Hydrazine Hydrate and Its Application in Water Treatment

Hydrazine hydrate, also known as hydrazine hydrate, is a monohydrate of hydrazine (N2H4 · H2O). The apparent state is a colorless transparent liquid with strong alkalinity. The density at 25 ℃ is 1.032, and its boiling point is 118.5 ℃ and ignition point is 73 ℃. It has good solubility and can be mixed with water, alcohol, etc. in any ratio. It is insoluble in ether and chloroform. It has permeability and corrosiveness, and can corrode glass, rubber, leather, and cork. It has strong reducibility and can spontaneously ignite or explode violently when encountering oxidants.

Hydrazine (N2H4) can be obtained by removing a molecule of water bound by itself from hydrazine hydrate. Hydrazine is a colorless oily liquid with a pungent odor. Hydrazine has a density of 1.013 at 25 ℃, a boiling point of 113.5 ℃, and is hygroscopic. It can emit smoke in the air. If exposed to air for a long time or subjected to high temperature for a short period of time, it can decompose in the form of explosion, and should be stored in a sealed manner in nitrogen gas. The danger of hydrazine is much greater than that of hydrazine hydrate, and the chemical properties of hydrazine hydrate mainly come from its structure, with no substantial difference in chemical properties.

In theory, when producing downstream products, because only hydrazine reacts with hydrazine hydrate, hydrazine can be used instead of hydrazine hydrate. However, the danger of hydrazine is too great, so in terms of safety, the cost invested in production, storage, transportation, and use is too high, far less safe, reliable, and economically practical than hydrazine hydrate.

Hydrazine can also be used in the production of water treatment agents, mainly for anti-corrosion during boiler shutdown and deoxygenation during operation, and its application in the market is constantly expanding. Dissolved oxygen is the main cause of corrosion in hot water circulation systems, boilers, and oil well water casings. Hydrazine hydrate can be directly used as a deoxidizer in these systems, with an estimated annual demand of 1500-2000 tons. It is soluble in water, alcohol, ammonia, and amine, and can form an azeotrope with water, especially showing strong reducibility in alkaline solutions.