• Journal of the Korean Chemical Society
• /
• v.38 no.5
• /
• pp.397-403
• /
• 1994

An activated catalyst prepared from a mixture of nickel nitrate hexahydrate with zinc in dry ethanol under reflux showed exceptional catalytic activity for the reduction of nitroarenes to the corresponding azoxy compounds exclusively in the presence of hydrazine monohydrate. However, when nickel nitrate hexahydrate was replaced by nickel chloride dihydrate with zinc, only the aminoarenes were formed in high yields. With unactivated catalyst, the reduction reaction from a mixture of nitroarenes, nickel nitrate or chloride, excess zinc and hydrazine monohydrate gave the corresponding azo, azoxy and amino compounds in much lower yields.

• Resources Recycling
• /
• v.15 no.4 s.72
• /
• pp.19-26
• /
• 2006

The preparation of Ag nano-powder from aqueous silver nitrate solution, which would be available for the recycling of silver bearing wastes, was investigated by a reductive precipitation reaction using hydrazine hydrate as a reducing agent. Silver solution was prepared by dissolving silver nitrate with distilled water, and then the dispersant, Tamol NN8906 or Tween 20, was also mixed to avoid the agglomeration of particles during the reductive reaction followed by the addition of hydrazine hydrate to prepare Ag nano-particles. Ag particles obtained from the reduction reaction from silver solution were characterized using the particle size analyzer and TEM to determine the particle size distribution and morphology. It was found that about 100% excess of hydrazine hydrate was required to reduce completely silver ions in the solution. Ag powders with very narrow distribution could be obtained when Tamol NN8906 was used as the dispersant. In case of Tween 20, the particle size distribution showed typically the bimodal or multimodal distribution and the morphology of Ag particles was found to be irregular shape in both cases.

• Korean Journal of Soil Science and Fertilizer
• /
• v.39 no.4
• /
• pp.204-208
• /
• 2006

This study is to describe continuous-flow analysis (CFA) for the determination of nitrate using hydrazine-copper in plant material and to test precision of this method compared with that of methods, which are RQflex method and salicylic acid method. Samples were leaves of watermelon, cucumber, melon and tomato. Nitrate values measured by the RQflex method were greater than those measured by CFA or salicylic acid method. The correlation of nitrate values between those measured by CFA and salicylic acid method was $R^2=0.9671$, and those measured by CFA between those measured by RQflex method was $R^2=0.9739$. Recovery rate of nitrate added to tissue extract by CFA method was $99.7{\pm}0.25%$.

• Proceedings of the Korean Society of Propulsion Engineers Conference
• /
• 2011.11a
• /
• pp.645-648
• /
• 2011

Hydrazine which has been used as monopropellant shows high performance, but because of its high toxicity research for new green propellant that could replace hydrazine is going on. Ionic liquid propellant that is one of the green propellant has lower toxicity, higher specific impulse, and higher density than hydrazine. To design the thruster which use Hydroxylamine Nitrate (HAN), one of ionic liquid propellant, as a propellant, a quantity of catalyst for full decomposition of a propellant is needed. In this study, reference point for HAN thruster design could be suggested through a design of a small scale thruster which used HAN propellant, and propellant decomposition capability evaluation with characteristic velocity efficiency.

• Korean Journal of Materials Research
• /
• v.15 no.5
• /
• pp.340-347
• /
• 2005

Silver nanoparticles were synthesized by chemical reduction method from aqueous silver nitrate solution ana hydrazine as a reduction agent. The morphology, particle size and shape were dependent on the mixing method, reaction temperature and time, molar ratio of hydrazine and silver nitrate, the kind of surfactant, and the addition of surfactant. The stability of the colloidal silver was achieved by the adsorption of surfactant molecules onto the particle. Silver nanoparticles have a characteristic absorption maximum at 430 nm under UV irradiation. It was found that the colloid was nanometer m size and formed very stable dispersion of silver. The Ag nanoparticles obtained showed the spherical shape with the size range of 10-30 nm.

• Restorative Dentistry and Endodontics
• /
• v.18 no.2
• /
• pp.469-481
• /
• 1993

The purpose of this study was to achieve the reduction of the galvanic current between the dental amalgam alloy and gold alloy. In order to measure the galvanic current between these two metals a prep in the size of $4{\times}13mm$ which was filled with amalgam and another prep of $4{\times}2mm$ was filled with gold alloy was made in the acrylic resin. These two preps were then connected to a 2mm diameter copper wire. Using an ammeter to measure the galvanic current, six different kinds of amalgam and gold alloy were immersed in saline solution with approximately 10mm distance between the two alloys. Chemical agents that are thought to reduce the galvanic current such as hydrazine. silver nitrate, potassium chromate, and bonding agents such as Scotch bond 2(3M) and All bond 2(Bisco) were applied to the alloy surface. Cathodic inhibitor such as hydrazine was applied to gold alloy where as anodic inhibitor such as silver nitrate and potassium chromate were applied to amalgam. Both bonding agents, Scotch bond 2(3M) and All bond 2 (Bisco), were applied to amalgam. The following results were obtained when the currency on the coated alloy surface was compared to the uncoated surface. 1. The galvanic currency went down as the time elapsed and after 30 minutes no change was detected. 2. Initial currency was higher in low copper amalgam compared to high copper amalgam. Intitial currency was the highest in low copper lathe-cut amalgam. 3. Group of gold coated with hydrazine had the most reduction in galvanic currency. 4. Group of amalgam coated with silver nitrate or potassium chromate also showed significant reduction in galvanic currency. 5. The bonding agents also helped reduce galvanic currency. 6. Of all the agents used to reduce galvanic currency, silver nitrate showed the best result.

• Nuclear Engineering and Technology
• /
• v.54 no.9
• /
• pp.3580-3585
• /
• 2022

The thermal stability of carbohydrazide, hydrazine nitrate, acetohydroxamic acid in nitric acid solutions has been studied at atmospheric pressure and above atmospheric pressure. The volumes of gaseous products of thermolysis and the maximum rate of gas evolution have been determined at atmospheric pressure. It has been shown that, despite the high rate of gas evolution and large volumes of evolved gases, the conditions for the development of autocatalytic oxidation are not created. Exothermic processes are observed in a closed vessel in the temperature range of 50-250 ℃. With an increase in the concentration of nitric acid, the temperatures of the onset of exothermic effects for all mixtures decrease, and the values of the total thermal effects of reactions increase, to the greatest extent for solutions with carbohydrazide.

• Bulletin of the Korean Chemical Society
• /
• v.16 no.4
• /
• pp.374-377
• /
• 1995

• Journal of the Korean Chemical Society
• /
• v.41 no.5
• /
• pp.256-265
• /
• 1997

A rapid and sequential method was studied, which can determine nitrite, nitrate and ammonium ion in soil or water samples with flow injection analysis. Geometric factors including injection volume, length of the reaction coil and flow rate of carrier solution were investigated prior to sample measurement. Nitrite was determined at 540 nm by Griess reaction producing azo dye between N-(1-naphthylethylenediamine dihydrochloride) and sulfanilamide. Nitrate was also measured under the help of reduction mechanism toward nitrite with hydrazine. Ammonium was analyzed at 440 nm with Nessler's reagent. At the optimum condition, the detection limit(S/N=3) has been shown 0.1 ㎍/mL N(NO2-), 0.4 ㎍/mL N(NO3-) and 0.3 ㎍/mL N(NH4+) respectively. The results measured by colorimetry, ion chromatography and FIA were compared showing 80%-125% reasonable match each other. Injection throughput rate could be performed better than 30 times per hour.

• Bulletin of the Korean Chemical Society
• /
• v.12 no.6
• /
• pp.709-709
• /
• 1991