. A structure-hypergolicity relationship study reveals the necessary features for the low ID.

Synthesis and characterization of energetic salts based on the new propan-2-ylidene methanetriamium cations

Development of new hypergolic ionic liquids is the key in replacing toxic N,N-dimethylhydrazine as green liquids propellants. Three salts based on the new propan-2-ylidene methanetriamium cations and dicyanamide anion were synthesized and characterized by 1H and 13C NMR, IR and Raman spectroscopy, elemental analysis, and TG/DTA. In addition, their crystal structures were determined by X-ray single crystal diffraction. N-(propan-2-ylidene) methanetriamium dicyanamide (1) crystallizes in the monoclinic space group P21/n, N,N′-bi(propan-2-ylidene) methanetriamium dicyanamide (2) in triclinic P−1, and N,N′,N″-tri(propan-2-ylidene) methanetriamium dicyanamide (3) in monoclinic C2/c. With heats of formation (from 1.56 to 1.80kJg−1) and densities (from 1.19 to 1.31gcm−3) in hand, the detonation pressure (P) and velocity (D), and specific impulse (Isp) values of salts were calculated as 8.94GPa, 4989ms−1 and 174.3s (1), 7.91GPa, 4815ms−1 and 179.0s (2), and 7.33GPa, 4693ms−1 and 180.6s (3), respectively. Impact sensitivities of 1, 2 and 3 were measured to be no less than 40J by hammer tests, which places these salts in the insensitive class. Moreover, the resulting salts are hypergolic with white fuming nitric acid and exhibit potential as bipropellants.

Chemical kinetics interpretation of hypergolicity of dicyanamide ionic liquid-based systems

Ionic liquids are candidates for replacing hydrazine and hydrazine derivatives systems. A detailed chemical kinetics model has been built to examine the gas-phase chemistry between isocyanic acid (HNCO), white fuming nitric acid (WFNA), N2O, CO2, and water, especially at low temperatures (ambient to 423K). This kinetics model is able to explain the gas-phase ignition observed during hypergolic ignition of the ionic liquid 1-butyl-3-methyl-imidazolium dicyanamide (BMIM-dca) with WFNA. Sensitivity analyses have been performed to examine the reaction pathways for ignition. Ignition is predicted to occur via an exothermic reaction between isocyanic acid (HNCO) and nitric acid (HONO2), and subsequent HONO2 thermal decomposition that has NO2 and OH radicals as the primary chain carriers. A detailed understanding of the initiation processes in the liquid phase is needed, as the BMIM-dca and WFNA begin to react to produce the above preignition species for the proposed chemical kinetics model to describe the ignition behavior of the system.

Ionic liquid solubilized boranes as hypergolic fluids

Borane compounds which are hydrogen storage materials are hypergolic with white fuming nitric acid as oxidizer. When dissolved in ionic liquids, the borane solutions exhibit ignition delay times which are superior to any known hypergolic ionic liquids. These borane–ionic liquid solutions appear to be the brightest hope so far to replace hydrazine and its derivatives as fuels in hypergolic propellant systems.

Determination of traces of neptunium-237 in enriched uranium solutions using inductively coupled plasma mass spectrometry

A procedure using inductively coupled plasma mass spectrometry (ICP-MS) has been developed for determining traces of 237Np in isotopically enriched solutions of U. The chemical treatment of the samples consists of: extracting 237Np in a 1 mol dm–3 solutions of nitric acid using 0.5 mol dm–3 thenoyltrifluoroacetone in xylene, leaving 99% of the U matrix in the aqueous phase; re-extracting 237Np in 10 mol dm–3 nitric acid; heating the extracted solution to white fumes in order to remove the excess of acid; and diluting the resulting solution with 2% HNO3. Optimization of the analytical parameters involved suppressing the spectral overlap between 237Np and 238U. By applying an additive continuous tension to the quadrupole on m/z 237 only, the interfering part of the 238U peak is eliminated and good resolution can be achieved between m/z 237 and 238, if the concentration of U is less than 100 mg dm–3. The operating conditions adopted result from a compromise between resolution and sensitivity. The suppression of the analyte signal, arising from U at a high concentration, is corrected for by adding an internal standard to the calibration and measuring solutions. The detection limit is about 0.005 µg of Np per gram of U, for an initial sample of 1 g of U and an additive continuous tension of 7.5 V. The analytical performance of ICP-MS is compared with that of α-spectrometry. The radiochemical determination of 237Np involves a tedious pre-treatment and measurement procedure. In contrast, ICP-MS appears to be a good alternative to α-spectrometry (for the determination of long-lived radionuclides) because of its simplicity, accuracy, excellent detection limits and rapidity of analysis.

Studies on the synergistic hypergolic ignition of hybrid systems

A variety of solid organic compounds, such as Schiff bases, azines, hydrazones, thiocarbonohydrazones, thiosemicarbazones, and hydroxy compounds, on mixing with metal powders, especially with magnesium, become synergistically hypergolic with white fuming nitric acid (WFNA). In the absence of magnesium powder, these compounds are either nonhypergolic or have longer ignition delays, when WFNA is used as oxidizer. The synergistic ignition behavior has been explained in terms of increased exothermicity of the system, primarily due to the heat evolving chemical reactions occurring between the fuels (organic compound and magnesium) and the oxidizer in the preignition stage.

最近のアーク炉設備の動向

An electric arc furnace itself has made a few drastic developments and improvements for the past few years. However, eccentric bottom tapping used in different steel plants in Europe coupled with operational know-how has shown good results which has also been introduced into this country and same good results are expected.Electrode regulating system by VVVF (variable voltage variable frequecy) or hydraulic pressure type electrode controller with hydraulic pressure servovalve is in a practical use.Power consumption has been saved by 3 to 10 percent by computer control equipped with arc furnaces.Scrap preheater has been popular as energy saving facility. Recent trend is to adopt such a system to pass waste gas in series in order to have better efficiency of the scrap preheater.At present, as solution of white fume and bad odor water washing system and simple after burning type will be most practical.Superiority of DC arc furnace is to reduce electrode consumption DC power source which occupies the large portion of equipment investment cost is getting relatively low, thus inviting an attention of people who are interested in the facility.

Trace Metals Analysis in Petroleum Products by Atomic Absorption

To provide information for customers who have regional environmental obligations, it was necessary to develop an analytical procedure to analyze for 25 metals in the range from 1 ppb to greater than 5 ppm in petroleum products. Atomic absorption is employed to determine 23 of the elements, namely: Al, Sb, Ba, Be, Bi, Ca, Cd, Co, Cr, Cu, Fe, K, Pb, Mg, Mn, Mo, Ni, Na, Si, Sn, Ti, V, and Zn. The general procedure is to ash the appropriate amount of sample by absorbing liquid samples on magnesium sulfonate ash aid (Conostan, Conoash M) or potassium sulfonate. Add 5 drops of H2SO4, heat to white fumes, fire, and ash at 650°C. The sulfonated ash is dissolved in dilute acid to provide the aspiration solution. Recovery studies on aluminum, antimony, beryllium, cadmium, and lead in the microgram per gram range are presented.

炭素鋼および低合金鋼中のマンガンの状態分析

This work, a part of a general investigation on the state analysis of steel, was carried out to develop a systematic method for isolation and determination of manganese compounds in carbon steel and low alloy steel.1. Isolation of manganese compound from steel.(a) The steel sample covered with close-texture filter paper as a diaphragm is, as an anode, dissolved into 130 ml of 1% NaC1- 5% EDTA electrolyte (pH 6-7) at a current density of 50 mA/cm2 for 2 hr. Remove the anode and the residue is collected into a beaker using methanol.(b) To the residue add 50 ml of 2% EDTA solution (pH5-6) and shake for 30 min. Filter and wash with water. To the filterate add 10 ml of HNO3 and 10 ml of HCIO4, and evaporate to dense white fumes. Determine Mn as carbide in accordance with section 2.(c) Transfer a part of the electrolyte to a beaker. Add 15 ml of HNO3 and 10 ml of HCIO4 and evaporate to dense white fumes. Determine Mn as solid solution in accordance with section 2.(d) Transfer the paper and residue (paragraph (b)) to a beaker, add 30 ml of 2% EDTA solution and 20 ml of 5% H202 and shake for 60 min. Filter and wash with water. To the filterate add 10 ml of HNO3 and 10 ml of HCIO4 and evaporate to dense white fumes. Determine Mn as sulfide in accordance with section 2.(e) Transfer the paper and residue (paragraph (d)) to a beaker, add 30 ml of HNO3 and 10 ml of HC104 and evaporate to dense white fumes. Determine Mn as oxide in accordance with section 2.2. Determination of manganeseAdd 50 ml of water, 3 ml of H2SO4, 4 ml of H3P04 and 20 ml of 5% NalO4, solution to each beakers (section 1 (b), (c), (d) and (e)), and boil for 5 min. Cool, dilute to 100 ml. Measure the absorbance of solution against water at 530 mμ.